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-rw-r--r--.dir-locals.el6
-rw-r--r--README.md23
-rw-r--r--chapter07/Makefile92
-rw-r--r--chapter07/README.md227
-rw-r--r--chapter07/docs/07-grammar.md88
-rw-r--r--chapter07/docs/07-graph1.gv107
-rw-r--r--chapter07/docs/07-graph1.svg268
-rw-r--r--chapter07/docs/07-graph2.gv62
-rw-r--r--chapter07/docs/07-graph2.svg184
-rw-r--r--chapter07/docs/07-graph3.gv108
-rw-r--r--chapter07/docs/07-graph3.svg373
-rw-r--r--chapter07/docs/07-graph4.gv96
-rw-r--r--chapter07/docs/07-graph4.svg329
-rw-r--r--chapter07/docs/build-graphs.sh6
-rw-r--r--chapter07/pom.xml14
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/GraphVisualizer.java256
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/IRPrinter.java124
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/Parser.java572
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/Utils.java39
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/node/AddNode.java158
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/node/BoolNode.java60
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/node/ConstantNode.java45
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/node/DivNode.java39
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/node/IfNode.java58
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/node/LoopNode.java35
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/node/MinusNode.java30
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/node/MulNode.java58
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/node/MultiNode.java7
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/node/Node.java467
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/node/NotNode.java30
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/node/PhiNode.java101
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/node/ProjNode.java49
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/node/RegionNode.java81
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/node/ReturnNode.java46
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/node/ScopeNode.java169
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/node/StartNode.java46
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/node/StopNode.java53
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/node/SubNode.java43
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/type/Type.java77
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/type/TypeInteger.java63
-rw-r--r--chapter07/src/main/java/com/seaofnodes/simple/type/TypeTuple.java32
-rw-r--r--chapter07/src/test/java/com/seaofnodes/simple/Chapter07Test.java1026
-rw-r--r--chapter08/Makefile92
-rw-r--r--chapter08/README.md2
-rw-r--r--chapter08/docs/08-grammar.md88
-rw-r--r--chapter08/docs/build-graphs.sh3
-rw-r--r--chapter08/pom.xml14
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/GraphVisualizer.java258
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/IRPrinter.java124
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/Parser.java574
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/Utils.java39
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/node/AddNode.java158
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/node/BoolNode.java60
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/node/ConstantNode.java45
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/node/DivNode.java39
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/node/IfNode.java58
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/node/LoopNode.java35
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/node/MinusNode.java30
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/node/MulNode.java58
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/node/MultiNode.java7
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/node/Node.java467
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/node/NotNode.java30
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/node/PhiNode.java101
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/node/ProjNode.java49
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/node/RegionNode.java81
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/node/ReturnNode.java46
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/node/ScopeNode.java193
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/node/StartNode.java46
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/node/StopNode.java53
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/node/SubNode.java43
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/type/Type.java77
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/type/TypeInteger.java63
-rw-r--r--chapter08/src/main/java/com/seaofnodes/simple/type/TypeTuple.java32
-rw-r--r--chapter08/src/test/java/com/seaofnodes/simple/Chapter08Test.java1028
-rw-r--r--pom.xml2
75 files changed, 9729 insertions, 13 deletions
diff --git a/.dir-locals.el b/.dir-locals.el
index c4e1e5c7..74fde018 100644
--- a/.dir-locals.el
+++ b/.dir-locals.el
@@ -1,4 +1,6 @@
;;; Directory Local Variables
;;; For more information see (info "(emacs) Directory Variables")
-
-((dired-mode . ((c-basic-offset . 4))))
+(
+ (dired-mode . ((c-basic-offset . 4)))
+ (java-mode . ((c-basic-offset . 4)))
+)
diff --git a/README.md b/README.md
index 59a342b1..3424c5d9 100644
--- a/README.md
+++ b/README.md
@@ -34,16 +34,17 @@ The simple language will be a small subset of C.
* [Chapter 4](chapter04/README.md): A non-constant external variable input named `arg`. Binary and Comparison operators involving constants and `arg`. Non-zero values will be truthy. Peephole optimizations involving algebraic simplifications.
* [Chapter 5](chapter05/README.md): `if` statement. CFG construction.
* [Chapter 6](chapter06/README.md): Peephole optimization around dead control flow.
-* Chapter 7: `while` statement.
-* Chapter 8: Global Value Numbering.
-* Chapter 9: Functions and calls.
-* Chapter 10: Boolean operators `&&`, `||` and `!` including short circuit.
-* Chapter 11: Memory effects: general memory edges in SSA. Peephole optimization around
+* [Chapter 7](chapter07/README.md): `while` statement. Looping construct - eager phi approach.
+* Chapter 8: Looping construct continued, lazy phi creation, `break` and `continue` statements.
+* Chapter 9: Global Value Numbering.
+* Chapter 10: Functions and calls.
+* Chapter 11: Boolean operators `&&`, `||` and `!` including short circuit.
+* Chapter 12: Memory effects: general memory edges in SSA. Peephole optimization around
load-after-store/store-after-store.
-* Chapter 12: Equivalence class aliasing, fine grained peephole optimizations. Free ptr-to analysis in SoN; but does not
+* Chapter 13: Equivalence class aliasing, fine grained peephole optimizations. Free ptr-to analysis in SoN; but does not
handle aliasing in arrays.
-* Chapter 13: One dimensional static length array type. Array load/store.
-* Chapter 14: Global Code Motion - unwind SoN to CFG. Scheduling.
-* Chapter 15: Instruction selection, BURS.
-* Chapter 16: Backend register allocation.
-* Chapter 17: Garbage Collection. \ No newline at end of file
+* Chapter 14: One dimensional static length array type. Array load/store.
+* Chapter 15: Global Code Motion - unwind SoN to CFG. Scheduling.
+* Chapter 16: Instruction selection, BURS.
+* Chapter 17: Backend register allocation.
+* Chapter 18: Garbage Collection. \ No newline at end of file
diff --git a/chapter07/Makefile b/chapter07/Makefile
new file mode 100644
index 00000000..56f69e12
--- /dev/null
+++ b/chapter07/Makefile
@@ -0,0 +1,92 @@
+SHELL := /bin/bash
+.DELETE_ON_ERROR:
+
+# for printing variable values
+# usage: make print-VARIABLE
+# > VARIABLE = value_of_variable
+print-% : ; @echo $* = $($*)
+
+# literal space
+space := $() $()
+
+# Decide OS-specific questions
+# jar-file seperator
+ifeq ($(OS),Windows_NT)
+ SEP = ;
+else
+ SEP = :
+endif
+# Find a reasonable ctags.
+CTAGS = $(shell which ctags)
+# Hack for MacOS: /usr/bin/ctags is unfriendly, so look for ctags from brew
+ifeq ($(UNAME),Darwin)
+ CTAGS = $(shell brew list ctags 2> /dev/null | grep bin/ctags)
+endif
+
+# Fun Args to javac. Mostly limit to java8 source definitions, and fairly
+# aggressive lint warnings.
+JAVAC_ARGS = -g
+
+# Source code
+SIMPLE := com/seaofnodes/simple
+SRC := src/main/java
+TST := src/test/java
+CLZDIR:= build/classes
+main_javas := $(wildcard $(SRC)/$(SIMPLE)/*java $(SRC)/$(SIMPLE)/*/*java)
+test_javas := $(wildcard $(TST)/$(SIMPLE)/*java $(TST)/$(SIMPLE)/*/*java)
+main_classes := $(patsubst $(SRC)/%java,$(CLZDIR)/main/%class,$(main_javas))
+test_classes := $(patsubst $(TST)/%java,$(CLZDIR)/test/%class,$(test_javas))
+test_cp := $(patsubst $(TST)/$(SIMPLE)/%.java,com.seaofnodes.simple.%,$(test_javas))
+classes = $(main_classes) $(test_classes)
+# All the libraries
+libs = $(wildcard lib/*jar)
+jars = $(subst $(space),$(SEP),$(libs))
+
+
+default_targets := $(main_classes) $(test_classes)
+# Optionally add ctags to the default target if a reasonable one was found.
+ifneq ($(CTAGS),)
+default_targets += tags
+endif
+
+default: $(default_targets)
+
+# Compile just the out-of-date files
+$(main_classes): build/classes/main/%class: $(SRC)/%java
+ @echo "compiling " $@ " because " $?
+ @[ -d $(CLZDIR)/main ] || mkdir -p $(CLZDIR)/main
+ @javac $(JAVAC_ARGS) -cp "$(CLZDIR)/main$(SEP)$(jars)" -sourcepath $(SRC) -d $(CLZDIR)/main $(main_javas)
+
+$(test_classes): $(CLZDIR)/test/%class: $(TST)/%java $(main_classes)
+ @echo "compiling " $@ " because " $?
+ @[ -d $(CLZDIR)/test ] || mkdir -p $(CLZDIR)/test
+ @javac $(JAVAC_ARGS) -cp "$(CLZDIR)/test$(SEP)$(CLZDIR)/main$(SEP)$(jars)" -sourcepath $(TST) -d $(CLZDIR)/test $(test_javas)
+
+# Base launch line for JVM tests
+JVM=nice java -ea -cp "build/classes/main${SEP}${jars}${SEP}$(CLZDIR)/test"
+
+tests: $(default_targets)
+ $(JVM) org.junit.runner.JUnitCore $(test_cp)
+
+.PHONY: clean
+clean:
+ rm -rf build
+ rm -f TAGS
+ (find . -name "*~" -exec rm {} \; 2>/dev/null; exit 0)
+
+# Download libs from maven
+lib: lib/junit-4.12.jar lib/hamcrest-core-1.3.jar
+
+# Jars
+lib/junit-4.12.jar:
+ @[ -d lib ] || mkdir -p lib
+ @(cd lib; wget https://repo1.maven.org/maven2/junit/junit/4.12/junit-4.12.jar)
+
+lib/hamcrest-core-1.3.jar:
+ @[ -d lib ] || mkdir -p lib
+ @(cd lib; wget https://repo1.maven.org/maven2/org/hamcrest/hamcrest-core/1.3/hamcrest-core-1.3.jar)
+
+# Build emacs tags (part of a tasty emacs ide experience)
+tags: $(main_javas) $(test_javas)
+ @rm -f TAGS
+ @$(CTAGS) -e --recurse=yes --extra=+q --fields=+fksaiS $(SRC) $(TST)
diff --git a/chapter07/README.md b/chapter07/README.md
new file mode 100644
index 00000000..c6bcdee4
--- /dev/null
+++ b/chapter07/README.md
@@ -0,0 +1,227 @@
+# Chapter 7
+
+In this chapter we introduce the `while` statement.
+
+Here is the [complete language grammar](docs/07-grammar.md) for this chapter.
+
+## Dealing With Back Edges
+
+The complication introduced by looping constructs is that variables flow back into the body of the loop on iteration.
+For example:
+
+```java
+while(arg < 10) {
+ arg = arg + 1;
+}
+return arg;
+```
+
+The variable `arg` is assigned a new value inside the body of the loop, and this then flows back into the body of the loop.
+
+In general, we will rewrite the looping construct as follows:
+
+```java
+loop_head:
+if( !(arg < 10) )
+ goto loop_exit;
+arg = arg + 1;
+goto loop_head;
+
+loop_exit:
+```
+
+Above is for illustration only, we do not have labels and `goto` statements in the language.
+
+From an SSA[^1] point of view, since `arg` flows back, it requires a `phi` node at the head. Conceptually we would like the outcome to be:
+
+```java
+// arg1 represents incoming arg
+//
+loop_head:
+arg2 = phi(arg1, arg3);
+if( !(arg2 < 10) )
+ goto loop_exit;
+arg3 = arg2 + 1;
+goto loop_head;
+
+loop_exit:
+```
+
+Notice that the phi for `arg2` refers to `arg3`, which is not known at the time we parse the `while` loop predicate. This is the crux of the problem that we need
+to solve in order to successfully construct the Sea of Nodes graph, which is always in SSA form.
+
+Recall from [Chapter 5](../chapter05/README.md) that when parsing `if` statements, we clone the symbol tables as we go past the `if` predicate.
+Later we merge the two sets of symbol tables at a `Region` - creating phis for all names that encountered a change in definition within the two
+branches of the `if` statement. In the case of the `if` statement, the phis are created at the merge point when we already know the definitions
+that are being merged.
+
+The essential idea for loop constructs is to eagerly create phis for all names in the symbol tables *before* we enter the loop's `if` condition,
+since we do not know which names will be redefined inside the body of the loop. When the loop terminates, we go back and remove unnecessary
+phis. We call this approach the "eager phi" approach.[^2]
+
+In [Chapter 8](../chapter08) we will implement a "lazy phi" approach that creates phis only when we encounter redefinition of a name.
+
+## New Node Types
+
+Our list of nodes remains the same as in [Chapter 5](../chapter05/README.md), however, we create a subtype of `Region` named `Loop` to better
+encapsulate some of the additional logic required. A key aspect of this is to temporarily disable peepholes of the `Region` and any phis
+created until we complete parsing the loop body. This is because our phis are not fully constructed until the loop end.
+
+## Detailed Steps
+
+1. We start by creating a new subclass of `Region`, the `Loop`. The `Loop` gets two control inputs,
+ the first one is the entry point, i.e. the current binding to `$ctrl`, and second one (`null`) is a placeholder for the back edge that is
+ set after loop is parsed. The absence of a back edge is used as an indicator to switch off peepholes of the region and
+ associated phis.
+
+ ```java
+ ctrl(new LoopNode(ctrl(),null).peephole());
+ ```
+
+ The newly created region becomes the current control.
+
+2. We duplicate the current Scope node. This involves duplicating all the symbols at
+ every level with the scope, and creating phis for every symbol except the `$ctrl` binding.
+
+ ```java
+ // Make a new Scope for the body.
+ _scope = _scope.dup(true);
+ ```
+
+ Note that the `dup` call is given an argument `true`. This triggers creating phis. The code
+ that creates the phis in the `dup()` method is shown below.
+
+ ```java
+ // boolean loop=true if this is a loop region
+
+ String[] reverse = reverse_names();
+ dup.add_def(ctrl()); // Control input is just copied
+ for( int i=1; i<nIns(); i++ ) {
+ if ( !loop ) { dup.add_def(in(i)); }
+ else {
+ // Loop region
+ // Create a phi node with second input as null - to be filled in
+ // by endLoop() below
+ dup.add_def(new PhiNode(reverse[i], ctrl(), in(i), null).peephole());
+ // Ensure our node has the same phi in case we created one
+ set_def(i, dup.in(i));
+ }
+ }
+ ```
+
+ Inside the `else` block both the duplicated scope and the original scope get the same phi node.
+
+3. Next we set up the `if` condition, very much like we do with regular ifs.
+
+ ```java
+ // Parse predicate
+ var pred = require(parseExpression(), ")");
+ // IfNode takes current control and predicate
+ IfNode ifNode = (IfNode)new IfNode(ctrl(), pred).<IfNode>keep().peephole();
+ // Setup projection nodes
+ Node ifT = new ProjNode(ifNode, 0, "True" ).peephole();
+ ifNode.unkeep();
+ Node ifF = new ProjNode(ifNode, 1, "False").peephole();
+ ```
+
+4. We set the control token to the `True` projection node `ifT`, but before that we make another clone of
+ the current scope.
+
+ ```java
+ // The exit scope, accounting for any side effects in the predicate
+ var exit = _scope.dup();
+ exit.ctrl(ifF);
+ ```
+
+ The new scope is saved as the exit scope that will live after the loop ends, therefore `$ctrl` in the exit scope is
+ set to the `False` projection. The exit scope captures any side effects of the loop's predicate.
+
+5. We now set the control to the `True` projection and parse the loop body.
+
+ ```java
+ // Parse the true side, which corresponds to loop body
+ ctrl(ifT); // set ctrl token to ifTrue projection
+ parseStatement(); // Parse loop body
+ ```
+
+6. After the loop body is parsed, we go back and process all the phis we created earlier.
+
+ ```java
+ // The true branch loops back, so whatever is current control gets
+ // added to head loop as input
+ head.endLoop(_scope, exit);
+ ```
+
+ The `endLoop` method sets the second control of the loop region to the control from the back edge.
+ It then goes through all the phis and sets the second data input on the phi to the corresponding entry
+ from the loop body; phis that were not used are peepholed and get replaced by the original input.
+
+ ```java
+ Node ctrl = ctrl();
+ ctrl.set_def(2,back.ctrl());
+ for( int i=1; i<nIns(); i++ ) {
+ PhiNode phi = (PhiNode)in(i);
+ assert phi.region()==ctrl && phi.in(2)==null;
+ phi.set_def(2,back.in(i));
+ // Do an eager useless-phi removal
+ Node in = phi.peephole();
+ if( in != phi )
+ phi.subsume(in);
+ }
+ ```
+
+7. Finally, both the original scope (head) we started with, and the duplicate created for the body are killed.
+ At exit the false control is the current control, and exit scope is set as the current scope.
+
+### Visualization
+
+The example quoted above is shown below at an intermediate state:
+
+![Graph1](./docs/07-graph1.svg)
+
+* Three Scopes are shown, reading clockwise, the loop head, exit and the body.
+
+The final graph looks like this:
+
+![Graph2](./docs/07-graph2.svg)
+
+## More Complex Examples
+
+### Nested Loops
+
+```java
+int sum = 0;
+int i = 0;
+while(i < arg) {
+ i = i + 1;
+ int j = 0;
+ while( j < arg ) {
+ sum = sum + j;
+ j = j + 1;
+ }
+}
+return sum;
+```
+
+![Graph2](./docs/07-graph3.svg)
+
+### Loop With Nested If
+
+```java
+int a = 1;
+int b = 2;
+while(a < 10) {
+ if (a == 2) a = 3;
+ else b = 4;
+}
+return b;
+```
+
+![Graph2](./docs/07-graph4.svg)
+
+
+[^1]: Cytron, R. et al (1991).
+ Efficiently computing static single assignment form and the control dependence graph, in ACM Transactions on Programming Languages and Systems, 13(4):451-490, 1991.
+
+[^2]: Click, C. (1995).
+ Combining Analyses, Combining Optimizations, 103. \ No newline at end of file
diff --git a/chapter07/docs/07-grammar.md b/chapter07/docs/07-grammar.md
new file mode 100644
index 00000000..50a2a129
--- /dev/null
+++ b/chapter07/docs/07-grammar.md
@@ -0,0 +1,88 @@
+# Grammar for Chapter 6
+
+```antlrv4
+grammar SimpleLanguage;
+
+program
+ : statement+ EOF
+ ;
+
+statement
+ : returnStatement
+ | declStatement
+ | blockStatment
+ | expressionStatement
+ | ifStatement
+ | whileStatement
+ | metaStatement
+ ;
+
+whileStatement
+ : 'while' '(' expression ')' statement
+ ;
+
+ifStatement
+ : 'if' '(' expression ')' statement ('else' statement)?
+ ;
+
+metaStatement
+ : '#showGraph' ';'
+ ;
+
+expressionStatement
+ : IDENTIFIER '=' expression ';'
+ ;
+
+blockStatement
+ : '{' statement+ '}'
+ ;
+
+declStatement
+ : 'int' IDENTIFIER '=' expression ';'
+ ;
+
+returnStatement
+ : 'return' expression ';'
+ ;
+
+expression
+ : comparisonExpression
+ ;
+
+comparisonExpression
+ : additiveExpression (('==' | '!='| '>'| '<'| '>='| '<=') additiveExpression)*
+ ;
+
+additiveExpression
+ : multiplicativeExpression (('+' | '-') multiplicativeExpression)*
+ ;
+
+multiplicativeExpression
+ : unaryExpression (('*' | '/') unaryExpression)*
+ ;
+
+unaryExpression
+ : ('-') unaryExpression
+ | primaryExpression
+ ;
+
+primaryExpression
+ : IDENTIFIER
+ | INTEGER_LITERAL
+ | 'true'
+ | 'false'
+ | '(' expression ')'
+ ;
+
+INTEGER_LITERAL
+ : [1-9][0-9]*
+ | [0]
+ ;
+
+IDENTIFIER
+ : NON_DIGIT (NON_DIGIT | DIGIT)*
+ ;
+
+NON_DIGIT: [a-zA-Z_];
+DEC_DIGIT: [0-9];
+``` \ No newline at end of file
diff --git a/chapter07/docs/07-graph1.gv b/chapter07/docs/07-graph1.gv
new file mode 100644
index 00000000..ba806a28
--- /dev/null
+++ b/chapter07/docs/07-graph1.gv
@@ -0,0 +1,107 @@
+digraph chapter07 {
+/*
+while(arg < 10) {
+ arg = arg + 1;
+ #showGraph;
+}
+return arg;
+
+*/
+ rankdir=BT;
+ ordering="in";
+ concentrate="true";
+ compound="true";
+ subgraph cluster_Nodes {
+ Start2 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">Start</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">$ctrl</TD><TD PORT="p1">arg</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Loop6 [ shape=box style=filled fillcolor=yellow label="Loop" ];
+ Phi_arg8 [ style=filled fillcolor=lightyellow label="&phi;_arg" ];
+ Con_9 [ label="10" ];
+ LT10 [ label="<" ];
+ If11 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">If</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">True</TD><TD PORT="p1" BGCOLOR="yellow">False</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Con_15 [ label="1" ];
+ Add16 [ label="+" ];
+ { rank=same; Loop6;Phi_arg8;}
+ }
+ node [shape=plaintext];
+ subgraph cluster_Scope7_1 {
+ Scope7_1 [label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD BGCOLOR="cyan">2</TD></TR>
+ </TABLE>>];
+ subgraph cluster_Scope7_2 {
+ Scope7_2 [label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD BGCOLOR="cyan">1</TD></TR>
+ </TABLE>>];
+ subgraph cluster_Scope7_3 {
+ Scope7_3 [label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD BGCOLOR="cyan">0</TD><TD PORT="Scope7_3_$ctrl">$ctrl</TD><TD PORT="Scope7_3_arg">arg</TD></TR>
+ </TABLE>>];
+ }
+ }
+ }
+ node [shape=plaintext];
+ subgraph cluster_Scope1_1 {
+ Scope1_1 [label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD BGCOLOR="cyan">1</TD></TR>
+ </TABLE>>];
+ subgraph cluster_Scope1_2 {
+ Scope1_2 [label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD BGCOLOR="cyan">0</TD><TD PORT="Scope1_2_$ctrl">$ctrl</TD><TD PORT="Scope1_2_arg">arg</TD></TR>
+ </TABLE>>];
+ }
+ }
+ node [shape=plaintext];
+ subgraph cluster_Scope14_1 {
+ Scope14_1 [label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD BGCOLOR="cyan">1</TD></TR>
+ </TABLE>>];
+ subgraph cluster_Scope14_2 {
+ Scope14_2 [label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD BGCOLOR="cyan">0</TD><TD PORT="Scope14_2_$ctrl">$ctrl</TD><TD PORT="Scope14_2_arg">arg</TD></TR>
+ </TABLE>>];
+ }
+ }
+ edge [ fontname=Helvetica, fontsize=8 ];
+ Loop6 -> Start2:p0[taillabel=1 color=red];
+ Phi_arg8 -> Loop6 [style=dotted taillabel=0];
+ Phi_arg8 -> Start2:p1[taillabel=1];
+ LT10 -> Phi_arg8[taillabel=1];
+ LT10 -> Con_9[taillabel=2];
+ If11 -> Loop6[taillabel=0 color=red];
+ If11 -> LT10[taillabel=1];
+ Add16 -> Phi_arg8[taillabel=1];
+ Add16 -> Con_15[taillabel=2];
+ edge [style=dashed color=cornflowerblue];
+ Scope7_3:"Scope7_3_$ctrl" -> If11:p0;
+ Scope7_3:"Scope7_3_arg" -> Add16;
+ edge [style=dashed color=cornflowerblue];
+ Scope1_2:"Scope1_2_$ctrl" -> Loop6;
+ Scope1_2:"Scope1_2_arg" -> Phi_arg8;
+ edge [style=dashed color=cornflowerblue];
+ Scope14_2:"Scope14_2_$ctrl" -> If11:p1;
+ Scope14_2:"Scope14_2_arg" -> Phi_arg8;
+}
diff --git a/chapter07/docs/07-graph1.svg b/chapter07/docs/07-graph1.svg
new file mode 100644
index 00000000..94248cfb
--- /dev/null
+++ b/chapter07/docs/07-graph1.svg
@@ -0,0 +1,268 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"
+ "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<!-- Generated by graphviz version 2.43.0 (0)
+ -->
+<!-- Title: chapter07 Pages: 1 -->
+<svg width="726pt" height="440pt"
+ viewBox="0.00 0.00 726.00 440.00" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
+<g id="graph0" class="graph" transform="scale(1 1) rotate(0) translate(4 436)">
+<title>chapter07</title>
+<polygon fill="white" stroke="transparent" points="-4,4 -4,-436 722,-436 722,4 -4,4"/>
+<g id="clust1" class="cluster">
+<title>cluster_Nodes</title>
+<polygon fill="none" stroke="black" points="196,-100 196,-424 502,-424 502,-100 196,-100"/>
+</g>
+<g id="clust3" class="cluster">
+<title>cluster_Scope7_1</title>
+<polygon fill="none" stroke="black" points="8,-8 8,-92 288,-92 288,-8 8,-8"/>
+</g>
+<g id="clust4" class="cluster">
+<title>cluster_Scope7_2</title>
+<polygon fill="none" stroke="black" points="80,-16 80,-84 280,-84 280,-16 80,-16"/>
+</g>
+<g id="clust5" class="cluster">
+<title>cluster_Scope7_3</title>
+<polygon fill="none" stroke="black" points="152,-24 152,-76 272,-76 272,-24 152,-24"/>
+</g>
+<g id="clust6" class="cluster">
+<title>cluster_Scope1_1</title>
+<polygon fill="none" stroke="black" points="510,-192 510,-260 710,-260 710,-192 510,-192"/>
+</g>
+<g id="clust7" class="cluster">
+<title>cluster_Scope1_2</title>
+<polygon fill="none" stroke="black" points="582,-200 582,-252 702,-252 702,-200 582,-200"/>
+</g>
+<g id="clust8" class="cluster">
+<title>cluster_Scope14_1</title>
+<polygon fill="none" stroke="black" points="296,-16 296,-84 496,-84 496,-16 296,-16"/>
+</g>
+<g id="clust9" class="cluster">
+<title>cluster_Scope14_2</title>
+<polygon fill="none" stroke="black" points="368,-24 368,-76 488,-76 488,-24 368,-24"/>
+</g>
+<!-- Start2 -->
+<g id="node1" class="node">
+<title>Start2</title>
+<polygon fill="yellow" stroke="transparent" points="365,-387 365,-412 446,-412 446,-387 365,-387"/>
+<polygon fill="none" stroke="black" points="365,-387 365,-412 446,-412 446,-387 365,-387"/>
+<text text-anchor="start" x="387" y="-395.8" font-family="Times,serif" font-size="14.00">Start</text>
+<polygon fill="none" stroke="black" points="365,-356 365,-387 446,-387 446,-356 365,-356"/>
+<polygon fill="yellow" stroke="transparent" points="370,-361 370,-382 410,-382 410,-361 370,-361"/>
+<polygon fill="none" stroke="black" points="370,-361 370,-382 410,-382 410,-361 370,-361"/>
+<text text-anchor="start" x="373" y="-367.8" font-family="Times,serif" font-size="14.00">$ctrl</text>
+<polygon fill="none" stroke="black" points="410,-361 410,-382 441,-382 441,-361 410,-361"/>
+<text text-anchor="start" x="413" y="-367.8" font-family="Times,serif" font-size="14.00">arg</text>
+</g>
+<!-- Loop6 -->
+<g id="node2" class="node">
+<title>Loop6</title>
+<polygon fill="yellow" stroke="black" points="494,-316 440,-316 440,-280 494,-280 494,-316"/>
+<text text-anchor="middle" x="467" y="-294.3" font-family="Times,serif" font-size="14.00">Loop</text>
+</g>
+<!-- Loop6&#45;&gt;Start2 -->
+<g id="edge1" class="edge">
+<title>Loop6&#45;&gt;Start2:p0</title>
+<path fill="none" stroke="red" d="M439.64,-314.34C422.52,-324.68 402.19,-338.54 393.85,-350.32"/>
+<polygon fill="red" stroke="red" points="390.45,-349.41 390,-360 396.95,-352 390.45,-349.41"/>
+<text text-anchor="middle" x="436.64" y="-307.94" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Phi_arg8 -->
+<g id="node3" class="node">
+<title>Phi_arg8</title>
+<ellipse fill="lightyellow" stroke="black" cx="385" cy="-298" rx="37.09" ry="18"/>
+<text text-anchor="middle" x="385" y="-294.3" font-family="Times,serif" font-size="14.00">φ_arg</text>
+</g>
+<!-- Phi_arg8&#45;&gt;Start2 -->
+<g id="edge3" class="edge">
+<title>Phi_arg8&#45;&gt;Start2:p1</title>
+<path fill="none" stroke="black" d="M402.63,-314.22C411.57,-323.35 421.25,-335.86 424.7,-349.71"/>
+<polygon fill="black" stroke="black" points="421.27,-350.52 426,-360 428.22,-349.64 421.27,-350.52"/>
+<text text-anchor="middle" x="399.63" y="-316.82" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Phi_arg8&#45;&gt;Loop6 -->
+<g id="edge2" class="edge">
+<title>Phi_arg8&#45;&gt;Loop6</title>
+<path fill="none" stroke="black" stroke-dasharray="1,5" d="M422.16,-298C424.62,-298 427.08,-298 429.55,-298"/>
+<polygon fill="black" stroke="black" points="429.67,-301.5 439.67,-298 429.67,-294.5 429.67,-301.5"/>
+<text text-anchor="middle" x="425.16" y="-291.6" font-family="Helvetica,sans-Serif" font-size="8.00">0</text>
+</g>
+<!-- Con_9 -->
+<g id="node4" class="node">
+<title>Con_9</title>
+<ellipse fill="none" stroke="black" cx="303" cy="-298" rx="27" ry="18"/>
+<text text-anchor="middle" x="303" y="-294.3" font-family="Times,serif" font-size="14.00">10</text>
+</g>
+<!-- LT10 -->
+<g id="node5" class="node">
+<title>LT10</title>
+<ellipse fill="none" stroke="black" cx="374" cy="-226" rx="27" ry="18"/>
+<text text-anchor="middle" x="374" y="-222.3" font-family="Times,serif" font-size="14.00">&lt;</text>
+</g>
+<!-- LT10&#45;&gt;Phi_arg8 -->
+<g id="edge4" class="edge">
+<title>LT10&#45;&gt;Phi_arg8</title>
+<path fill="none" stroke="black" d="M376.66,-243.95C377.87,-251.65 379.34,-260.97 380.7,-269.64"/>
+<polygon fill="black" stroke="black" points="377.28,-270.39 382.29,-279.72 384.19,-269.3 377.28,-270.39"/>
+<text text-anchor="middle" x="373.66" y="-246.55" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- LT10&#45;&gt;Con_9 -->
+<g id="edge5" class="edge">
+<title>LT10&#45;&gt;Con_9</title>
+<path fill="none" stroke="black" d="M359.29,-241.5C349.39,-251.27 336.16,-264.31 325.01,-275.3"/>
+<polygon fill="black" stroke="black" points="322.36,-273 317.69,-282.51 327.27,-277.99 322.36,-273"/>
+<text text-anchor="middle" x="356.29" y="-244.1" font-family="Helvetica,sans-Serif" font-size="8.00">2</text>
+</g>
+<!-- If11 -->
+<g id="node6" class="node">
+<title>If11</title>
+<polygon fill="yellow" stroke="transparent" points="327,-143 327,-168 421,-168 421,-143 327,-143"/>
+<polygon fill="none" stroke="black" points="327,-143 327,-168 421,-168 421,-143 327,-143"/>
+<text text-anchor="start" x="368.5" y="-151.8" font-family="Times,serif" font-size="14.00">If</text>
+<polygon fill="none" stroke="black" points="327,-112 327,-143 421,-143 421,-112 327,-112"/>
+<polygon fill="yellow" stroke="transparent" points="332,-117 332,-138 372,-138 372,-117 332,-117"/>
+<polygon fill="none" stroke="black" points="332,-117 332,-138 372,-138 372,-117 332,-117"/>
+<text text-anchor="start" x="335" y="-123.8" font-family="Times,serif" font-size="14.00">True</text>
+<polygon fill="yellow" stroke="transparent" points="372,-117 372,-138 416,-138 416,-117 372,-117"/>
+<polygon fill="none" stroke="black" points="372,-117 372,-138 416,-138 416,-117 372,-117"/>
+<text text-anchor="start" x="375" y="-123.8" font-family="Times,serif" font-size="14.00">False</text>
+</g>
+<!-- If11&#45;&gt;Loop6 -->
+<g id="edge6" class="edge">
+<title>If11&#45;&gt;Loop6</title>
+<path fill="none" stroke="red" d="M396.87,-172.17C401.36,-178.63 405.94,-185.46 410,-192 426.23,-218.13 442.79,-249.22 453.84,-270.75"/>
+<polygon fill="red" stroke="red" points="450.85,-272.6 458.51,-279.92 457.09,-269.42 450.85,-272.6"/>
+<text text-anchor="middle" x="393.87" y="-174.77" font-family="Helvetica,sans-Serif" font-size="8.00">0</text>
+</g>
+<!-- If11&#45;&gt;LT10 -->
+<g id="edge7" class="edge">
+<title>If11&#45;&gt;LT10</title>
+<path fill="none" stroke="black" d="M374,-172.28C374,-180.58 374,-189.48 374,-197.56"/>
+<polygon fill="black" stroke="black" points="370.5,-197.6 374,-207.6 377.5,-197.6 370.5,-197.6"/>
+<text text-anchor="middle" x="371" y="-174.88" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Con_15 -->
+<g id="node7" class="node">
+<title>Con_15</title>
+<ellipse fill="none" stroke="black" cx="231" cy="-298" rx="27" ry="18"/>
+<text text-anchor="middle" x="231" y="-294.3" font-family="Times,serif" font-size="14.00">1</text>
+</g>
+<!-- Add16 -->
+<g id="node8" class="node">
+<title>Add16</title>
+<ellipse fill="none" stroke="black" cx="241" cy="-226" rx="27" ry="18"/>
+<text text-anchor="middle" x="241" y="-222.3" font-family="Times,serif" font-size="14.00">+</text>
+</g>
+<!-- Add16&#45;&gt;Phi_arg8 -->
+<g id="edge8" class="edge">
+<title>Add16&#45;&gt;Phi_arg8</title>
+<path fill="none" stroke="black" d="M262.25,-237.33C285.48,-248.62 323.06,-266.89 350.53,-280.24"/>
+<polygon fill="black" stroke="black" points="349.26,-283.52 359.78,-284.74 352.32,-277.22 349.26,-283.52"/>
+<text text-anchor="middle" x="265.25" y="-239.93" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Add16&#45;&gt;Con_15 -->
+<g id="edge9" class="edge">
+<title>Add16&#45;&gt;Con_15</title>
+<path fill="none" stroke="black" d="M238.58,-243.95C237.48,-251.65 236.15,-260.97 234.91,-269.64"/>
+<polygon fill="black" stroke="black" points="231.42,-269.33 233.47,-279.72 238.35,-270.32 231.42,-269.33"/>
+<text text-anchor="middle" x="235.58" y="-246.55" font-family="Helvetica,sans-Serif" font-size="8.00">2</text>
+</g>
+<!-- Scope7_1 -->
+<g id="node9" class="node">
+<title>Scope7_1</title>
+<polygon fill="cyan" stroke="transparent" points="35,-39 35,-60 51,-60 51,-39 35,-39"/>
+<polygon fill="none" stroke="black" points="35,-39 35,-60 51,-60 51,-39 35,-39"/>
+<text text-anchor="start" x="38" y="-45.8" font-family="Times,serif" font-size="14.00">2</text>
+</g>
+<!-- Scope7_2 -->
+<g id="node10" class="node">
+<title>Scope7_2</title>
+<polygon fill="cyan" stroke="transparent" points="107,-39 107,-60 123,-60 123,-39 107,-39"/>
+<polygon fill="none" stroke="black" points="107,-39 107,-60 123,-60 123,-39 107,-39"/>
+<text text-anchor="start" x="110" y="-45.8" font-family="Times,serif" font-size="14.00">1</text>
+</g>
+<!-- Scope7_3 -->
+<g id="node11" class="node">
+<title>Scope7_3</title>
+<polygon fill="cyan" stroke="transparent" points="169,-39 169,-60 185,-60 185,-39 169,-39"/>
+<polygon fill="none" stroke="black" points="169,-39 169,-60 185,-60 185,-39 169,-39"/>
+<text text-anchor="start" x="172" y="-45.8" font-family="Times,serif" font-size="14.00">0</text>
+<polygon fill="none" stroke="black" points="185,-39 185,-60 225,-60 225,-39 185,-39"/>
+<text text-anchor="start" x="188" y="-45.8" font-family="Times,serif" font-size="14.00">$ctrl</text>
+<polygon fill="none" stroke="black" points="225,-39 225,-60 256,-60 256,-39 225,-39"/>
+<text text-anchor="start" x="228" y="-45.8" font-family="Times,serif" font-size="14.00">arg</text>
+</g>
+<!-- Scope7_3&#45;&gt;If11 -->
+<g id="edge10" class="edge">
+<title>Scope7_3:Scope7_3_$ctrl&#45;&gt;If11:p0</title>
+<path fill="none" stroke="cornflowerblue" stroke-dasharray="5,2" d="M205,-61C205,-74.83 289.37,-114.99 321.05,-124.81"/>
+<polygon fill="cornflowerblue" stroke="cornflowerblue" points="320.48,-128.27 331,-127 321.98,-121.43 320.48,-128.27"/>
+</g>
+<!-- Scope7_3&#45;&gt;Add16 -->
+<g id="edge11" class="edge">
+<title>Scope7_3:Scope7_3_arg&#45;&gt;Add16</title>
+<path fill="none" stroke="cornflowerblue" stroke-dasharray="5,2" d="M241,-61C241,-109.09 241,-165.12 241,-197.67"/>
+<polygon fill="cornflowerblue" stroke="cornflowerblue" points="237.5,-197.76 241,-207.76 244.5,-197.76 237.5,-197.76"/>
+</g>
+<!-- Scope1_1 -->
+<g id="node12" class="node">
+<title>Scope1_1</title>
+<polygon fill="cyan" stroke="transparent" points="537,-215 537,-236 553,-236 553,-215 537,-215"/>
+<polygon fill="none" stroke="black" points="537,-215 537,-236 553,-236 553,-215 537,-215"/>
+<text text-anchor="start" x="540" y="-221.8" font-family="Times,serif" font-size="14.00">1</text>
+</g>
+<!-- Scope1_2 -->
+<g id="node13" class="node">
+<title>Scope1_2</title>
+<polygon fill="cyan" stroke="transparent" points="599,-215 599,-236 615,-236 615,-215 599,-215"/>
+<polygon fill="none" stroke="black" points="599,-215 599,-236 615,-236 615,-215 599,-215"/>
+<text text-anchor="start" x="602" y="-221.8" font-family="Times,serif" font-size="14.00">0</text>
+<polygon fill="none" stroke="black" points="615,-215 615,-236 655,-236 655,-215 615,-215"/>
+<text text-anchor="start" x="618" y="-221.8" font-family="Times,serif" font-size="14.00">$ctrl</text>
+<polygon fill="none" stroke="black" points="655,-215 655,-236 686,-236 686,-215 655,-215"/>
+<text text-anchor="start" x="658" y="-221.8" font-family="Times,serif" font-size="14.00">arg</text>
+</g>
+<!-- Scope1_2&#45;&gt;Loop6 -->
+<g id="edge12" class="edge">
+<title>Scope1_2:Scope1_2_$ctrl&#45;&gt;Loop6</title>
+<path fill="none" stroke="cornflowerblue" stroke-dasharray="5,2" d="M635,-237C635,-264.54 553.92,-282.77 504.41,-291.34"/>
+<polygon fill="cornflowerblue" stroke="cornflowerblue" points="503.65,-287.92 494.37,-293.02 504.81,-294.82 503.65,-287.92"/>
+</g>
+<!-- Scope1_2&#45;&gt;Phi_arg8 -->
+<g id="edge13" class="edge">
+<title>Scope1_2:Scope1_2_arg&#45;&gt;Phi_arg8</title>
+<path fill="none" stroke="cornflowerblue" stroke-dasharray="5,2" d="M671,-237C671,-275.71 624.96,-252.41 587,-260 518.46,-273.71 498.88,-263.33 431,-280 428.04,-280.73 425,-281.58 421.97,-282.52"/>
+<polygon fill="cornflowerblue" stroke="cornflowerblue" points="420.79,-279.23 412.41,-285.72 423.01,-285.86 420.79,-279.23"/>
+</g>
+<!-- Scope14_1 -->
+<g id="node14" class="node">
+<title>Scope14_1</title>
+<polygon fill="cyan" stroke="transparent" points="323,-39 323,-60 339,-60 339,-39 323,-39"/>
+<polygon fill="none" stroke="black" points="323,-39 323,-60 339,-60 339,-39 323,-39"/>
+<text text-anchor="start" x="326" y="-45.8" font-family="Times,serif" font-size="14.00">1</text>
+</g>
+<!-- Scope14_2 -->
+<g id="node15" class="node">
+<title>Scope14_2</title>
+<polygon fill="cyan" stroke="transparent" points="385,-39 385,-60 401,-60 401,-39 385,-39"/>
+<polygon fill="none" stroke="black" points="385,-39 385,-60 401,-60 401,-39 385,-39"/>
+<text text-anchor="start" x="388" y="-45.8" font-family="Times,serif" font-size="14.00">0</text>
+<polygon fill="none" stroke="black" points="401,-39 401,-60 441,-60 441,-39 401,-39"/>
+<text text-anchor="start" x="404" y="-45.8" font-family="Times,serif" font-size="14.00">$ctrl</text>
+<polygon fill="none" stroke="black" points="441,-39 441,-60 472,-60 472,-39 441,-39"/>
+<text text-anchor="start" x="444" y="-45.8" font-family="Times,serif" font-size="14.00">arg</text>
+</g>
+<!-- Scope14_2&#45;&gt;Phi_arg8 -->
+<g id="edge15" class="edge">
+<title>Scope14_2:Scope14_2_arg&#45;&gt;Phi_arg8</title>
+<path fill="none" stroke="cornflowerblue" stroke-dasharray="5,2" d="M457,-61C457,-151.88 449.62,-178.21 410,-260 408.01,-264.11 405.61,-268.3 403.09,-272.3"/>
+<polygon fill="cornflowerblue" stroke="cornflowerblue" points="400.15,-270.4 397.51,-280.67 405.97,-274.28 400.15,-270.4"/>
+</g>
+<!-- Scope14_2&#45;&gt;If11 -->
+<g id="edge14" class="edge">
+<title>Scope14_2:Scope14_2_$ctrl&#45;&gt;If11:p1</title>
+<path fill="none" stroke="cornflowerblue" stroke-dasharray="5,2" d="M421,-61C421,-84.4 401.06,-88.09 395.45,-105.95"/>
+<polygon fill="cornflowerblue" stroke="cornflowerblue" points="391.97,-105.6 394,-116 398.89,-106.6 391.97,-105.6"/>
+</g>
+</g>
+</svg>
diff --git a/chapter07/docs/07-graph2.gv b/chapter07/docs/07-graph2.gv
new file mode 100644
index 00000000..f4cfcb45
--- /dev/null
+++ b/chapter07/docs/07-graph2.gv
@@ -0,0 +1,62 @@
+digraph chapter07 {
+/*
+while(arg < 10) {
+ arg = arg + 1;
+ #showGraph;
+}
+return arg;
+
+*/
+ rankdir=BT;
+ ordering="in";
+ concentrate="true";
+ compound="true";
+ subgraph cluster_Nodes {
+ Start2 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">Start</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">$ctrl</TD><TD PORT="p1">arg</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Stop3 [ shape=box style=filled fillcolor=yellow label="Stop" ];
+ Loop6 [ shape=box style=filled fillcolor=yellow label="Loop" ];
+ Phi_arg8 [ style=filled fillcolor=lightyellow label="&phi;_arg" ];
+ Con_9 [ label="10" ];
+ LT10 [ label="<" ];
+ If11 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">If</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">True</TD><TD PORT="p1" BGCOLOR="yellow">False</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Con_15 [ label="1" ];
+ Add16 [ label="+" ];
+ Return17 [ shape=box style=filled fillcolor=yellow label="Return" ];
+ { rank=same; Loop6;Phi_arg8;}
+ }
+ node [shape=plaintext];
+ edge [ fontname=Helvetica, fontsize=8 ];
+ Stop3 -> Return17[taillabel=0 color=red];
+ Loop6 -> Start2:p0[taillabel=1 color=red];
+ Loop6 -> If11:p0[taillabel=2 color=red constraint=false];
+ Phi_arg8 -> Loop6 [style=dotted taillabel=0];
+ Phi_arg8 -> Start2:p1[taillabel=1];
+ Phi_arg8 -> Add16[taillabel=2 constraint=false];
+ LT10 -> Phi_arg8[taillabel=1];
+ LT10 -> Con_9[taillabel=2];
+ If11 -> Loop6[taillabel=0 color=red];
+ If11 -> LT10[taillabel=1];
+ Add16 -> Phi_arg8[taillabel=1];
+ Add16 -> Con_15[taillabel=2];
+ Return17 -> If11:p1[taillabel=0 color=red];
+ Return17 -> Phi_arg8[taillabel=1];
+ edge [style=dashed color=cornflowerblue];
+} \ No newline at end of file
diff --git a/chapter07/docs/07-graph2.svg b/chapter07/docs/07-graph2.svg
new file mode 100644
index 00000000..1fec9556
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@@ -0,0 +1,184 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"
+ "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<!-- Generated by graphviz version 2.43.0 (0)
+ -->
+<!-- Title: chapter07 Pages: 1 -->
+<svg width="330pt" height="492pt"
+ viewBox="0.00 0.00 330.00 492.00" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
+<g id="graph0" class="graph" transform="scale(1 1) rotate(0) translate(4 488)">
+<title>chapter07</title>
+<polygon fill="white" stroke="transparent" points="-4,4 -4,-488 326,-488 326,4 -4,4"/>
+<g id="clust1" class="cluster">
+<title>cluster_Nodes</title>
+<polygon fill="none" stroke="black" points="8,-8 8,-476 314,-476 314,-8 8,-8"/>
+</g>
+<!-- Start2 -->
+<g id="node1" class="node">
+<title>Start2</title>
+<polygon fill="yellow" stroke="transparent" points="141,-439 141,-464 222,-464 222,-439 141,-439"/>
+<polygon fill="none" stroke="black" points="141,-439 141,-464 222,-464 222,-439 141,-439"/>
+<text text-anchor="start" x="163" y="-447.8" font-family="Times,serif" font-size="14.00">Start</text>
+<polygon fill="none" stroke="black" points="141,-408 141,-439 222,-439 222,-408 141,-408"/>
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+<text text-anchor="start" x="149" y="-419.8" font-family="Times,serif" font-size="14.00">$ctrl</text>
+<polygon fill="none" stroke="black" points="186,-413 186,-434 217,-434 217,-413 186,-413"/>
+<text text-anchor="start" x="189" y="-419.8" font-family="Times,serif" font-size="14.00">arg</text>
+</g>
+<!-- Stop3 -->
+<g id="node2" class="node">
+<title>Stop3</title>
+<polygon fill="yellow" stroke="black" points="153,-52 99,-52 99,-16 153,-16 153,-52"/>
+<text text-anchor="middle" x="126" y="-30.3" font-family="Times,serif" font-size="14.00">Stop</text>
+</g>
+<!-- Return17 -->
+<g id="node10" class="node">
+<title>Return17</title>
+<polygon fill="yellow" stroke="black" points="159,-124 93,-124 93,-88 159,-88 159,-124"/>
+<text text-anchor="middle" x="126" y="-102.3" font-family="Times,serif" font-size="14.00">Return</text>
+</g>
+<!-- Stop3&#45;&gt;Return17 -->
+<g id="edge1" class="edge">
+<title>Stop3&#45;&gt;Return17</title>
+<path fill="none" stroke="red" d="M126,-52.3C126,-60.02 126,-69.29 126,-77.89"/>
+<polygon fill="red" stroke="red" points="122.5,-77.9 126,-87.9 129.5,-77.9 122.5,-77.9"/>
+<text text-anchor="middle" x="123" y="-54.9" font-family="Helvetica,sans-Serif" font-size="8.00">0</text>
+</g>
+<!-- Loop6 -->
+<g id="node3" class="node">
+<title>Loop6</title>
+<polygon fill="yellow" stroke="black" points="306,-368 252,-368 252,-332 306,-332 306,-368"/>
+<text text-anchor="middle" x="279" y="-346.3" font-family="Times,serif" font-size="14.00">Loop</text>
+</g>
+<!-- Loop6&#45;&gt;Start2 -->
+<g id="edge2" class="edge">
+<title>Loop6&#45;&gt;Start2:p0</title>
+<path fill="none" stroke="red" d="M251.93,-364.13C226.34,-376.71 189.56,-395.24 173.73,-405.41"/>
+<polygon fill="red" stroke="red" points="171.34,-402.85 166,-412 175.88,-408.18 171.34,-402.85"/>
+<text text-anchor="middle" x="248.93" y="-357.73" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- If11 -->
+<g id="node7" class="node">
+<title>If11</title>
+<polygon fill="yellow" stroke="transparent" points="32,-195 32,-220 126,-220 126,-195 32,-195"/>
+<polygon fill="none" stroke="black" points="32,-195 32,-220 126,-220 126,-195 32,-195"/>
+<text text-anchor="start" x="73.5" y="-203.8" font-family="Times,serif" font-size="14.00">If</text>
+<polygon fill="none" stroke="black" points="32,-164 32,-195 126,-195 126,-164 32,-164"/>
+<polygon fill="yellow" stroke="transparent" points="37,-169 37,-190 77,-190 77,-169 37,-169"/>
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+<text text-anchor="start" x="40" y="-175.8" font-family="Times,serif" font-size="14.00">True</text>
+<polygon fill="yellow" stroke="transparent" points="77,-169 77,-190 121,-190 121,-169 77,-169"/>
+<polygon fill="none" stroke="black" points="77,-169 77,-190 121,-190 121,-169 77,-169"/>
+<text text-anchor="start" x="80" y="-175.8" font-family="Times,serif" font-size="14.00">False</text>
+</g>
+<!-- Loop6&#45;&gt;If11 -->
+<g id="edge3" class="edge">
+<title>Loop6&#45;&gt;If11:p0</title>
+<path fill="none" stroke="red" d="M251.78,-335.24C248.86,-334.04 245.9,-332.93 243,-332 156.98,-304.48 103.76,-362.82 43,-296 18.41,-268.96 14.64,-203.69 27.49,-184.44"/>
+<polygon fill="red" stroke="red" points="29.46,-187.33 36,-179 25.69,-181.43 29.46,-187.33"/>
+<text text-anchor="middle" x="248.78" y="-328.84" font-family="Helvetica,sans-Serif" font-size="8.00">2</text>
+</g>
+<!-- Phi_arg8 -->
+<g id="node4" class="node">
+<title>Phi_arg8</title>
+<ellipse fill="lightyellow" stroke="black" cx="125" cy="-350" rx="37.09" ry="18"/>
+<text text-anchor="middle" x="125" y="-346.3" font-family="Times,serif" font-size="14.00">φ_arg</text>
+</g>
+<!-- Phi_arg8&#45;&gt;Start2 -->
+<g id="edge5" class="edge">
+<title>Phi_arg8&#45;&gt;Start2:p1</title>
+<path fill="none" stroke="black" d="M154.55,-360.93C173.21,-369 194.84,-382.27 200.56,-401.87"/>
+<polygon fill="black" stroke="black" points="197.12,-402.59 202,-412 204.05,-401.61 197.12,-402.59"/>
+<text text-anchor="middle" x="151.55" y="-363.53" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Phi_arg8&#45;&gt;Loop6 -->
+<g id="edge4" class="edge">
+<title>Phi_arg8&#45;&gt;Loop6</title>
+<path fill="none" stroke="black" stroke-dasharray="1,5" d="M143.47,-334.01C153.54,-326.34 166.66,-317.98 180,-314 203,-307.14 211.35,-306.06 234,-314 241.14,-316.5 247.99,-320.67 254.09,-325.3"/>
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+<text text-anchor="middle" x="140.47" y="-327.61" font-family="Helvetica,sans-Serif" font-size="8.00">0</text>
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+<!-- Add16 -->
+<g id="node9" class="node">
+<title>Add16</title>
+<ellipse fill="none" stroke="black" cx="203" cy="-278" rx="27" ry="18"/>
+<text text-anchor="middle" x="203" y="-274.3" font-family="Times,serif" font-size="14.00">+</text>
+</g>
+<!-- Con_9 -->
+<g id="node5" class="node">
+<title>Con_9</title>
+<ellipse fill="none" stroke="black" cx="43" cy="-350" rx="27" ry="18"/>
+<text text-anchor="middle" x="43" y="-346.3" font-family="Times,serif" font-size="14.00">10</text>
+</g>
+<!-- LT10 -->
+<g id="node6" class="node">
+<title>LT10</title>
+<ellipse fill="none" stroke="black" cx="79" cy="-278" rx="27" ry="18"/>
+<text text-anchor="middle" x="79" y="-274.3" font-family="Times,serif" font-size="14.00">&lt;</text>
+</g>
+<!-- LT10&#45;&gt;Phi_arg8 -->
+<g id="edge7" class="edge">
+<title>LT10&#45;&gt;Phi_arg8</title>
+<path fill="none" stroke="black" d="M89.44,-294.88C95.12,-303.53 102.28,-314.42 108.68,-324.17"/>
+<polygon fill="black" stroke="black" points="105.87,-326.26 114.28,-332.69 111.72,-322.41 105.87,-326.26"/>
+<text text-anchor="middle" x="86.44" y="-297.48" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- LT10&#45;&gt;Con_9 -->
+<g id="edge8" class="edge">
+<title>LT10&#45;&gt;Con_9</title>
+<path fill="none" stroke="black" d="M70.65,-295.24C66.29,-303.72 60.85,-314.29 55.96,-323.8"/>
+<polygon fill="black" stroke="black" points="52.77,-322.36 51.3,-332.85 58.99,-325.56 52.77,-322.36"/>
+<text text-anchor="middle" x="67.65" y="-297.84" font-family="Helvetica,sans-Serif" font-size="8.00">2</text>
+</g>
+<!-- If11&#45;&gt;Loop6 -->
+<g id="edge9" class="edge">
+<title>If11&#45;&gt;Loop6</title>
+<path fill="none" stroke="red" d="M134.07,-205.07C167.93,-214.93 210.21,-231.94 239,-260 256.28,-276.84 266.71,-302.48 272.57,-321.93"/>
+<polygon fill="red" stroke="red" points="269.24,-323.03 275.3,-331.72 275.98,-321.15 269.24,-323.03"/>
+<text text-anchor="middle" x="137.07" y="-198.67" font-family="Helvetica,sans-Serif" font-size="8.00">0</text>
+</g>
+<!-- If11&#45;&gt;LT10 -->
+<g id="edge10" class="edge">
+<title>If11&#45;&gt;LT10</title>
+<path fill="none" stroke="black" d="M79,-224.28C79,-232.58 79,-241.48 79,-249.56"/>
+<polygon fill="black" stroke="black" points="75.5,-249.6 79,-259.6 82.5,-249.6 75.5,-249.6"/>
+<text text-anchor="middle" x="76" y="-226.88" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Con_15 -->
+<g id="node8" class="node">
+<title>Con_15</title>
+<ellipse fill="none" stroke="black" cx="207" cy="-350" rx="27" ry="18"/>
+<text text-anchor="middle" x="207" y="-346.3" font-family="Times,serif" font-size="14.00">1</text>
+</g>
+<!-- Add16&#45;&gt;Phi_arg8 -->
+<g id="edge11" class="edge">
+<title>Add16&#45;&gt;Phi_arg8</title>
+<path fill="none" stroke="black" d="M180.01,-299.63C170.41,-308.25 159.23,-318.28 149.47,-327.04"/>
+<polygon fill="black" stroke="black" points="182.48,-302.11 187.59,-292.83 177.81,-296.9 182.48,-302.11"/>
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+<text text-anchor="middle" x="184.59" y="-295.43" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Add16&#45;&gt;Con_15 -->
+<g id="edge12" class="edge">
+<title>Add16&#45;&gt;Con_15</title>
+<path fill="none" stroke="black" d="M203.99,-296.3C204.43,-304.02 204.96,-313.29 205.45,-321.89"/>
+<polygon fill="black" stroke="black" points="201.96,-322.11 206.02,-331.9 208.95,-321.71 201.96,-322.11"/>
+<text text-anchor="middle" x="200.99" y="-298.9" font-family="Helvetica,sans-Serif" font-size="8.00">2</text>
+</g>
+<!-- Return17&#45;&gt;Phi_arg8 -->
+<g id="edge14" class="edge">
+<title>Return17&#45;&gt;Phi_arg8</title>
+<path fill="none" stroke="black" d="M133.07,-124.33C136.84,-134.53 141.09,-147.78 143,-160 151.97,-217.35 140.08,-285.24 131.79,-322.03"/>
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+<text text-anchor="middle" x="130.07" y="-126.93" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Return17&#45;&gt;If11 -->
+<g id="edge13" class="edge">
+<title>Return17&#45;&gt;If11:p1</title>
+<path fill="none" stroke="red" d="M113.92,-124C108.25,-133.3 102.24,-145.44 99.95,-157.94"/>
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diff --git a/chapter07/docs/07-graph3.gv b/chapter07/docs/07-graph3.gv
new file mode 100644
index 00000000..4482100b
--- /dev/null
+++ b/chapter07/docs/07-graph3.gv
@@ -0,0 +1,108 @@
+digraph chapter07 {
+/*
+int sum = 0;
+int i = 0;
+while(i < arg) {
+ i = i + 1;
+ int j = 0;
+ while( j < arg ) {
+ sum = sum + j;
+ j = j + 1;
+ }
+}
+return sum;
+
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+ concentrate="true";
+ compound="true";
+ subgraph cluster_Nodes {
+ Start2 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
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+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">$ctrl</TD><TD PORT="p1">arg</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Stop3 [ shape=box style=filled fillcolor=yellow label="Stop" ];
+ Con_6 [ label="0" ];
+ Con_7 [ label="0" ];
+ Loop8 [ shape=box style=filled fillcolor=yellow label="Loop" ];
+ Phi_sum11 [ style=filled fillcolor=lightyellow label="&phi;_sum" ];
+ Phi_i12 [ style=filled fillcolor=lightyellow label="&phi;_i" ];
+ LT13 [ label="<" ];
+ If14 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">If</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">True</TD><TD PORT="p1" BGCOLOR="yellow">False</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Con_18 [ label="1" ];
+ Add19 [ label="+" ];
+ Con_20 [ label="0" ];
+ Loop21 [ shape=box style=filled fillcolor=yellow label="Loop" ];
+ Phi_sum24 [ style=filled fillcolor=lightyellow label="&phi;_sum" ];
+ Phi_j26 [ style=filled fillcolor=lightyellow label="&phi;_j" ];
+ LT27 [ label="<" ];
+ If28 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">If</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">True</TD><TD PORT="p1" BGCOLOR="yellow">False</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Add32 [ label="+" ];
+ Con_33 [ label="1" ];
+ Add34 [ label="+" ];
+ Return35 [ shape=box style=filled fillcolor=yellow label="Return" ];
+ { rank=same; Loop8;Phi_sum11;Phi_i12;}
+ { rank=same; Loop21;Phi_sum24;Phi_j26;}
+ }
+ node [shape=plaintext];
+ edge [ fontname=Helvetica, fontsize=8 ];
+ Stop3 -> Return35[taillabel=0 color=red];
+ Loop8 -> Start2:p0[taillabel=1 color=red];
+ Loop8 -> If28:p1[taillabel=2 color=red constraint=false];
+ Phi_sum11 -> Loop8 [style=dotted taillabel=0];
+ Phi_sum11 -> Con_6[taillabel=1];
+ Phi_sum11 -> Phi_sum24[taillabel=2 constraint=false];
+ Phi_i12 -> Loop8 [style=dotted taillabel=0];
+ Phi_i12 -> Con_7[taillabel=1];
+ Phi_i12 -> Add19[taillabel=2 constraint=false];
+ LT13 -> Phi_i12[taillabel=1];
+ LT13 -> Start2:p1[taillabel=2];
+ If14 -> Loop8[taillabel=0 color=red];
+ If14 -> LT13[taillabel=1];
+ Add19 -> Phi_i12[taillabel=1];
+ Add19 -> Con_18[taillabel=2];
+ Loop21 -> If14:p0[taillabel=1 color=red];
+ Loop21 -> If28:p0[taillabel=2 color=red constraint=false];
+ Phi_sum24 -> Loop21 [style=dotted taillabel=0];
+ Phi_sum24 -> Phi_sum11[taillabel=1];
+ Phi_sum24 -> Add32[taillabel=2 constraint=false];
+ Phi_j26 -> Loop21 [style=dotted taillabel=0];
+ Phi_j26 -> Con_20[taillabel=1];
+ Phi_j26 -> Add34[taillabel=2 constraint=false];
+ LT27 -> Phi_j26[taillabel=1];
+ LT27 -> Start2:p1[taillabel=2];
+ If28 -> Loop21[taillabel=0 color=red];
+ If28 -> LT27[taillabel=1];
+ Add32 -> Phi_j26[taillabel=1];
+ Add32 -> Phi_sum24[taillabel=2];
+ Add34 -> Phi_j26[taillabel=1];
+ Add34 -> Con_33[taillabel=2];
+ Return35 -> If14:p1[taillabel=0 color=red];
+ Return35 -> Phi_sum11[taillabel=1];
+ edge [style=dashed color=cornflowerblue];
+} \ No newline at end of file
diff --git a/chapter07/docs/07-graph3.svg b/chapter07/docs/07-graph3.svg
new file mode 100644
index 00000000..a9a0e8d0
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+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"
+ "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<!-- Generated by graphviz version 2.43.0 (0)
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+ viewBox="0.00 0.00 462.00 592.00" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
+<g id="graph0" class="graph" transform="scale(1 1) rotate(0) translate(4 588)">
+<title>chapter07</title>
+<polygon fill="white" stroke="transparent" points="-4,4 -4,-588 458,-588 458,4 -4,4"/>
+<g id="clust1" class="cluster">
+<title>cluster_Nodes</title>
+<polygon fill="none" stroke="black" points="8,-8 8,-576 446,-576 446,-8 8,-8"/>
+</g>
+<!-- Start2 -->
+<g id="node1" class="node">
+<title>Start2</title>
+<polygon fill="yellow" stroke="transparent" points="148,-539 148,-564 229,-564 229,-539 148,-539"/>
+<polygon fill="none" stroke="black" points="148,-539 148,-564 229,-564 229,-539 148,-539"/>
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+<text text-anchor="start" x="156" y="-519.8" font-family="Times,serif" font-size="14.00">$ctrl</text>
+<polygon fill="none" stroke="black" points="193,-513 193,-534 224,-534 224,-513 193,-513"/>
+<text text-anchor="start" x="196" y="-519.8" font-family="Times,serif" font-size="14.00">arg</text>
+</g>
+<!-- Stop3 -->
+<g id="node2" class="node">
+<title>Stop3</title>
+<polygon fill="yellow" stroke="black" points="432,-152 378,-152 378,-116 432,-116 432,-152"/>
+<text text-anchor="middle" x="405" y="-130.3" font-family="Times,serif" font-size="14.00">Stop</text>
+</g>
+<!-- Return35 -->
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+<polygon fill="yellow" stroke="black" points="438,-224 372,-224 372,-188 438,-188 438,-224"/>
+<text text-anchor="middle" x="405" y="-202.3" font-family="Times,serif" font-size="14.00">Return</text>
+</g>
+<!-- Stop3&#45;&gt;Return35 -->
+<g id="edge1" class="edge">
+<title>Stop3&#45;&gt;Return35</title>
+<path fill="none" stroke="red" d="M405,-152.3C405,-160.02 405,-169.29 405,-177.89"/>
+<polygon fill="red" stroke="red" points="401.5,-177.9 405,-187.9 408.5,-177.9 401.5,-177.9"/>
+<text text-anchor="middle" x="402" y="-154.9" font-family="Helvetica,sans-Serif" font-size="8.00">0</text>
+</g>
+<!-- Con_6 -->
+<g id="node3" class="node">
+<title>Con_6</title>
+<ellipse fill="none" stroke="black" cx="94" cy="-536" rx="27" ry="18"/>
+<text text-anchor="middle" x="94" y="-532.3" font-family="Times,serif" font-size="14.00">0</text>
+</g>
+<!-- Con_7 -->
+<g id="node4" class="node">
+<title>Con_7</title>
+<ellipse fill="none" stroke="black" cx="282" cy="-536" rx="27" ry="18"/>
+<text text-anchor="middle" x="282" y="-532.3" font-family="Times,serif" font-size="14.00">0</text>
+</g>
+<!-- Loop8 -->
+<g id="node5" class="node">
+<title>Loop8</title>
+<polygon fill="yellow" stroke="black" points="426,-468 372,-468 372,-432 426,-432 426,-468"/>
+<text text-anchor="middle" x="399" y="-446.3" font-family="Times,serif" font-size="14.00">Loop</text>
+</g>
+<!-- Loop8&#45;&gt;Start2 -->
+<g id="edge2" class="edge">
+<title>Loop8&#45;&gt;Start2:p0</title>
+<path fill="none" stroke="red" d="M371.74,-464.61C368.82,-465.84 365.87,-467 363,-468 325.58,-481 197.82,-470.79 176.14,-502.03"/>
+<polygon fill="red" stroke="red" points="172.67,-501.41 173,-512 179.34,-503.51 172.67,-501.41"/>
+<text text-anchor="middle" x="368.74" y="-458.21" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- If28 -->
+<g id="node17" class="node">
+<title>If28</title>
+<polygon fill="yellow" stroke="transparent" points="142,-51 142,-76 236,-76 236,-51 142,-51"/>
+<polygon fill="none" stroke="black" points="142,-51 142,-76 236,-76 236,-51 142,-51"/>
+<text text-anchor="start" x="183.5" y="-59.8" font-family="Times,serif" font-size="14.00">If</text>
+<polygon fill="none" stroke="black" points="142,-20 142,-51 236,-51 236,-20 142,-20"/>
+<polygon fill="yellow" stroke="transparent" points="147,-25 147,-46 187,-46 187,-25 147,-25"/>
+<polygon fill="none" stroke="black" points="147,-25 147,-46 187,-46 187,-25 147,-25"/>
+<text text-anchor="start" x="150" y="-31.8" font-family="Times,serif" font-size="14.00">True</text>
+<polygon fill="yellow" stroke="transparent" points="187,-25 187,-46 231,-46 231,-25 187,-25"/>
+<polygon fill="none" stroke="black" points="187,-25 187,-46 231,-46 231,-25 187,-25"/>
+<text text-anchor="start" x="190" y="-31.8" font-family="Times,serif" font-size="14.00">False</text>
+</g>
+<!-- Loop8&#45;&gt;If28 -->
+<g id="edge3" class="edge">
+<title>Loop8&#45;&gt;If28:p1</title>
+<path fill="none" stroke="red" d="M371.72,-435.44C368.81,-434.2 365.86,-433.02 363,-432 300.87,-409.81 259.6,-448 219,-396 176.78,-341.93 243.11,-308.12 292,-260 311.77,-240.54 330.24,-248.63 343,-224 350.36,-209.79 353.65,-199.94 343,-188 248.88,-82.54 121.12,-257.46 27,-152 16.35,-140.06 16.65,-128.2 27,-116 90.22,-41.43 180.78,-154.57 244,-80 259.81,-61.35 261.04,-42.53 244,-25 236.29,-17.07 221.85,-12.04 214.15,-15.39"/>
+<polygon fill="red" stroke="red" points="211.13,-13.62 209,-24 217.14,-17.22 211.13,-13.62"/>
+<text text-anchor="middle" x="368.72" y="-429.04" font-family="Helvetica,sans-Serif" font-size="8.00">2</text>
+</g>
+<!-- Phi_sum11 -->
+<g id="node6" class="node">
+<title>Phi_sum11</title>
+<ellipse fill="lightyellow" stroke="black" cx="149" cy="-450" rx="40.89" ry="18"/>
+<text text-anchor="middle" x="149" y="-446.3" font-family="Times,serif" font-size="14.00">φ_sum</text>
+</g>
+<!-- Phi_sum11&#45;&gt;Con_6 -->
+<g id="edge5" class="edge">
+<title>Phi_sum11&#45;&gt;Con_6</title>
+<path fill="none" stroke="black" d="M138.13,-467.6C130.07,-479.91 118.95,-496.89 109.89,-510.73"/>
+<polygon fill="black" stroke="black" points="106.84,-509.01 104.29,-519.29 112.69,-512.84 106.84,-509.01"/>
+<text text-anchor="middle" x="135.13" y="-470.2" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Phi_sum11&#45;&gt;Loop8 -->
+<g id="edge4" class="edge">
+<title>Phi_sum11&#45;&gt;Loop8</title>
+<path fill="none" stroke="black" stroke-dasharray="1,5" d="M173.66,-435.44C188.78,-427.38 208.85,-418.16 228,-414 282.73,-402.12 301.16,-395.46 354,-414 361.14,-416.5 367.99,-420.67 374.09,-425.3"/>
+<polygon fill="black" stroke="black" points="371.99,-428.1 381.92,-431.78 376.45,-422.71 371.99,-428.1"/>
+<text text-anchor="middle" x="170.66" y="-429.04" font-family="Helvetica,sans-Serif" font-size="8.00">0</text>
+</g>
+<!-- Phi_sum24 -->
+<g id="node14" class="node">
+<title>Phi_sum24</title>
+<ellipse fill="lightyellow" stroke="black" cx="149" cy="-206" rx="40.89" ry="18"/>
+<text text-anchor="middle" x="149" y="-202.3" font-family="Times,serif" font-size="14.00">φ_sum</text>
+</g>
+<!-- Phi_i12 -->
+<g id="node7" class="node">
+<title>Phi_i12</title>
+<ellipse fill="lightyellow" stroke="black" cx="255" cy="-450" rx="27" ry="18"/>
+<text text-anchor="middle" x="255" y="-446.3" font-family="Times,serif" font-size="14.00">φ_i</text>
+</g>
+<!-- Phi_i12&#45;&gt;Con_7 -->
+<g id="edge8" class="edge">
+<title>Phi_i12&#45;&gt;Con_7</title>
+<path fill="none" stroke="black" d="M260.46,-468C264.22,-479.69 269.28,-495.44 273.56,-508.73"/>
+<polygon fill="black" stroke="black" points="270.24,-509.86 276.64,-518.31 276.91,-507.72 270.24,-509.86"/>
+<text text-anchor="middle" x="257.46" y="-470.6" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Phi_i12&#45;&gt;Loop8 -->
+<g id="edge7" class="edge">
+<title>Phi_i12&#45;&gt;Loop8</title>
+<path fill="none" stroke="black" stroke-dasharray="1,5" d="M269.22,-434.43C277.37,-426.68 288.29,-418.11 300,-414 322.65,-406.06 331.35,-406.06 354,-414 361.14,-416.5 367.99,-420.67 374.09,-425.3"/>
+<polygon fill="black" stroke="black" points="371.99,-428.1 381.92,-431.78 376.45,-422.71 371.99,-428.1"/>
+<text text-anchor="middle" x="266.22" y="-428.03" font-family="Helvetica,sans-Serif" font-size="8.00">0</text>
+</g>
+<!-- Add19 -->
+<g id="node11" class="node">
+<title>Add19</title>
+<ellipse fill="none" stroke="black" cx="327" cy="-378" rx="27" ry="18"/>
+<text text-anchor="middle" x="327" y="-374.3" font-family="Times,serif" font-size="14.00">+</text>
+</g>
+<!-- LT13 -->
+<g id="node8" class="node">
+<title>LT13</title>
+<ellipse fill="none" stroke="black" cx="255" cy="-378" rx="27" ry="18"/>
+<text text-anchor="middle" x="255" y="-374.3" font-family="Times,serif" font-size="14.00">&lt;</text>
+</g>
+<!-- LT13&#45;&gt;Start2 -->
+<g id="edge11" class="edge">
+<title>LT13&#45;&gt;Start2:p1</title>
+<path fill="none" stroke="black" d="M241.85,-394.14C233.87,-404.19 224.26,-418.05 219,-432 207.64,-462.12 208.62,-473.77 208.94,-501.81"/>
+<polygon fill="black" stroke="black" points="205.44,-502.02 209,-512 212.44,-501.98 205.44,-502.02"/>
+<text text-anchor="middle" x="238.85" y="-396.74" font-family="Helvetica,sans-Serif" font-size="8.00">2</text>
+</g>
+<!-- LT13&#45;&gt;Phi_i12 -->
+<g id="edge10" class="edge">
+<title>LT13&#45;&gt;Phi_i12</title>
+<path fill="none" stroke="black" d="M255,-396.3C255,-404.02 255,-413.29 255,-421.89"/>
+<polygon fill="black" stroke="black" points="251.5,-421.9 255,-431.9 258.5,-421.9 251.5,-421.9"/>
+<text text-anchor="middle" x="252" y="-398.9" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- If14 -->
+<g id="node9" class="node">
+<title>If14</title>
+<polygon fill="yellow" stroke="transparent" points="309,-295 309,-320 403,-320 403,-295 309,-295"/>
+<polygon fill="none" stroke="black" points="309,-295 309,-320 403,-320 403,-295 309,-295"/>
+<text text-anchor="start" x="350.5" y="-303.8" font-family="Times,serif" font-size="14.00">If</text>
+<polygon fill="none" stroke="black" points="309,-264 309,-295 403,-295 403,-264 309,-264"/>
+<polygon fill="yellow" stroke="transparent" points="314,-269 314,-290 354,-290 354,-269 314,-269"/>
+<polygon fill="none" stroke="black" points="314,-269 314,-290 354,-290 354,-269 314,-269"/>
+<text text-anchor="start" x="317" y="-275.8" font-family="Times,serif" font-size="14.00">True</text>
+<polygon fill="yellow" stroke="transparent" points="354,-269 354,-290 398,-290 398,-269 354,-269"/>
+<polygon fill="none" stroke="black" points="354,-269 354,-290 398,-290 398,-269 354,-269"/>
+<text text-anchor="start" x="357" y="-275.8" font-family="Times,serif" font-size="14.00">False</text>
+</g>
+<!-- If14&#45;&gt;Loop8 -->
+<g id="edge12" class="edge">
+<title>If14&#45;&gt;Loop8</title>
+<path fill="none" stroke="red" d="M364.6,-324.19C372.47,-352.77 384.02,-394.64 391.52,-421.86"/>
+<polygon fill="red" stroke="red" points="388.24,-423.15 394.27,-431.86 394.99,-421.29 388.24,-423.15"/>
+<text text-anchor="middle" x="361.6" y="-326.79" font-family="Helvetica,sans-Serif" font-size="8.00">0</text>
+</g>
+<!-- If14&#45;&gt;LT13 -->
+<g id="edge13" class="edge">
+<title>If14&#45;&gt;LT13</title>
+<path fill="none" stroke="black" d="M318.68,-324.04C305.44,-335.05 290.9,-347.14 279.06,-356.99"/>
+<polygon fill="black" stroke="black" points="276.79,-354.32 271.34,-363.41 281.27,-359.7 276.79,-354.32"/>
+<text text-anchor="middle" x="315.68" y="-326.64" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Con_18 -->
+<g id="node10" class="node">
+<title>Con_18</title>
+<ellipse fill="none" stroke="black" cx="327" cy="-450" rx="27" ry="18"/>
+<text text-anchor="middle" x="327" y="-446.3" font-family="Times,serif" font-size="14.00">1</text>
+</g>
+<!-- Add19&#45;&gt;Phi_i12 -->
+<g id="edge14" class="edge">
+<title>Add19&#45;&gt;Phi_i12</title>
+<path fill="none" stroke="black" d="M304.96,-400.43C296.13,-409.01 285.99,-418.87 277.15,-427.46"/>
+<polygon fill="black" stroke="black" points="307.7,-402.65 312.43,-393.17 302.82,-397.63 307.7,-402.65"/>
+<polygon fill="black" stroke="black" points="274.53,-425.13 269.8,-434.62 279.41,-430.15 274.53,-425.13"/>
+<text text-anchor="middle" x="309.43" y="-395.77" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Add19&#45;&gt;Con_18 -->
+<g id="edge15" class="edge">
+<title>Add19&#45;&gt;Con_18</title>
+<path fill="none" stroke="black" d="M327,-396.3C327,-404.02 327,-413.29 327,-421.89"/>
+<polygon fill="black" stroke="black" points="323.5,-421.9 327,-431.9 330.5,-421.9 323.5,-421.9"/>
+<text text-anchor="middle" x="324" y="-398.9" font-family="Helvetica,sans-Serif" font-size="8.00">2</text>
+</g>
+<!-- Con_20 -->
+<g id="node12" class="node">
+<title>Con_20</title>
+<ellipse fill="none" stroke="black" cx="63" cy="-292" rx="27" ry="18"/>
+<text text-anchor="middle" x="63" y="-288.3" font-family="Times,serif" font-size="14.00">0</text>
+</g>
+<!-- Loop21 -->
+<g id="node13" class="node">
+<title>Loop21</title>
+<polygon fill="yellow" stroke="black" points="334,-224 280,-224 280,-188 334,-188 334,-224"/>
+<text text-anchor="middle" x="307" y="-202.3" font-family="Times,serif" font-size="14.00">Loop</text>
+</g>
+<!-- Loop21&#45;&gt;If14 -->
+<g id="edge16" class="edge">
+<title>Loop21&#45;&gt;If14:p0</title>
+<path fill="none" stroke="red" d="M319.08,-224C324.75,-233.3 330.76,-245.44 333.05,-257.94"/>
+<polygon fill="red" stroke="red" points="329.57,-258.38 334,-268 336.54,-257.71 329.57,-258.38"/>
+<text text-anchor="middle" x="316.08" y="-226.6" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Loop21&#45;&gt;If28 -->
+<g id="edge17" class="edge">
+<title>Loop21&#45;&gt;If28:p0</title>
+<path fill="none" stroke="red" d="M279.81,-191.15C276.88,-189.96 273.91,-188.88 271,-188 218.54,-172.13 62.82,-193.49 27,-152 -19.29,-98.38 63.73,-40.46 135.9,-35.36"/>
+<polygon fill="red" stroke="red" points="136.13,-38.86 146,-35 135.88,-31.86 136.13,-38.86"/>
+<text text-anchor="middle" x="276.81" y="-184.75" font-family="Helvetica,sans-Serif" font-size="8.00">2</text>
+</g>
+<!-- Phi_sum24&#45;&gt;Phi_sum11 -->
+<g id="edge19" class="edge">
+<title>Phi_sum24&#45;&gt;Phi_sum11</title>
+<path fill="none" stroke="black" d="M149,-234.1C149,-280.5 149,-374.66 149,-421.4"/>
+<polygon fill="black" stroke="black" points="152.5,-234.02 149,-224.02 145.5,-234.02 152.5,-234.02"/>
+<polygon fill="black" stroke="black" points="145.5,-421.68 149,-431.68 152.5,-421.68 145.5,-421.68"/>
+<text text-anchor="middle" x="146" y="-226.62" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Phi_sum24&#45;&gt;Loop21 -->
+<g id="edge18" class="edge">
+<title>Phi_sum24&#45;&gt;Loop21</title>
+<path fill="none" stroke="black" stroke-dasharray="1,5" d="M168.72,-190.18C179.62,-182.46 193.79,-173.99 208,-170 231.11,-163.51 239.35,-162.06 262,-170 269.14,-172.5 275.99,-176.67 282.09,-181.3"/>
+<polygon fill="black" stroke="black" points="279.99,-184.1 289.92,-187.78 284.45,-178.71 279.99,-184.1"/>
+<text text-anchor="middle" x="165.72" y="-183.78" font-family="Helvetica,sans-Serif" font-size="8.00">0</text>
+</g>
+<!-- Add32 -->
+<g id="node18" class="node">
+<title>Add32</title>
+<ellipse fill="none" stroke="black" cx="142" cy="-134" rx="27" ry="18"/>
+<text text-anchor="middle" x="142" y="-130.3" font-family="Times,serif" font-size="14.00">+</text>
+</g>
+<!-- Phi_j26 -->
+<g id="node15" class="node">
+<title>Phi_j26</title>
+<ellipse fill="lightyellow" stroke="black" cx="63" cy="-206" rx="27" ry="18"/>
+<text text-anchor="middle" x="63" y="-202.3" font-family="Times,serif" font-size="14.00">φ_j</text>
+</g>
+<!-- Phi_j26&#45;&gt;Con_20 -->
+<g id="edge22" class="edge">
+<title>Phi_j26&#45;&gt;Con_20</title>
+<path fill="none" stroke="black" d="M63,-224.4C63,-235.74 63,-250.77 63,-263.68"/>
+<polygon fill="black" stroke="black" points="59.5,-263.9 63,-273.9 66.5,-263.9 59.5,-263.9"/>
+<text text-anchor="middle" x="60" y="-227" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Phi_j26&#45;&gt;Loop21 -->
+<g id="edge21" class="edge">
+<title>Phi_j26&#45;&gt;Loop21</title>
+<path fill="none" stroke="black" stroke-dasharray="1,5" d="M77.22,-190.43C85.37,-182.68 96.29,-174.11 108,-170 172.59,-147.34 197.41,-147.34 262,-170 269.14,-172.5 275.99,-176.67 282.09,-181.3"/>
+<polygon fill="black" stroke="black" points="279.99,-184.1 289.92,-187.78 284.45,-178.71 279.99,-184.1"/>
+<text text-anchor="middle" x="74.22" y="-184.03" font-family="Helvetica,sans-Serif" font-size="8.00">0</text>
+</g>
+<!-- Add34 -->
+<g id="node20" class="node">
+<title>Add34</title>
+<ellipse fill="none" stroke="black" cx="225" cy="-134" rx="27" ry="18"/>
+<text text-anchor="middle" x="225" y="-130.3" font-family="Times,serif" font-size="14.00">+</text>
+</g>
+<!-- LT27 -->
+<g id="node16" class="node">
+<title>LT27</title>
+<ellipse fill="none" stroke="black" cx="63" cy="-134" rx="27" ry="18"/>
+<text text-anchor="middle" x="63" y="-130.3" font-family="Times,serif" font-size="14.00">&lt;</text>
+</g>
+<!-- LT27&#45;&gt;Start2 -->
+<g id="edge25" class="edge">
+<title>LT27&#45;&gt;Start2:p1</title>
+<path fill="none" stroke="black" d="M49.72,-150.09C41.69,-160.12 32.07,-173.98 27,-188 11.37,-231.26 17,-245.01 17,-291 17,-291 17,-291 17,-379 17,-432.79 54.71,-437.48 99,-468 139.14,-495.66 199.24,-464.69 207.94,-501.72"/>
+<polygon fill="black" stroke="black" points="204.49,-502.41 209,-512 211.45,-501.69 204.49,-502.41"/>
+<text text-anchor="middle" x="46.72" y="-152.69" font-family="Helvetica,sans-Serif" font-size="8.00">2</text>
+</g>
+<!-- LT27&#45;&gt;Phi_j26 -->
+<g id="edge24" class="edge">
+<title>LT27&#45;&gt;Phi_j26</title>
+<path fill="none" stroke="black" d="M63,-152.3C63,-160.02 63,-169.29 63,-177.89"/>
+<polygon fill="black" stroke="black" points="59.5,-177.9 63,-187.9 66.5,-177.9 59.5,-177.9"/>
+<text text-anchor="middle" x="60" y="-154.9" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- If28&#45;&gt;Loop21 -->
+<g id="edge26" class="edge">
+<title>If28&#45;&gt;Loop21</title>
+<path fill="none" stroke="red" d="M227.35,-80.17C239.01,-90.79 251.3,-103.21 261,-116 275.71,-135.38 288.07,-160.15 296.27,-178.63"/>
+<polygon fill="red" stroke="red" points="293.1,-180.12 300.27,-187.92 299.53,-177.35 293.1,-180.12"/>
+<text text-anchor="middle" x="224.35" y="-82.77" font-family="Helvetica,sans-Serif" font-size="8.00">0</text>
+</g>
+<!-- If28&#45;&gt;LT27 -->
+<g id="edge27" class="edge">
+<title>If28&#45;&gt;LT27</title>
+<path fill="none" stroke="black" d="M142.44,-80.04C124.74,-91.84 105.18,-104.88 89.9,-115.07"/>
+<polygon fill="black" stroke="black" points="87.82,-112.24 81.44,-120.7 91.71,-118.07 87.82,-112.24"/>
+<text text-anchor="middle" x="139.44" y="-82.64" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Add32&#45;&gt;Phi_sum24 -->
+<g id="edge29" class="edge">
+<title>Add32&#45;&gt;Phi_sum24</title>
+<path fill="none" stroke="black" d="M144.73,-162.33C145.24,-167.45 145.78,-172.79 146.29,-177.9"/>
+<polygon fill="black" stroke="black" points="148.21,-161.91 143.73,-152.3 141.24,-162.6 148.21,-161.91"/>
+<polygon fill="black" stroke="black" points="142.81,-178.29 147.29,-187.9 149.78,-177.6 142.81,-178.29"/>
+<text text-anchor="middle" x="140.73" y="-154.9" font-family="Helvetica,sans-Serif" font-size="8.00">2</text>
+</g>
+<!-- Add32&#45;&gt;Phi_j26 -->
+<g id="edge28" class="edge">
+<title>Add32&#45;&gt;Phi_j26</title>
+<path fill="none" stroke="black" d="M126.39,-148.83C114.92,-158.99 99.15,-172.97 86.21,-184.44"/>
+<polygon fill="black" stroke="black" points="83.74,-181.95 78.58,-191.2 88.38,-187.19 83.74,-181.95"/>
+<text text-anchor="middle" x="123.39" y="-151.43" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Con_33 -->
+<g id="node19" class="node">
+<title>Con_33</title>
+<ellipse fill="none" stroke="black" cx="235" cy="-206" rx="27" ry="18"/>
+<text text-anchor="middle" x="235" y="-202.3" font-family="Times,serif" font-size="14.00">1</text>
+</g>
+<!-- Add34&#45;&gt;Phi_j26 -->
+<g id="edge30" class="edge">
+<title>Add34&#45;&gt;Phi_j26</title>
+<path fill="none" stroke="black" d="M193.01,-148.01C167.45,-158.51 130.76,-173.83 99,-188 97.2,-188.8 95.36,-189.64 93.5,-190.49"/>
+<polygon fill="black" stroke="black" points="194.64,-151.12 202.57,-144.09 191.99,-144.65 194.64,-151.12"/>
+<polygon fill="black" stroke="black" points="91.85,-187.39 84.25,-194.78 94.79,-193.74 91.85,-187.39"/>
+<text text-anchor="middle" x="199.57" y="-146.69" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Add34&#45;&gt;Con_33 -->
+<g id="edge31" class="edge">
+<title>Add34&#45;&gt;Con_33</title>
+<path fill="none" stroke="black" d="M227.42,-151.95C228.52,-159.65 229.85,-168.97 231.09,-177.64"/>
+<polygon fill="black" stroke="black" points="227.65,-178.32 232.53,-187.72 234.58,-177.33 227.65,-178.32"/>
+<text text-anchor="middle" x="224.42" y="-154.55" font-family="Helvetica,sans-Serif" font-size="8.00">2</text>
+</g>
+<!-- Return35&#45;&gt;Phi_sum11 -->
+<g id="edge33" class="edge">
+<title>Return35&#45;&gt;Phi_sum11</title>
+<path fill="none" stroke="black" d="M371.93,-220.42C343.47,-232.34 305.01,-249.46 292,-260 233.39,-307.47 185.4,-383.86 162.87,-423.42"/>
+<polygon fill="black" stroke="black" points="159.79,-421.75 157.95,-432.19 165.89,-425.18 159.79,-421.75"/>
+<text text-anchor="middle" x="368.93" y="-214.02" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Return35&#45;&gt;If14 -->
+<g id="edge32" class="edge">
+<title>Return35&#45;&gt;If14:p1</title>
+<path fill="none" stroke="red" d="M391.86,-224.13C385.8,-233.37 379.43,-245.41 377.01,-257.92"/>
+<polygon fill="red" stroke="red" points="373.52,-257.7 376,-268 380.48,-258.4 373.52,-257.7"/>
+<text text-anchor="middle" x="388.86" y="-226.73" font-family="Helvetica,sans-Serif" font-size="8.00">0</text>
+</g>
+</g>
+</svg>
diff --git a/chapter07/docs/07-graph4.gv b/chapter07/docs/07-graph4.gv
new file mode 100644
index 00000000..24ace3da
--- /dev/null
+++ b/chapter07/docs/07-graph4.gv
@@ -0,0 +1,96 @@
+digraph chapter07 {
+/*
+int a = 1;
+int b = 2;
+while(a < 10) {
+ if (a == 2) a = 3;
+ else b = 4;
+}
+return b;
+
+*/
+ rankdir=BT;
+ ordering="in";
+ concentrate="true";
+ compound="true";
+ subgraph cluster_Nodes {
+ Start2 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">Start</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">$ctrl</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Stop3 [ shape=box style=filled fillcolor=yellow label="Stop" ];
+ Con_6 [ label="1" ];
+ Con_7 [ label="2" ];
+ Loop8 [ shape=box style=filled fillcolor=yellow label="Loop" ];
+ Phi_a11 [ style=filled fillcolor=lightyellow label="&phi;_a" ];
+ Phi_b12 [ style=filled fillcolor=lightyellow label="&phi;_b" ];
+ Con_13 [ label="10" ];
+ LT14 [ label="<" ];
+ If15 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">If</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">True</TD><TD PORT="p1" BGCOLOR="yellow">False</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Con_19 [ label="2" ];
+ EQ20 [ label="==" ];
+ If21 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">If</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">True</TD><TD PORT="p1" BGCOLOR="yellow">False</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Con_25 [ label="3" ];
+ Con_26 [ label="4" ];
+ Region27 [ shape=box style=filled fillcolor=yellow label="Region" ];
+ Phi_a28 [ style=filled fillcolor=lightyellow label="&phi;_a" ];
+ Phi_b29 [ style=filled fillcolor=lightyellow label="&phi;_b" ];
+ Return30 [ shape=box style=filled fillcolor=yellow label="Return" ];
+ { rank=same; Loop8;Phi_a11;Phi_b12;}
+ { rank=same; Region27;Phi_b29;Phi_a28;}
+ }
+ node [shape=plaintext];
+ edge [ fontname=Helvetica, fontsize=8 ];
+ Stop3 -> Return30[taillabel=0 color=red];
+ Loop8 -> Start2:p0[taillabel=1 color=red];
+ Loop8 -> Region27[taillabel=2 color=red constraint=false];
+ Phi_a11 -> Loop8 [style=dotted taillabel=0];
+ Phi_a11 -> Con_6[taillabel=1];
+ Phi_a11 -> Phi_a28[taillabel=2 constraint=false];
+ Phi_b12 -> Loop8 [style=dotted taillabel=0];
+ Phi_b12 -> Con_7[taillabel=1];
+ Phi_b12 -> Phi_b29[taillabel=2 constraint=false];
+ LT14 -> Phi_a11[taillabel=1];
+ LT14 -> Con_13[taillabel=2];
+ If15 -> Loop8[taillabel=0 color=red];
+ If15 -> LT14[taillabel=1];
+ EQ20 -> Phi_a11[taillabel=1];
+ EQ20 -> Con_19[taillabel=2];
+ If21 -> If15:p0[taillabel=0 color=red];
+ If21 -> EQ20[taillabel=1];
+ Region27 -> If21:p0[taillabel=1 color=red];
+ Region27 -> If21:p1[taillabel=2 color=red];
+ Phi_a28 -> Region27 [style=dotted taillabel=0];
+ Phi_a28 -> Con_25[taillabel=1];
+ Phi_a28 -> Phi_a11[taillabel=2 constraint=false];
+ Phi_b29 -> Region27 [style=dotted taillabel=0];
+ Phi_b29 -> Phi_b12[taillabel=1];
+ Phi_b29 -> Con_26[taillabel=2 constraint=false];
+ Return30 -> If15:p1[taillabel=0 color=red];
+ Return30 -> Phi_b12[taillabel=1];
+ edge [style=dashed color=cornflowerblue];
+}
diff --git a/chapter07/docs/07-graph4.svg b/chapter07/docs/07-graph4.svg
new file mode 100644
index 00000000..cf42453d
--- /dev/null
+++ b/chapter07/docs/07-graph4.svg
@@ -0,0 +1,329 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"
+ "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<!-- Generated by graphviz version 2.43.0 (0)
+ -->
+<!-- Title: chapter07 Pages: 1 -->
+<svg width="394pt" height="545pt"
+ viewBox="0.00 0.00 394.00 545.35" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
+<g id="graph0" class="graph" transform="scale(1 1) rotate(0) translate(4 541.35)">
+<title>chapter07</title>
+<polygon fill="white" stroke="transparent" points="-4,4 -4,-541.35 390,-541.35 390,4 -4,4"/>
+<g id="clust1" class="cluster">
+<title>cluster_Nodes</title>
+<polygon fill="none" stroke="black" points="8,-33.35 8,-529.35 378,-529.35 378,-33.35 8,-33.35"/>
+</g>
+<!-- Start2 -->
+<g id="node1" class="node">
+<title>Start2</title>
+<polygon fill="yellow" stroke="transparent" points="312,-492.35 312,-517.35 362,-517.35 362,-492.35 312,-492.35"/>
+<polygon fill="none" stroke="black" points="312,-492.35 312,-517.35 362,-517.35 362,-492.35 312,-492.35"/>
+<text text-anchor="start" x="318.5" y="-501.15" font-family="Times,serif" font-size="14.00">Start</text>
+<polygon fill="none" stroke="black" points="312,-461.35 312,-492.35 362,-492.35 362,-461.35 312,-461.35"/>
+<polygon fill="yellow" stroke="transparent" points="317,-466.35 317,-487.35 357,-487.35 357,-466.35 317,-466.35"/>
+<polygon fill="none" stroke="black" points="317,-466.35 317,-487.35 357,-487.35 357,-466.35 317,-466.35"/>
+<text text-anchor="start" x="320" y="-473.15" font-family="Times,serif" font-size="14.00">$ctrl</text>
+</g>
+<!-- Stop3 -->
+<g id="node2" class="node">
+<title>Stop3</title>
+<polygon fill="yellow" stroke="black" points="370,-77.35 316,-77.35 316,-41.35 370,-41.35 370,-77.35"/>
+<text text-anchor="middle" x="343" y="-55.65" font-family="Times,serif" font-size="14.00">Stop</text>
+</g>
+<!-- Return30 -->
+<g id="node19" class="node">
+<title>Return30</title>
+<polygon fill="yellow" stroke="black" points="370,-163.35 304,-163.35 304,-127.35 370,-127.35 370,-163.35"/>
+<text text-anchor="middle" x="337" y="-141.65" font-family="Times,serif" font-size="14.00">Return</text>
+</g>
+<!-- Stop3&#45;&gt;Return30 -->
+<g id="edge1" class="edge">
+<title>Stop3&#45;&gt;Return30</title>
+<path fill="none" stroke="red" d="M341.76,-77.75C340.95,-89.09 339.87,-104.12 338.95,-117.03"/>
+<polygon fill="red" stroke="red" points="335.44,-117.03 338.22,-127.25 342.42,-117.53 335.44,-117.03"/>
+<text text-anchor="middle" x="338.76" y="-80.35" font-family="Helvetica,sans-Serif" font-size="8.00">0</text>
+</g>
+<!-- Con_6 -->
+<g id="node3" class="node">
+<title>Con_6</title>
+<ellipse fill="none" stroke="black" cx="196" cy="-489.35" rx="27" ry="18"/>
+<text text-anchor="middle" x="196" y="-485.65" font-family="Times,serif" font-size="14.00">1</text>
+</g>
+<!-- Con_7 -->
+<g id="node4" class="node">
+<title>Con_7</title>
+<ellipse fill="none" stroke="black" cx="124" cy="-489.35" rx="27" ry="18"/>
+<text text-anchor="middle" x="124" y="-485.65" font-family="Times,serif" font-size="14.00">2</text>
+</g>
+<!-- Loop8 -->
+<g id="node5" class="node">
+<title>Loop8</title>
+<polygon fill="yellow" stroke="black" points="367,-421.35 313,-421.35 313,-385.35 367,-385.35 367,-421.35"/>
+<text text-anchor="middle" x="340" y="-399.65" font-family="Times,serif" font-size="14.00">Loop</text>
+</g>
+<!-- Loop8&#45;&gt;Start2 -->
+<g id="edge2" class="edge">
+<title>Loop8&#45;&gt;Start2:p0</title>
+<path fill="none" stroke="red" d="M338.71,-421.43C338.08,-430.88 337.4,-443.1 337.13,-455.02"/>
+<polygon fill="red" stroke="red" points="333.62,-455.3 337,-465.35 340.62,-455.39 333.62,-455.3"/>
+<text text-anchor="middle" x="335.71" y="-424.03" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Region27 -->
+<g id="node16" class="node">
+<title>Region27</title>
+<polygon fill="yellow" stroke="black" points="298,-77.35 232,-77.35 232,-41.35 298,-41.35 298,-77.35"/>
+<text text-anchor="middle" x="265" y="-55.65" font-family="Times,serif" font-size="14.00">Region</text>
+</g>
+<!-- Loop8&#45;&gt;Region27 -->
+<g id="edge3" class="edge">
+<title>Loop8&#45;&gt;Region27</title>
+<path fill="none" stroke="red" d="M312.6,-389.27C286.36,-376.62 248.79,-358.1 235,-349.35 191.17,-321.51 165.74,-324.02 143,-277.35 130.54,-251.78 139.66,-241.59 143,-213.35 145.69,-190.65 153.07,-131.47 167,-113.35 174.64,-103.41 199.67,-89.94 222.53,-79.07"/>
+<polygon fill="red" stroke="red" points="224.22,-82.15 231.8,-74.74 221.25,-75.8 224.22,-82.15"/>
+<text text-anchor="middle" x="309.6" y="-382.87" font-family="Helvetica,sans-Serif" font-size="8.00">2</text>
+</g>
+<!-- Phi_a11 -->
+<g id="node6" class="node">
+<title>Phi_a11</title>
+<ellipse fill="lightyellow" stroke="black" cx="196" cy="-403.35" rx="27" ry="18"/>
+<text text-anchor="middle" x="196" y="-399.65" font-family="Times,serif" font-size="14.00">φ_a</text>
+</g>
+<!-- Phi_a11&#45;&gt;Con_6 -->
+<g id="edge5" class="edge">
+<title>Phi_a11&#45;&gt;Con_6</title>
+<path fill="none" stroke="black" d="M196,-421.75C196,-433.09 196,-448.12 196,-461.03"/>
+<polygon fill="black" stroke="black" points="192.5,-461.25 196,-471.25 199.5,-461.25 192.5,-461.25"/>
+<text text-anchor="middle" x="193" y="-424.35" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Phi_a11&#45;&gt;Loop8 -->
+<g id="edge4" class="edge">
+<title>Phi_a11&#45;&gt;Loop8</title>
+<path fill="none" stroke="black" stroke-dasharray="1,5" d="M210.22,-387.78C218.37,-380.03 229.29,-371.45 241,-367.35 263.65,-359.4 272.35,-359.4 295,-367.35 302.14,-369.85 308.99,-374.02 315.09,-378.65"/>
+<polygon fill="black" stroke="black" points="312.99,-381.44 322.92,-385.13 317.45,-376.05 312.99,-381.44"/>
+<text text-anchor="middle" x="207.22" y="-381.38" font-family="Helvetica,sans-Serif" font-size="8.00">0</text>
+</g>
+<!-- Phi_a28 -->
+<g id="node17" class="node">
+<title>Phi_a28</title>
+<ellipse fill="lightyellow" stroke="black" cx="187" cy="-59.35" rx="27" ry="18"/>
+<text text-anchor="middle" x="187" y="-55.65" font-family="Times,serif" font-size="14.00">φ_a</text>
+</g>
+<!-- Phi_b12 -->
+<g id="node7" class="node">
+<title>Phi_b12</title>
+<ellipse fill="lightyellow" stroke="black" cx="124" cy="-403.35" rx="27.1" ry="18"/>
+<text text-anchor="middle" x="124" y="-399.65" font-family="Times,serif" font-size="14.00">φ_b</text>
+</g>
+<!-- Phi_b12&#45;&gt;Con_7 -->
+<g id="edge8" class="edge">
+<title>Phi_b12&#45;&gt;Con_7</title>
+<path fill="none" stroke="black" d="M124,-421.75C124,-433.09 124,-448.12 124,-461.03"/>
+<polygon fill="black" stroke="black" points="120.5,-461.25 124,-471.25 127.5,-461.25 120.5,-461.25"/>
+<text text-anchor="middle" x="121" y="-424.35" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Phi_b12&#45;&gt;Loop8 -->
+<g id="edge7" class="edge">
+<title>Phi_b12&#45;&gt;Loop8</title>
+<path fill="none" stroke="black" stroke-dasharray="1,5" d="M138.22,-387.78C146.37,-380.03 157.29,-371.45 169,-367.35 221.84,-348.81 242.16,-348.81 295,-367.35 302.14,-369.85 308.99,-374.02 315.09,-378.65"/>
+<polygon fill="black" stroke="black" points="312.99,-381.44 322.92,-385.13 317.45,-376.05 312.99,-381.44"/>
+<text text-anchor="middle" x="135.22" y="-381.38" font-family="Helvetica,sans-Serif" font-size="8.00">0</text>
+</g>
+<!-- Phi_b29 -->
+<g id="node18" class="node">
+<title>Phi_b29</title>
+<ellipse fill="lightyellow" stroke="black" cx="43" cy="-59.35" rx="27.1" ry="18"/>
+<text text-anchor="middle" x="43" y="-55.65" font-family="Times,serif" font-size="14.00">φ_b</text>
+</g>
+<!-- Con_13 -->
+<g id="node8" class="node">
+<title>Con_13</title>
+<ellipse fill="none" stroke="black" cx="268" cy="-403.35" rx="27" ry="18"/>
+<text text-anchor="middle" x="268" y="-399.65" font-family="Times,serif" font-size="14.00">10</text>
+</g>
+<!-- LT14 -->
+<g id="node9" class="node">
+<title>LT14</title>
+<ellipse fill="none" stroke="black" cx="271" cy="-331.35" rx="27" ry="18"/>
+<text text-anchor="middle" x="271" y="-327.65" font-family="Times,serif" font-size="14.00">&lt;</text>
+</g>
+<!-- LT14&#45;&gt;Phi_a11 -->
+<g id="edge10" class="edge">
+<title>LT14&#45;&gt;Phi_a11</title>
+<path fill="none" stroke="black" d="M255.82,-346.51C245.15,-356.47 230.68,-369.98 218.65,-381.21"/>
+<polygon fill="black" stroke="black" points="216.08,-378.82 211.15,-388.2 220.85,-383.94 216.08,-378.82"/>
+<text text-anchor="middle" x="252.82" y="-349.11" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- LT14&#45;&gt;Con_13 -->
+<g id="edge11" class="edge">
+<title>LT14&#45;&gt;Con_13</title>
+<path fill="none" stroke="black" d="M270.26,-349.65C269.93,-357.36 269.53,-366.63 269.16,-375.23"/>
+<polygon fill="black" stroke="black" points="265.66,-375.1 268.73,-385.24 272.66,-375.4 265.66,-375.1"/>
+<text text-anchor="middle" x="267.26" y="-352.25" font-family="Helvetica,sans-Serif" font-size="8.00">2</text>
+</g>
+<!-- If15 -->
+<g id="node10" class="node">
+<title>If15</title>
+<polygon fill="yellow" stroke="transparent" points="260,-248.35 260,-273.35 354,-273.35 354,-248.35 260,-248.35"/>
+<polygon fill="none" stroke="black" points="260,-248.35 260,-273.35 354,-273.35 354,-248.35 260,-248.35"/>
+<text text-anchor="start" x="301.5" y="-257.15" font-family="Times,serif" font-size="14.00">If</text>
+<polygon fill="none" stroke="black" points="260,-217.35 260,-248.35 354,-248.35 354,-217.35 260,-217.35"/>
+<polygon fill="yellow" stroke="transparent" points="265,-222.35 265,-243.35 305,-243.35 305,-222.35 265,-222.35"/>
+<polygon fill="none" stroke="black" points="265,-222.35 265,-243.35 305,-243.35 305,-222.35 265,-222.35"/>
+<text text-anchor="start" x="268" y="-229.15" font-family="Times,serif" font-size="14.00">True</text>
+<polygon fill="yellow" stroke="transparent" points="305,-222.35 305,-243.35 349,-243.35 349,-222.35 305,-222.35"/>
+<polygon fill="none" stroke="black" points="305,-222.35 305,-243.35 349,-243.35 349,-222.35 305,-222.35"/>
+<text text-anchor="start" x="308" y="-229.15" font-family="Times,serif" font-size="14.00">False</text>
+</g>
+<!-- If15&#45;&gt;Loop8 -->
+<g id="edge12" class="edge">
+<title>If15&#45;&gt;Loop8</title>
+<path fill="none" stroke="red" d="M314.79,-277.64C317.5,-288.87 320.49,-301.65 323,-313.35 327.43,-333.98 331.89,-357.43 335.12,-375.08"/>
+<polygon fill="red" stroke="red" points="331.74,-376.02 336.97,-385.24 338.63,-374.77 331.74,-376.02"/>
+<text text-anchor="middle" x="311.79" y="-280.24" font-family="Helvetica,sans-Serif" font-size="8.00">0</text>
+</g>
+<!-- If15&#45;&gt;LT14 -->
+<g id="edge13" class="edge">
+<title>If15&#45;&gt;LT14</title>
+<path fill="none" stroke="black" d="M293.59,-277.62C289.8,-286.48 285.72,-296.01 282.08,-304.5"/>
+<polygon fill="black" stroke="black" points="278.78,-303.32 278.05,-313.89 285.21,-306.08 278.78,-303.32"/>
+<text text-anchor="middle" x="290.59" y="-280.22" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Con_19 -->
+<g id="node11" class="node">
+<title>Con_19</title>
+<ellipse fill="none" stroke="black" cx="130" cy="-331.35" rx="27" ry="18"/>
+<text text-anchor="middle" x="130" y="-327.65" font-family="Times,serif" font-size="14.00">2</text>
+</g>
+<!-- EQ20 -->
+<g id="node12" class="node">
+<title>EQ20</title>
+<ellipse fill="none" stroke="black" cx="179" cy="-245.35" rx="27" ry="18"/>
+<text text-anchor="middle" x="179" y="-241.65" font-family="Times,serif" font-size="14.00">==</text>
+</g>
+<!-- EQ20&#45;&gt;Phi_a11 -->
+<g id="edge14" class="edge">
+<title>EQ20&#45;&gt;Phi_a11</title>
+<path fill="none" stroke="black" d="M180.85,-263.34C183.79,-290.3 189.54,-343.11 193.05,-375.31"/>
+<polygon fill="black" stroke="black" points="189.59,-375.81 194.15,-385.38 196.55,-375.06 189.59,-375.81"/>
+<text text-anchor="middle" x="177.85" y="-265.94" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- EQ20&#45;&gt;Con_19 -->
+<g id="edge15" class="edge">
+<title>EQ20&#45;&gt;Con_19</title>
+<path fill="none" stroke="black" d="M169.55,-262.54C162.5,-274.63 152.74,-291.37 144.67,-305.19"/>
+<polygon fill="black" stroke="black" points="141.43,-303.8 139.42,-314.2 147.48,-307.33 141.43,-303.8"/>
+<text text-anchor="middle" x="166.55" y="-265.14" font-family="Helvetica,sans-Serif" font-size="8.00">2</text>
+</g>
+<!-- If21 -->
+<g id="node13" class="node">
+<title>If21</title>
+<polygon fill="yellow" stroke="transparent" points="184,-148.35 184,-173.35 278,-173.35 278,-148.35 184,-148.35"/>
+<polygon fill="none" stroke="black" points="184,-148.35 184,-173.35 278,-173.35 278,-148.35 184,-148.35"/>
+<text text-anchor="start" x="225.5" y="-157.15" font-family="Times,serif" font-size="14.00">If</text>
+<polygon fill="none" stroke="black" points="184,-117.35 184,-148.35 278,-148.35 278,-117.35 184,-117.35"/>
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+<polygon fill="none" stroke="black" points="189,-122.35 189,-143.35 229,-143.35 229,-122.35 189,-122.35"/>
+<text text-anchor="start" x="192" y="-129.15" font-family="Times,serif" font-size="14.00">True</text>
+<polygon fill="yellow" stroke="transparent" points="229,-122.35 229,-143.35 273,-143.35 273,-122.35 229,-122.35"/>
+<polygon fill="none" stroke="black" points="229,-122.35 229,-143.35 273,-143.35 273,-122.35 229,-122.35"/>
+<text text-anchor="start" x="232" y="-129.15" font-family="Times,serif" font-size="14.00">False</text>
+</g>
+<!-- If21&#45;&gt;If15 -->
+<g id="edge16" class="edge">
+<title>If21&#45;&gt;If15:p0</title>
+<path fill="none" stroke="red" d="M266.11,-177.35C274.25,-187.13 281.31,-198.68 283.92,-211.16"/>
+<polygon fill="red" stroke="red" points="280.47,-211.77 285,-221.35 287.43,-211.03 280.47,-211.77"/>
+<text text-anchor="middle" x="263.11" y="-179.95" font-family="Helvetica,sans-Serif" font-size="8.00">0</text>
+</g>
+<!-- If21&#45;&gt;EQ20 -->
+<g id="edge17" class="edge">
+<title>If21&#45;&gt;EQ20</title>
+<path fill="none" stroke="black" d="M214.55,-177.35C207.43,-190.76 199.21,-206.25 192.47,-218.96"/>
+<polygon fill="black" stroke="black" points="189.24,-217.58 187.65,-228.05 195.42,-220.86 189.24,-217.58"/>
+<text text-anchor="middle" x="211.55" y="-179.95" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Con_25 -->
+<g id="node14" class="node">
+<title>Con_25</title>
+<ellipse fill="none" stroke="black" cx="111" cy="-145.35" rx="27" ry="18"/>
+<text text-anchor="middle" x="111" y="-141.65" font-family="Times,serif" font-size="14.00">3</text>
+</g>
+<!-- Con_26 -->
+<g id="node15" class="node">
+<title>Con_26</title>
+<ellipse fill="none" stroke="black" cx="115" cy="-59.35" rx="27" ry="18"/>
+<text text-anchor="middle" x="115" y="-55.65" font-family="Times,serif" font-size="14.00">4</text>
+</g>
+<!-- Region27&#45;&gt;If21 -->
+<g id="edge18" class="edge">
+<title>Region27&#45;&gt;If21:p0</title>
+<path fill="none" stroke="red" d="M236.34,-77.55C225.26,-86.1 214.31,-97.52 210.45,-111.09"/>
+<polygon fill="red" stroke="red" points="206.94,-110.95 209,-121.35 213.87,-111.94 206.94,-110.95"/>
+<text text-anchor="middle" x="233.34" y="-80.15" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Region27&#45;&gt;If21 -->
+<g id="edge19" class="edge">
+<title>Region27&#45;&gt;If21:p1</title>
+<path fill="none" stroke="red" d="M258.9,-77.46C255.95,-86.91 252.79,-99.16 251.55,-111.27"/>
+<polygon fill="red" stroke="red" points="248.05,-111.17 251,-121.35 255.04,-111.55 248.05,-111.17"/>
+<text text-anchor="middle" x="255.9" y="-80.06" font-family="Helvetica,sans-Serif" font-size="8.00">2</text>
+</g>
+<!-- Phi_a28&#45;&gt;Phi_a11 -->
+<g id="edge22" class="edge">
+<title>Phi_a28&#45;&gt;Phi_a11</title>
+<path fill="none" stroke="black" d="M156.38,-74.81C123.24,-90.46 75.08,-113.23 75,-113.35 59.78,-137.38 66.63,-150.16 75,-177.35 90.81,-228.71 98.49,-247.23 143,-277.35 204.81,-319.16 260.23,-255.2 307,-313.35 317.03,-325.81 315.54,-335.81 307,-349.35 306.7,-349.82 259.29,-372.35 226.54,-387.88"/>
+<polygon fill="black" stroke="black" points="158.14,-77.85 165.69,-70.41 155.15,-71.52 158.14,-77.85"/>
+<polygon fill="black" stroke="black" points="224.86,-384.81 217.32,-392.25 227.86,-391.13 224.86,-384.81"/>
+<text text-anchor="middle" x="162.69" y="-73.01" font-family="Helvetica,sans-Serif" font-size="8.00">2</text>
+</g>
+<!-- Phi_a28&#45;&gt;Con_25 -->
+<g id="edge21" class="edge">
+<title>Phi_a28&#45;&gt;Con_25</title>
+<path fill="none" stroke="black" d="M173.41,-75.36C161.74,-88.26 144.74,-107.05 131.43,-121.77"/>
+<polygon fill="black" stroke="black" points="128.58,-119.7 124.47,-129.46 133.77,-124.39 128.58,-119.7"/>
+<text text-anchor="middle" x="170.41" y="-77.96" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Phi_a28&#45;&gt;Region27 -->
+<g id="edge20" class="edge">
+<title>Phi_a28&#45;&gt;Region27</title>
+<path fill="none" stroke="black" stroke-dasharray="1,5" d="M214.12,-59.35C216.58,-59.35 219.04,-59.35 221.5,-59.35"/>
+<polygon fill="black" stroke="black" points="221.61,-62.85 231.61,-59.35 221.61,-55.85 221.61,-62.85"/>
+<text text-anchor="middle" x="217.12" y="-52.95" font-family="Helvetica,sans-Serif" font-size="8.00">0</text>
+</g>
+<!-- Phi_b29&#45;&gt;Phi_b12 -->
+<g id="edge24" class="edge">
+<title>Phi_b29&#45;&gt;Phi_b12</title>
+<path fill="none" stroke="black" d="M44.59,-87.64C48.34,-139.92 60.11,-257.16 94,-349.35 97.54,-358.97 102.7,-368.9 107.74,-377.53"/>
+<polygon fill="black" stroke="black" points="48.07,-87.25 43.91,-77.51 41.09,-87.72 48.07,-87.25"/>
+<polygon fill="black" stroke="black" points="104.9,-379.59 113.09,-386.31 110.88,-375.95 104.9,-379.59"/>
+<text text-anchor="middle" x="40.91" y="-80.11" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Phi_b29&#45;&gt;Con_26 -->
+<g id="edge25" class="edge">
+<title>Phi_b29&#45;&gt;Con_26</title>
+<path fill="none" stroke="black" d="M70.56,-59.35C73,-59.35 75.44,-59.35 77.89,-59.35"/>
+<polygon fill="black" stroke="black" points="77.92,-62.85 87.92,-59.35 77.92,-55.85 77.92,-62.85"/>
+<text text-anchor="middle" x="73.56" y="-52.95" font-family="Helvetica,sans-Serif" font-size="8.00">2</text>
+</g>
+<!-- Phi_b29&#45;&gt;Region27 -->
+<g id="edge23" class="edge">
+<title>Phi_b29&#45;&gt;Region27</title>
+<path fill="none" stroke="black" stroke-dasharray="1,5" d="M54.68,-42.66C62.75,-32.67 74.44,-20.87 88,-15.35 139.86,5.79 161.51,4.17 214,-15.35 224.63,-19.3 234.53,-26.57 242.72,-34.08"/>
+<polygon fill="black" stroke="black" points="240.44,-36.75 250.02,-41.26 245.34,-31.75 240.44,-36.75"/>
+<text text-anchor="middle" x="51.68" y="-36.26" font-family="Helvetica,sans-Serif" font-size="8.00">0</text>
+</g>
+<!-- Return30&#45;&gt;Phi_b12 -->
+<g id="edge27" class="edge">
+<title>Return30&#45;&gt;Phi_b12</title>
+<path fill="none" stroke="black" d="M313.98,-163.53C307.84,-168.06 301.19,-172.92 295,-177.35 272.13,-193.69 260.87,-191.65 243,-213.35 223.27,-237.31 230.02,-250.17 215,-277.35 196.27,-311.22 188.92,-318.16 166,-349.35 158.65,-359.34 150.22,-370.11 142.84,-379.32"/>
+<polygon fill="black" stroke="black" points="139.98,-377.29 136.43,-387.27 145.43,-381.68 139.98,-377.29"/>
+<text text-anchor="middle" x="310.98" y="-166.13" font-family="Helvetica,sans-Serif" font-size="8.00">1</text>
+</g>
+<!-- Return30&#45;&gt;If15 -->
+<g id="edge26" class="edge">
+<title>Return30&#45;&gt;If15:p1</title>
+<path fill="none" stroke="red" d="M333.39,-163.54C331,-176.2 328.14,-194.14 327.27,-211.34"/>
+<polygon fill="red" stroke="red" points="323.77,-211.26 327,-221.35 330.76,-211.44 323.77,-211.26"/>
+<text text-anchor="middle" x="330.39" y="-166.14" font-family="Helvetica,sans-Serif" font-size="8.00">0</text>
+</g>
+</g>
+</svg>
diff --git a/chapter07/docs/build-graphs.sh b/chapter07/docs/build-graphs.sh
new file mode 100644
index 00000000..27b2b72f
--- /dev/null
+++ b/chapter07/docs/build-graphs.sh
@@ -0,0 +1,6 @@
+dot -Tsvg 07-graph1.gv > 07-graph1.svg
+dot -Tsvg 07-graph2.gv > 07-graph2.svg
+dot -Tsvg 07-graph3.gv > 07-graph3.svg
+dot -Tsvg 07-graph4.gv > 07-graph4.svg
+
+
diff --git a/chapter07/pom.xml b/chapter07/pom.xml
new file mode 100644
index 00000000..28d119b5
--- /dev/null
+++ b/chapter07/pom.xml
@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+ xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+ xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+ <modelVersion>4.0.0</modelVersion>
+ <parent>
+ <groupId>com.seaofnodes</groupId>
+ <artifactId>simple</artifactId>
+ <version>1.0</version>
+ </parent>
+ <artifactId>chapter07</artifactId>
+ <packaging>jar</packaging>
+ <name>Chapter 7</name>
+</project> \ No newline at end of file
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/GraphVisualizer.java b/chapter07/src/main/java/com/seaofnodes/simple/GraphVisualizer.java
new file mode 100644
index 00000000..ce3522bc
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/GraphVisualizer.java
@@ -0,0 +1,256 @@
+package com.seaofnodes.simple;
+
+import com.seaofnodes.simple.node.*;
+
+import java.util.*;
+
+/**
+ * Simple visualizer that outputs GraphViz dot format.
+ * The dot output must be saved to a file and run manually via dot to generate the SVG output.
+ * Currently, this is done manually.
+ */
+public class GraphVisualizer {
+
+ /**
+ * If set to true we put the control nodes in a separate cluster from
+ * data nodes.
+ */
+ boolean _separateControlCluster = false;
+
+ public GraphVisualizer(boolean separateControlCluster) { this._separateControlCluster = separateControlCluster; }
+ public GraphVisualizer() { this(false); }
+
+ public String generateDotOutput(Parser parser) {
+
+ // Since the graph has cycles, we need to create a flat list of all the
+ // nodes in the graph.
+ Collection<Node> all = findAll(parser);
+ StringBuilder sb = new StringBuilder();
+ sb.append("digraph chapter07 {\n");
+ sb.append("/*\n");
+ sb.append(parser.src());
+ sb.append("\n*/\n");
+
+ // To keep the Scopes below the graph and pointing up into the graph we
+ // need to group the Nodes in a subgraph cluster, and the scopes into a
+ // different subgraph cluster. THEN we can draw edges between the
+ // scopes and nodes. If we try to cross subgraph cluster borders while
+ // still making the subgraphs DOT gets confused.
+ sb.append("\trankdir=BT;\n"); // Force Nodes before Scopes
+
+ // Preserve node input order
+ sb.append("\tordering=\"in\";\n");
+
+ // Merge multiple edges hitting the same node. Makes common shared
+ // nodes much prettier to look at.
+ sb.append("\tconcentrate=\"true\";\n");
+
+ // Force nested scopes to order
+ sb.append("\tcompound=\"true\";\n");
+
+ // Just the Nodes first, in a cluster no edges
+ nodes(sb, all);
+
+ // Now the scopes, in a cluster no edges
+ scope(sb,parser._scope );
+ for( ScopeNode scope : parser._xScopes )
+ scope( sb, scope );
+
+ // Walk the Node edges
+ nodeEdges(sb, all);
+
+ // Walk the active Scope edges
+ scopeEdges( sb, parser._scope );
+ for( ScopeNode scope : parser._xScopes )
+ scopeEdges( sb, scope );
+
+ sb.append("}\n");
+ return sb.toString();
+ }
+
+ private void nodesByCluster(StringBuilder sb, boolean doCtrl, Collection<Node> all) {
+ if (!_separateControlCluster && doCtrl) // all nodes in 1 cluster
+ return;
+ // Just the Nodes first, in a cluster no edges
+ sb.append(doCtrl ? "\tsubgraph cluster_Controls {\n" : "\tsubgraph cluster_Nodes {\n"); // Magic "cluster_" in the subgraph name
+ for (Node n : all) {
+ if (n instanceof ProjNode || n instanceof ScopeNode)
+ continue; // Do not emit, rolled into MultiNode or Scope cluster already
+ if (_separateControlCluster && doCtrl && !n.isCFG()) continue;
+ if (_separateControlCluster && !doCtrl && n.isCFG()) continue;
+ sb.append("\t\t").append(n.uniqueName()).append(" [ ");
+ String lab = n.glabel();
+ if (n instanceof MultiNode) {
+ // Make a box with the MultiNode on top, and all the projections on the bottom
+ sb.append("shape=plaintext label=<\n");
+ sb.append("\t\t\t<TABLE BORDER=\"0\" CELLBORDER=\"1\" CELLSPACING=\"0\" CELLPADDING=\"4\">\n");
+ sb.append("\t\t\t<TR><TD BGCOLOR=\"yellow\">").append(lab).append("</TD></TR>\n");
+ sb.append("\t\t\t<TR>");
+ boolean doProjTable = false;
+ for (Node use : n._outputs) {
+ if (use instanceof ProjNode proj) {
+ if (!doProjTable) {
+ doProjTable = true;
+ sb.append("<TD>").append("\n");
+ sb.append("\t\t\t\t<TABLE BORDER=\"0\" CELLBORDER=\"1\" CELLSPACING=\"0\">").append("\n");
+ sb.append("\t\t\t\t<TR>");
+ }
+ sb.append("<TD PORT=\"p").append(proj._idx).append("\"");
+ if (proj.isCFG()) sb.append(" BGCOLOR=\"yellow\"");
+ sb.append(">").append(proj.glabel()).append("</TD>");
+ }
+ }
+ if (doProjTable) {
+ sb.append("</TR>").append("\n");
+ sb.append("\t\t\t\t</TABLE>").append("\n");
+ sb.append("\t\t\t</TD>");
+ }
+ sb.append("</TR>\n");
+ sb.append("\t\t\t</TABLE>>\n\t\t");
+
+ } else {
+ // control nodes have box shape
+ // other nodes are ellipses, i.e. default shape
+ if (n.isCFG()) sb.append("shape=box style=filled fillcolor=yellow ");
+ else if (n instanceof PhiNode) sb.append("style=filled fillcolor=lightyellow ");
+ sb.append("label=\"").append(lab).append("\" ");
+ }
+ sb.append("];\n");
+ }
+ if (!_separateControlCluster) {
+ // Force Region & Phis to line up
+ for (Node n : all) {
+ if (n instanceof RegionNode region) {
+ sb.append("\t\t{ rank=same; ");
+ sb.append(region).append(";");
+ for (Node phi : region._outputs)
+ if (phi instanceof PhiNode) sb.append(phi.uniqueName()).append(";");
+ sb.append("}\n");
+ }
+ }
+ }
+ sb.append("\t}\n"); // End Node cluster
+ }
+
+ private void nodes(StringBuilder sb, Collection<Node> all) {
+ nodesByCluster(sb, true, all);
+ nodesByCluster(sb, false, all);
+ }
+
+ // Build a nested scope display, walking the _prev edge
+ private void scope( StringBuilder sb, ScopeNode scope ) {
+ sb.append("\tnode [shape=plaintext];\n");
+ int level=1;
+ for( int idx = scope._scopes.size()-1; idx>=0; idx-- ) {
+ var syms = scope._scopes.get(idx);
+ String scopeName = makeScopeName(scope, level);
+ sb.append("\tsubgraph cluster_").append(scopeName).append(" {\n"); // Magic "cluster_" in the subgraph name
+ sb.append("\t\t").append(scopeName).append(" [label=<\n");
+ sb.append("\t\t\t<TABLE BORDER=\"0\" CELLBORDER=\"1\" CELLSPACING=\"0\">\n");
+ // Add the scope level
+ int scopeLevel = scope._scopes.size()-level;
+ sb.append("\t\t\t<TR><TD BGCOLOR=\"cyan\">").append(scopeLevel).append("</TD>");
+ for(String name: syms.keySet())
+ sb.append("<TD PORT=\"").append(makePortName(scopeName, name)).append("\">").append(name).append("</TD>");
+ sb.append("</TR>\n");
+ sb.append("\t\t\t</TABLE>>];\n");
+ level++;
+ }
+ // Scope clusters nest, so the graphics shows the nested scopes, so
+ // they are not closed as they are printed; so they just keep nesting.
+ // We close them all at once here.
+ sb.append( "\t}\n".repeat( level-1 ) ); // End all Scope clusters
+ }
+
+ private String makeScopeName(ScopeNode sn, int level) { return sn.uniqueName() + "_" + level; }
+ private String makePortName(String scopeName, String varName) { return scopeName + "_" + varName; }
+
+ // Walk the node edges
+ private void nodeEdges(StringBuilder sb, Collection<Node> all) {
+ // All them edge labels
+ sb.append("\tedge [ fontname=Helvetica, fontsize=8 ];\n");
+ for( Node n : all ) {
+ // Do not display the Constant->Start edge;
+ // ProjNodes handled by Multi;
+ // ScopeNodes are done separately
+ if( n instanceof ConstantNode || n instanceof ProjNode || n instanceof ScopeNode )
+ continue;
+ for( int i=0; i<n.nIns(); i++ ) {
+ Node def = n.in(i);
+ if( n instanceof PhiNode && def instanceof RegionNode ) {
+ // Draw a dotted use->def edge from Phi to Region.
+ sb.append('\t').append(n.uniqueName());
+ sb.append(" -> ");
+ sb.append(def.uniqueName());
+ sb.append(" [style=dotted taillabel=").append(i).append("];\n");
+ } else if( def != null ) {
+ // Most edges land here use->def
+ sb.append('\t').append(n.uniqueName()).append(" -> ");
+ if( def instanceof ProjNode proj ) {
+ String mname = proj.ctrl().uniqueName();
+ sb.append(mname).append(":p").append(proj._idx);
+ } else sb.append(def.uniqueName());
+ // Number edges, so we can see how they track
+ sb.append("[taillabel=").append(i);
+ // control edges are colored red
+ if( def.isCFG() )
+ sb.append(" color=red");
+ // Backedges do not add a ranking constraint
+ if( i==2 && (n instanceof PhiNode || n instanceof LoopNode) )
+ sb.append(" constraint=false");
+ sb.append("];\n");
+ }
+ }
+ }
+ }
+
+ // Walk the scope edges
+ private void scopeEdges( StringBuilder sb, ScopeNode scope ) {
+ sb.append("\tedge [style=dashed color=cornflowerblue];\n");
+ int level=1;
+ for( int i = scope._scopes.size()-1; i>=0; i-- ) {
+ var syms = scope._scopes.get(i);
+ String scopeName = makeScopeName(scope, level);
+ for( String name : syms.keySet() ) {
+ int idx = syms.get(name);
+ Node def = scope.in(idx);
+ if( def==null ) continue;
+ sb.append("\t")
+ .append(scopeName).append(":")
+ .append('"').append(makePortName(scopeName, name)).append('"') // wrap port name with quotes because $ctrl is not valid unquoted
+ .append(" -> ");
+ if( def instanceof ProjNode proj ) {
+ String mname = proj.ctrl().uniqueName();
+ sb.append(mname).append(":p").append(proj._idx);
+ } else sb.append(def.uniqueName());
+ sb.append(";\n");
+ }
+ level++;
+ }
+ }
+
+ /**
+ * Finds all nodes in the graph.
+ */
+ private Collection<Node> findAll(Parser parser) {
+ final HashMap<Integer, Node> all = new HashMap<>();
+ for( Node n : Parser.START._outputs )
+ walk(all, n);
+ for( Node n : parser._scope._inputs )
+ walk(all, n);
+ return all.values();
+ }
+
+ /**
+ * Walk a subgraph and populate distinct nodes in the all list.
+ */
+ private void walk(HashMap<Integer,Node> all, Node n) {
+ if(n == null ) return;
+ if (all.get(n._nid) != null) return; // Been there, done that
+ all.put(n._nid, n);
+ for (Node c : n._inputs)
+ walk(all, c);
+ for( Node c : n._outputs )
+ walk(all, c);
+ }
+}
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/IRPrinter.java b/chapter07/src/main/java/com/seaofnodes/simple/IRPrinter.java
new file mode 100644
index 00000000..dc6d9f4f
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/IRPrinter.java
@@ -0,0 +1,124 @@
+package com.seaofnodes.simple;
+
+import com.seaofnodes.simple.node.LoopNode;
+import com.seaofnodes.simple.node.Node;
+
+import java.util.ArrayList;
+import java.util.BitSet;
+
+public class IRPrinter {
+
+ // Another bulk pretty-printer. Makes more effort at basic-block grouping.
+ public static String prettyPrint(Node node, int depth) {
+ // First, a Breadth First Search at a fixed depth.
+ BFS bfs = new BFS(node,depth);
+ // Convert just that set to a post-order
+ ArrayList<Node> rpos = new ArrayList<>();
+ BitSet visit = new BitSet();
+ for( int i=bfs._lim; i< bfs._bfs.size(); i++ )
+ postOrd( bfs._bfs.get(i), rpos, visit, bfs._bs);
+ // Reverse the post-order walk
+ StringBuilder sb = new StringBuilder();
+ boolean gap=false;
+ for( int i=rpos.size()-1; i>=0; i-- ) {
+ Node n = rpos.get(i);
+ if( n.isCFG() || n.isMultiHead() ) {
+ if( !gap ) sb.append("\n"); // Blank before multihead
+ n._print_line(sb); // Print head
+ while( --i >= 0 ) {
+ Node t = rpos.get(i);
+ if( !t.isMultiTail() ) { i++; break; }
+ t._print_line(sb);
+ }
+ sb.append("\n"); // Blank after multitail
+ gap = true;
+ } else {
+ n._print_line( sb );
+ gap = false;
+ }
+ }
+ return sb.toString();
+ }
+
+ private static void postOrd(Node n, ArrayList<Node> rpos, BitSet visit, BitSet bfs) {
+ if( !bfs.get(n._nid) )
+ return; // Not in the BFS visit
+ if( visit.get(n._nid) ) return; // Already post-order walked
+ visit.set(n._nid);
+ // First walk the CFG, then everything
+ if( n.isCFG() ) {
+ for( Node use : n._outputs )
+ if( use.isCFG() && use.nOuts()>=1 && !(use._outputs.get(0) instanceof LoopNode) )
+ postOrd(use, rpos,visit,bfs);
+ for( Node use : n._outputs )
+ if( use.isCFG() )
+ postOrd(use,rpos,visit,bfs);
+ }
+ for( Node use : n._outputs )
+ postOrd(use, rpos,visit,bfs);
+ // Post-order
+ rpos.add(n);
+ }
+
+ // Breadth-first search, broken out in a class to keep in more independent.
+ // Maintains a root-set of Nodes at the limit (or past by 1 if MultiHead).
+ public static class BFS {
+ // A breadth first search, plus MultiHeads for any MultiTails
+ public final ArrayList<Node> _bfs;
+ public final BitSet _bs; // Visited members by node id
+ public final int _depth; // Depth limit
+ public final int _lim; // From here to _bfs._len can be roots for a reverse search
+ public BFS( Node base, int d ) {
+ _depth = d;
+ _bfs = new ArrayList<>();
+ _bs = new BitSet();
+
+ add(base); // Prime the pump
+ int idx=0, lim=1; // Limit is where depth counter changes
+ while( idx < _bfs.size() ) { // Ran out of nodes below depth
+ Node n = _bfs.get(idx++);
+ for( Node def : n._inputs )
+ if( def!=null && !_bs.get(def._nid) )
+ add(def);
+ if( idx==lim ) { // Depth counter changes at limit
+ if( --d < 0 )
+ break; // Ran out of depth
+ lim = _bfs.size(); // New depth limit
+ }
+ }
+ // Toss things past the limit except multi-heads
+ while( idx < _bfs.size() ) {
+ Node n = _bfs.get(idx);
+ if( n.isMultiHead() ) idx++;
+ else del(idx);
+ }
+ // Root set is any node with no inputs in the visited set
+ lim = _bfs.size();
+ for( int i=_bfs.size()-1; i>=0; i-- )
+ if( !any_visited(_bfs.get(i)) )
+ swap( i,--lim);
+ _lim = lim;
+ }
+ void swap( int x, int y ) {
+ if( x==y ) return;
+ Node tx = _bfs.get(x);
+ Node ty = _bfs.get(y);
+ _bfs.set(x,ty);
+ _bfs.set(y,tx);
+ }
+ void add(Node n) {
+ _bfs.add(n);
+ _bs.set(n._nid);
+ }
+ void del(int idx) {
+ Node n = Utils.del(_bfs, idx);
+ _bs.clear(n._nid);
+ }
+ boolean any_visited( Node n ) {
+ for( Node def : n._inputs )
+ if( def!=null && _bs.get(def._nid) )
+ return true;
+ return false;
+ }
+ }
+}
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/Parser.java b/chapter07/src/main/java/com/seaofnodes/simple/Parser.java
new file mode 100644
index 00000000..99594c95
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/Parser.java
@@ -0,0 +1,572 @@
+package com.seaofnodes.simple;
+
+import com.seaofnodes.simple.node.*;
+import com.seaofnodes.simple.type.*;
+
+import java.util.*;
+
+/**
+ * The Parser converts a Simple source program to the Sea of Nodes intermediate
+ * representation directly in one pass. There is no intermediate Abstract
+ * Syntax Tree structure.
+ * <p>
+ * This is a simple recursive descent parser. All lexical analysis is done here as well.
+ */
+public class Parser {
+ /**
+ * A Global Static, unique to each compilation. This is a public, so we
+ * can make constants everywhere without having to thread the StartNode
+ * through the entire parser and optimizer.
+ * <p>
+ * To make the compiler multithreaded, this field will have to move into a TLS.
+ */
+ public static StartNode START;
+
+ public StopNode STOP;
+
+ // The Lexer. Thin wrapper over a byte[] buffer with a cursor.
+ private final Lexer _lexer;
+
+ /**
+ * Current ScopeNode - ScopeNodes change as we parse code, but at any point of time
+ * there is one current ScopeNode. The reason the current ScopeNode can change is to do with how
+ * we handle branching. See {@link #parseIf()}.
+ * <p>
+ * Each ScopeNode contains a stack of lexical scopes, each scope is a symbol table that binds
+ * variable names to Nodes. The top of this stack represents current scope.
+ * <p>
+ * We keep a list of all ScopeNodes so that we can show them in graphs.
+ * @see #parseIf()
+ * @see #_xScopes
+ */
+ public ScopeNode _scope;
+
+ /**
+ * List of keywords disallowed as identifiers
+ */
+ private final HashSet<String> KEYWORDS = new HashSet<>(){{
+ add("else");
+ add("false");
+ add("if");
+ add("int");
+ add("return");
+ add("true");
+ add("while");
+ }};
+
+
+ /**
+ * We clone ScopeNodes when control flows branch; it is useful to have
+ * a list of all active ScopeNodes for purposes of visualization of the SoN graph
+ */
+ public final Stack<ScopeNode> _xScopes = new Stack<>();
+
+ public Parser(String source, TypeInteger arg) {
+ Node.reset();
+ _lexer = new Lexer(source);
+ _scope = new ScopeNode();
+ START = new StartNode(new Type[]{ Type.CONTROL, arg });
+ STOP = new StopNode();
+ }
+
+ public Parser(String source) {
+ this(source, TypeInteger.BOT);
+ }
+
+ @Override
+ public String toString() { return _lexer.toString(); }
+
+ String src() { return new String( _lexer._input ); }
+
+ // Debugging utility to find a Node by index
+ public static Node find(int nid) { return START.find(nid); }
+
+ private Node ctrl() { return _scope.ctrl(); }
+
+ private Node ctrl(Node n) { return _scope.ctrl(n); }
+
+ public StopNode parse() { return parse(false); }
+ public StopNode parse(boolean show) {
+ // Enter a new scope for the initial control and arguments
+ _scope.push();
+ _scope.define(ScopeNode.CTRL, new ProjNode(START, 0, ScopeNode.CTRL).peephole());
+ _scope.define(ScopeNode.ARG0, new ProjNode(START, 1, ScopeNode.ARG0).peephole());
+ parseBlock();
+ _scope.pop();
+ if (!_lexer.isEOF()) throw error("Syntax error, unexpected " + _lexer.getAnyNextToken());
+ STOP.peephole();
+ if( show ) showGraph();
+ return STOP;
+ }
+
+
+ /**
+ * Parses a block
+ *
+ * <pre>
+ * '{' statements '}'
+ * </pre>
+ * Does not parse the opening or closing '{}'
+ * @return a {@link Node} or {@code null}
+ */
+ private Node parseBlock() {
+ // Enter a new scope
+ _scope.push();
+ while (!peek('}') && !_lexer.isEOF())
+ parseStatement();
+ // Exit scope
+ _scope.pop();
+ return null;
+ }
+
+ /**
+ * Parses a statement
+ *
+ * <pre>
+ * returnStatement | declStatement | blockStatement | ifStatement | expressionStatement
+ * </pre>
+ * @return a {@link Node} or {@code null}
+ */
+ private Node parseStatement() {
+ if (matchx("return") ) return parseReturn();
+ else if (matchx("int")) return parseDecl();
+ else if (match ("{" )) return require(parseBlock(),"}");
+ else if (matchx("if" )) return parseIf();
+ else if (matchx("while")) return parseWhile();
+ else if (matchx("#showGraph")) return require(showGraph(),";");
+ else return parseExpressionStatement();
+ }
+
+ /**
+ * Parses a while statement
+ *
+ * <pre>
+ * while ( expression ) statement
+ * </pre>
+ * @return a {@link Node}, never {@code null}
+ */
+ private Node parseWhile() {
+ require("(");
+
+ // Loop region has two control inputs, the first one is the entry
+ // point, and second one is back edge that is set after loop is parsed
+ // (see end_loop() call below). Note that the absence of back edge is
+ // used as an indicator to switch off peepholes of the region and
+ // associated phis.
+
+ ctrl(new LoopNode(ctrl(),null).peephole());
+ ScopeNode head = _xScopes.push(_scope).keep(); // Save the current scope as the loop head
+ // Make a new Scope for the body.
+ _scope = _scope.dup(true);
+
+ // Parse predicate
+ var pred = require(parseExpression(), ")");
+ // IfNode takes current control and predicate
+ IfNode ifNode = (IfNode)new IfNode(ctrl(), pred).<IfNode>keep().peephole();
+ // Setup projection nodes
+ Node ifT = new ProjNode(ifNode, 0, "True" ).peephole();
+ ifNode.unkeep();
+ Node ifF = new ProjNode(ifNode, 1, "False").peephole();
+ // The exit scope, accounting for any side effects in the predicate
+ var exit = _scope.dup();
+ _xScopes.push(exit);
+ exit.ctrl(ifF);
+
+ // Parse the true side, which corresponds to loop body
+ ctrl(ifT); // set ctrl token to ifTrue projection
+ parseStatement(); // Parse loop body
+
+ // The true branch loops back, so whatever is current control gets
+ // added to head loop as input
+ head.endLoop(_scope, exit);
+ head.unkeep().kill();
+ _xScopes.pop();
+ _xScopes.pop(); // Discard pushed from graph display
+
+ // At exit the false control is the current control, and
+ // the scope is the exit scope after the exit test.
+ return (_scope = exit);
+ }
+
+ /**
+ * Parses a statement
+ *
+ * <pre>
+ * if ( expression ) statement [else statement]
+ * </pre>
+ * @return a {@link Node}, never {@code null}
+ */
+ private Node parseIf() {
+ require("(");
+ // Parse predicate
+ var pred = require(parseExpression(), ")");
+ // IfNode takes current control and predicate
+ IfNode ifNode = (IfNode)new IfNode(ctrl(), pred).<IfNode>keep().peephole();
+ // Setup projection nodes
+ Node ifT = new ProjNode(ifNode, 0, "True" ).peephole();
+ ifNode.unkeep();
+ Node ifF = new ProjNode(ifNode, 1, "False").peephole();
+ // In if true branch, the ifT proj node becomes the ctrl
+ // But first clone the scope and set it as current
+ int ndefs = _scope.nIns();
+ ScopeNode fScope = _scope.dup(); // Duplicate current scope
+ _xScopes.push(fScope); // For graph visualization we need all scopes
+
+ // Parse the true side
+ ctrl(ifT); // set ctrl token to ifTrue projection
+ parseStatement(); // Parse true-side
+ ScopeNode tScope = _scope;
+
+ // Parse the false side
+ _scope = fScope; // Restore scope, then parse else block if any
+ ctrl(ifF); // Ctrl token is now set to ifFalse projection
+ if (matchx("else")) {
+ parseStatement();
+ fScope = _scope;
+ }
+
+ if( tScope.nIns() != ndefs || fScope.nIns() != ndefs )
+ throw error("Cannot define a new name on one arm of an if");
+
+ // Merge results
+ _scope = tScope;
+ _xScopes.pop(); // Discard pushed from graph display
+
+ return ctrl(tScope.mergeScopes(fScope));
+ }
+
+
+ /**
+ * Parses a return statement; "return" already parsed.
+ * The $ctrl edge is killed.
+ *
+ * <pre>
+ * 'return' expr ;
+ * </pre>
+ * @return an expression {@link Node}, never {@code null}
+ */
+ private Node parseReturn() {
+ var expr = require(parseExpression(), ";");
+ Node ret = STOP.addReturn(new ReturnNode(ctrl(), expr).peephole());
+ ctrl(new ConstantNode(Type.XCONTROL).peephole()); // Kill control
+ return ret;
+ }
+
+ /**
+ * Dumps out the node graph
+ * @return {@code null}
+ */
+ private Node showGraph() {
+ System.out.println(new GraphVisualizer().generateDotOutput(this));
+ return null;
+ }
+
+ /**
+ * Parses an expression statement
+ *
+ * <pre>
+ * name '=' expression ';'
+ * </pre>
+ * @return an expression {@link Node}, never {@code null}
+ */
+ private Node parseExpressionStatement() {
+ var name = requireId();
+ require("=");
+ var expr = require(parseExpression(), ";");
+ if( _scope.update(name, expr)==null )
+ throw error("Undefined name '" + name + "'");
+ return expr;
+ }
+
+ /**
+ * Parses a declStatement
+ *
+ * <pre>
+ * 'int' name = expression ';'
+ * </pre>
+ * @return an expression {@link Node}, never {@code null}
+ */
+ private Node parseDecl() {
+ // Type is 'int' for now
+ var name = requireId();
+ require("=");
+ var expr = require(parseExpression(), ";");
+ if( _scope.define(name,expr) == null )
+ throw error("Redefining name '" + name + "'");
+ return expr;
+ }
+
+ /**
+ * Parse an expression of the form:
+ *
+ * <pre>
+ * expr : compareExpr
+ * </pre>
+ * @return an expression {@link Node}, never {@code null}
+ */
+ private Node parseExpression() { return parseComparison(); }
+
+ /**
+ * Parse an expression of the form:
+ *
+ * <pre>
+ * expr : additiveExpr op additiveExpr
+ * </pre>
+ * @return an comparator expression {@link Node}, never {@code null}
+ */
+ private Node parseComparison() {
+ var lhs = parseAddition();
+ if (match("==")) return new BoolNode.EQ(lhs, parseComparison()).peephole();
+ if (match("!=")) return new NotNode(new BoolNode.EQ(lhs, parseComparison()).peephole()).peephole();
+ if (match("<" )) return new BoolNode.LT(lhs, parseComparison()).peephole();
+ if (match("<=")) return new BoolNode.LE(lhs, parseComparison()).peephole();
+ if (match(">" )) return new BoolNode.LT(parseComparison(), lhs).peephole();
+ if (match(">=")) return new BoolNode.LE(parseComparison(), lhs).peephole();
+ return lhs;
+ }
+
+ /**
+ * Parse an additive expression
+ *
+ * <pre>
+ * additiveExpr : multiplicativeExpr (('+' | '-') multiplicativeExpr)*
+ * </pre>
+ * @return an add expression {@link Node}, never {@code null}
+ */
+ private Node parseAddition() {
+ var lhs = parseMultiplication();
+ if (match("+")) return new AddNode(lhs, parseAddition()).peephole();
+ if (match("-")) return new SubNode(lhs, parseAddition()).peephole();
+ return lhs;
+ }
+
+ /**
+ * Parse an multiplicativeExpr expression
+ *
+ * <pre>
+ * multiplicativeExpr : unaryExpr (('*' | '/') unaryExpr)*
+ * </pre>
+ * @return a multiply expression {@link Node}, never {@code null}
+ */
+ private Node parseMultiplication() {
+ var lhs = parseUnary();
+ if (match("*")) return new MulNode(lhs, parseMultiplication()).peephole();
+ if (match("/")) return new DivNode(lhs, parseMultiplication()).peephole();
+ return lhs;
+ }
+
+ /**
+ * Parse a unary minus expression.
+ *
+ * <pre>
+ * unaryExpr : ('-') unaryExpr | primaryExpr
+ * </pre>
+ * @return a unary expression {@link Node}, never {@code null}
+ */
+ private Node parseUnary() {
+ if (match("-")) return new MinusNode(parseUnary()).peephole();
+ return parsePrimary();
+ }
+
+ /**
+ * Parse a primary expression:
+ *
+ * <pre>
+ * primaryExpr : integerLiteral | Identifier | true | false | '(' expression ')'
+ * </pre>
+ * @return a primary {@link Node}, never {@code null}
+ */
+ private Node parsePrimary() {
+ if( _lexer.isNumber() ) return parseIntegerLiteral();
+ if( match("(") ) return require(parseExpression(), ")");
+ if( matchx("true" ) ) return new ConstantNode(TypeInteger.constant(1)).peephole();
+ if( matchx("false") ) return new ConstantNode(TypeInteger.constant(0)).peephole();
+ String name = _lexer.matchId();
+ if( name == null) throw errorSyntax("an identifier or expression");
+ Node n = _scope.lookup(name);
+ if( n!=null ) return n;
+ throw error("Undefined name '" + name + "'");
+ }
+
+ /**
+ * Parse integer literal
+ *
+ * <pre>
+ * integerLiteral: [1-9][0-9]* | [0]
+ * </pre>
+ */
+ private ConstantNode parseIntegerLiteral() {
+ return (ConstantNode) new ConstantNode(_lexer.parseNumber()).peephole();
+ }
+
+ //////////////////////////////////
+ // Utilities for lexical analysis
+
+ // Return true and skip if "syntax" is next in the stream.
+ private boolean match (String syntax) { return _lexer.match (syntax); }
+ // Match must be "exact", not be followed by more id letters
+ private boolean matchx(String syntax) { return _lexer.matchx(syntax); }
+ // Return true and do NOT skip if 'ch' is next
+ private boolean peek(char ch) { return _lexer.peek(ch); }
+
+ // Require and return an identifier
+ private String requireId() {
+ String id = _lexer.matchId();
+ if (id != null && !KEYWORDS.contains(id) ) return id;
+ throw error("Expected an identifier, found '"+id+"'");
+ }
+
+ // Require an exact match
+ private void require(String syntax) { require(null, syntax); }
+ private Node require(Node n, String syntax) {
+ if (match(syntax)) return n;
+ throw errorSyntax(syntax);
+ }
+
+ RuntimeException errorSyntax(String syntax) {
+ return error("Syntax error, expected " + syntax + ": " + _lexer.getAnyNextToken());
+ }
+
+ static RuntimeException error(String errorMessage) {
+ return new RuntimeException(errorMessage);
+ }
+
+ ////////////////////////////////////
+ // Lexer components
+
+ private static class Lexer {
+
+ // Input buffer; an array of text bytes read from a file or a string
+ private final byte[] _input;
+ // Tracks current position in input buffer
+ private int _position = 0;
+
+ /**
+ * Record the source text for lexing
+ */
+ public Lexer(String source) {
+ this(source.getBytes());
+ }
+
+ /**
+ * Direct from disk file source
+ */
+ public Lexer(byte[] buf) {
+ _input = buf;
+ }
+
+ // Very handy in the debugger, shows the unparsed program
+ @Override
+ public String toString() {
+ return new String(_input, _position, _input.length - _position);
+ }
+
+ // True if at EOF
+ private boolean isEOF() {
+ return _position >= _input.length;
+ }
+
+ // Peek next character, or report EOF
+ private char peek() {
+ return isEOF() ? Character.MAX_VALUE // Special value that causes parsing to terminate
+ : (char) _input[_position];
+ }
+
+ private char nextChar() {
+ char ch = peek();
+ _position++;
+ return ch;
+ }
+
+ // True if a white space
+ private boolean isWhiteSpace() {
+ return peek() <= ' '; // Includes all the use space, tab, newline, CR
+ }
+
+ /**
+ * Return the next non-white-space character
+ */
+ private void skipWhiteSpace() {
+ while (isWhiteSpace()) _position++;
+ }
+
+
+ // Return true, if we find "syntax" after skipping white space; also
+ // then advance the cursor past syntax.
+ // Return false otherwise, and do not advance the cursor.
+ boolean match(String syntax) {
+ skipWhiteSpace();
+ int len = syntax.length();
+ if (_position + len > _input.length) return false;
+ for (int i = 0; i < len; i++)
+ if ((char) _input[_position + i] != syntax.charAt(i))
+ return false;
+ _position += len;
+ return true;
+ }
+
+ boolean matchx(String syntax) {
+ if( !match(syntax) ) return false;
+ if( !isIdLetter(peek()) ) return true;
+ _position -= syntax.length();
+ return false;
+ }
+
+ private boolean peek(char ch) {
+ skipWhiteSpace();
+ return peek()==ch;
+ }
+
+ // Return an identifier or null
+ String matchId() {
+ skipWhiteSpace();
+ return isIdStart(peek()) ? parseId() : null;
+ }
+
+ // Used for errors
+ String getAnyNextToken() {
+ if (isEOF()) return "";
+ if (isIdStart(peek())) return parseId();
+ if (isPunctuation(peek())) return parsePunctuation();
+ return String.valueOf(peek());
+ }
+
+ boolean isNumber() {return isNumber(peek());}
+ boolean isNumber(char ch) {return Character.isDigit(ch);}
+
+ private Type parseNumber() {
+ int start = _position;
+ while (isNumber(nextChar())) ;
+ String snum = new String(_input, start, --_position - start);
+ if (snum.length() > 1 && snum.charAt(0) == '0')
+ throw error("Syntax error: integer values cannot start with '0'");
+ return TypeInteger.constant(Long.parseLong(snum));
+ }
+
+ // First letter of an identifier
+ private boolean isIdStart(char ch) {
+ return Character.isAlphabetic(ch) || ch == '_';
+ }
+
+ // All characters of an identifier, e.g. "_x123"
+ private boolean isIdLetter(char ch) {
+ return Character.isLetterOrDigit(ch) || ch == '_';
+ }
+
+ private String parseId() {
+ int start = _position;
+ while (isIdLetter(nextChar())) ;
+ return new String(_input, start, --_position - start);
+ }
+
+ //
+ private boolean isPunctuation(char ch) {
+ return "=;[]<>()+-/*".indexOf(ch) != -1;
+ }
+
+ private String parsePunctuation() {
+ int start = _position;
+ return new String(_input, start, 1);
+ }
+ }
+}
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/Utils.java b/chapter07/src/main/java/com/seaofnodes/simple/Utils.java
new file mode 100644
index 00000000..4d663c25
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/Utils.java
@@ -0,0 +1,39 @@
+package com.seaofnodes.simple;
+
+import java.util.ArrayList;
+
+public class Utils {
+ public static RuntimeException TODO() { return TODO("Not yet implemented"); }
+ public static RuntimeException TODO(String msg) { return new RuntimeException(msg); }
+
+ /**
+ * Fast, constant-time, element removal. Does not preserve order
+ *
+ * @param array ArrayList to modify
+ * @param i element to be removed
+ * @return element removed
+ */
+ public static <E> E del(ArrayList<E> array, int i) {
+ if ( i >= 0 && i < array.size() ) {
+ E tmp = array.get(i);
+ E last = array.removeLast();
+ if (i < array.size()) array.set(i, last);
+ return tmp;
+ }
+ return null;
+ }
+
+ /**
+ * Search a list for an element by reference
+ *
+ * @param ary List to search in
+ * @param x Object to be searched
+ * @return >= 0 on success, -1 on failure
+ */
+ public static <E> int find( ArrayList<E> ary, E x ) {
+ for( int i=0; i<ary.size(); i++ )
+ if( ary.get(i)==x )
+ return i;
+ return -1;
+ }
+} \ No newline at end of file
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/node/AddNode.java b/chapter07/src/main/java/com/seaofnodes/simple/node/AddNode.java
new file mode 100644
index 00000000..85d7b20e
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/node/AddNode.java
@@ -0,0 +1,158 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.*;
+
+import java.util.BitSet;
+
+public class AddNode extends Node {
+ public AddNode(Node lhs, Node rhs) {
+ super(null, lhs, rhs);
+ }
+
+ @Override public String label() { return "Add"; }
+
+ @Override public String glabel() { return "+"; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ in(1)._print0(sb.append("("), visited);
+ in(2)._print0(sb.append("+"), visited);
+ return sb.append(")");
+ }
+
+
+ @Override
+ public Type compute() {
+ if( in(1)._type instanceof TypeInteger i0 &&
+ in(2)._type instanceof TypeInteger i1 ) {
+ if (i0.isConstant() && i1.isConstant())
+ return TypeInteger.constant(i0.value()+i1.value());
+ return i0.meet(i1);
+ }
+ return Type.BOTTOM;
+ }
+
+ @Override
+ public Node idealize () {
+ Node lhs = in(1);
+ Node rhs = in(2);
+ Type t1 = lhs._type;
+ Type t2 = rhs._type;
+
+ // Already handled by peephole constant folding
+ assert !(t1.isConstant() && t2.isConstant());
+
+ // Add of 0. We do not check for (0+x) because this will already
+ // canonicalize to (x+0)
+ if( t2 instanceof TypeInteger i && i.value()==0 )
+ return lhs;
+
+ // Add of same to a multiply by 2
+ if( lhs==rhs )
+ return new MulNode(lhs,new ConstantNode(TypeInteger.constant(2)).peephole());
+
+ // Goal: a left-spine set of adds, with constants on the rhs (which then fold).
+
+ // Move non-adds to RHS
+ if( !(lhs instanceof AddNode) && rhs instanceof AddNode )
+ return swap12();
+
+ // Now we might see (add add non) or (add non non) or (add add add) but never (add non add)
+
+ // Do we have x + (y + z) ?
+ // Swap to (x + y) + z
+ // Rotate (add add add) to remove the add on RHS
+ if( rhs instanceof AddNode add )
+ return new AddNode(new AddNode(lhs,add.in(1)).peephole(), add.in(2));
+
+ // Now we might see (add add non) or (add non non) but never (add non add) nor (add add add)
+ if( !(lhs instanceof AddNode) )
+ // Rotate; look for (add (phi cons) con/(phi cons))
+ return spline_cmp(lhs,rhs) ? swap12() : phiCon(this,true);
+
+ // Now we only see (add add non)
+
+ // Do we have (x + con1) + con2?
+ // Replace with (x + (con1+con2) which then fold the constants
+ if( lhs.in(2)._type.isConstant() && t2.isConstant() )
+ return new AddNode(lhs.in(1),new AddNode(lhs.in(2),rhs).peephole());
+
+
+ // Do we have ((x + (phi cons)) + con) ?
+ // Do we have ((x + (phi cons)) + (phi cons)) ?
+ // Push constant up through the phi: x + (phi con0+con0 con1+con1...)
+ Node phicon = phiCon(this,true);
+ if( phicon!=null ) return phicon;
+
+ // Now we sort along the spline via rotates, to gather similar things together.
+
+ // Do we rotate (x + y) + z
+ // into (x + z) + y ?
+ if( spline_cmp(lhs.in(2),rhs) )
+ return new AddNode(new AddNode(lhs.in(1),rhs).peephole(),lhs.in(2));
+
+ return null;
+ }
+
+ // Rotation is only valid for associative ops, e.g. Add, Mul, And, Or.
+ // Do we have ((phi cons)|(x + (phi cons)) + con|(phi cons)) ?
+ // Push constant up through the phi: x + (phi con0+con0 con1+con1...)
+ static Node phiCon(Node op, boolean rotate) {
+ Node lhs = op.in(1);
+ Node rhs = op.in(2);
+ // LHS is either a Phi of constants, or another op with Phi of constants
+ PhiNode lphi = pcon(lhs);
+ if( rotate && lphi==null && lhs.nIns() > 2 ) {
+ // Only valid to rotate constants if both are same associative ops
+ if( lhs.getClass() != op.getClass() ) return null;
+ lphi = pcon(lhs.in(2)); // Will rotate with the Phi push
+ }
+ if( lphi==null ) return null;
+
+ // RHS is a constant or a Phi of constants
+ if( !(rhs instanceof ConstantNode con) && pcon(rhs)==null )
+ return null;
+
+ // If both are Phis, must be same Region
+ if( rhs instanceof PhiNode && lphi.in(0) != rhs.in(0) )
+ return null;
+
+ // Note that this is the exact reverse of Phi pulling a common op down
+ // to reduce total op-count. We don't get in an endless push-up
+ // push-down peephole cycle because the constants all fold first.
+ Node[] ns = new Node[lphi.nIns()];
+ ns[0] = lphi.in(0);
+ // Push constant up through the phi: x + (phi con0+con0 con1+con1...)
+ for( int i=1; i<ns.length; i++ )
+ ns[i] = op.copy(lphi.in(i), rhs instanceof PhiNode ? rhs.in(i) : rhs).peephole();
+ String label = lphi._label + (rhs instanceof PhiNode rphi ? rphi._label : "");
+ Node phi = new PhiNode(label,ns).peephole();
+ // Rotate needs another op, otherwise just the phi
+ return lhs==lphi ? phi : op.copy(lhs.in(1),phi);
+ }
+
+ static PhiNode pcon(Node op) {
+ return op instanceof PhiNode phi && phi.all_cons() ? phi : null;
+ }
+
+ // Compare two off-spline nodes and decide what order they should be in.
+ // Do we rotate ((x + hi) + lo) into ((x + lo) + hi) ?
+ // Generally constants always go right, then Phi-of-constants, then muls, then others.
+ // Ties with in a category sort by node ID.
+ // TRUE if swapping hi and lo.
+ static boolean spline_cmp( Node hi, Node lo ) {
+ if( lo._type.isConstant() ) return false;
+ if( hi._type.isConstant() ) return true ;
+
+ if( lo instanceof PhiNode && lo.all_cons() ) return false;
+ if( hi instanceof PhiNode && hi.all_cons() ) return true ;
+
+ if( lo instanceof PhiNode && !(hi instanceof PhiNode) ) return true;
+ if( hi instanceof PhiNode && !(lo instanceof PhiNode) ) return false;
+
+ // Same category of "others"
+ return lo._nid > hi._nid;
+ }
+
+ @Override Node copy(Node lhs, Node rhs) { return new AddNode(lhs,rhs); }
+}
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/node/BoolNode.java b/chapter07/src/main/java/com/seaofnodes/simple/node/BoolNode.java
new file mode 100644
index 00000000..d65fbf14
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/node/BoolNode.java
@@ -0,0 +1,60 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeInteger;
+
+import java.util.BitSet;
+
+abstract public class BoolNode extends Node {
+
+ public BoolNode(Node lhs, Node rhs) {
+ super(null, lhs, rhs);
+ }
+
+ abstract String op(); // String opcode name
+
+ @Override
+ public String label() { return getClass().getSimpleName(); }
+
+ @Override
+ public String glabel() { return op(); }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ in(1)._print0(sb.append("("), visited);
+ in(2)._print0(sb.append(op()), visited);
+ return sb.append(")");
+ }
+
+ @Override
+ public Type compute() {
+ if( in(1)._type instanceof TypeInteger i0 &&
+ in(2)._type instanceof TypeInteger i1 ) {
+ if (i0.isConstant() && i1.isConstant())
+ return TypeInteger.constant(doOp(i0.value(), i1.value()) ? 1 : 0);
+ return i0.meet(i1);
+ }
+ return Type.BOTTOM;
+ }
+
+ abstract boolean doOp(long lhs, long rhs);
+
+ @Override
+ public Node idealize() {
+ // Compare of same
+ if( in(1)==in(2) )
+ return new ConstantNode(TypeInteger.constant(doOp(3,3)?1:0));
+
+ // Do we have ((x * (phi cons)) * con) ?
+ // Do we have ((x * (phi cons)) * (phi cons)) ?
+ // Push constant up through the phi: x * (phi con0*con0 con1*con1...)
+ Node phicon = AddNode.phiCon(this,false);
+ if( phicon!=null ) return phicon;
+
+ return null;
+ }
+
+ public static class EQ extends BoolNode { public EQ(Node lhs, Node rhs) { super(lhs,rhs); } String op() { return "=="; } boolean doOp(long lhs, long rhs) { return lhs == rhs; } Node copy(Node lhs, Node rhs) { return new EQ(lhs,rhs); } }
+ public static class LT extends BoolNode { public LT(Node lhs, Node rhs) { super(lhs,rhs); } String op() { return "<" ; } boolean doOp(long lhs, long rhs) { return lhs < rhs; } Node copy(Node lhs, Node rhs) { return new LT(lhs,rhs); } }
+ public static class LE extends BoolNode { public LE(Node lhs, Node rhs) { super(lhs,rhs); } String op() { return "<="; } boolean doOp(long lhs, long rhs) { return lhs <= rhs; } Node copy(Node lhs, Node rhs) { return new LE(lhs,rhs); } }
+}
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/node/ConstantNode.java b/chapter07/src/main/java/com/seaofnodes/simple/node/ConstantNode.java
new file mode 100644
index 00000000..0e13d2f2
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/node/ConstantNode.java
@@ -0,0 +1,45 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.Parser;
+import com.seaofnodes.simple.type.Type;
+
+import java.util.BitSet;
+
+/**
+ * A Constant node represents a constant value. At present, the only constants
+ * that we allow are integer literals; therefore Constants contain an integer
+ * value. As we add other types of constants, we will refactor how we represent
+ * Constants.
+ * <p>
+ * Constants have no semantic inputs. However, we set Start as an input to
+ * Constants to enable a forward graph walk. This edge carries no semantic
+ * meaning, and it is present <em>solely</em> to allow visitation.
+ * <p>
+ * The Constant's value is the value stored in it.
+ */
+public class ConstantNode extends Node {
+ Type _con;
+ public ConstantNode( Type type ) {
+ super(Parser.START);
+ _con = type;
+ }
+
+ @Override
+ public String label() { return ""+_con; }
+
+ @Override
+ public String uniqueName() { return "Con_" + _nid; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ return _con._print(sb);
+ }
+
+ @Override public boolean isMultiTail() { return true; }
+
+ @Override
+ public Type compute() { return _con; }
+
+ @Override
+ public Node idealize() { return null; }
+}
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/node/DivNode.java b/chapter07/src/main/java/com/seaofnodes/simple/node/DivNode.java
new file mode 100644
index 00000000..b0e12547
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/node/DivNode.java
@@ -0,0 +1,39 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeInteger;
+
+import java.util.BitSet;
+
+public class DivNode extends Node {
+ public DivNode(Node lhs, Node rhs) { super(null, lhs, rhs); }
+
+ @Override public String label() { return "Div"; }
+
+ @Override public String glabel() { return "//"; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ in(1)._print0(sb.append("("), visited);
+ in(2)._print0(sb.append("/"), visited);
+ return sb.append(")");
+ }
+
+ @Override
+ public Type compute() {
+ if (in(1)._type instanceof TypeInteger i0 &&
+ in(2)._type instanceof TypeInteger i1) {
+ if (i0.isConstant() && i1.isConstant())
+ return i1.value() == 0
+ ? TypeInteger.ZERO
+ : TypeInteger.constant(i0.value()/i1.value());
+ return i0.meet(i1);
+ }
+ return Type.BOTTOM;
+ }
+
+ @Override
+ public Node idealize() { return null; }
+
+ @Override Node copy(Node lhs, Node rhs) { return new DivNode(lhs,rhs); }
+}
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/node/IfNode.java b/chapter07/src/main/java/com/seaofnodes/simple/node/IfNode.java
new file mode 100644
index 00000000..e573010d
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/node/IfNode.java
@@ -0,0 +1,58 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeInteger;
+import com.seaofnodes.simple.type.TypeTuple;
+
+import java.util.BitSet;
+
+public class IfNode extends MultiNode {
+
+ public IfNode(Node ctrl, Node pred) {
+ super(ctrl, pred);
+ }
+
+ @Override
+ public String label() { return "If"; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ sb.append("if( ");
+ return in(1)._print0(sb, visited).append(" )");
+ }
+
+ @Override public boolean isCFG() { return true; }
+ @Override public boolean isMultiHead() { return true; }
+
+ public Node ctrl() { return in(0); }
+ public Node pred() { return in(1); }
+
+ @Override
+ public Type compute() {
+ // If the If node is not reachable then neither is any following Proj
+ if (ctrl()._type != Type.CONTROL && ctrl()._type != Type.BOTTOM )
+ return TypeTuple.IF_NEITHER;
+ // If constant is 0 then false branch is reachable
+ // Else true branch is reachable
+ if (pred()._type instanceof TypeInteger ti && ti.isConstant()) {
+ if (ti.value() == 0) return TypeTuple.IF_FALSE;
+ else return TypeTuple.IF_TRUE;
+ }
+
+ // Hunt up the immediate dominator tree. If we find an identical if
+ // test on either the true or false branch, then this test matches.
+ for( Node dom = idom(), prior=this; dom!=null; prior=dom, dom = dom.idom() )
+ if( dom instanceof IfNode iff && iff.pred()==pred() )
+ return prior instanceof ProjNode proj
+ // Repeated test, dominated on one side. Test result is the same.
+ ? (proj._idx==0 ? TypeTuple.IF_TRUE : TypeTuple.IF_FALSE)
+ : null; // Repeated test not dominated on one side
+
+ return TypeTuple.IF_BOTH;
+ }
+
+ @Override
+ public Node idealize() {
+ return null;
+ }
+}
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/node/LoopNode.java b/chapter07/src/main/java/com/seaofnodes/simple/node/LoopNode.java
new file mode 100644
index 00000000..eaf19199
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/node/LoopNode.java
@@ -0,0 +1,35 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+
+import java.util.BitSet;
+
+public class LoopNode extends RegionNode {
+
+ public LoopNode( Node entry, Node back) { super(null,entry,back); }
+
+ Node entry() { return in(1); }
+ Node back () { return in(2); }
+
+ @Override
+ public String label() { return "Loop"; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ return sb.append("Loop").append(_nid);
+ }
+
+ @Override
+ public Type compute() {
+ return inProgress() ? Type.CONTROL : super.compute();
+ }
+
+ @Override
+ public Node idealize() {
+ return inProgress() ? null : super.idealize();
+ }
+
+ @Override Node idom() { return entry(); }
+
+ @Override public boolean inProgress() { return back()==null; }
+}
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/node/MinusNode.java b/chapter07/src/main/java/com/seaofnodes/simple/node/MinusNode.java
new file mode 100644
index 00000000..8a96693d
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/node/MinusNode.java
@@ -0,0 +1,30 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeInteger;
+
+import java.util.BitSet;
+
+public class MinusNode extends Node {
+ public MinusNode(Node in) { super(null, in); }
+
+ @Override public String label() { return "Minus"; }
+
+ @Override public String glabel() { return "-"; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ in(1)._print0(sb.append("(-"), visited);
+ return sb.append(")");
+ }
+
+ @Override
+ public Type compute() {
+ if (in(1)._type instanceof TypeInteger i0)
+ return i0.isConstant() ? TypeInteger.constant(-i0.value()) : i0;
+ return Type.BOTTOM;
+ }
+
+ @Override
+ public Node idealize() { return null; }
+}
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/node/MulNode.java b/chapter07/src/main/java/com/seaofnodes/simple/node/MulNode.java
new file mode 100644
index 00000000..70e6c0db
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/node/MulNode.java
@@ -0,0 +1,58 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeInteger;
+
+import java.util.BitSet;
+
+public class MulNode extends Node {
+ public MulNode(Node lhs, Node rhs) { super(null, lhs, rhs); }
+
+ @Override public String label() { return "Mul"; }
+
+ @Override public String glabel() { return "*"; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ in(1)._print0(sb.append("("), visited);
+ in(2)._print0(sb.append("*"), visited);
+ return sb.append(")");
+ }
+
+ @Override
+ public Type compute() {
+ if (in(1)._type instanceof TypeInteger i0 &&
+ in(2)._type instanceof TypeInteger i1) {
+ if (i0.isConstant() && i1.isConstant())
+ return TypeInteger.constant(i0.value()*i1.value());
+ return i0.meet(i1);
+ }
+ return Type.BOTTOM;
+ }
+
+ @Override
+ public Node idealize() {
+ Node lhs = in(1);
+ Node rhs = in(2);
+ Type t1 = lhs._type;
+ Type t2 = rhs._type;
+
+ // Mul of 1. We do not check for (1*x) because this will already
+ // canonicalize to (x*1)
+ if ( t2.isConstant() && t2 instanceof TypeInteger i && i.value()==1 )
+ return lhs;
+
+ // Move constants to RHS: con*arg becomes arg*con
+ if ( t1.isConstant() && !t2.isConstant() )
+ return swap12();
+
+ // Do we have ((x * (phi cons)) * con) ?
+ // Do we have ((x * (phi cons)) * (phi cons)) ?
+ // Push constant up through the phi: x * (phi con0*con0 con1*con1...)
+ Node phicon = AddNode.phiCon(this,true);
+ if( phicon!=null ) return phicon;
+
+ return null;
+ }
+ @Override Node copy(Node lhs, Node rhs) { return new MulNode(lhs,rhs); }
+}
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/node/MultiNode.java b/chapter07/src/main/java/com/seaofnodes/simple/node/MultiNode.java
new file mode 100644
index 00000000..81c90f68
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/node/MultiNode.java
@@ -0,0 +1,7 @@
+package com.seaofnodes.simple.node;
+
+public abstract class MultiNode extends Node {
+
+ public MultiNode(Node... inputs) { super(inputs); }
+
+}
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/node/Node.java b/chapter07/src/main/java/com/seaofnodes/simple/node/Node.java
new file mode 100644
index 00000000..fcc8df85
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/node/Node.java
@@ -0,0 +1,467 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.Utils;
+import com.seaofnodes.simple.type.Type;
+
+import java.util.*;
+
+/**
+ * All Nodes in the Sea of Nodes IR inherit from the Node class.
+ * The Node class provides common functionality used by all subtypes.
+ * Subtypes of Node specialize by overriding methods.
+ */
+public abstract class Node {
+
+ /**
+ * Each node has a unique dense Node ID within a compilation context
+ * The ID is useful for debugging, for using as an offset in a bitvector,
+ * as well as for computing equality of nodes (to be implemented later).
+ */
+ public final int _nid;
+
+ /**
+ * Inputs to the node. These are use-def references to Nodes.
+ * <p>
+ * Generally fixed length, ordered, nulls allowed, no unused trailing space.
+ * Ordering is required because e.g. "a/b" is different from "b/a".
+ * The first input (offset 0) is often a {@link #isCFG} node.
+ */
+ public final ArrayList<Node> _inputs;
+
+ /**
+ * Outputs reference Nodes that are not null and have this Node as an
+ * input. These nodes are users of this node, thus these are def-use
+ * references to Nodes.
+ * <p>
+ * Outputs directly match inputs, making a directed graph that can be
+ * walked in either direction. These outputs are typically used for
+ * efficient optimizations but otherwise have no semantics meaning.
+ */
+ public final ArrayList<Node> _outputs;
+
+
+ /**
+ * Current computed type for this Node. This value changes as the graph
+ * changes and more knowledge is gained about the program.
+ */
+ public Type _type;
+
+
+ /**
+ * Immediate dominator tree depth, used to approximate a real IDOM during
+ * parsing where we do not have the whole program, and also peepholes
+ * change the CFG incrementally.
+ * <p>
+ * See {@link <a href="https://en.wikipedia.org/wiki/Dominator_(graph_theory)">...</a>}
+ */
+ int _idepth;
+
+ /**
+ * A private Global Static mutable counter, for unique node id generation.
+ * To make the compiler multithreaded, this field will have to move into a TLS.
+ * Starting with value 1, to avoid bugs confusing node ID 0 with uninitialized values.
+ * */
+ private static int UNIQUE_ID = 1;
+
+ protected Node(Node... inputs) {
+ _nid = UNIQUE_ID++; // allocate unique dense ID
+ _inputs = new ArrayList<>();
+ Collections.addAll(_inputs,inputs);
+ _outputs = new ArrayList<>();
+ for( Node n : _inputs )
+ if( n != null )
+ n.addUse( this );
+ }
+
+ // Easy reading label for debugger, e.g. "Add" or "Region" or "EQ"
+ public abstract String label();
+
+ // Unique label for graph visualization, e.g. "Add12" or "Region30" or "EQ99"
+ public String uniqueName() { return label() + _nid; }
+
+ // Graphical label, e.g. "+" or "Region" or "=="
+ public String glabel() { return label(); }
+
+
+ // ------------------------------------------------------------------------
+
+ // Debugger Printing.
+
+ // {@code toString} is what you get in the debugger. It has to print 1
+ // line (because this is what a debugger typically displays by default) and
+ // has to be robust with broken graph/nodes.
+ @Override
+ public final String toString() { return print(); }
+
+ // This is a *deep* print. This version will fail on cycles, which we will
+ // correct later when we can parse programs with loops. We print with a
+ // tik-tok style; the common _print0 calls the per-Node _print1, which
+ // calls back to _print0;
+ public final String print() {
+ return _print0(new StringBuilder(), new BitSet()).toString();
+ }
+ // This is the common print: check for repeats, check for DEAD and print
+ // "DEAD" else call the per-Node print1.
+ final StringBuilder _print0(StringBuilder sb, BitSet visited) {
+ if (visited.get(_nid))
+ return sb.append(label());
+ visited.set(_nid);
+ return isDead()
+ ? sb.append(uniqueName()).append(":DEAD")
+ : _print1(sb, visited);
+ }
+ // Every Node implements this; a partial-line recursive print
+ abstract StringBuilder _print1(StringBuilder sb, BitSet visited);
+
+
+ // Print a node on 1 line, columnar aligned, as:
+ // NNID NNAME DDEF DDEF [[ UUSE UUSE ]] TYPE
+ // 1234 sssss 1234 1234 1234 1234 1234 1234 tttttt
+ public void _print_line( StringBuilder sb ) {
+ sb.append("%4d %-7.7s ".formatted(_nid,label()));
+ if( _inputs==null ) {
+ sb.append("DEAD\n");
+ return;
+ }
+ for( Node def : _inputs )
+ sb.append(def==null ? "____ " : "%4d ".formatted(def._nid));
+ for( int i = _inputs.size(); i<3; i++ )
+ sb.append(" ");
+ sb.append(" [[ ");
+ for( Node use : _outputs )
+ sb.append("%4d ".formatted(use._nid));
+ int lim = 5 - Math.max(_inputs.size(),3);
+ for( int i = _outputs.size(); i<lim; i++ )
+ sb.append(" ");
+ sb.append(" ]] ");
+ if( _type!= null ) _type._print(sb);
+ sb.append("\n");
+ }
+
+ public boolean isMultiHead() { return false; }
+ public boolean isMultiTail() { return false; }
+
+ // ------------------------------------------------------------------------
+ // Graph Node & Edge manipulation
+
+ /**
+ * Gets the ith input node
+ * @param i Offset of the input node
+ * @return Input node or null
+ */
+ public Node in(int i) { return _inputs.get(i); }
+
+ public int nIns() { return _inputs.size(); }
+
+ public Node out(int i) { return _outputs.get(i); }
+
+ public int nOuts() { return _outputs.size(); }
+
+ public boolean isUnused() { return nOuts() == 0; }
+
+ public boolean isCFG() { return false; }
+
+ /**
+ * Change a <em>def</em> into a Node. Keeps the edges correct, by removing
+ * the corresponding <em>use->def</em> edge. This may make the original
+ * <em>def</em> go dead. This function is co-recursive with {@link #kill}.
+ * <p>
+
+ * This method is the normal path for altering a Node, because it does the
+ * proper default edge maintenance. It also <em>immediately</em> kills
+ * Nodes that lose their last use; at times care must be taken to avoid
+ * killing Nodes that are being used without having an output Node. This
+ * definitely happens in the middle of recursive {@link #peephole} calls.
+ *
+ * @param idx which def to set
+ * @param new_def the new definition
+ * @return new_def for flow coding
+ */
+ Node set_def(int idx, Node new_def ) {
+ Node old_def = in(idx);
+ if( old_def == new_def ) return this; // No change
+ // If new def is not null, add the corresponding def->use edge
+ // This needs to happen before removing the old node's def->use edge as
+ // the new_def might get killed if the old node kills it recursively.
+ if( new_def != null )
+ new_def.addUse(this);
+ if( old_def != null && // If the old def exists, remove a def->use edge
+ old_def.delUse(this) ) // If we removed the last use, the old def is now dead
+ old_def.kill(); // Kill old def
+ // Set the new_def over the old (killed) edge
+ _inputs.set(idx,new_def);
+ // Return self for easy flow-coding
+ return new_def;
+ }
+
+ // Remove the numbered input, compressing the inputs in-place. This
+ // shuffles the order deterministically - which is suitable for Region and
+ // Phi, but not for every Node.
+ void delDef(int idx) {
+ Node old_def = in(idx);
+ if( old_def != null && // If the old def exists, remove a def->use edge
+ old_def.delUse(this) ) // If we removed the last use, the old def is now dead
+ old_def.kill(); // Kill old def
+ Utils.del(_inputs, idx);
+ }
+
+ /**
+ * Add a new def to an existing Node. Keep the edges correct by
+ * adding the corresponding <em>def->use</em> edge.
+ *
+ * @param new_def the new definition, appended to the end of existing definitions
+ * @return new_def for flow coding
+ */
+ public Node add_def(Node new_def) {
+ // Add use->def edge
+ _inputs.add(new_def);
+ // If new def is not null, add the corresponding def->use edge
+ if( new_def != null )
+ new_def.addUse(this);
+ return new_def;
+ }
+
+ // Breaks the edge invariants, used temporarily
+ protected <N extends Node> N addUse(Node n) { _outputs.add(n); return (N)this; }
+
+ // Remove node 'use' from 'def's (i.e. our) output list, by compressing the list in-place.
+ // Return true if the output list is empty afterward.
+ // Error is 'use' does not exist; ok for 'use' to be null.
+ protected boolean delUse( Node use ) {
+ Utils.del(_outputs, Utils.find(_outputs, use));
+ return _outputs.size() == 0;
+ }
+
+ // Shortcut for "popping" n nodes. A "pop" is basically a
+ // set_def(last,null) followed by lowering the nIns() count.
+ void pop_n(int n) {
+ for( int i=0; i<n; i++ ) {
+ Node old_def = _inputs.removeLast();
+ if( old_def != null && // If it exists and
+ old_def.delUse(this) ) // If we removed the last use, the old def is now dead
+ old_def.kill(); // Kill old def
+ }
+ }
+
+ /**
+ * Kill a Node with no <em>uses</em>, by setting all of its <em>defs</em>
+ * to null. This may recursively kill more Nodes and is basically dead
+ * code elimination. This function is co-recursive with {@link #pop_n}.
+ */
+ public void kill( ) {
+ assert isUnused(); // Has no uses, so it is dead
+ pop_n(nIns()); // Set all inputs to null, recursively killing unused Nodes
+ _type=null; // Flag as dead
+ assert isDead(); // Really dead now
+ }
+
+ // Mostly used for asserts and printing.
+ boolean isDead() { return isUnused() && nIns()==0 && _type==null; }
+
+ // Shortcuts to stop DCE mid-parse
+ // Add bogus null use to keep node alive
+ public <N extends Node> N keep() { return addUse(null); }
+ // Remove bogus null.
+ public <N extends Node> N unkeep() { delUse(null); return (N)this; }
+
+
+ // Replace self with nnn in the graph, making 'this' go dead
+ void subsume( Node nnn ) {
+ assert nnn!=this;
+ while( nOuts() > 0 ) {
+ Node n = _outputs.removeLast();
+ int idx = Utils.find(n._inputs, this);
+ n._inputs.set(idx,nnn);
+ nnn.addUse(n);
+ }
+ kill();
+ }
+
+ // ------------------------------------------------------------------------
+ // Graph-based optimizations
+
+ /**
+ * We allow disabling peephole opt so that we can observe the
+ * full graph, vs the optimized graph.
+ */
+ public static boolean _disablePeephole = false;
+
+ /**
+ * Try to peephole at this node and return a better replacement Node if
+ * possible. We compute a {@link Type} and then check and replace:
+ * <ul>
+ * <li>if the Type {@link Type#isConstant}, we replace with a {@link ConstantNode}</li>
+ * <li>in a future chapter we will look for a
+ * <a href="https://en.wikipedia.org/wiki/Common_subexpression_elimination">Common Subexpression</a>
+ * to eliminate.</li>
+ * <li>we ask the Node for a better replacement. The "better replacement"
+ * is things like {@code (1+2)} becomes {@code 3} and {@code (1+(x+2))} becomes
+ * {@code (x+(1+2))}. By canonicalizing expressions we fold common addressing
+ * math constants, remove algebraic identities and generally simplify the
+ * code. </li>
+ * </ul>
+ */
+ public final Node peephole( ) {
+ // Compute initial or improved Type
+ Type type = _type = compute();
+
+ if (_disablePeephole)
+ return this; // Peephole optimizations turned off
+
+ // Replace constant computations from non-constants with a constant node
+ if (!(this instanceof ConstantNode) && type.isConstant())
+ return deadCodeElim(new ConstantNode(type).peephole());
+
+ // Future chapter: Global Value Numbering goes here
+
+ // Ask each node for a better replacement
+ Node n = idealize();
+ if( n != null ) // Something changed
+ // Recursively optimize
+ return deadCodeElim(n.peephole());
+
+ return this; // No progress
+ }
+
+ // m is the new Node, self is the old.
+ // Return 'm', which may have zero uses but is alive nonetheless.
+ // If self has zero uses (and is not 'm'), {@link #kill} self.
+ private Node deadCodeElim(Node m) {
+ // If self is going dead and not being returned here (Nodes returned
+ // from peephole commonly have no uses (yet)), then kill self.
+ if( m != this && isUnused() ) {
+ // Killing self - and since self recursively kills self's inputs we
+ // might end up killing 'm', which we are returning as a live Node.
+ // So we add a bogus extra null output edge to stop kill().
+ m.keep(); // Keep m alive
+ kill(); // Kill self because replacing with 'm'
+ m.unkeep(); // Okay to peephole m
+ }
+ return m;
+ }
+
+ /**
+ * This function needs to be
+ * <a href="https://en.wikipedia.org/wiki/Monotonic_function">Monotonic</a>
+ * as it is part of a Monotone Analysis Framework.
+ * <a href="https://www.cse.psu.edu/~gxt29/teaching/cse597s21/slides/08monotoneFramework.pdf">See for example this set of slides</a>.
+ * <p>
+ * For Chapter 2, all our Types are really integer constants, and so all
+ * the needed properties are trivially true, and we can ignore the high
+ * theory. Much later on, this will become important and allow us to do
+ * many fancy complex optimizations trivially... because theory.
+ * <p>
+ * compute() needs to be stand-alone, and cannot recursively call compute
+ * on its inputs programs are cyclic (have loops!) and this will just
+ * infinitely recurse until stack overflow. Instead, compute typically
+ * computes a new type from the {@link #_type} field of its inputs.
+ */
+ public abstract Type compute();
+
+ /**
+ * This function rewrites the current Node into a more "idealized" form.
+ * This is the bulk of our peephole rewrite rules, and we use this to
+ * e.g. turn arbitrary collections of adds and multiplies with mixed
+ * constants into a normal form that's easy for hardware to implement.
+ * Example: An array addressing expression:
+ * <pre> ary[idx+1]</pre>
+ * might turn into Sea-of-Nodes IR:
+ * <pre> (ary+12)+((idx+1) * 4)</pre>
+ * This expression can then be idealized into:
+ * <pre> ary + ((idx*4) + (12 + (1*4)))</pre>
+ * And more folding:
+ * <pre> ary + ((idx<<2) + 16)</pre>
+ * And during code-gen:
+ * <pre> MOV4 Rary,Ridx,16 // or some such hardware-specific notation </pre>
+ * <p>
+ * {@link #idealize} has a very specific calling convention:
+ * <ul>
+ * <li>If NO change is made, return {@code null}
+ * <li>If ANY change is made, return not-null; this can be {@code this}
+ * <li>The returned Node does NOT call {@link #peephole} on itself; the {@link #peephole} call will recursively peephole it.
+ * <li>Any NEW nodes that are not directly returned DO call {@link #peephole}.
+ * </ul>
+ * <p>
+ * Examples:
+ * <table border="3">
+ * <tr><th> before </th><th> after </th><th>return </th><th>comment </th></tr>
+ * <tr><td>{@code (x+5) }</td><td>{@code (x+5) }</td><td>{@code null }</td><td>No change</td></tr>
+ * <tr><td>{@code (5+x) }</td><td>{@code (x+5) }</td><td>{@code this }</td><td>Swapped arguments</td></tr>
+ * <tr><td>{@code ((x+1)+2)}</td><td>{@code (x+(1+2))}</td><td>{@code (x+_) }</td><td>Returns 2 new Nodes</td></tr>
+ * </table>
+ *
+ * The last entry deserves more discussion. The new Node {@code (1+2)}
+ * created in {@link #idealize} calls {@link #peephole} (which then folds
+ * into a constant). The other new Node {@code (x+3)} does not call
+ * peephole, because it is returned and peephole itself will recursively
+ * call peephole.
+ * <p>
+ * Since idealize calls peephole and peephole calls idealize, you must be
+ * careful that all idealizations are <em>monotonic</em>: all transforms remove
+ * some feature, so that the set of available transforms always shrinks.
+ * If you don't, you risk an infinite peephole loop!
+ *
+ * @return Either a new or changed node, or null for no changes.
+ */
+ public abstract Node idealize();
+
+
+ // ------------------------------------------------------------------------
+ // Peephole utilities
+
+ // Swap inputs without letting either input go dead during the swap.
+ Node swap12() {
+ Node tmp = in(1);
+ _inputs.set(1,in(2));
+ _inputs.set(2,tmp);
+ return this;
+ }
+
+ // does this node contain all constants?
+ // Ignores in(0), as is usually control.
+ boolean all_cons() {
+ for( int i=1; i<nIns(); i++ )
+ if( !(in(i)._type.isConstant()) )
+ return false;
+ return true;
+ }
+
+ // Return the immediate dominator of this Node and compute dom tree depth.
+ Node idom() {
+ Node idom = in(0);
+ if( idom._idepth==0 ) idom.idom(); // Recursively set _idepth
+ if( _idepth==0 ) _idepth = idom._idepth+1;
+ return idom;
+ }
+
+ // Make a shallow copy (same class) of this Node, with given inputs and
+ // empty outputs and a new Node ID. The original inputs are ignored.
+ // Does not need to be implemented in isCFG() nodes.
+ Node copy(Node lhs, Node rhs) { throw Utils.TODO("Binary ops need to implement copy"); }
+
+ /**
+ * Used to allow repeating tests in the same JVM. This just resets the
+ * Node unique id generator, and is done as part of making a new Parser.
+ */
+ public static void reset() { UNIQUE_ID = 1; _disablePeephole=false; }
+
+ /**
+ * Debugging utility to find a Node by index
+ */
+ public Node find(int nid) { return _find(new BitSet(),nid); }
+ private Node _find(BitSet visit, int nid) {
+ if( _nid==nid ) return this;
+ if( visit.get(_nid) ) return null;
+ visit.set(_nid);
+ for( Node def : _inputs )
+ if( def!=null ) {
+ Node rez = def._find(visit,nid);
+ if( rez != null ) return rez;
+ }
+ for( Node use : _outputs ) {
+ Node rez = use._find(visit,nid);
+ if( rez != null ) return rez;
+ }
+ return null;
+ }
+}
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/node/NotNode.java b/chapter07/src/main/java/com/seaofnodes/simple/node/NotNode.java
new file mode 100644
index 00000000..04e6c75b
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/node/NotNode.java
@@ -0,0 +1,30 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeInteger;
+
+import java.util.BitSet;
+
+public class NotNode extends Node {
+ public NotNode(Node in) { super(null, in); }
+
+ @Override public String label() { return "Not"; }
+
+ @Override public String glabel() { return "!"; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ in(1)._print0(sb.append("(!"), visited);
+ return sb.append(")");
+ }
+
+ @Override
+ public Type compute() {
+ if( in(1)._type instanceof TypeInteger i0 )
+ return i0.isConstant() ? TypeInteger.constant(i0.value()==0 ? 1 : 0) : i0;
+ return Type.BOTTOM;
+ }
+
+ @Override
+ public Node idealize() { return null; }
+}
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/node/PhiNode.java b/chapter07/src/main/java/com/seaofnodes/simple/node/PhiNode.java
new file mode 100644
index 00000000..202dbe37
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/node/PhiNode.java
@@ -0,0 +1,101 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+
+import java.util.BitSet;
+
+public class PhiNode extends Node {
+
+ final String _label;
+
+ public PhiNode(String label, Node... inputs) { super(inputs); _label = label; }
+
+ @Override public String label() { return "Phi_"+_label; }
+
+ @Override public String glabel() { return "&phi;_"+_label; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ if( region().inProgress() )
+ sb.append("Z");
+ sb.append("Phi(");
+ for( Node in : _inputs ) {
+ if (in == null) sb.append("____");
+ else in._print0(sb, visited);
+ sb.append(",");
+ }
+ sb.setLength(sb.length()-1);
+ sb.append(")");
+ return sb;
+ }
+
+ RegionNode region() { return (RegionNode)in(0); }
+ @Override public boolean isMultiTail() { return true; }
+
+ @Override
+ public Type compute() {
+ if( !(region() instanceof RegionNode r) || r.inProgress() )
+ return Type.BOTTOM;
+ Type t = Type.TOP;
+ for (int i = 1; i < nIns(); i++)
+ t = t.meet(in(i)._type);
+ return t;
+ }
+
+ @Override
+ public Node idealize() {
+ if( !(region() instanceof RegionNode r ) || r.inProgress() )
+ return null;
+
+ // If we have only a single unique input, become it.
+ Node live = singleUniqueInput();
+ if (live != null)
+ return live;
+
+ // Pull "down" a common data op. One less op in the world. One more
+ // Phi, but Phis do not make code.
+ // Phi(op(A,B),op(Q,R),op(X,Y)) becomes
+ // op(Phi(A,Q,X), Phi(B,R,Y)).
+ Node op = in(1);
+ if( op.nIns()==3 && op.in(0)==null && !op.isCFG() && same_op() ) {
+ Node[] lhss = new Node[nIns()];
+ Node[] rhss = new Node[nIns()];
+ lhss[0] = rhss[0] = in(0); // Set Region
+ for( int i=1; i<nIns(); i++ ) {
+ lhss[i] = in(i).in(1);
+ rhss[i] = in(i).in(2);
+ }
+ Node phi_lhs = new PhiNode(_label,lhss).peephole();
+ Node phi_rhs = new PhiNode(_label,rhss).peephole();
+ return op.copy(phi_lhs,phi_rhs);
+ }
+
+ return null;
+ }
+
+ private boolean same_op() {
+ for( int i=2; i<nIns(); i++ )
+ if( in(1).getClass() != in(i).getClass() )
+ return false;
+ return true;
+ }
+
+ /**
+ * If only single unique input, return it
+ */
+ private Node singleUniqueInput() {
+ Node live = null;
+ for( int i=1; i<nIns(); i++ )
+ if( region().in(i)._type != Type.XCONTROL && in(i) != this )
+ if( live == null || live == in(i) ) live = in(i);
+ else return null;
+ return live;
+ }
+
+ @Override
+ boolean all_cons() {
+ if( !(region() instanceof RegionNode r) || r.inProgress() )
+ return false;
+ return super.all_cons();
+ }
+}
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/node/ProjNode.java b/chapter07/src/main/java/com/seaofnodes/simple/node/ProjNode.java
new file mode 100644
index 00000000..79ba9d13
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/node/ProjNode.java
@@ -0,0 +1,49 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeTuple;
+
+import java.util.BitSet;
+
+public class ProjNode extends Node {
+
+ // Which slice of the incoming multi-part value
+ public final int _idx;
+
+ // Debugging label
+ public final String _label;
+
+ public ProjNode(MultiNode ctrl, int idx, String label) {
+ super(ctrl);
+ _idx = idx;
+ _label = label;
+ }
+
+ @Override
+ public String label() { return _label; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) { return sb.append(_label); }
+
+ @Override public boolean isCFG() { return _idx==0 || ctrl() instanceof IfNode; }
+ @Override public boolean isMultiTail() { return in(0).isMultiHead(); }
+
+ public MultiNode ctrl() { return (MultiNode)in(0); }
+
+ @Override
+ public Type compute() {
+ Type t = ctrl()._type;
+ return t instanceof TypeTuple tt ? tt._types[_idx] : Type.BOTTOM;
+ }
+
+ @Override
+ public Node idealize() {
+ if( ctrl()._type instanceof TypeTuple tt ) {
+ if( tt._types[_idx]==Type.XCONTROL )
+ return new ConstantNode(Type.XCONTROL).peephole(); // We are dead
+ if( tt._types[1-_idx]==Type.XCONTROL ) // Only true for IfNodes
+ return ctrl().in(0); // We become our input control
+ }
+ return null;
+ }
+}
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/node/RegionNode.java b/chapter07/src/main/java/com/seaofnodes/simple/node/RegionNode.java
new file mode 100644
index 00000000..3b793758
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/node/RegionNode.java
@@ -0,0 +1,81 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.Utils;
+import com.seaofnodes.simple.type.Type;
+
+import java.util.Collection;
+import java.util.BitSet;
+
+public class RegionNode extends Node {
+ public RegionNode(Node... inputs) { super(inputs); }
+
+ @Override
+ public String label() { return "Region"; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ return sb.append(label()).append(_nid);
+ }
+
+ @Override public boolean isCFG() { return true; }
+ @Override public boolean isMultiHead() { return true; }
+
+ @Override
+ public Type compute() {
+ Type t = Type.XCONTROL;
+ for (int i = 1; i < nIns(); i++)
+ t = t.meet(in(i)._type);
+ return t;
+ }
+
+ @Override
+ public Node idealize() {
+ int path = findDeadInput();
+ if( path != 0 ) {
+ for( Node phi : _outputs )
+ if( phi instanceof PhiNode )
+ phi.delDef(path);
+ delDef(path);
+
+ // If down to a single input, become that input - but also make all
+ // Phis an identity on *their* single input.
+ if( nIns()==2 ) {
+ for( Node phi : _outputs )
+ if( phi instanceof PhiNode )
+ // Currently does not happen, because no loops
+ throw Utils.TODO();
+ return in(1);
+ }
+ return this;
+ }
+ return null;
+ }
+
+ private int findDeadInput() {
+ for( int i=1; i<nIns(); i++ )
+ if( in(i)._type==Type.XCONTROL )
+ return i;
+ return 0; // All inputs alive
+ }
+
+ // Immediate dominator of Region is a little more complicated.
+ private Node _idom; // Immediate dominator cache
+ @Override Node idom() {
+ if( _idom != null ) return _idom; // Return cached copy
+ if( nIns()!=3 ) return null; // Fails for anything other than 2-inputs
+ // Walk the LHS & RHS idom trees in parallel until they match, or either fails
+ Node lhs = in(1).idom();
+ Node rhs = in(2).idom();
+ while( lhs != rhs ) {
+ if( lhs==null || rhs==null ) return null;
+ var comp = lhs._idepth - rhs._idepth;
+ if( comp >= 0 ) lhs = lhs.idom();
+ if( comp <= 0 ) rhs = rhs.idom();
+ }
+ if( lhs==null ) return null;
+ _idepth = lhs._idepth+1;
+ return (_idom=lhs);
+ }
+
+ public boolean inProgress() { return false; }
+}
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/node/ReturnNode.java b/chapter07/src/main/java/com/seaofnodes/simple/node/ReturnNode.java
new file mode 100644
index 00000000..4dea773a
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/node/ReturnNode.java
@@ -0,0 +1,46 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.*;
+
+import java.util.BitSet;
+
+/**
+ * The Return node has two inputs. The first input is a control node and the
+ * second is the data node that supplies the return value.
+ * <p>
+ * In this presentation, Return functions as a Stop node, since multiple <code>return</code> statements are not possible.
+ * The Stop node will be introduced in Chapter 6 when we implement <code>if</code> statements.
+ * <p>
+ * The Return's output is the value from the data node.
+ */
+public class ReturnNode extends Node {
+
+ public ReturnNode(Node ctrl, Node data) {
+ super(ctrl, data);
+ }
+
+ public Node ctrl() { return in(0); }
+ public Node expr() { return in(1); }
+
+ @Override
+ public String label() { return "Return"; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ return expr()._print0(sb.append("return "), visited).append(";");
+ }
+
+ @Override public boolean isCFG() { return true; }
+
+ @Override
+ public Type compute() {
+ return new TypeTuple(ctrl()._type,expr()._type);
+ }
+
+ @Override
+ public Node idealize() {
+ if( ctrl()._type==Type.XCONTROL )
+ return ctrl();
+ return null;
+ }
+}
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/node/ScopeNode.java b/chapter07/src/main/java/com/seaofnodes/simple/node/ScopeNode.java
new file mode 100644
index 00000000..cc6af152
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/node/ScopeNode.java
@@ -0,0 +1,169 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+
+import java.util.*;
+
+/**
+ * The Scope node is purely a parser helper - it tracks names to nodes with a
+ * stack of scopes.
+ */
+public class ScopeNode extends Node {
+
+ /**
+ * The control is a name that binds to the currently active control
+ * node in the graph
+ */
+ public static final String CTRL = "$ctrl";
+ public static final String ARG0 = "arg";
+
+ /**
+ * Names for every input edge
+ */
+ public final Stack<HashMap<String, Integer>> _scopes;
+
+
+ // A new ScopeNode
+ public ScopeNode() {
+ _scopes = new Stack<>();
+ _type = Type.BOTTOM;
+ }
+
+
+ @Override public String label() { return "Scope"; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ sb.append("Scope[ ");
+ String[] names = reverse_names();
+ for( int j=0; j<nIns(); j++ ) {
+ sb.append(names[j]).append(":");
+ Node n = in(j);
+ n._print0(sb, visited).append(" ");
+ }
+ sb.setLength(sb.length()-1);
+ return sb.append("]");
+ }
+
+ // Expensive...
+ public String[] reverse_names() {
+ String[] names = new String[nIns()];
+ for( HashMap<String,Integer> syms : _scopes )
+ for( String name : syms.keySet() )
+ names[syms.get(name)] = name;
+ return names;
+ }
+
+ @Override public Type compute() { return Type.BOTTOM; }
+
+ @Override public Node idealize() { return null; }
+
+ public void push() { _scopes.push(new HashMap<>()); }
+ public void pop() { pop_n(_scopes.pop().size()); }
+
+ // Create a new name in the current scope
+ public Node define( String name, Node n ) {
+ HashMap<String,Integer> syms = _scopes.lastElement();
+ if( syms.put(name,nIns()) != null )
+ return null; // Double define
+ return add_def(n);
+ }
+
+ // Lookup a name. It is recursive to support lazy Phis on loops (coming in chapter 8).
+ public Node lookup(String name) { return update(name,null,_scopes.size()-1); }
+ // If the name is present in any scope, then redefine else null
+ public Node update(String name, Node n) { return update(name,n,_scopes.size()-1); }
+ // Both recursive lookup and update.
+ private Node update( String name, Node n, int i ) {
+ if( i<0 ) return null; // Missed in all scopes, not found
+ var syms = _scopes.get(i);
+ var idx = syms.get(name);
+ if( idx == null ) return update(name,n,i-1); // Missed in this scope, recursively look
+ Node old = in(idx);
+ // If n is null we are looking up rather than updating
+ return n==null ? old : set_def(idx,n);
+ }
+
+ public Node ctrl() { return in(0); }
+
+ /**
+ * The ctrl of a ScopeNode is always bound to the currently active
+ * control node in the graph, via a special name '$ctrl' that is not
+ * a valid identifier in the language grammar and hence cannot be
+ * referenced in Simple code.
+ *
+ * @param n The node to be bound to '$ctrl'
+ *
+ * @return Node that was bound
+ */
+ public Node ctrl(Node n) { return set_def(0,n); }
+
+ /**
+ * Duplicate a ScopeNode; including all levels, up to Nodes. So this is
+ * neither shallow (would dup the Scope but not the internal HashMap
+ * tables), nor deep (would dup the Scope, the HashMap tables, but then
+ * also the program Nodes).
+ * <p>
+ * The new Scope is a full-fledged Node with proper use<->def edges.
+ */
+ public ScopeNode dup() { return dup(false); }
+ public ScopeNode dup(boolean loop) {
+ ScopeNode dup = new ScopeNode();
+ // Our goals are:
+ // 1) duplicate the name bindings of the ScopeNode across all stack levels
+ // 2) Make the new ScopeNode a user of all the nodes bound
+ // 3) Ensure that the order of defs is the same to allow easy merging
+ for( HashMap<String,Integer> syms : _scopes )
+ dup._scopes.push(new HashMap<>(syms));
+ String[] reverse = reverse_names();
+ dup.add_def(ctrl()); // Control input is just copied
+ for( int i=1; i<nIns(); i++ ) {
+ if ( !loop ) { dup.add_def(in(i)); }
+ else {
+ // Create a phi node with second input as null - to be filled in
+ // by endLoop() below
+ dup.add_def(new PhiNode(reverse[i], ctrl(), in(i), null).peephole());
+ // Ensure our node has the same phi in case we created one
+ set_def(i, dup.in(i));
+ }
+ }
+ return dup;
+ }
+
+ /**
+ * Merges the names whose node bindings differ, by creating Phi node for such names
+ * The names could occur at all stack levels, but a given name can only differ in the
+ * innermost stack level where the name is bound.
+ *
+ * @param that The ScopeNode to be merged into this
+ * @return A new node representing the merge point
+ */
+ public Node mergeScopes(ScopeNode that) {
+ RegionNode r = (RegionNode) ctrl(new RegionNode(null,ctrl(), that.ctrl()).keep());
+ String[] ns = reverse_names();
+ // Note that we skip i==0, which is bound to '$ctrl'
+ for (int i = 1; i < nIns(); i++)
+ if( in(i) != that.in(i) ) // No need for redundant Phis
+ set_def(i, new PhiNode(ns[i], r, in(i), that.in(i)).peephole());
+ that.kill(); // Kill merged scope
+ return r.unkeep().peephole();
+ }
+
+ // Merge the backedge scope into this loop head scope
+ // We set the second input to the phi from the back edge (i.e. loop body)
+ public void endLoop(ScopeNode back, ScopeNode exit ) {
+ Node ctrl = ctrl();
+ assert ctrl instanceof LoopNode loop && loop.inProgress();
+ ctrl.set_def(2,back.ctrl());
+ for( int i=1; i<nIns(); i++ ) {
+ PhiNode phi = (PhiNode)in(i);
+ assert phi.region()==ctrl && phi.in(2)==null;
+ phi.set_def(2,back.in(i));
+ // Do an eager useless-phi removal
+ Node in = phi.peephole();
+ if( in != phi )
+ phi.subsume(in);
+ }
+ back.kill(); // Loop backedge is dead
+ }
+}
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/node/StartNode.java b/chapter07/src/main/java/com/seaofnodes/simple/node/StartNode.java
new file mode 100644
index 00000000..19d03e0f
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/node/StartNode.java
@@ -0,0 +1,46 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeTuple;
+
+import java.util.BitSet;
+
+/**
+ * The Start node represents the start of the function. For now, we do not
+ * have any inputs to Start because our function does not yet accept
+ * parameters. When we add parameters the value of Start will be a tuple, and
+ * will require Projections to extract the values. We discuss this in detail
+ * in Chapter 9: Functions and Calls.
+ */
+public class StartNode extends MultiNode {
+
+ final TypeTuple _args;
+
+ public StartNode(Type[] args) {
+ super();
+ _args = new TypeTuple(args);
+ _type = _args;
+ }
+
+ @Override
+ public String label() { return "Start"; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ return sb.append(label());
+ }
+
+ @Override public boolean isCFG() { return true; }
+ @Override public boolean isMultiHead() { return true; }
+
+ @Override
+ public TypeTuple compute() { return _args; }
+
+ @Override
+ public Node idealize() { return null; }
+
+ // No immediate dominator, and idepth==0
+ @Override
+ Node idom() { return null; }
+
+}
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/node/StopNode.java b/chapter07/src/main/java/com/seaofnodes/simple/node/StopNode.java
new file mode 100644
index 00000000..c4375771
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/node/StopNode.java
@@ -0,0 +1,53 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+
+import java.util.BitSet;
+
+public class StopNode extends Node {
+ public StopNode(Node... inputs) {
+ super(inputs);
+ }
+
+ @Override
+ public String label() {
+ return "Stop";
+ }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ if( ret()!=null ) return ret()._print0(sb, visited);
+ sb.append("Stop[ ");
+ for( Node ret : _inputs )
+ ret._print0(sb, visited).append(" ");
+ return sb.append("]");
+ }
+
+ @Override public boolean isCFG() { return true; }
+
+ // If a single Return, return it.
+ // Otherwise, null because ambiguous.
+ public ReturnNode ret() {
+ return nIns()==1 ? (ReturnNode)in(0) : null;
+ }
+
+ @Override
+ public Type compute() {
+ return Type.BOTTOM;
+ }
+
+ @Override
+ public Node idealize() {
+ int len = nIns();
+ for( int i=0; i<nIns(); i++ )
+ if( in(i)._type==Type.XCONTROL )
+ delDef(i--);
+ if( len != nIns() ) return this;
+ return null;
+ }
+
+ public Node addReturn(Node node) {
+ return add_def(node);
+ }
+
+}
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/node/SubNode.java b/chapter07/src/main/java/com/seaofnodes/simple/node/SubNode.java
new file mode 100644
index 00000000..1484ab8a
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/node/SubNode.java
@@ -0,0 +1,43 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeInteger;
+
+import java.util.BitSet;
+
+public class SubNode extends Node {
+ public SubNode(Node lhs, Node rhs) { super(null, lhs, rhs); }
+
+ @Override public String label() { return "Sub"; }
+
+ @Override public String glabel() { return "-"; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ in(1)._print0(sb.append("("), visited);
+ in(2)._print0(sb.append("-"), visited);
+ return sb.append(")");
+ }
+
+ @Override
+ public Type compute() {
+ if (in(1)._type instanceof TypeInteger i0 &&
+ in(2)._type instanceof TypeInteger i1) {
+ if (i0.isConstant() && i1.isConstant())
+ return TypeInteger.constant(i0.value()-i1.value());
+ return i0.meet(i1);
+ }
+ return Type.BOTTOM;
+ }
+
+ @Override
+ public Node idealize() {
+ // Sub of same is 0
+ if( in(1)==in(2) )
+ return new ConstantNode(TypeInteger.constant(0));
+
+ return null;
+ }
+
+ @Override Node copy(Node lhs, Node rhs) { return new SubNode(lhs,rhs); }
+}
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/type/Type.java b/chapter07/src/main/java/com/seaofnodes/simple/type/Type.java
new file mode 100644
index 00000000..f88403a5
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/type/Type.java
@@ -0,0 +1,77 @@
+package com.seaofnodes.simple.type;
+
+
+/**
+ * These types are part of a Monotone Analysis Framework,
+ * @see <a href="https://www.cse.psu.edu/~gxt29/teaching/cse597s21/slides/08monotoneFramework.pdf">see for example this set of slides</a>.
+ * <p>
+ * The types form a lattice; @see <a href="https://en.wikipedia.org/wiki/Lattice_(order)">a symmetric complete bounded (ranked) lattice.</a>
+ * <p>
+ * This wild lattice theory will be needed later to allow us to easily beef up
+ * the analysis and optimization of the Simple compiler... but we don't need it
+ * now, just know that it is coming along in a later Chapter.
+ * <p>g
+ * One of the fun things here is that while the theory is deep and subtle, the
+ * actual implementation is darn near trivial and is generally really obvious
+ * what we're doing with it. Right now, it's just simple integer math to do
+ * simple constant folding e.g. 1+2 == 3 stuff.
+ */
+
+public class Type {
+
+ // ----------------------------------------------------------
+ // Simple types are implemented fully here. "Simple" means: the code and
+ // type hierarchy are simple, not that the Type is conceptually simple.
+ static final byte TBOT = 0; // Bottom (ALL)
+ static final byte TTOP = 1; // Top (ANY)
+ static final byte TCTRL = 2; // Ctrl flow bottom
+ static final byte TXCTRL = 3; // Ctrl flow top (mini-lattice: any-xctrl-ctrl-all)
+ static final byte TSIMPLE = 4; // End of the Simple Types
+ static final byte TINT = 5; // All Integers; see TypeInteger
+ static final byte TTUPLE = 6; // Tuples; finite collections of unrelated Types, kept in parallel
+
+ public final byte _type;
+
+ public boolean is_simple() { return _type < TSIMPLE; }
+ private static final String[] STRS = new String[]{"Bot","Top","Ctrl","~Ctrl"};
+ protected Type(byte type) { _type = type; }
+
+ public static final Type BOTTOM = new Type( TBOT ); // ALL
+ public static final Type TOP = new Type( TTOP ); // ANY
+ public static final Type CONTROL = new Type( TCTRL ); // Ctrl
+ public static final Type XCONTROL = new Type( TXCTRL ); // ~Ctrl
+
+ public boolean isConstant() { return _type == TTOP || _type == TXCTRL; }
+
+ public StringBuilder _print(StringBuilder sb) {return is_simple() ? sb.append(STRS[_type]) : sb;}
+
+ public final Type meet(Type t) {
+ // Shortcut for the self case
+ if( t == this ) return this;
+ // Same-type is always safe in the subclasses
+ if( _type==t._type ) return xmeet(t);
+ // Reverse; xmeet 2nd arg is never "is_simple" and never equal to "this".
+ if( is_simple() ) return this.xmeet(t );
+ if( t.is_simple() ) return t .xmeet(this);
+ return BOTTOM; // Mixing 2 unrelated types
+ }
+
+ // Compute meet right now. Overridden in subclasses.
+ // Handle cases where 'this.is_simple()' and unequal to 't'.
+ // Subclassed xmeet calls can assert that '!t.is_simple()'.
+ protected Type xmeet(Type t) {
+ assert is_simple(); // Should be overridden in subclass
+ // ANY meet anything is thing; thing meet ALL is ALL
+ if( _type==TBOT || t._type==TTOP ) return this;
+ if( _type==TTOP || t._type==TBOT ) return t;
+ // 'this' is {TCTRL,TXCTRL}
+ if( !t.is_simple() ) return BOTTOM;
+ // 't' is {TCTRL,TXCTRL}
+ return _type==TCTRL || t._type==TCTRL ? CONTROL : XCONTROL;
+ }
+
+ @Override
+ public final String toString() {
+ return _print(new StringBuilder()).toString();
+ }
+}
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/type/TypeInteger.java b/chapter07/src/main/java/com/seaofnodes/simple/type/TypeInteger.java
new file mode 100644
index 00000000..93f5eae3
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/type/TypeInteger.java
@@ -0,0 +1,63 @@
+package com.seaofnodes.simple.type;
+
+/**
+ * Integer Type
+ */
+public class TypeInteger extends Type {
+
+ public final static TypeInteger TOP = new TypeInteger(false, 0);
+ public final static TypeInteger BOT = new TypeInteger(false, 1);
+ public final static TypeInteger ZERO= new TypeInteger(true, 0);
+
+ private final boolean _is_con;
+
+ /**
+ * The constant value or
+ * if not constant then 0=bottom, 1=top.
+ */
+ private final long _con;
+
+ public TypeInteger(boolean is_con, long con) {
+ super(TINT);
+ _is_con = is_con;
+ _con = con;
+ }
+
+ public static TypeInteger constant(long con) { return new TypeInteger(true, con); }
+
+ public boolean isTop() { return !_is_con && _con==0; }
+ public boolean isBot() { return !_is_con && _con==1; }
+
+ @Override
+ public StringBuilder _print(StringBuilder sb) {
+ if (isTop()) return sb.append("IntTop");
+ if (isBot()) return sb.append("IntBot");
+ return sb.append(_con);
+ }
+
+ @Override
+ public boolean isConstant() { return _is_con; }
+
+ public long value() { return _con; }
+
+ @Override
+ public Type xmeet(Type other) {
+ if( this==other ) return this;
+ if (!(other instanceof TypeInteger i)) return super.meet(other);
+ // BOT wins
+ if ( isBot() ) return this;
+ if ( i.isBot() ) return i ;
+ // TOP loses
+ if ( i.isTop() ) return this;
+ if ( isTop() ) return i ;
+ assert isConstant() && i.isConstant();
+ return _con==i._con ? this : TypeInteger.BOT;
+ }
+
+ @Override
+ public boolean equals( Object o ) {
+ if( o==this ) return true;
+ if( !(o instanceof TypeInteger i) ) return false;
+ return _con==i._con && _is_con==i._is_con;
+ }
+}
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/type/TypeTuple.java b/chapter07/src/main/java/com/seaofnodes/simple/type/TypeTuple.java
new file mode 100644
index 00000000..f8c3b3c8
--- /dev/null
+++ b/chapter07/src/main/java/com/seaofnodes/simple/type/TypeTuple.java
@@ -0,0 +1,32 @@
+package com.seaofnodes.simple.type;
+
+public class TypeTuple extends Type {
+
+ public final Type[] _types;
+
+ public TypeTuple(Type... _types) {
+ super(TTUPLE);
+ this._types = _types;
+ }
+
+ @Override
+ public Type xmeet(Type other) {
+ throw new UnsupportedOperationException("Meet on Tuple Type not yet implemented");
+ }
+
+ @Override
+ public StringBuilder _print(StringBuilder sb) {
+ sb.append("[");
+ for( Type t : _types )
+ t._print(sb).append(",");
+ sb.setLength(sb.length()-1);
+ sb.append("]");
+ return sb;
+ }
+
+ public static final TypeTuple IF_BOTH = new TypeTuple(new Type[]{Type.CONTROL, Type.CONTROL});
+ public static final TypeTuple IF_NEITHER = new TypeTuple(new Type[]{Type.XCONTROL,Type.XCONTROL});
+ public static final TypeTuple IF_TRUE = new TypeTuple(new Type[]{Type.CONTROL, Type.XCONTROL});
+ public static final TypeTuple IF_FALSE = new TypeTuple(new Type[]{Type.XCONTROL,Type.CONTROL});
+
+}
diff --git a/chapter07/src/test/java/com/seaofnodes/simple/Chapter07Test.java b/chapter07/src/test/java/com/seaofnodes/simple/Chapter07Test.java
new file mode 100644
index 00000000..efcf90f5
--- /dev/null
+++ b/chapter07/src/test/java/com/seaofnodes/simple/Chapter07Test.java
@@ -0,0 +1,1026 @@
+package com.seaofnodes.simple;
+
+import com.seaofnodes.simple.node.*;
+import com.seaofnodes.simple.type.TypeInteger;
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+public class Chapter07Test {
+
+ @Test
+ public void testChapter7Example() {
+ Parser parser = new Parser(
+ """
+ while(arg < 10) {
+ arg = arg + 1;
+ #showGraph;
+ }
+ return arg;
+ """);
+ Node._disablePeephole = true;
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Loop6,arg,(Phi_arg+1));", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ Node._disablePeephole = false;
+ }
+
+ @Test
+ public void testChapter7Regression() {
+ Parser parser = new Parser(
+
+"""
+int a = 1;
+if(arg){}else{
+ while(a < 10) {
+ a = a + 1;
+ }
+}
+return a;
+""");
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Region23,1,Phi(Loop11,1,(Phi_a+1)));", stop.toString());
+ }
+
+ @Test
+ public void testChapter7WhileNested() {
+ Parser parser = new Parser(
+
+"""
+int sum = 0;
+int i = 0;
+while(i < arg) {
+ i = i + 1;
+ int j = 0;
+ while( j < arg ) {
+ sum = sum + j;
+ j = j + 1;
+ }
+}
+return sum;
+""");
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Loop8,0,Phi(Loop21,Phi_sum,(Phi(Loop,0,(Phi_j+1))+Phi_sum)));", stop.toString());
+ System.out.println(IRPrinter.prettyPrint(stop,99));
+ }
+
+ @Test
+ public void testChapter7WhileScope() {
+ Parser parser = new Parser(
+"""
+int a = 1;
+int b = 2;
+while(a < 10) {
+ if (a == 2) a = 3;
+ else b = 4;
+}
+return b;
+""");
+ Node._disablePeephole = true;
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Loop8,2,Phi(Region27,Phi_b,4));", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ Node._disablePeephole = false;
+ System.out.println(IRPrinter.prettyPrint(stop,99));
+ }
+
+ @Test
+ public void testChapter7WhileNestedIfAndInc() {
+ Parser parser = new Parser(
+"""
+int a = 1;
+int b = 2;
+while(a < 10) {
+ if (a == 2) a = 3;
+ else b = 4;
+ b = b + 1;
+ a = a + 1;
+}
+return b;
+""");
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Loop8,2,(Phi(Region27,Phi_b,4)+1));", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ System.out.println(IRPrinter.prettyPrint(stop,99));
+ }
+
+
+ @Test
+ public void testChapter7While() {
+ Parser parser = new Parser(
+"""
+int a = 1;
+while(a < 10) {
+ a = a + 1;
+ a = a + 2;
+}
+return a;
+""");
+ Node._disablePeephole = true;
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Loop7,1,((Phi_a+1)+2));", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ Node._disablePeephole = false;
+ }
+
+ @Test
+ public void testChapter7WhilePeep() {
+ Parser parser = new Parser(
+"""
+int a = 1;
+while(a < 10) {
+ a = a + 1;
+ a = a + 2;
+}
+return a;
+""");
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Loop7,1,(Phi_a+3));", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ }
+
+ @Test
+ public void testChapter7While2() {
+ Parser parser = new Parser(
+"""
+int a = 1;
+while(arg) a = 2;
+return a;
+""");
+ Node._disablePeephole = true;
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Loop7,1,2);", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ Node._disablePeephole = false;
+ System.out.println(IRPrinter.prettyPrint(stop,99));
+ }
+
+ @Test
+ public void testChapter7While2Peep() {
+ Parser parser = new Parser(
+"""
+int a = 1;
+while(arg) a = 2;
+return a;
+""");
+ StopNode stop = parser.parse(false);
+ assertEquals("return Phi(Loop7,1,2);", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ System.out.println(IRPrinter.prettyPrint(stop, 99));
+ }
+
+ @Test
+ public void testChapter7While3() {
+ Parser parser = new Parser(
+"""
+int a = 1;
+while(a < 10) {
+ int b = a + 1;
+ a = b + 2;
+}
+return a;
+""");
+ Node._disablePeephole = true;
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Loop7,1,((Phi_a+1)+2));", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ Node._disablePeephole = false;
+ }
+
+ @Test
+ public void testChapter7While3Peep() {
+ Parser parser = new Parser(
+"""
+int a = 1;
+while(a < 10) {
+ int b = a + 1;
+ a = b + 2;
+}
+return a;
+""");
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Loop7,1,(Phi_a+3));", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ }
+
+ @Test
+ public void testChapter7While4() {
+ Parser parser = new Parser(
+"""
+int a = 1;
+int b = 2;
+while(a < 10) {
+ int b = a + 1;
+ a = b + 2;
+}
+return a;
+""");
+ Node._disablePeephole = true;
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Loop8,1,((Phi_a+1)+2));", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ Node._disablePeephole = false;
+ }
+
+ @Test
+ public void testChapter7While4Peep() {
+ Parser parser = new Parser(
+"""
+int a = 1;
+int b = 2;
+while(a < 10) {
+ int b = a + 1;
+ a = b + 2;
+}
+return a;
+""");
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Loop8,1,(Phi_a+3));", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ }
+
+ @Test
+ public void testChapter6PeepholeReturn() {
+ Parser parser = new Parser(
+"""
+if( true ) return 2;
+return 1;
+""");
+ StopNode stop = parser.parse(true);
+ assertEquals("return 2;", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ }
+
+ @Test
+ public void testChapter6PeepholeRotate() {
+ Parser parser = new Parser(
+"""
+int a = 1;
+if (arg)
+ a = 2;
+return (arg < a) < 3;
+""");
+ StopNode stop = parser.parse(false);
+ assertEquals("return ((arg<Phi(Region12,2,1))<3);", stop.toString());
+ }
+
+ @Test
+ public void testChapter6PeepholeCFG() {
+ Parser parser = new Parser(
+"""
+int a=1;
+if( true )
+ a=2;
+else
+ a=3;
+return a;
+""");
+ StopNode stop = parser.parse(true);
+ assertEquals("return 2;", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ }
+
+ @Test
+ public void testChapter6IfIf() {
+ Parser parser = new Parser(
+"""
+int a=1;
+if( arg!=1 )
+ a=2;
+else
+ a=3;
+int b=4;
+if( a==2 )
+ b=42;
+else
+ b=5;
+return b;""", TypeInteger.BOT);
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Region32,42,5);", stop.toString());
+ }
+
+ @Test
+ public void testChapter6IfArgIf() {
+ Parser parser = new Parser(
+"""
+int a=1;
+if( 1==1 )
+ a=2;
+else
+ a=3;
+int b=4;
+if( arg==2 )
+ b=a;
+else
+ b=5;
+return b;""", TypeInteger.BOT);
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Region28,2,5);", stop.toString());
+ }
+
+ @Test
+ public void testChapter6Merge3With2() {
+ Parser parser = new Parser(
+"""
+int a=1;
+if( arg==1 )
+ if( arg==2 )
+ a=2;
+ else
+ a=3;
+else if( arg==3 )
+ a=4;
+else
+ a=5;
+return a;
+#showGraph;""", TypeInteger.constant(2));
+ StopNode stop = parser.parse();
+ assertEquals("return 5;", stop.toString());
+ }
+
+ @Test
+ public void testChapter6Merge3With1() {
+ Parser parser = new Parser(
+"""
+int a=1;
+if( arg==1 )
+ if( arg==2 )
+ a=2;
+ else
+ a=3;
+else if( arg==3 )
+ a=4;
+else
+ a=5;
+return a;
+""", TypeInteger.constant(1));
+ StopNode stop = parser.parse(true);
+ assertEquals("return 3;", stop.toString());
+ }
+
+ @Test
+ public void testChapter6Merge3Peephole() {
+ Parser parser = new Parser(
+"""
+int a=1;
+if( arg==1 )
+ if( 1==2 )
+ a=2;
+ else
+ a=3;
+else if( arg==3 )
+ a=4;
+else
+ a=5;
+return a;
+""", TypeInteger.BOT);
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Region36,3,Phi(Region34,4,5));", stop.toString());
+ }
+
+ @Test
+ public void testChapter6Merge3Peephole1() {
+ Parser parser = new Parser(
+"""
+int a=1;
+if( arg==1 )
+ if( 1==2 )
+ a=2;
+ else
+ a=3;
+else if( arg==3 )
+ a=4;
+else
+ a=5;
+return a;
+""", TypeInteger.constant(1));
+ StopNode stop = parser.parse(true);
+ assertEquals("return 3;", stop.toString());
+ }
+
+ @Test
+ public void testChapter6Merge3Peephole3() {
+ Parser parser = new Parser(
+"""
+int a=1;
+if( arg==1 )
+ if( 1==2 )
+ a=2;
+ else
+ a=3;
+else if( arg==3 )
+ a=4;
+else
+ a=5;
+return a;
+""", TypeInteger.constant(3));
+ StopNode stop = parser.parse(true);
+ assertEquals("return 4;", stop.toString());
+ }
+
+ @Test
+ public void testChapter6Demo1NonConst() {
+ Parser parser = new Parser("""
+int a = 0;
+int b = 1;
+if( arg ) {
+ a = 2;
+ if( arg ) { b = 2; }
+ else b = 3;
+}
+return a+b;
+""");
+ StopNode ret = parser.parse(true);
+ assertEquals("return Phi(Region22,4,1);", ret.toString());
+ }
+
+
+ @Test
+ public void testChapter6Demo1True() {
+ Parser parser = new Parser("""
+int a = 0;
+int b = 1;
+if( arg ) {
+ a = 2;
+ if( arg ) { b = 2; }
+ else b = 3;
+}
+return a+b;
+""", TypeInteger.constant(1));
+ StopNode ret = parser.parse(true);
+ assertEquals("return 4;", ret.toString());
+ }
+
+ @Test
+ public void testChapter6Demo1False() {
+ Parser parser = new Parser("""
+int a = 0;
+int b = 1;
+if( arg ) {
+ a = 2;
+ if( arg ) { b = 2; }
+ else b = 3;
+}
+return a+b;
+""", TypeInteger.constant(0));
+ StopNode ret = parser.parse(true);
+ assertEquals("return 1;", ret.toString());
+ }
+
+ @Test
+ public void testChapter6Demo2NonConst() {
+ Parser parser = new Parser("""
+int a = 0;
+int b = 1;
+int c = 0;
+if( arg ) {
+ a = 1;
+ if( arg==2 ) { c=2; } else { c=3; }
+ if( arg ) { b = 2; }
+ else b = 3;
+}
+return a+b+c;
+""");
+ StopNode ret = parser.parse(true);
+ assertEquals("return (Phi(Region33,Phi(Region22,2,3),0)+Phi(Region,3,1));", ret.toString());
+ }
+
+
+ @Test
+ public void testChapter6Demo2True() {
+ Parser parser = new Parser("""
+int a = 0;
+int b = 1;
+int c = 0;
+if( arg ) {
+ a = 1;
+ if( arg==2 ) { c=2; } else { c=3; }
+ if( arg ) { b = 2; }
+ else b = 3;
+}
+return a+b+c;
+""", TypeInteger.constant(1));
+ StopNode ret = parser.parse(true);
+ assertEquals("return 6;", ret.toString());
+ }
+
+ @Test
+ public void testChapter6Demo2arg2() {
+ Parser parser = new Parser("""
+int a = 0;
+int b = 1;
+int c = 0;
+if( arg ) {
+ a = 1;
+ if( arg==2 ) { c=2; } else { c=3; }
+ if( arg ) { b = 2; }
+ else b = 3;
+}
+return a+b+c;
+""", TypeInteger.constant(2));
+ StopNode ret = parser.parse(true);
+ assertEquals("return 5;", ret.toString());
+ }
+
+
+
+ @Test
+ public void testChapter5IfStmt() {
+ Parser parser = new Parser(
+"""
+int a = 1;
+if (arg == 1)
+ a = arg+2;
+else {
+ a = arg-3;
+ #showGraph;
+}
+#showGraph;
+return a;""");
+ StopNode ret = parser.parse(true);
+ assertEquals("return Phi(Region17,(arg+2),(arg-3));", ret.toString());
+ }
+
+ @Test
+ public void testChapter5Test() {
+ Parser parser = new Parser(
+"""
+int c = 3;
+int b = 2;
+if (arg == 1) {
+ b = 3;
+ c = 4;
+}
+return c;""", TypeInteger.BOT);
+ StopNode ret = parser.parse(true);
+ assertEquals("return Phi(Region16,4,3);", ret.toString());
+ }
+
+ @Test
+ public void testChapter5Return2() {
+ Parser parser = new Parser(
+"""
+if( arg==1 )
+ return 3;
+else
+ return 4;
+#showGraph;""", TypeInteger.BOT);
+ StopNode stop = parser.parse();
+ assertEquals("Stop[ return 3; return 4; ]", stop.toString());
+ }
+
+ @Test
+ public void testChapter5IfMergeB() {
+ Parser parser = new Parser(
+"""
+int a=arg+1;
+int b=0;
+if( arg==1 )
+ b=a;
+else
+ b=a+1;
+return a+b;""");
+ StopNode ret = parser.parse(true);
+ assertEquals("return ((arg*2)+Phi(Region20,2,3));", ret.toString());
+ }
+
+ @Test
+ public void testChapter5IfMerge2() {
+ Parser parser = new Parser(
+"""
+int a=arg+1;
+int b=arg+2;
+if( arg==1 )
+ b=b+a;
+else
+ a=b+1;
+return a+b;""");
+ StopNode ret = parser.parse(true);
+ assertEquals("return ((Phi(Region31,(arg*2),arg)+arg)+Phi(Region,4,5));", ret.toString());
+ }
+
+ @Test
+ public void testChapter5Merge3() {
+ Parser parser = new Parser(
+"""
+int a=1;
+if( arg==1 )
+ if( arg==2 )
+ a=2;
+ else
+ a=3;
+else if( arg==3 )
+ a=4;
+else
+ a=5;
+return a;
+#showGraph;""", TypeInteger.BOT);
+ StopNode stop = parser.parse();
+ assertEquals("return Phi(Region33,Phi(Region21,2,3),Phi(Region31,4,5));", stop.toString());
+ }
+
+ @Test
+ public void testChapter5Merge4() {
+ Parser parser = new Parser(
+"""
+int a=0;
+int b=0;
+if( arg )
+ a=1;
+if( arg==0 )
+ b=2;
+return arg+a+b;
+#showGraph;""", TypeInteger.BOT);
+ StopNode stop = parser.parse();
+ assertEquals("return ((arg+Phi(Region13,1,0))+Phi(Region22,2,0));", stop.toString());
+ }
+
+ @Test
+ public void testChapter5Merge5() {
+ Parser parser = new Parser(
+"""
+int a=arg==2;
+if( arg==1 )
+{
+ a=arg==3;
+}
+return a;""");
+ StopNode ret = parser.parse(true);
+ assertEquals("return (arg==Phi(Region16,3,2));", ret.toString());
+ }
+
+ @Test
+ public void testChapter5True() {
+ StopNode stop = new Parser("return true;").parse();
+ assertEquals("return 1;",stop.toString());
+ }
+
+ @Test
+ public void testChapter5HalfDef() {
+ try {
+ new Parser("if( arg==1 ) int b=2; return b;").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Cannot define a new name on one arm of an if",e.getMessage());
+ }
+ }
+
+ @Test
+ public void testChapter5HalfDef2() {
+ try {
+ new Parser("if( arg==1 ) { int b=2; } else { int b=3; } return b;").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Undefined name 'b'",e.getMessage());
+ }
+ }
+
+ @Test
+ public void testChapter5BadNum() {
+ try {
+ new Parser("return 1-;").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Syntax error, expected an identifier or expression: ;",e.getMessage());
+ }
+ }
+
+ @Test
+ public void testChapter5Keyword1() {
+ try {
+ new Parser("int true=0; return true;").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Expected an identifier, found 'true'",e.getMessage());
+ }
+ }
+
+ @Test
+ public void testChapter5Keyword2() {
+ try {
+ new Parser("int else=arg; if(else) else=2; else else=1; return else;").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Expected an identifier, found 'else'",e.getMessage());
+ }
+ }
+
+ @Test
+ public void testChapter5Keyword3() {
+ try {
+ new Parser("int a=1; ififif(arg)inta=2;return a;").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Syntax error, expected =: (",e.getMessage());
+ }
+ }
+
+ @Test
+ public void testChapter4Peephole() {
+ Parser parser = new Parser("return 1+arg+2; #showGraph;");
+ StopNode ret = parser.parse();
+ assertEquals("return (arg+3);", ret.print());
+ }
+
+ @Test
+ public void testChapter4Peephole2() {
+ Parser parser = new Parser("return (1+arg)+2;");
+ StopNode ret = parser.parse();
+ assertEquals("return (arg+3);", ret.print());
+ }
+
+ @Test
+ public void testChapter4Add0() {
+ Parser parser = new Parser("return 0+arg;");
+ StopNode ret = parser.parse();
+ assertEquals("return arg;", ret.print());
+ }
+
+ @Test
+ public void testChapter4AddAddMul() {
+ Parser parser = new Parser("return arg+0+arg;");
+ StopNode ret = parser.parse();
+ assertEquals("return (arg*2);", ret.print());
+ }
+
+ @Test
+ public void testChapter4Peephole3() {
+ Parser parser = new Parser("return 1+arg+2+arg+3; #showGraph;");
+ StopNode ret = parser.parse();
+ assertEquals("return ((arg*2)+6);", ret.print());
+ }
+
+ @Test
+ public void testChapter4Mul1() {
+ Parser parser = new Parser("return 1*arg;");
+ StopNode ret = parser.parse();
+ assertEquals("return arg;", ret.print());
+ }
+
+ @Test
+ public void testChapter4VarArg() {
+ Parser parser = new Parser("return arg; #showGraph;");
+ StopNode stop = parser.parse();
+ ReturnNode ret = stop.ret();
+ assertTrue(ret.in(0) instanceof ProjNode);
+ assertTrue(ret.in(1) instanceof ProjNode);
+ }
+
+ @Test
+ public void testChapter4ConstantArg() {
+ Parser parser = new Parser("return arg; #showGraph;", TypeInteger.constant(2));
+ StopNode ret = parser.parse();
+ assertEquals("return 2;", ret.print());
+ }
+
+ @Test
+ public void testChapter4CompEq() {
+ Parser parser = new Parser("return 3==3; #showGraph;");
+ StopNode ret = parser.parse();
+ assertEquals("return 1;", ret.print());
+ }
+
+ @Test
+ public void testChapter4CompEq2() {
+ Parser parser = new Parser("return 3==4; #showGraph;");
+ StopNode ret = parser.parse();
+ assertEquals("return 0;", ret.print());
+ }
+
+ @Test
+ public void testChapter4CompNEq() {
+ Parser parser = new Parser("return 3!=3; #showGraph;");
+ StopNode ret = parser.parse();
+ assertEquals("return 0;", ret.print());
+ }
+
+ @Test
+ public void testChapter4CompNEq2() {
+ Parser parser = new Parser("return 3!=4; #showGraph;");
+ StopNode ret = parser.parse();
+ assertEquals("return 1;", ret.print());
+ }
+
+ @Test
+ public void testChapter4Bug1() {
+ Parser parser = new Parser("int a=arg+1; int b=a; b=1; return a+2; #showGraph;");
+ StopNode ret = parser.parse();
+ assertEquals("return (arg+3);", ret.print());
+ }
+
+ @Test
+ public void testChapter4Bug2() {
+ Parser parser = new Parser("int a=arg+1; a=a; return a; #showGraph;");
+ StopNode ret = parser.parse();
+ assertEquals("return (arg+1);", ret.print());
+ }
+
+ @Test
+ public void testChapter4Bug3() {
+ try {
+ new Parser("inta=1; return a;").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Undefined name 'inta'",e.getMessage());
+ }
+ }
+
+ @Test
+ public void testChapter4Bug4() {
+ Parser parser = new Parser("return -arg;");
+ StopNode ret = parser.parse();
+ assertEquals("return (-arg);", ret.print());
+ }
+
+ @Test
+ public void testVarDecl() {
+ Parser parser = new Parser("int a=1; return a;");
+ StopNode ret = parser.parse();
+ assertEquals("return 1;", ret.print());
+ }
+
+ @Test
+ public void testVarAdd() {
+ Parser parser = new Parser("int a=1; int b=2; return a+b;");
+ StopNode ret = parser.parse();
+ assertEquals("return 3;", ret.print());
+ }
+
+ @Test
+ public void testVarScope() {
+ Parser parser = new Parser("int a=1; int b=2; int c=0; { int b=3; c=a+b; } return c;");
+ StopNode ret = parser.parse();
+ assertEquals("return 4;", ret.print());
+ }
+
+ @Test
+ public void testVarScopeNoPeephole() {
+ Parser parser = new Parser("int a=1; int b=2; int c=0; { int b=3; c=a+b; #showGraph; } return c; #showGraph;");
+ Node._disablePeephole = true;
+ StopNode ret = parser.parse();
+ Node._disablePeephole = false;
+ assertEquals("return (1+3);", ret.print());
+ }
+
+ @Test
+ public void testVarDist() {
+ Parser parser = new Parser("int x0=1; int y0=2; int x1=3; int y1=4; return (x0-x1)*(x0-x1) + (y0-y1)*(y0-y1); #showGraph;");
+ StopNode ret = parser.parse();
+ assertEquals("return 8;", ret.print());
+ }
+
+ @Test
+ public void testSelfAssign() {
+ try {
+ new Parser("int a=a; return a;").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Undefined name 'a'",e.getMessage());
+ }
+ }
+
+ @Test
+ public void testChapter2ParseGrammar() {
+ Parser parser = new Parser("return 1+2*3+-5;");
+ Node._disablePeephole = true; // disable peephole so we can observe full graph
+ StopNode ret = parser.parse();
+ assertEquals("return (1+((2*3)+(-5)));", ret.print());
+ GraphVisualizer gv = new GraphVisualizer();
+ System.out.println(gv.generateDotOutput(parser));
+ Node._disablePeephole = false;
+ }
+
+ @Test
+ public void testChapter2AddPeephole() {
+ Parser parser = new Parser("return 1+2;");
+ StopNode ret = parser.parse();
+ assertEquals("return 3;", ret.print());
+ }
+
+ @Test
+ public void testChapter2SubPeephole() {
+ Parser parser = new Parser("return 1-2;");
+ StopNode ret = parser.parse();
+ assertEquals("return -1;", ret.print());
+ }
+
+ @Test
+ public void testChapter2MulPeephole() {
+ Parser parser = new Parser("return 2*3;");
+ StopNode ret = parser.parse();
+ assertEquals("return 6;", ret.print());
+ }
+
+ @Test
+ public void testChapter2DivPeephole() {
+ Parser parser = new Parser("return 6/3;");
+ StopNode ret = parser.parse();
+ assertEquals("return 2;", ret.print());
+ }
+
+ @Test
+ public void testChapter2MinusPeephole() {
+ Parser parser = new Parser("return 6/-3;");
+ StopNode ret = parser.parse();
+ assertEquals("return -2;", ret.print());
+ }
+
+ @Test
+ public void testChapter2Example() {
+ Parser parser = new Parser("return 1+2*3+-5;");
+ StopNode ret = parser.parse();
+ assertEquals("return 2;", ret.print());
+ GraphVisualizer gv = new GraphVisualizer();
+ System.out.println(gv.generateDotOutput(parser));
+ }
+
+ @Test
+ public void testSimpleProgram() {
+ Parser parser = new Parser("return 1;");
+ StopNode stop = parser.parse();
+ StartNode start = Parser.START;
+ ReturnNode ret = (ReturnNode)stop.in(0);
+
+ assertTrue(ret.ctrl() instanceof ProjNode);
+ Node expr = ret.expr();
+ if( expr instanceof ConstantNode con ) {
+ assertEquals(start,con.in(0));
+ assertEquals(TypeInteger.constant(1), con._type);
+ } else {
+ fail();
+ }
+ }
+
+ @Test
+ public void testZero() {
+ Parser parser = new Parser("return 0;");
+ parser.parse();
+ StartNode start = Parser.START;
+ for( Node use : start._outputs )
+ if( use instanceof ConstantNode con )
+ assertEquals(TypeInteger.constant(0),con._type);
+ }
+
+ @Test
+ public void testBad1() {
+ try {
+ new Parser("ret").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Syntax error, expected =: ",e.getMessage());
+ }
+ }
+
+ @Test
+ public void testBad2() {
+ try {
+ new Parser("return 0123;").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Syntax error: integer values cannot start with '0'",e.getMessage());
+ }
+ }
+
+ @Test
+ public void testNotBad3() {
+ // this test used to fail in chapter 1
+ assertEquals("return 12;", new Parser("return --12;").parse().print());
+ }
+
+ @Test
+ public void testBad4() {
+ try {
+ new Parser("return 100").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Syntax error, expected ;: ",e.getMessage());
+ }
+ }
+
+ @Test
+ public void testNotBad5() {
+ // this test used to fail in chapter 1
+ assertEquals("return -100;", new Parser("return -100;").parse().print());
+ }
+
+ @Test
+ public void testBad6() {
+ try {
+ new Parser("int a=1; int b=2; int c=0; { int b=3; c=a+b;").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Syntax error, expected }: ",e.getMessage());
+ }
+ }
+
+ @Test
+ public void testBad7() {
+ try {
+ new Parser("return 1;}").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Syntax error, unexpected }",e.getMessage());
+ }
+ }
+
+}
diff --git a/chapter08/Makefile b/chapter08/Makefile
new file mode 100644
index 00000000..56f69e12
--- /dev/null
+++ b/chapter08/Makefile
@@ -0,0 +1,92 @@
+SHELL := /bin/bash
+.DELETE_ON_ERROR:
+
+# for printing variable values
+# usage: make print-VARIABLE
+# > VARIABLE = value_of_variable
+print-% : ; @echo $* = $($*)
+
+# literal space
+space := $() $()
+
+# Decide OS-specific questions
+# jar-file seperator
+ifeq ($(OS),Windows_NT)
+ SEP = ;
+else
+ SEP = :
+endif
+# Find a reasonable ctags.
+CTAGS = $(shell which ctags)
+# Hack for MacOS: /usr/bin/ctags is unfriendly, so look for ctags from brew
+ifeq ($(UNAME),Darwin)
+ CTAGS = $(shell brew list ctags 2> /dev/null | grep bin/ctags)
+endif
+
+# Fun Args to javac. Mostly limit to java8 source definitions, and fairly
+# aggressive lint warnings.
+JAVAC_ARGS = -g
+
+# Source code
+SIMPLE := com/seaofnodes/simple
+SRC := src/main/java
+TST := src/test/java
+CLZDIR:= build/classes
+main_javas := $(wildcard $(SRC)/$(SIMPLE)/*java $(SRC)/$(SIMPLE)/*/*java)
+test_javas := $(wildcard $(TST)/$(SIMPLE)/*java $(TST)/$(SIMPLE)/*/*java)
+main_classes := $(patsubst $(SRC)/%java,$(CLZDIR)/main/%class,$(main_javas))
+test_classes := $(patsubst $(TST)/%java,$(CLZDIR)/test/%class,$(test_javas))
+test_cp := $(patsubst $(TST)/$(SIMPLE)/%.java,com.seaofnodes.simple.%,$(test_javas))
+classes = $(main_classes) $(test_classes)
+# All the libraries
+libs = $(wildcard lib/*jar)
+jars = $(subst $(space),$(SEP),$(libs))
+
+
+default_targets := $(main_classes) $(test_classes)
+# Optionally add ctags to the default target if a reasonable one was found.
+ifneq ($(CTAGS),)
+default_targets += tags
+endif
+
+default: $(default_targets)
+
+# Compile just the out-of-date files
+$(main_classes): build/classes/main/%class: $(SRC)/%java
+ @echo "compiling " $@ " because " $?
+ @[ -d $(CLZDIR)/main ] || mkdir -p $(CLZDIR)/main
+ @javac $(JAVAC_ARGS) -cp "$(CLZDIR)/main$(SEP)$(jars)" -sourcepath $(SRC) -d $(CLZDIR)/main $(main_javas)
+
+$(test_classes): $(CLZDIR)/test/%class: $(TST)/%java $(main_classes)
+ @echo "compiling " $@ " because " $?
+ @[ -d $(CLZDIR)/test ] || mkdir -p $(CLZDIR)/test
+ @javac $(JAVAC_ARGS) -cp "$(CLZDIR)/test$(SEP)$(CLZDIR)/main$(SEP)$(jars)" -sourcepath $(TST) -d $(CLZDIR)/test $(test_javas)
+
+# Base launch line for JVM tests
+JVM=nice java -ea -cp "build/classes/main${SEP}${jars}${SEP}$(CLZDIR)/test"
+
+tests: $(default_targets)
+ $(JVM) org.junit.runner.JUnitCore $(test_cp)
+
+.PHONY: clean
+clean:
+ rm -rf build
+ rm -f TAGS
+ (find . -name "*~" -exec rm {} \; 2>/dev/null; exit 0)
+
+# Download libs from maven
+lib: lib/junit-4.12.jar lib/hamcrest-core-1.3.jar
+
+# Jars
+lib/junit-4.12.jar:
+ @[ -d lib ] || mkdir -p lib
+ @(cd lib; wget https://repo1.maven.org/maven2/junit/junit/4.12/junit-4.12.jar)
+
+lib/hamcrest-core-1.3.jar:
+ @[ -d lib ] || mkdir -p lib
+ @(cd lib; wget https://repo1.maven.org/maven2/org/hamcrest/hamcrest-core/1.3/hamcrest-core-1.3.jar)
+
+# Build emacs tags (part of a tasty emacs ide experience)
+tags: $(main_javas) $(test_javas)
+ @rm -f TAGS
+ @$(CTAGS) -e --recurse=yes --extra=+q --fields=+fksaiS $(SRC) $(TST)
diff --git a/chapter08/README.md b/chapter08/README.md
new file mode 100644
index 00000000..656ea0ef
--- /dev/null
+++ b/chapter08/README.md
@@ -0,0 +1,2 @@
+# Chapter 8
+
diff --git a/chapter08/docs/08-grammar.md b/chapter08/docs/08-grammar.md
new file mode 100644
index 00000000..cee33030
--- /dev/null
+++ b/chapter08/docs/08-grammar.md
@@ -0,0 +1,88 @@
+# Grammar for Chapter 8
+
+```antlrv4
+grammar SimpleLanguage;
+
+program
+ : statement+ EOF
+ ;
+
+statement
+ : returnStatement
+ | declStatement
+ | blockStatment
+ | expressionStatement
+ | ifStatement
+ | whileStatement
+ | metaStatement
+ ;
+
+whileStatement
+ : 'while' '(' expression ')' statement
+ ;
+
+ifStatement
+ : 'if' '(' expression ')' statement ('else' statement)?
+ ;
+
+metaStatement
+ : '#showGraph' ';'
+ ;
+
+expressionStatement
+ : IDENTIFIER '=' expression ';'
+ ;
+
+blockStatement
+ : '{' statement+ '}'
+ ;
+
+declStatement
+ : 'int' IDENTIFIER '=' expression ';'
+ ;
+
+returnStatement
+ : 'return' expression ';'
+ ;
+
+expression
+ : comparisonExpression
+ ;
+
+comparisonExpression
+ : additiveExpression (('==' | '!='| '>'| '<'| '>='| '<=') additiveExpression)*
+ ;
+
+additiveExpression
+ : multiplicativeExpression (('+' | '-') multiplicativeExpression)*
+ ;
+
+multiplicativeExpression
+ : unaryExpression (('*' | '/') unaryExpression)*
+ ;
+
+unaryExpression
+ : ('-') unaryExpression
+ | primaryExpression
+ ;
+
+primaryExpression
+ : IDENTIFIER
+ | INTEGER_LITERAL
+ | 'true'
+ | 'false'
+ | '(' expression ')'
+ ;
+
+INTEGER_LITERAL
+ : [1-9][0-9]*
+ | [0]
+ ;
+
+IDENTIFIER
+ : NON_DIGIT (NON_DIGIT | DIGIT)*
+ ;
+
+NON_DIGIT: [a-zA-Z_];
+DEC_DIGIT: [0-9];
+``` \ No newline at end of file
diff --git a/chapter08/docs/build-graphs.sh b/chapter08/docs/build-graphs.sh
new file mode 100644
index 00000000..73c39624
--- /dev/null
+++ b/chapter08/docs/build-graphs.sh
@@ -0,0 +1,3 @@
+dot -Tsvg 07-graph1.gv > 07-graph1.svg
+
+
diff --git a/chapter08/pom.xml b/chapter08/pom.xml
new file mode 100644
index 00000000..5942485f
--- /dev/null
+++ b/chapter08/pom.xml
@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+ xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+ xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+ <modelVersion>4.0.0</modelVersion>
+ <parent>
+ <groupId>com.seaofnodes</groupId>
+ <artifactId>simple</artifactId>
+ <version>1.0</version>
+ </parent>
+ <artifactId>chapter08</artifactId>
+ <packaging>jar</packaging>
+ <name>Chapter 8</name>
+</project> \ No newline at end of file
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/GraphVisualizer.java b/chapter08/src/main/java/com/seaofnodes/simple/GraphVisualizer.java
new file mode 100644
index 00000000..c823641d
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/GraphVisualizer.java
@@ -0,0 +1,258 @@
+package com.seaofnodes.simple;
+
+import com.seaofnodes.simple.node.*;
+
+import java.util.*;
+
+/**
+ * Simple visualizer that outputs GraphViz dot format.
+ * The dot output must be saved to a file and run manually via dot to generate the SVG output.
+ * Currently, this is done manually.
+ */
+public class GraphVisualizer {
+
+ /**
+ * If set to true we put the control nodes in a separate cluster from
+ * data nodes.
+ */
+ boolean _separateControlCluster = false;
+
+ public GraphVisualizer(boolean separateControlCluster) { this._separateControlCluster = separateControlCluster; }
+ public GraphVisualizer() { this(false); }
+
+ public String generateDotOutput(Parser parser) {
+
+ // Since the graph has cycles, we need to create a flat list of all the
+ // nodes in the graph.
+ Collection<Node> all = findAll(parser);
+ StringBuilder sb = new StringBuilder();
+ sb.append("digraph chapter08 {\n");
+ sb.append("/*\n");
+ sb.append(parser.src());
+ sb.append("\n*/\n");
+
+ // To keep the Scopes below the graph and pointing up into the graph we
+ // need to group the Nodes in a subgraph cluster, and the scopes into a
+ // different subgraph cluster. THEN we can draw edges between the
+ // scopes and nodes. If we try to cross subgraph cluster borders while
+ // still making the subgraphs DOT gets confused.
+ sb.append("\trankdir=BT;\n"); // Force Nodes before Scopes
+
+ // Preserve node input order
+ sb.append("\tordering=\"in\";\n");
+
+ // Merge multiple edges hitting the same node. Makes common shared
+ // nodes much prettier to look at.
+ sb.append("\tconcentrate=\"true\";\n");
+
+ // Force nested scopes to order
+ sb.append("\tcompound=\"true\";\n");
+
+ // Just the Nodes first, in a cluster no edges
+ nodes(sb, all);
+
+ // Now the scopes, in a cluster no edges
+ scope(sb,parser._scope );
+ for( ScopeNode scope : parser._xScopes )
+ scope( sb, scope );
+
+ // Walk the Node edges
+ nodeEdges(sb, all);
+
+ // Walk the active Scope edges
+ scopeEdges( sb, parser._scope );
+ for( ScopeNode scope : parser._xScopes )
+ scopeEdges( sb, scope );
+
+ sb.append("}\n");
+ return sb.toString();
+ }
+
+ private void nodesByCluster(StringBuilder sb, boolean doCtrl, Collection<Node> all) {
+ if (!_separateControlCluster && doCtrl) // all nodes in 1 cluster
+ return;
+ // Just the Nodes first, in a cluster no edges
+ sb.append(doCtrl ? "\tsubgraph cluster_Controls {\n" : "\tsubgraph cluster_Nodes {\n"); // Magic "cluster_" in the subgraph name
+ for( Node n : all ) {
+ if( n instanceof ProjNode || n instanceof ScopeNode )
+ continue; // Do not emit, rolled into MultiNode or Scope cluster already
+ if (_separateControlCluster && doCtrl && !n.isCFG()) continue;
+ if (_separateControlCluster && !doCtrl && n.isCFG()) continue;
+ sb.append("\t\t").append(n.uniqueName()).append(" [ ");
+ String lab = n.glabel();
+ if( n instanceof MultiNode ) {
+ // Make a box with the MultiNode on top, and all the projections on the bottom
+ sb.append("shape=plaintext label=<\n");
+ sb.append("\t\t\t<TABLE BORDER=\"0\" CELLBORDER=\"1\" CELLSPACING=\"0\" CELLPADDING=\"4\">\n");
+ sb.append("\t\t\t<TR><TD BGCOLOR=\"yellow\">").append(lab).append("</TD></TR>\n");
+ sb.append("\t\t\t<TR>");
+ boolean doProjTable = false;
+ for( Node use : n._outputs ) {
+ if( use instanceof ProjNode proj ) {
+ if (!doProjTable) {
+ doProjTable = true;
+ sb.append("<TD>").append("\n");
+ sb.append("\t\t\t\t<TABLE BORDER=\"0\" CELLBORDER=\"1\" CELLSPACING=\"0\">").append("\n");
+ sb.append("\t\t\t\t<TR>");
+ }
+ sb.append("<TD PORT=\"p").append(proj._idx).append("\"");
+ if( proj.isCFG() ) sb.append(" BGCOLOR=\"yellow\"");
+ sb.append(">").append(proj.glabel()).append("</TD>");
+ }
+ }
+ if (doProjTable) {
+ sb.append("</TR>").append("\n");
+ sb.append("\t\t\t\t</TABLE>").append("\n");
+ sb.append("\t\t\t</TD>");
+ }
+ sb.append("</TR>\n");
+ sb.append("\t\t\t</TABLE>>\n\t\t");
+
+ } else {
+ // control nodes have box shape
+ // other nodes are ellipses, i.e. default shape
+ if (n.isCFG()) sb.append("shape=box style=filled fillcolor=yellow ");
+ else if (n instanceof PhiNode) sb.append("style=filled fillcolor=lightyellow ");
+ sb.append("label=\"").append(lab).append("\" ");
+ }
+ sb.append("];\n");
+ }
+ if (!_separateControlCluster) {
+ // Force Region & Phis to line up
+ for( Node n : all ) {
+ if( n instanceof RegionNode region ) {
+ sb.append("\t\t{ rank=same; ");
+ sb.append(region).append(";") ;
+ for( Node phi : region._outputs )
+ if (phi instanceof PhiNode) sb.append(phi.uniqueName()).append(";");
+ sb.append("}\n");
+ }
+ }
+ }
+ sb.append("\t}\n"); // End Node cluster
+ }
+
+ private void nodes(StringBuilder sb, Collection<Node> all) {
+ nodesByCluster(sb, true, all);
+ nodesByCluster(sb, false, all);
+ }
+
+ // Build a nested scope display, walking the _prev edge
+ private void scope( StringBuilder sb, ScopeNode scope ) {
+ sb.append("\tnode [shape=plaintext];\n");
+ int level=1;
+ for( int idx = scope._scopes.size()-1; idx>=0; idx-- ) {
+ var syms = scope._scopes.get(idx);
+ String scopeName = makeScopeName(scope, level);
+ sb.append("\tsubgraph cluster_").append(scopeName).append(" {\n"); // Magic "cluster_" in the subgraph name
+ sb.append("\t\t").append(scopeName).append(" [label=<\n");
+ sb.append("\t\t\t<TABLE BORDER=\"0\" CELLBORDER=\"1\" CELLSPACING=\"0\">\n");
+ // Add the scope level
+ int scopeLevel = scope._scopes.size()-level;
+ sb.append("\t\t\t<TR><TD BGCOLOR=\"cyan\">").append(scopeLevel).append("</TD>");
+ for(String name: syms.keySet())
+ sb.append("<TD PORT=\"").append(makePortName(scopeName, name)).append("\">").append(name).append("</TD>");
+ sb.append("</TR>\n");
+ sb.append("\t\t\t</TABLE>>];\n");
+ level++;
+ }
+ // Scope clusters nest, so the graphics shows the nested scopes, so
+ // they are not closed as they are printed; so they just keep nesting.
+ // We close them all at once here.
+ sb.append( "\t}\n".repeat( level-1 ) ); // End all Scope clusters
+ }
+
+ private String makeScopeName(ScopeNode sn, int level) { return sn.uniqueName() + "_" + level; }
+ private String makePortName(String scopeName, String varName) { return scopeName + "_" + varName; }
+
+ // Walk the node edges
+ private void nodeEdges(StringBuilder sb, Collection<Node> all) {
+ // All them edge labels
+ sb.append("\tedge [ fontname=Helvetica, fontsize=8 ];\n");
+ for( Node n : all ) {
+ // Do not display the Constant->Start edge;
+ // ProjNodes handled by Multi;
+ // ScopeNodes are done separately
+ if( n instanceof ConstantNode || n instanceof ProjNode || n instanceof ScopeNode )
+ continue;
+ for( int i=0; i<n.nIns(); i++ ) {
+ Node def = n.in(i);
+ if( n instanceof PhiNode && def instanceof RegionNode ) {
+ // Draw a dotted use->def edge from Phi to Region.
+ sb.append('\t').append(n.uniqueName());
+ sb.append(" -> ");
+ sb.append(def.uniqueName());
+ sb.append(" [style=dotted taillabel=").append(i).append("];\n");
+ } else if( def != null ) {
+ // Most edges land here use->def
+ sb.append('\t').append(n.uniqueName()).append(" -> ");
+ if( def instanceof ProjNode proj ) {
+ String mname = proj.ctrl().uniqueName();
+ sb.append(mname).append(":p").append(proj._idx);
+ } else sb.append(def.uniqueName());
+ // Number edges, so we can see how they track
+ sb.append("[taillabel=").append(i);
+ // control edges are colored red
+ if( def.isCFG() )
+ sb.append(" color=red");
+ // Backedges do not add a ranking constraint
+ if( i==2 && (n instanceof PhiNode || n instanceof LoopNode) )
+ sb.append(" constraint=false");
+ sb.append("];\n");
+ }
+ }
+ }
+ }
+
+ // Walk the scope edges
+ private void scopeEdges( StringBuilder sb, ScopeNode scope ) {
+ sb.append("\tedge [style=dashed color=cornflowerblue];\n");
+ int level=1;
+ for( int i = scope._scopes.size()-1; i>=0; i-- ) {
+ var syms = scope._scopes.get(i);
+ String scopeName = makeScopeName(scope, level);
+ for( String name : syms.keySet() ) {
+ int idx = syms.get(name);
+ Node def = scope.in(idx);
+ while( def instanceof ScopeNode lazy )
+ def = lazy.in(idx);
+ if( def==null ) continue;
+ sb.append("\t")
+ .append(scopeName).append(":")
+ .append('"').append(makePortName(scopeName, name)).append('"') // wrap port name with quotes because $ctrl is not valid unquoted
+ .append(" -> ");
+ if( def instanceof ProjNode proj ) {
+ String mname = proj.ctrl().uniqueName();
+ sb.append(mname).append(":p").append(proj._idx);
+ } else sb.append(def.uniqueName());
+ sb.append(";\n");
+ }
+ level++;
+ }
+ }
+
+ /**
+ * Finds all nodes in the graph.
+ */
+ private Collection<Node> findAll(Parser parser) {
+ final HashMap<Integer, Node> all = new HashMap<>();
+ for( Node n : Parser.START._outputs )
+ walk(all, n);
+ for( Node n : parser._scope._inputs )
+ walk(all, n);
+ return all.values();
+ }
+
+ /**
+ * Walk a subgraph and populate distinct nodes in the all list.
+ */
+ private void walk(HashMap<Integer,Node> all, Node n) {
+ if(n == null ) return;
+ if (all.get(n._nid) != null) return; // Been there, done that
+ all.put(n._nid, n);
+ for (Node c : n._inputs)
+ walk(all, c);
+ for( Node c : n._outputs )
+ walk(all, c);
+ }
+}
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/IRPrinter.java b/chapter08/src/main/java/com/seaofnodes/simple/IRPrinter.java
new file mode 100644
index 00000000..dc6d9f4f
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/IRPrinter.java
@@ -0,0 +1,124 @@
+package com.seaofnodes.simple;
+
+import com.seaofnodes.simple.node.LoopNode;
+import com.seaofnodes.simple.node.Node;
+
+import java.util.ArrayList;
+import java.util.BitSet;
+
+public class IRPrinter {
+
+ // Another bulk pretty-printer. Makes more effort at basic-block grouping.
+ public static String prettyPrint(Node node, int depth) {
+ // First, a Breadth First Search at a fixed depth.
+ BFS bfs = new BFS(node,depth);
+ // Convert just that set to a post-order
+ ArrayList<Node> rpos = new ArrayList<>();
+ BitSet visit = new BitSet();
+ for( int i=bfs._lim; i< bfs._bfs.size(); i++ )
+ postOrd( bfs._bfs.get(i), rpos, visit, bfs._bs);
+ // Reverse the post-order walk
+ StringBuilder sb = new StringBuilder();
+ boolean gap=false;
+ for( int i=rpos.size()-1; i>=0; i-- ) {
+ Node n = rpos.get(i);
+ if( n.isCFG() || n.isMultiHead() ) {
+ if( !gap ) sb.append("\n"); // Blank before multihead
+ n._print_line(sb); // Print head
+ while( --i >= 0 ) {
+ Node t = rpos.get(i);
+ if( !t.isMultiTail() ) { i++; break; }
+ t._print_line(sb);
+ }
+ sb.append("\n"); // Blank after multitail
+ gap = true;
+ } else {
+ n._print_line( sb );
+ gap = false;
+ }
+ }
+ return sb.toString();
+ }
+
+ private static void postOrd(Node n, ArrayList<Node> rpos, BitSet visit, BitSet bfs) {
+ if( !bfs.get(n._nid) )
+ return; // Not in the BFS visit
+ if( visit.get(n._nid) ) return; // Already post-order walked
+ visit.set(n._nid);
+ // First walk the CFG, then everything
+ if( n.isCFG() ) {
+ for( Node use : n._outputs )
+ if( use.isCFG() && use.nOuts()>=1 && !(use._outputs.get(0) instanceof LoopNode) )
+ postOrd(use, rpos,visit,bfs);
+ for( Node use : n._outputs )
+ if( use.isCFG() )
+ postOrd(use,rpos,visit,bfs);
+ }
+ for( Node use : n._outputs )
+ postOrd(use, rpos,visit,bfs);
+ // Post-order
+ rpos.add(n);
+ }
+
+ // Breadth-first search, broken out in a class to keep in more independent.
+ // Maintains a root-set of Nodes at the limit (or past by 1 if MultiHead).
+ public static class BFS {
+ // A breadth first search, plus MultiHeads for any MultiTails
+ public final ArrayList<Node> _bfs;
+ public final BitSet _bs; // Visited members by node id
+ public final int _depth; // Depth limit
+ public final int _lim; // From here to _bfs._len can be roots for a reverse search
+ public BFS( Node base, int d ) {
+ _depth = d;
+ _bfs = new ArrayList<>();
+ _bs = new BitSet();
+
+ add(base); // Prime the pump
+ int idx=0, lim=1; // Limit is where depth counter changes
+ while( idx < _bfs.size() ) { // Ran out of nodes below depth
+ Node n = _bfs.get(idx++);
+ for( Node def : n._inputs )
+ if( def!=null && !_bs.get(def._nid) )
+ add(def);
+ if( idx==lim ) { // Depth counter changes at limit
+ if( --d < 0 )
+ break; // Ran out of depth
+ lim = _bfs.size(); // New depth limit
+ }
+ }
+ // Toss things past the limit except multi-heads
+ while( idx < _bfs.size() ) {
+ Node n = _bfs.get(idx);
+ if( n.isMultiHead() ) idx++;
+ else del(idx);
+ }
+ // Root set is any node with no inputs in the visited set
+ lim = _bfs.size();
+ for( int i=_bfs.size()-1; i>=0; i-- )
+ if( !any_visited(_bfs.get(i)) )
+ swap( i,--lim);
+ _lim = lim;
+ }
+ void swap( int x, int y ) {
+ if( x==y ) return;
+ Node tx = _bfs.get(x);
+ Node ty = _bfs.get(y);
+ _bfs.set(x,ty);
+ _bfs.set(y,tx);
+ }
+ void add(Node n) {
+ _bfs.add(n);
+ _bs.set(n._nid);
+ }
+ void del(int idx) {
+ Node n = Utils.del(_bfs, idx);
+ _bs.clear(n._nid);
+ }
+ boolean any_visited( Node n ) {
+ for( Node def : n._inputs )
+ if( def!=null && _bs.get(def._nid) )
+ return true;
+ return false;
+ }
+ }
+}
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/Parser.java b/chapter08/src/main/java/com/seaofnodes/simple/Parser.java
new file mode 100644
index 00000000..28b8f432
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/Parser.java
@@ -0,0 +1,574 @@
+package com.seaofnodes.simple;
+
+import com.seaofnodes.simple.node.*;
+import com.seaofnodes.simple.type.*;
+
+import java.util.*;
+
+/**
+ * The Parser converts a Simple source program to the Sea of Nodes intermediate
+ * representation directly in one pass. There is no intermediate Abstract
+ * Syntax Tree structure.
+ * <p>
+ * This is a simple recursive descent parser. All lexical analysis is done here as well.
+ */
+public class Parser {
+ public static boolean LAZY = false;
+
+ /**
+ * A Global Static, unique to each compilation. This is a public, so we
+ * can make constants everywhere without having to thread the StartNode
+ * through the entire parser and optimizer.
+ * <p>
+ * To make the compiler multithreaded, this field will have to move into a TLS.
+ */
+ public static StartNode START;
+
+ public StopNode STOP;
+
+ // The Lexer. Thin wrapper over a byte[] buffer with a cursor.
+ private final Lexer _lexer;
+
+ /**
+ * Current ScopeNode - ScopeNodes change as we parse code, but at any point of time
+ * there is one current ScopeNode. The reason the current ScopeNode can change is to do with how
+ * we handle branching. See {@link #parseIf()}.
+ * <p>
+ * Each ScopeNode contains a stack of lexical scopes, each scope is a symbol table that binds
+ * variable names to Nodes. The top of this stack represents current scope.
+ * <p>
+ * We keep a list of all ScopeNodes so that we can show them in graphs.
+ * @see #parseIf()
+ * @see #_xScopes
+ */
+ public ScopeNode _scope;
+
+ /**
+ * List of keywords disallowed as identifiers
+ */
+ private final HashSet<String> KEYWORDS = new HashSet<>(){{
+ add("else");
+ add("false");
+ add("if");
+ add("int");
+ add("return");
+ add("true");
+ add("while");
+ }};
+
+
+ /**
+ * We clone ScopeNodes when control flows branch; it is useful to have
+ * a list of all active ScopeNodes for purposes of visualization of the SoN graph
+ */
+ public final Stack<ScopeNode> _xScopes = new Stack<>();
+
+ public Parser(String source, TypeInteger arg) {
+ Node.reset();
+ _lexer = new Lexer(source);
+ _scope = new ScopeNode();
+ START = new StartNode(new Type[]{ Type.CONTROL, arg });
+ STOP = new StopNode();
+ }
+
+ public Parser(String source) {
+ this(source, TypeInteger.BOT);
+ }
+
+ @Override
+ public String toString() { return _lexer.toString(); }
+
+ String src() { return new String( _lexer._input ); }
+
+ // Debugging utility to find a Node by index
+ public static Node find(int nid) { return START.find(nid); }
+
+ private Node ctrl() { return _scope.ctrl(); }
+
+ private Node ctrl(Node n) { return _scope.ctrl(n); }
+
+ public StopNode parse() { return parse(false); }
+ public StopNode parse(boolean show) {
+ // Enter a new scope for the initial control and arguments
+ _scope.push();
+ _scope.define(ScopeNode.CTRL, new ProjNode(START, 0, ScopeNode.CTRL).peephole());
+ _scope.define(ScopeNode.ARG0, new ProjNode(START, 1, ScopeNode.ARG0).peephole());
+ parseBlock();
+ _scope.pop();
+ if (!_lexer.isEOF()) throw error("Syntax error, unexpected " + _lexer.getAnyNextToken());
+ STOP.peephole();
+ if( show ) showGraph();
+ return STOP;
+ }
+
+
+ /**
+ * Parses a block
+ *
+ * <pre>
+ * '{' statements '}'
+ * </pre>
+ * Does not parse the opening or closing '{}'
+ * @return a {@link Node} or {@code null}
+ */
+ private Node parseBlock() {
+ // Enter a new scope
+ _scope.push();
+ while (!peek('}') && !_lexer.isEOF())
+ parseStatement();
+ // Exit scope
+ _scope.pop();
+ return null;
+ }
+
+ /**
+ * Parses a statement
+ *
+ * <pre>
+ * returnStatement | declStatement | blockStatement | ifStatement | expressionStatement
+ * </pre>
+ * @return a {@link Node} or {@code null}
+ */
+ private Node parseStatement() {
+ if (matchx("return") ) return parseReturn();
+ else if (matchx("int")) return parseDecl();
+ else if (match ("{" )) return require(parseBlock(),"}");
+ else if (matchx("if" )) return parseIf();
+ else if (matchx("while")) return parseWhile();
+ else if (matchx("#showGraph")) return require(showGraph(),";");
+ else return parseExpressionStatement();
+ }
+
+ /**
+ * Parses a while statement
+ *
+ * <pre>
+ * while ( expression ) statement
+ * </pre>
+ * @return a {@link Node}, never {@code null}
+ */
+ private Node parseWhile() {
+ require("(");
+
+ // Loop region has two control inputs, the first one is the entry
+ // point, and second one is back edge that is set after loop is parsed
+ // (see end_loop() call below). Note that the absence of back edge is
+ // used as an indicator to switch off peepholes of the region and
+ // associated phis.
+
+ ctrl(new LoopNode(ctrl(),null).peephole());
+ ScopeNode head = _xScopes.push(_scope).keep(); // Save the current scope as the loop head
+ // Make a new Scope for the body, which has lazy-phi loop markers.
+ _scope = _scope.dup(true);
+
+ // Parse predicate
+ var pred = require(parseExpression(), ")");
+ // IfNode takes current control and predicate
+ IfNode ifNode = (IfNode)new IfNode(ctrl(), pred).<IfNode>keep().peephole();
+ // Setup projection nodes
+ Node ifT = new ProjNode(ifNode, 0, "True" ).peephole();
+ ifNode.unkeep();
+ Node ifF = new ProjNode(ifNode, 1, "False").peephole();
+ // The exit scope, accounting for any side effects in the predicate
+ var exit = _scope.dup();
+ _xScopes.push(exit);
+ exit.ctrl(ifF);
+
+ // Parse the true side, which corresponds to loop body
+ ctrl(ifT); // set ctrl token to ifTrue projection
+ parseStatement(); // Parse loop body
+
+ // The true branch loops back, so whatever is current control gets
+ // added to head loop as input
+ head.endLoop(_scope, exit);
+ head.unkeep().kill();
+ _xScopes.pop();
+ _xScopes.pop(); // Discard pushed from graph display
+
+ // At exit the false control is the current control, and
+ // the scope is the exit scope after the exit test.
+ return (_scope = exit);
+ }
+
+ /**
+ * Parses a statement
+ *
+ * <pre>
+ * if ( expression ) statement [else statement]
+ * </pre>
+ * @return a {@link Node}, never {@code null}
+ */
+ private Node parseIf() {
+ require("(");
+ // Parse predicate
+ var pred = require(parseExpression(), ")");
+ // IfNode takes current control and predicate
+ IfNode ifNode = (IfNode)new IfNode(ctrl(), pred).<IfNode>keep().peephole();
+ // Setup projection nodes
+ Node ifT = new ProjNode(ifNode, 0, "True" ).peephole();
+ ifNode.unkeep();
+ Node ifF = new ProjNode(ifNode, 1, "False").peephole();
+ // In if true branch, the ifT proj node becomes the ctrl
+ // But first clone the scope and set it as current
+ int ndefs = _scope.nIns();
+ ScopeNode fScope = _scope.dup(); // Duplicate current scope
+ _xScopes.push(fScope); // For graph visualization we need all scopes
+
+ // Parse the true side
+ ctrl(ifT); // set ctrl token to ifTrue projection
+ parseStatement(); // Parse true-side
+ ScopeNode tScope = _scope;
+
+ // Parse the false side
+ _scope = fScope; // Restore scope, then parse else block if any
+ ctrl(ifF); // Ctrl token is now set to ifFalse projection
+ if (matchx("else")) {
+ parseStatement();
+ fScope = _scope;
+ }
+
+ if( tScope.nIns() != ndefs || fScope.nIns() != ndefs )
+ throw error("Cannot define a new name on one arm of an if");
+
+ // Merge results
+ _scope = tScope;
+ _xScopes.pop(); // Discard pushed from graph display
+
+ return ctrl(tScope.mergeScopes(fScope));
+ }
+
+
+ /**
+ * Parses a return statement; "return" already parsed.
+ * The $ctrl edge is killed.
+ *
+ * <pre>
+ * 'return' expr ;
+ * </pre>
+ * @return an expression {@link Node}, never {@code null}
+ */
+ private Node parseReturn() {
+ var expr = require(parseExpression(), ";");
+ Node ret = STOP.addReturn(new ReturnNode(ctrl(), expr).peephole());
+ ctrl(new ConstantNode(Type.XCONTROL).peephole()); // Kill control
+ return ret;
+ }
+
+ /**
+ * Dumps out the node graph
+ * @return {@code null}
+ */
+ private Node showGraph() {
+ System.out.println(new GraphVisualizer().generateDotOutput(this));
+ return null;
+ }
+
+ /**
+ * Parses an expression statement
+ *
+ * <pre>
+ * name '=' expression ';'
+ * </pre>
+ * @return an expression {@link Node}, never {@code null}
+ */
+ private Node parseExpressionStatement() {
+ var name = requireId();
+ require("=");
+ var expr = require(parseExpression(), ";");
+ if( _scope.update(name, expr)==null )
+ throw error("Undefined name '" + name + "'");
+ return expr;
+ }
+
+ /**
+ * Parses a declStatement
+ *
+ * <pre>
+ * 'int' name = expression ';'
+ * </pre>
+ * @return an expression {@link Node}, never {@code null}
+ */
+ private Node parseDecl() {
+ // Type is 'int' for now
+ var name = requireId();
+ require("=");
+ var expr = require(parseExpression(), ";");
+ if( _scope.define(name,expr) == null )
+ throw error("Redefining name '" + name + "'");
+ return expr;
+ }
+
+ /**
+ * Parse an expression of the form:
+ *
+ * <pre>
+ * expr : compareExpr
+ * </pre>
+ * @return an expression {@link Node}, never {@code null}
+ */
+ private Node parseExpression() { return parseComparison(); }
+
+ /**
+ * Parse an expression of the form:
+ *
+ * <pre>
+ * expr : additiveExpr op additiveExpr
+ * </pre>
+ * @return an comparator expression {@link Node}, never {@code null}
+ */
+ private Node parseComparison() {
+ var lhs = parseAddition();
+ if (match("==")) return new BoolNode.EQ(lhs, parseComparison()).peephole();
+ if (match("!=")) return new NotNode(new BoolNode.EQ(lhs, parseComparison()).peephole()).peephole();
+ if (match("<" )) return new BoolNode.LT(lhs, parseComparison()).peephole();
+ if (match("<=")) return new BoolNode.LE(lhs, parseComparison()).peephole();
+ if (match(">" )) return new BoolNode.LT(parseComparison(), lhs).peephole();
+ if (match(">=")) return new BoolNode.LE(parseComparison(), lhs).peephole();
+ return lhs;
+ }
+
+ /**
+ * Parse an additive expression
+ *
+ * <pre>
+ * additiveExpr : multiplicativeExpr (('+' | '-') multiplicativeExpr)*
+ * </pre>
+ * @return an add expression {@link Node}, never {@code null}
+ */
+ private Node parseAddition() {
+ var lhs = parseMultiplication();
+ if (match("+")) return new AddNode(lhs, parseAddition()).peephole();
+ if (match("-")) return new SubNode(lhs, parseAddition()).peephole();
+ return lhs;
+ }
+
+ /**
+ * Parse an multiplicativeExpr expression
+ *
+ * <pre>
+ * multiplicativeExpr : unaryExpr (('*' | '/') unaryExpr)*
+ * </pre>
+ * @return a multiply expression {@link Node}, never {@code null}
+ */
+ private Node parseMultiplication() {
+ var lhs = parseUnary();
+ if (match("*")) return new MulNode(lhs, parseMultiplication()).peephole();
+ if (match("/")) return new DivNode(lhs, parseMultiplication()).peephole();
+ return lhs;
+ }
+
+ /**
+ * Parse a unary minus expression.
+ *
+ * <pre>
+ * unaryExpr : ('-') unaryExpr | primaryExpr
+ * </pre>
+ * @return a unary expression {@link Node}, never {@code null}
+ */
+ private Node parseUnary() {
+ if (match("-")) return new MinusNode(parseUnary()).peephole();
+ return parsePrimary();
+ }
+
+ /**
+ * Parse a primary expression:
+ *
+ * <pre>
+ * primaryExpr : integerLiteral | Identifier | true | false | '(' expression ')'
+ * </pre>
+ * @return a primary {@link Node}, never {@code null}
+ */
+ private Node parsePrimary() {
+ if( _lexer.isNumber() ) return parseIntegerLiteral();
+ if( match("(") ) return require(parseExpression(), ")");
+ if( matchx("true" ) ) return new ConstantNode(TypeInteger.constant(1)).peephole();
+ if( matchx("false") ) return new ConstantNode(TypeInteger.constant(0)).peephole();
+ String name = _lexer.matchId();
+ if( name == null) throw errorSyntax("an identifier or expression");
+ Node n = _scope.lookup(name);
+ if( n!=null ) return n;
+ throw error("Undefined name '" + name + "'");
+ }
+
+ /**
+ * Parse integer literal
+ *
+ * <pre>
+ * integerLiteral: [1-9][0-9]* | [0]
+ * </pre>
+ */
+ private ConstantNode parseIntegerLiteral() {
+ return (ConstantNode) new ConstantNode(_lexer.parseNumber()).peephole();
+ }
+
+ //////////////////////////////////
+ // Utilities for lexical analysis
+
+ // Return true and skip if "syntax" is next in the stream.
+ private boolean match (String syntax) { return _lexer.match (syntax); }
+ // Match must be "exact", not be followed by more id letters
+ private boolean matchx(String syntax) { return _lexer.matchx(syntax); }
+ // Return true and do NOT skip if 'ch' is next
+ private boolean peek(char ch) { return _lexer.peek(ch); }
+
+ // Require and return an identifier
+ private String requireId() {
+ String id = _lexer.matchId();
+ if (id != null && !KEYWORDS.contains(id) ) return id;
+ throw error("Expected an identifier, found '"+id+"'");
+ }
+
+ // Require an exact match
+ private void require(String syntax) { require(null, syntax); }
+ private Node require(Node n, String syntax) {
+ if (match(syntax)) return n;
+ throw errorSyntax(syntax);
+ }
+
+ RuntimeException errorSyntax(String syntax) {
+ return error("Syntax error, expected " + syntax + ": " + _lexer.getAnyNextToken());
+ }
+
+ static RuntimeException error(String errorMessage) {
+ return new RuntimeException(errorMessage);
+ }
+
+ ////////////////////////////////////
+ // Lexer components
+
+ private static class Lexer {
+
+ // Input buffer; an array of text bytes read from a file or a string
+ private final byte[] _input;
+ // Tracks current position in input buffer
+ private int _position = 0;
+
+ /**
+ * Record the source text for lexing
+ */
+ public Lexer(String source) {
+ this(source.getBytes());
+ }
+
+ /**
+ * Direct from disk file source
+ */
+ public Lexer(byte[] buf) {
+ _input = buf;
+ }
+
+ // Very handy in the debugger, shows the unparsed program
+ @Override
+ public String toString() {
+ return new String(_input, _position, _input.length - _position);
+ }
+
+ // True if at EOF
+ private boolean isEOF() {
+ return _position >= _input.length;
+ }
+
+ // Peek next character, or report EOF
+ private char peek() {
+ return isEOF() ? Character.MAX_VALUE // Special value that causes parsing to terminate
+ : (char) _input[_position];
+ }
+
+ private char nextChar() {
+ char ch = peek();
+ _position++;
+ return ch;
+ }
+
+ // True if a white space
+ private boolean isWhiteSpace() {
+ return peek() <= ' '; // Includes all the use space, tab, newline, CR
+ }
+
+ /**
+ * Return the next non-white-space character
+ */
+ private void skipWhiteSpace() {
+ while (isWhiteSpace()) _position++;
+ }
+
+
+ // Return true, if we find "syntax" after skipping white space; also
+ // then advance the cursor past syntax.
+ // Return false otherwise, and do not advance the cursor.
+ boolean match(String syntax) {
+ skipWhiteSpace();
+ int len = syntax.length();
+ if (_position + len > _input.length) return false;
+ for (int i = 0; i < len; i++)
+ if ((char) _input[_position + i] != syntax.charAt(i))
+ return false;
+ _position += len;
+ return true;
+ }
+
+ boolean matchx(String syntax) {
+ if( !match(syntax) ) return false;
+ if( !isIdLetter(peek()) ) return true;
+ _position -= syntax.length();
+ return false;
+ }
+
+ private boolean peek(char ch) {
+ skipWhiteSpace();
+ return peek()==ch;
+ }
+
+ // Return an identifier or null
+ String matchId() {
+ skipWhiteSpace();
+ return isIdStart(peek()) ? parseId() : null;
+ }
+
+ // Used for errors
+ String getAnyNextToken() {
+ if (isEOF()) return "";
+ if (isIdStart(peek())) return parseId();
+ if (isPunctuation(peek())) return parsePunctuation();
+ return String.valueOf(peek());
+ }
+
+ boolean isNumber() {return isNumber(peek());}
+ boolean isNumber(char ch) {return Character.isDigit(ch);}
+
+ private Type parseNumber() {
+ int start = _position;
+ while (isNumber(nextChar())) ;
+ String snum = new String(_input, start, --_position - start);
+ if (snum.length() > 1 && snum.charAt(0) == '0')
+ throw error("Syntax error: integer values cannot start with '0'");
+ return TypeInteger.constant(Long.parseLong(snum));
+ }
+
+ // First letter of an identifier
+ private boolean isIdStart(char ch) {
+ return Character.isAlphabetic(ch) || ch == '_';
+ }
+
+ // All characters of an identifier, e.g. "_x123"
+ private boolean isIdLetter(char ch) {
+ return Character.isLetterOrDigit(ch) || ch == '_';
+ }
+
+ private String parseId() {
+ int start = _position;
+ while (isIdLetter(nextChar())) ;
+ return new String(_input, start, --_position - start);
+ }
+
+ //
+ private boolean isPunctuation(char ch) {
+ return "=;[]<>()+-/*".indexOf(ch) != -1;
+ }
+
+ private String parsePunctuation() {
+ int start = _position;
+ return new String(_input, start, 1);
+ }
+ }
+}
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/Utils.java b/chapter08/src/main/java/com/seaofnodes/simple/Utils.java
new file mode 100644
index 00000000..4d663c25
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/Utils.java
@@ -0,0 +1,39 @@
+package com.seaofnodes.simple;
+
+import java.util.ArrayList;
+
+public class Utils {
+ public static RuntimeException TODO() { return TODO("Not yet implemented"); }
+ public static RuntimeException TODO(String msg) { return new RuntimeException(msg); }
+
+ /**
+ * Fast, constant-time, element removal. Does not preserve order
+ *
+ * @param array ArrayList to modify
+ * @param i element to be removed
+ * @return element removed
+ */
+ public static <E> E del(ArrayList<E> array, int i) {
+ if ( i >= 0 && i < array.size() ) {
+ E tmp = array.get(i);
+ E last = array.removeLast();
+ if (i < array.size()) array.set(i, last);
+ return tmp;
+ }
+ return null;
+ }
+
+ /**
+ * Search a list for an element by reference
+ *
+ * @param ary List to search in
+ * @param x Object to be searched
+ * @return >= 0 on success, -1 on failure
+ */
+ public static <E> int find( ArrayList<E> ary, E x ) {
+ for( int i=0; i<ary.size(); i++ )
+ if( ary.get(i)==x )
+ return i;
+ return -1;
+ }
+} \ No newline at end of file
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/node/AddNode.java b/chapter08/src/main/java/com/seaofnodes/simple/node/AddNode.java
new file mode 100644
index 00000000..85d7b20e
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/node/AddNode.java
@@ -0,0 +1,158 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.*;
+
+import java.util.BitSet;
+
+public class AddNode extends Node {
+ public AddNode(Node lhs, Node rhs) {
+ super(null, lhs, rhs);
+ }
+
+ @Override public String label() { return "Add"; }
+
+ @Override public String glabel() { return "+"; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ in(1)._print0(sb.append("("), visited);
+ in(2)._print0(sb.append("+"), visited);
+ return sb.append(")");
+ }
+
+
+ @Override
+ public Type compute() {
+ if( in(1)._type instanceof TypeInteger i0 &&
+ in(2)._type instanceof TypeInteger i1 ) {
+ if (i0.isConstant() && i1.isConstant())
+ return TypeInteger.constant(i0.value()+i1.value());
+ return i0.meet(i1);
+ }
+ return Type.BOTTOM;
+ }
+
+ @Override
+ public Node idealize () {
+ Node lhs = in(1);
+ Node rhs = in(2);
+ Type t1 = lhs._type;
+ Type t2 = rhs._type;
+
+ // Already handled by peephole constant folding
+ assert !(t1.isConstant() && t2.isConstant());
+
+ // Add of 0. We do not check for (0+x) because this will already
+ // canonicalize to (x+0)
+ if( t2 instanceof TypeInteger i && i.value()==0 )
+ return lhs;
+
+ // Add of same to a multiply by 2
+ if( lhs==rhs )
+ return new MulNode(lhs,new ConstantNode(TypeInteger.constant(2)).peephole());
+
+ // Goal: a left-spine set of adds, with constants on the rhs (which then fold).
+
+ // Move non-adds to RHS
+ if( !(lhs instanceof AddNode) && rhs instanceof AddNode )
+ return swap12();
+
+ // Now we might see (add add non) or (add non non) or (add add add) but never (add non add)
+
+ // Do we have x + (y + z) ?
+ // Swap to (x + y) + z
+ // Rotate (add add add) to remove the add on RHS
+ if( rhs instanceof AddNode add )
+ return new AddNode(new AddNode(lhs,add.in(1)).peephole(), add.in(2));
+
+ // Now we might see (add add non) or (add non non) but never (add non add) nor (add add add)
+ if( !(lhs instanceof AddNode) )
+ // Rotate; look for (add (phi cons) con/(phi cons))
+ return spline_cmp(lhs,rhs) ? swap12() : phiCon(this,true);
+
+ // Now we only see (add add non)
+
+ // Do we have (x + con1) + con2?
+ // Replace with (x + (con1+con2) which then fold the constants
+ if( lhs.in(2)._type.isConstant() && t2.isConstant() )
+ return new AddNode(lhs.in(1),new AddNode(lhs.in(2),rhs).peephole());
+
+
+ // Do we have ((x + (phi cons)) + con) ?
+ // Do we have ((x + (phi cons)) + (phi cons)) ?
+ // Push constant up through the phi: x + (phi con0+con0 con1+con1...)
+ Node phicon = phiCon(this,true);
+ if( phicon!=null ) return phicon;
+
+ // Now we sort along the spline via rotates, to gather similar things together.
+
+ // Do we rotate (x + y) + z
+ // into (x + z) + y ?
+ if( spline_cmp(lhs.in(2),rhs) )
+ return new AddNode(new AddNode(lhs.in(1),rhs).peephole(),lhs.in(2));
+
+ return null;
+ }
+
+ // Rotation is only valid for associative ops, e.g. Add, Mul, And, Or.
+ // Do we have ((phi cons)|(x + (phi cons)) + con|(phi cons)) ?
+ // Push constant up through the phi: x + (phi con0+con0 con1+con1...)
+ static Node phiCon(Node op, boolean rotate) {
+ Node lhs = op.in(1);
+ Node rhs = op.in(2);
+ // LHS is either a Phi of constants, or another op with Phi of constants
+ PhiNode lphi = pcon(lhs);
+ if( rotate && lphi==null && lhs.nIns() > 2 ) {
+ // Only valid to rotate constants if both are same associative ops
+ if( lhs.getClass() != op.getClass() ) return null;
+ lphi = pcon(lhs.in(2)); // Will rotate with the Phi push
+ }
+ if( lphi==null ) return null;
+
+ // RHS is a constant or a Phi of constants
+ if( !(rhs instanceof ConstantNode con) && pcon(rhs)==null )
+ return null;
+
+ // If both are Phis, must be same Region
+ if( rhs instanceof PhiNode && lphi.in(0) != rhs.in(0) )
+ return null;
+
+ // Note that this is the exact reverse of Phi pulling a common op down
+ // to reduce total op-count. We don't get in an endless push-up
+ // push-down peephole cycle because the constants all fold first.
+ Node[] ns = new Node[lphi.nIns()];
+ ns[0] = lphi.in(0);
+ // Push constant up through the phi: x + (phi con0+con0 con1+con1...)
+ for( int i=1; i<ns.length; i++ )
+ ns[i] = op.copy(lphi.in(i), rhs instanceof PhiNode ? rhs.in(i) : rhs).peephole();
+ String label = lphi._label + (rhs instanceof PhiNode rphi ? rphi._label : "");
+ Node phi = new PhiNode(label,ns).peephole();
+ // Rotate needs another op, otherwise just the phi
+ return lhs==lphi ? phi : op.copy(lhs.in(1),phi);
+ }
+
+ static PhiNode pcon(Node op) {
+ return op instanceof PhiNode phi && phi.all_cons() ? phi : null;
+ }
+
+ // Compare two off-spline nodes and decide what order they should be in.
+ // Do we rotate ((x + hi) + lo) into ((x + lo) + hi) ?
+ // Generally constants always go right, then Phi-of-constants, then muls, then others.
+ // Ties with in a category sort by node ID.
+ // TRUE if swapping hi and lo.
+ static boolean spline_cmp( Node hi, Node lo ) {
+ if( lo._type.isConstant() ) return false;
+ if( hi._type.isConstant() ) return true ;
+
+ if( lo instanceof PhiNode && lo.all_cons() ) return false;
+ if( hi instanceof PhiNode && hi.all_cons() ) return true ;
+
+ if( lo instanceof PhiNode && !(hi instanceof PhiNode) ) return true;
+ if( hi instanceof PhiNode && !(lo instanceof PhiNode) ) return false;
+
+ // Same category of "others"
+ return lo._nid > hi._nid;
+ }
+
+ @Override Node copy(Node lhs, Node rhs) { return new AddNode(lhs,rhs); }
+}
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/node/BoolNode.java b/chapter08/src/main/java/com/seaofnodes/simple/node/BoolNode.java
new file mode 100644
index 00000000..d65fbf14
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/node/BoolNode.java
@@ -0,0 +1,60 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeInteger;
+
+import java.util.BitSet;
+
+abstract public class BoolNode extends Node {
+
+ public BoolNode(Node lhs, Node rhs) {
+ super(null, lhs, rhs);
+ }
+
+ abstract String op(); // String opcode name
+
+ @Override
+ public String label() { return getClass().getSimpleName(); }
+
+ @Override
+ public String glabel() { return op(); }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ in(1)._print0(sb.append("("), visited);
+ in(2)._print0(sb.append(op()), visited);
+ return sb.append(")");
+ }
+
+ @Override
+ public Type compute() {
+ if( in(1)._type instanceof TypeInteger i0 &&
+ in(2)._type instanceof TypeInteger i1 ) {
+ if (i0.isConstant() && i1.isConstant())
+ return TypeInteger.constant(doOp(i0.value(), i1.value()) ? 1 : 0);
+ return i0.meet(i1);
+ }
+ return Type.BOTTOM;
+ }
+
+ abstract boolean doOp(long lhs, long rhs);
+
+ @Override
+ public Node idealize() {
+ // Compare of same
+ if( in(1)==in(2) )
+ return new ConstantNode(TypeInteger.constant(doOp(3,3)?1:0));
+
+ // Do we have ((x * (phi cons)) * con) ?
+ // Do we have ((x * (phi cons)) * (phi cons)) ?
+ // Push constant up through the phi: x * (phi con0*con0 con1*con1...)
+ Node phicon = AddNode.phiCon(this,false);
+ if( phicon!=null ) return phicon;
+
+ return null;
+ }
+
+ public static class EQ extends BoolNode { public EQ(Node lhs, Node rhs) { super(lhs,rhs); } String op() { return "=="; } boolean doOp(long lhs, long rhs) { return lhs == rhs; } Node copy(Node lhs, Node rhs) { return new EQ(lhs,rhs); } }
+ public static class LT extends BoolNode { public LT(Node lhs, Node rhs) { super(lhs,rhs); } String op() { return "<" ; } boolean doOp(long lhs, long rhs) { return lhs < rhs; } Node copy(Node lhs, Node rhs) { return new LT(lhs,rhs); } }
+ public static class LE extends BoolNode { public LE(Node lhs, Node rhs) { super(lhs,rhs); } String op() { return "<="; } boolean doOp(long lhs, long rhs) { return lhs <= rhs; } Node copy(Node lhs, Node rhs) { return new LE(lhs,rhs); } }
+}
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/node/ConstantNode.java b/chapter08/src/main/java/com/seaofnodes/simple/node/ConstantNode.java
new file mode 100644
index 00000000..0e13d2f2
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/node/ConstantNode.java
@@ -0,0 +1,45 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.Parser;
+import com.seaofnodes.simple.type.Type;
+
+import java.util.BitSet;
+
+/**
+ * A Constant node represents a constant value. At present, the only constants
+ * that we allow are integer literals; therefore Constants contain an integer
+ * value. As we add other types of constants, we will refactor how we represent
+ * Constants.
+ * <p>
+ * Constants have no semantic inputs. However, we set Start as an input to
+ * Constants to enable a forward graph walk. This edge carries no semantic
+ * meaning, and it is present <em>solely</em> to allow visitation.
+ * <p>
+ * The Constant's value is the value stored in it.
+ */
+public class ConstantNode extends Node {
+ Type _con;
+ public ConstantNode( Type type ) {
+ super(Parser.START);
+ _con = type;
+ }
+
+ @Override
+ public String label() { return ""+_con; }
+
+ @Override
+ public String uniqueName() { return "Con_" + _nid; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ return _con._print(sb);
+ }
+
+ @Override public boolean isMultiTail() { return true; }
+
+ @Override
+ public Type compute() { return _con; }
+
+ @Override
+ public Node idealize() { return null; }
+}
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/node/DivNode.java b/chapter08/src/main/java/com/seaofnodes/simple/node/DivNode.java
new file mode 100644
index 00000000..b0e12547
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/node/DivNode.java
@@ -0,0 +1,39 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeInteger;
+
+import java.util.BitSet;
+
+public class DivNode extends Node {
+ public DivNode(Node lhs, Node rhs) { super(null, lhs, rhs); }
+
+ @Override public String label() { return "Div"; }
+
+ @Override public String glabel() { return "//"; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ in(1)._print0(sb.append("("), visited);
+ in(2)._print0(sb.append("/"), visited);
+ return sb.append(")");
+ }
+
+ @Override
+ public Type compute() {
+ if (in(1)._type instanceof TypeInteger i0 &&
+ in(2)._type instanceof TypeInteger i1) {
+ if (i0.isConstant() && i1.isConstant())
+ return i1.value() == 0
+ ? TypeInteger.ZERO
+ : TypeInteger.constant(i0.value()/i1.value());
+ return i0.meet(i1);
+ }
+ return Type.BOTTOM;
+ }
+
+ @Override
+ public Node idealize() { return null; }
+
+ @Override Node copy(Node lhs, Node rhs) { return new DivNode(lhs,rhs); }
+}
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/node/IfNode.java b/chapter08/src/main/java/com/seaofnodes/simple/node/IfNode.java
new file mode 100644
index 00000000..e573010d
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/node/IfNode.java
@@ -0,0 +1,58 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeInteger;
+import com.seaofnodes.simple.type.TypeTuple;
+
+import java.util.BitSet;
+
+public class IfNode extends MultiNode {
+
+ public IfNode(Node ctrl, Node pred) {
+ super(ctrl, pred);
+ }
+
+ @Override
+ public String label() { return "If"; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ sb.append("if( ");
+ return in(1)._print0(sb, visited).append(" )");
+ }
+
+ @Override public boolean isCFG() { return true; }
+ @Override public boolean isMultiHead() { return true; }
+
+ public Node ctrl() { return in(0); }
+ public Node pred() { return in(1); }
+
+ @Override
+ public Type compute() {
+ // If the If node is not reachable then neither is any following Proj
+ if (ctrl()._type != Type.CONTROL && ctrl()._type != Type.BOTTOM )
+ return TypeTuple.IF_NEITHER;
+ // If constant is 0 then false branch is reachable
+ // Else true branch is reachable
+ if (pred()._type instanceof TypeInteger ti && ti.isConstant()) {
+ if (ti.value() == 0) return TypeTuple.IF_FALSE;
+ else return TypeTuple.IF_TRUE;
+ }
+
+ // Hunt up the immediate dominator tree. If we find an identical if
+ // test on either the true or false branch, then this test matches.
+ for( Node dom = idom(), prior=this; dom!=null; prior=dom, dom = dom.idom() )
+ if( dom instanceof IfNode iff && iff.pred()==pred() )
+ return prior instanceof ProjNode proj
+ // Repeated test, dominated on one side. Test result is the same.
+ ? (proj._idx==0 ? TypeTuple.IF_TRUE : TypeTuple.IF_FALSE)
+ : null; // Repeated test not dominated on one side
+
+ return TypeTuple.IF_BOTH;
+ }
+
+ @Override
+ public Node idealize() {
+ return null;
+ }
+}
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/node/LoopNode.java b/chapter08/src/main/java/com/seaofnodes/simple/node/LoopNode.java
new file mode 100644
index 00000000..eaf19199
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/node/LoopNode.java
@@ -0,0 +1,35 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+
+import java.util.BitSet;
+
+public class LoopNode extends RegionNode {
+
+ public LoopNode( Node entry, Node back) { super(null,entry,back); }
+
+ Node entry() { return in(1); }
+ Node back () { return in(2); }
+
+ @Override
+ public String label() { return "Loop"; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ return sb.append("Loop").append(_nid);
+ }
+
+ @Override
+ public Type compute() {
+ return inProgress() ? Type.CONTROL : super.compute();
+ }
+
+ @Override
+ public Node idealize() {
+ return inProgress() ? null : super.idealize();
+ }
+
+ @Override Node idom() { return entry(); }
+
+ @Override public boolean inProgress() { return back()==null; }
+}
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/node/MinusNode.java b/chapter08/src/main/java/com/seaofnodes/simple/node/MinusNode.java
new file mode 100644
index 00000000..8a96693d
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/node/MinusNode.java
@@ -0,0 +1,30 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeInteger;
+
+import java.util.BitSet;
+
+public class MinusNode extends Node {
+ public MinusNode(Node in) { super(null, in); }
+
+ @Override public String label() { return "Minus"; }
+
+ @Override public String glabel() { return "-"; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ in(1)._print0(sb.append("(-"), visited);
+ return sb.append(")");
+ }
+
+ @Override
+ public Type compute() {
+ if (in(1)._type instanceof TypeInteger i0)
+ return i0.isConstant() ? TypeInteger.constant(-i0.value()) : i0;
+ return Type.BOTTOM;
+ }
+
+ @Override
+ public Node idealize() { return null; }
+}
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/node/MulNode.java b/chapter08/src/main/java/com/seaofnodes/simple/node/MulNode.java
new file mode 100644
index 00000000..70e6c0db
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/node/MulNode.java
@@ -0,0 +1,58 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeInteger;
+
+import java.util.BitSet;
+
+public class MulNode extends Node {
+ public MulNode(Node lhs, Node rhs) { super(null, lhs, rhs); }
+
+ @Override public String label() { return "Mul"; }
+
+ @Override public String glabel() { return "*"; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ in(1)._print0(sb.append("("), visited);
+ in(2)._print0(sb.append("*"), visited);
+ return sb.append(")");
+ }
+
+ @Override
+ public Type compute() {
+ if (in(1)._type instanceof TypeInteger i0 &&
+ in(2)._type instanceof TypeInteger i1) {
+ if (i0.isConstant() && i1.isConstant())
+ return TypeInteger.constant(i0.value()*i1.value());
+ return i0.meet(i1);
+ }
+ return Type.BOTTOM;
+ }
+
+ @Override
+ public Node idealize() {
+ Node lhs = in(1);
+ Node rhs = in(2);
+ Type t1 = lhs._type;
+ Type t2 = rhs._type;
+
+ // Mul of 1. We do not check for (1*x) because this will already
+ // canonicalize to (x*1)
+ if ( t2.isConstant() && t2 instanceof TypeInteger i && i.value()==1 )
+ return lhs;
+
+ // Move constants to RHS: con*arg becomes arg*con
+ if ( t1.isConstant() && !t2.isConstant() )
+ return swap12();
+
+ // Do we have ((x * (phi cons)) * con) ?
+ // Do we have ((x * (phi cons)) * (phi cons)) ?
+ // Push constant up through the phi: x * (phi con0*con0 con1*con1...)
+ Node phicon = AddNode.phiCon(this,true);
+ if( phicon!=null ) return phicon;
+
+ return null;
+ }
+ @Override Node copy(Node lhs, Node rhs) { return new MulNode(lhs,rhs); }
+}
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/node/MultiNode.java b/chapter08/src/main/java/com/seaofnodes/simple/node/MultiNode.java
new file mode 100644
index 00000000..81c90f68
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/node/MultiNode.java
@@ -0,0 +1,7 @@
+package com.seaofnodes.simple.node;
+
+public abstract class MultiNode extends Node {
+
+ public MultiNode(Node... inputs) { super(inputs); }
+
+}
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/node/Node.java b/chapter08/src/main/java/com/seaofnodes/simple/node/Node.java
new file mode 100644
index 00000000..fcc8df85
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/node/Node.java
@@ -0,0 +1,467 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.Utils;
+import com.seaofnodes.simple.type.Type;
+
+import java.util.*;
+
+/**
+ * All Nodes in the Sea of Nodes IR inherit from the Node class.
+ * The Node class provides common functionality used by all subtypes.
+ * Subtypes of Node specialize by overriding methods.
+ */
+public abstract class Node {
+
+ /**
+ * Each node has a unique dense Node ID within a compilation context
+ * The ID is useful for debugging, for using as an offset in a bitvector,
+ * as well as for computing equality of nodes (to be implemented later).
+ */
+ public final int _nid;
+
+ /**
+ * Inputs to the node. These are use-def references to Nodes.
+ * <p>
+ * Generally fixed length, ordered, nulls allowed, no unused trailing space.
+ * Ordering is required because e.g. "a/b" is different from "b/a".
+ * The first input (offset 0) is often a {@link #isCFG} node.
+ */
+ public final ArrayList<Node> _inputs;
+
+ /**
+ * Outputs reference Nodes that are not null and have this Node as an
+ * input. These nodes are users of this node, thus these are def-use
+ * references to Nodes.
+ * <p>
+ * Outputs directly match inputs, making a directed graph that can be
+ * walked in either direction. These outputs are typically used for
+ * efficient optimizations but otherwise have no semantics meaning.
+ */
+ public final ArrayList<Node> _outputs;
+
+
+ /**
+ * Current computed type for this Node. This value changes as the graph
+ * changes and more knowledge is gained about the program.
+ */
+ public Type _type;
+
+
+ /**
+ * Immediate dominator tree depth, used to approximate a real IDOM during
+ * parsing where we do not have the whole program, and also peepholes
+ * change the CFG incrementally.
+ * <p>
+ * See {@link <a href="https://en.wikipedia.org/wiki/Dominator_(graph_theory)">...</a>}
+ */
+ int _idepth;
+
+ /**
+ * A private Global Static mutable counter, for unique node id generation.
+ * To make the compiler multithreaded, this field will have to move into a TLS.
+ * Starting with value 1, to avoid bugs confusing node ID 0 with uninitialized values.
+ * */
+ private static int UNIQUE_ID = 1;
+
+ protected Node(Node... inputs) {
+ _nid = UNIQUE_ID++; // allocate unique dense ID
+ _inputs = new ArrayList<>();
+ Collections.addAll(_inputs,inputs);
+ _outputs = new ArrayList<>();
+ for( Node n : _inputs )
+ if( n != null )
+ n.addUse( this );
+ }
+
+ // Easy reading label for debugger, e.g. "Add" or "Region" or "EQ"
+ public abstract String label();
+
+ // Unique label for graph visualization, e.g. "Add12" or "Region30" or "EQ99"
+ public String uniqueName() { return label() + _nid; }
+
+ // Graphical label, e.g. "+" or "Region" or "=="
+ public String glabel() { return label(); }
+
+
+ // ------------------------------------------------------------------------
+
+ // Debugger Printing.
+
+ // {@code toString} is what you get in the debugger. It has to print 1
+ // line (because this is what a debugger typically displays by default) and
+ // has to be robust with broken graph/nodes.
+ @Override
+ public final String toString() { return print(); }
+
+ // This is a *deep* print. This version will fail on cycles, which we will
+ // correct later when we can parse programs with loops. We print with a
+ // tik-tok style; the common _print0 calls the per-Node _print1, which
+ // calls back to _print0;
+ public final String print() {
+ return _print0(new StringBuilder(), new BitSet()).toString();
+ }
+ // This is the common print: check for repeats, check for DEAD and print
+ // "DEAD" else call the per-Node print1.
+ final StringBuilder _print0(StringBuilder sb, BitSet visited) {
+ if (visited.get(_nid))
+ return sb.append(label());
+ visited.set(_nid);
+ return isDead()
+ ? sb.append(uniqueName()).append(":DEAD")
+ : _print1(sb, visited);
+ }
+ // Every Node implements this; a partial-line recursive print
+ abstract StringBuilder _print1(StringBuilder sb, BitSet visited);
+
+
+ // Print a node on 1 line, columnar aligned, as:
+ // NNID NNAME DDEF DDEF [[ UUSE UUSE ]] TYPE
+ // 1234 sssss 1234 1234 1234 1234 1234 1234 tttttt
+ public void _print_line( StringBuilder sb ) {
+ sb.append("%4d %-7.7s ".formatted(_nid,label()));
+ if( _inputs==null ) {
+ sb.append("DEAD\n");
+ return;
+ }
+ for( Node def : _inputs )
+ sb.append(def==null ? "____ " : "%4d ".formatted(def._nid));
+ for( int i = _inputs.size(); i<3; i++ )
+ sb.append(" ");
+ sb.append(" [[ ");
+ for( Node use : _outputs )
+ sb.append("%4d ".formatted(use._nid));
+ int lim = 5 - Math.max(_inputs.size(),3);
+ for( int i = _outputs.size(); i<lim; i++ )
+ sb.append(" ");
+ sb.append(" ]] ");
+ if( _type!= null ) _type._print(sb);
+ sb.append("\n");
+ }
+
+ public boolean isMultiHead() { return false; }
+ public boolean isMultiTail() { return false; }
+
+ // ------------------------------------------------------------------------
+ // Graph Node & Edge manipulation
+
+ /**
+ * Gets the ith input node
+ * @param i Offset of the input node
+ * @return Input node or null
+ */
+ public Node in(int i) { return _inputs.get(i); }
+
+ public int nIns() { return _inputs.size(); }
+
+ public Node out(int i) { return _outputs.get(i); }
+
+ public int nOuts() { return _outputs.size(); }
+
+ public boolean isUnused() { return nOuts() == 0; }
+
+ public boolean isCFG() { return false; }
+
+ /**
+ * Change a <em>def</em> into a Node. Keeps the edges correct, by removing
+ * the corresponding <em>use->def</em> edge. This may make the original
+ * <em>def</em> go dead. This function is co-recursive with {@link #kill}.
+ * <p>
+
+ * This method is the normal path for altering a Node, because it does the
+ * proper default edge maintenance. It also <em>immediately</em> kills
+ * Nodes that lose their last use; at times care must be taken to avoid
+ * killing Nodes that are being used without having an output Node. This
+ * definitely happens in the middle of recursive {@link #peephole} calls.
+ *
+ * @param idx which def to set
+ * @param new_def the new definition
+ * @return new_def for flow coding
+ */
+ Node set_def(int idx, Node new_def ) {
+ Node old_def = in(idx);
+ if( old_def == new_def ) return this; // No change
+ // If new def is not null, add the corresponding def->use edge
+ // This needs to happen before removing the old node's def->use edge as
+ // the new_def might get killed if the old node kills it recursively.
+ if( new_def != null )
+ new_def.addUse(this);
+ if( old_def != null && // If the old def exists, remove a def->use edge
+ old_def.delUse(this) ) // If we removed the last use, the old def is now dead
+ old_def.kill(); // Kill old def
+ // Set the new_def over the old (killed) edge
+ _inputs.set(idx,new_def);
+ // Return self for easy flow-coding
+ return new_def;
+ }
+
+ // Remove the numbered input, compressing the inputs in-place. This
+ // shuffles the order deterministically - which is suitable for Region and
+ // Phi, but not for every Node.
+ void delDef(int idx) {
+ Node old_def = in(idx);
+ if( old_def != null && // If the old def exists, remove a def->use edge
+ old_def.delUse(this) ) // If we removed the last use, the old def is now dead
+ old_def.kill(); // Kill old def
+ Utils.del(_inputs, idx);
+ }
+
+ /**
+ * Add a new def to an existing Node. Keep the edges correct by
+ * adding the corresponding <em>def->use</em> edge.
+ *
+ * @param new_def the new definition, appended to the end of existing definitions
+ * @return new_def for flow coding
+ */
+ public Node add_def(Node new_def) {
+ // Add use->def edge
+ _inputs.add(new_def);
+ // If new def is not null, add the corresponding def->use edge
+ if( new_def != null )
+ new_def.addUse(this);
+ return new_def;
+ }
+
+ // Breaks the edge invariants, used temporarily
+ protected <N extends Node> N addUse(Node n) { _outputs.add(n); return (N)this; }
+
+ // Remove node 'use' from 'def's (i.e. our) output list, by compressing the list in-place.
+ // Return true if the output list is empty afterward.
+ // Error is 'use' does not exist; ok for 'use' to be null.
+ protected boolean delUse( Node use ) {
+ Utils.del(_outputs, Utils.find(_outputs, use));
+ return _outputs.size() == 0;
+ }
+
+ // Shortcut for "popping" n nodes. A "pop" is basically a
+ // set_def(last,null) followed by lowering the nIns() count.
+ void pop_n(int n) {
+ for( int i=0; i<n; i++ ) {
+ Node old_def = _inputs.removeLast();
+ if( old_def != null && // If it exists and
+ old_def.delUse(this) ) // If we removed the last use, the old def is now dead
+ old_def.kill(); // Kill old def
+ }
+ }
+
+ /**
+ * Kill a Node with no <em>uses</em>, by setting all of its <em>defs</em>
+ * to null. This may recursively kill more Nodes and is basically dead
+ * code elimination. This function is co-recursive with {@link #pop_n}.
+ */
+ public void kill( ) {
+ assert isUnused(); // Has no uses, so it is dead
+ pop_n(nIns()); // Set all inputs to null, recursively killing unused Nodes
+ _type=null; // Flag as dead
+ assert isDead(); // Really dead now
+ }
+
+ // Mostly used for asserts and printing.
+ boolean isDead() { return isUnused() && nIns()==0 && _type==null; }
+
+ // Shortcuts to stop DCE mid-parse
+ // Add bogus null use to keep node alive
+ public <N extends Node> N keep() { return addUse(null); }
+ // Remove bogus null.
+ public <N extends Node> N unkeep() { delUse(null); return (N)this; }
+
+
+ // Replace self with nnn in the graph, making 'this' go dead
+ void subsume( Node nnn ) {
+ assert nnn!=this;
+ while( nOuts() > 0 ) {
+ Node n = _outputs.removeLast();
+ int idx = Utils.find(n._inputs, this);
+ n._inputs.set(idx,nnn);
+ nnn.addUse(n);
+ }
+ kill();
+ }
+
+ // ------------------------------------------------------------------------
+ // Graph-based optimizations
+
+ /**
+ * We allow disabling peephole opt so that we can observe the
+ * full graph, vs the optimized graph.
+ */
+ public static boolean _disablePeephole = false;
+
+ /**
+ * Try to peephole at this node and return a better replacement Node if
+ * possible. We compute a {@link Type} and then check and replace:
+ * <ul>
+ * <li>if the Type {@link Type#isConstant}, we replace with a {@link ConstantNode}</li>
+ * <li>in a future chapter we will look for a
+ * <a href="https://en.wikipedia.org/wiki/Common_subexpression_elimination">Common Subexpression</a>
+ * to eliminate.</li>
+ * <li>we ask the Node for a better replacement. The "better replacement"
+ * is things like {@code (1+2)} becomes {@code 3} and {@code (1+(x+2))} becomes
+ * {@code (x+(1+2))}. By canonicalizing expressions we fold common addressing
+ * math constants, remove algebraic identities and generally simplify the
+ * code. </li>
+ * </ul>
+ */
+ public final Node peephole( ) {
+ // Compute initial or improved Type
+ Type type = _type = compute();
+
+ if (_disablePeephole)
+ return this; // Peephole optimizations turned off
+
+ // Replace constant computations from non-constants with a constant node
+ if (!(this instanceof ConstantNode) && type.isConstant())
+ return deadCodeElim(new ConstantNode(type).peephole());
+
+ // Future chapter: Global Value Numbering goes here
+
+ // Ask each node for a better replacement
+ Node n = idealize();
+ if( n != null ) // Something changed
+ // Recursively optimize
+ return deadCodeElim(n.peephole());
+
+ return this; // No progress
+ }
+
+ // m is the new Node, self is the old.
+ // Return 'm', which may have zero uses but is alive nonetheless.
+ // If self has zero uses (and is not 'm'), {@link #kill} self.
+ private Node deadCodeElim(Node m) {
+ // If self is going dead and not being returned here (Nodes returned
+ // from peephole commonly have no uses (yet)), then kill self.
+ if( m != this && isUnused() ) {
+ // Killing self - and since self recursively kills self's inputs we
+ // might end up killing 'm', which we are returning as a live Node.
+ // So we add a bogus extra null output edge to stop kill().
+ m.keep(); // Keep m alive
+ kill(); // Kill self because replacing with 'm'
+ m.unkeep(); // Okay to peephole m
+ }
+ return m;
+ }
+
+ /**
+ * This function needs to be
+ * <a href="https://en.wikipedia.org/wiki/Monotonic_function">Monotonic</a>
+ * as it is part of a Monotone Analysis Framework.
+ * <a href="https://www.cse.psu.edu/~gxt29/teaching/cse597s21/slides/08monotoneFramework.pdf">See for example this set of slides</a>.
+ * <p>
+ * For Chapter 2, all our Types are really integer constants, and so all
+ * the needed properties are trivially true, and we can ignore the high
+ * theory. Much later on, this will become important and allow us to do
+ * many fancy complex optimizations trivially... because theory.
+ * <p>
+ * compute() needs to be stand-alone, and cannot recursively call compute
+ * on its inputs programs are cyclic (have loops!) and this will just
+ * infinitely recurse until stack overflow. Instead, compute typically
+ * computes a new type from the {@link #_type} field of its inputs.
+ */
+ public abstract Type compute();
+
+ /**
+ * This function rewrites the current Node into a more "idealized" form.
+ * This is the bulk of our peephole rewrite rules, and we use this to
+ * e.g. turn arbitrary collections of adds and multiplies with mixed
+ * constants into a normal form that's easy for hardware to implement.
+ * Example: An array addressing expression:
+ * <pre> ary[idx+1]</pre>
+ * might turn into Sea-of-Nodes IR:
+ * <pre> (ary+12)+((idx+1) * 4)</pre>
+ * This expression can then be idealized into:
+ * <pre> ary + ((idx*4) + (12 + (1*4)))</pre>
+ * And more folding:
+ * <pre> ary + ((idx<<2) + 16)</pre>
+ * And during code-gen:
+ * <pre> MOV4 Rary,Ridx,16 // or some such hardware-specific notation </pre>
+ * <p>
+ * {@link #idealize} has a very specific calling convention:
+ * <ul>
+ * <li>If NO change is made, return {@code null}
+ * <li>If ANY change is made, return not-null; this can be {@code this}
+ * <li>The returned Node does NOT call {@link #peephole} on itself; the {@link #peephole} call will recursively peephole it.
+ * <li>Any NEW nodes that are not directly returned DO call {@link #peephole}.
+ * </ul>
+ * <p>
+ * Examples:
+ * <table border="3">
+ * <tr><th> before </th><th> after </th><th>return </th><th>comment </th></tr>
+ * <tr><td>{@code (x+5) }</td><td>{@code (x+5) }</td><td>{@code null }</td><td>No change</td></tr>
+ * <tr><td>{@code (5+x) }</td><td>{@code (x+5) }</td><td>{@code this }</td><td>Swapped arguments</td></tr>
+ * <tr><td>{@code ((x+1)+2)}</td><td>{@code (x+(1+2))}</td><td>{@code (x+_) }</td><td>Returns 2 new Nodes</td></tr>
+ * </table>
+ *
+ * The last entry deserves more discussion. The new Node {@code (1+2)}
+ * created in {@link #idealize} calls {@link #peephole} (which then folds
+ * into a constant). The other new Node {@code (x+3)} does not call
+ * peephole, because it is returned and peephole itself will recursively
+ * call peephole.
+ * <p>
+ * Since idealize calls peephole and peephole calls idealize, you must be
+ * careful that all idealizations are <em>monotonic</em>: all transforms remove
+ * some feature, so that the set of available transforms always shrinks.
+ * If you don't, you risk an infinite peephole loop!
+ *
+ * @return Either a new or changed node, or null for no changes.
+ */
+ public abstract Node idealize();
+
+
+ // ------------------------------------------------------------------------
+ // Peephole utilities
+
+ // Swap inputs without letting either input go dead during the swap.
+ Node swap12() {
+ Node tmp = in(1);
+ _inputs.set(1,in(2));
+ _inputs.set(2,tmp);
+ return this;
+ }
+
+ // does this node contain all constants?
+ // Ignores in(0), as is usually control.
+ boolean all_cons() {
+ for( int i=1; i<nIns(); i++ )
+ if( !(in(i)._type.isConstant()) )
+ return false;
+ return true;
+ }
+
+ // Return the immediate dominator of this Node and compute dom tree depth.
+ Node idom() {
+ Node idom = in(0);
+ if( idom._idepth==0 ) idom.idom(); // Recursively set _idepth
+ if( _idepth==0 ) _idepth = idom._idepth+1;
+ return idom;
+ }
+
+ // Make a shallow copy (same class) of this Node, with given inputs and
+ // empty outputs and a new Node ID. The original inputs are ignored.
+ // Does not need to be implemented in isCFG() nodes.
+ Node copy(Node lhs, Node rhs) { throw Utils.TODO("Binary ops need to implement copy"); }
+
+ /**
+ * Used to allow repeating tests in the same JVM. This just resets the
+ * Node unique id generator, and is done as part of making a new Parser.
+ */
+ public static void reset() { UNIQUE_ID = 1; _disablePeephole=false; }
+
+ /**
+ * Debugging utility to find a Node by index
+ */
+ public Node find(int nid) { return _find(new BitSet(),nid); }
+ private Node _find(BitSet visit, int nid) {
+ if( _nid==nid ) return this;
+ if( visit.get(_nid) ) return null;
+ visit.set(_nid);
+ for( Node def : _inputs )
+ if( def!=null ) {
+ Node rez = def._find(visit,nid);
+ if( rez != null ) return rez;
+ }
+ for( Node use : _outputs ) {
+ Node rez = use._find(visit,nid);
+ if( rez != null ) return rez;
+ }
+ return null;
+ }
+}
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/node/NotNode.java b/chapter08/src/main/java/com/seaofnodes/simple/node/NotNode.java
new file mode 100644
index 00000000..04e6c75b
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/node/NotNode.java
@@ -0,0 +1,30 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeInteger;
+
+import java.util.BitSet;
+
+public class NotNode extends Node {
+ public NotNode(Node in) { super(null, in); }
+
+ @Override public String label() { return "Not"; }
+
+ @Override public String glabel() { return "!"; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ in(1)._print0(sb.append("(!"), visited);
+ return sb.append(")");
+ }
+
+ @Override
+ public Type compute() {
+ if( in(1)._type instanceof TypeInteger i0 )
+ return i0.isConstant() ? TypeInteger.constant(i0.value()==0 ? 1 : 0) : i0;
+ return Type.BOTTOM;
+ }
+
+ @Override
+ public Node idealize() { return null; }
+}
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/node/PhiNode.java b/chapter08/src/main/java/com/seaofnodes/simple/node/PhiNode.java
new file mode 100644
index 00000000..202dbe37
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/node/PhiNode.java
@@ -0,0 +1,101 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+
+import java.util.BitSet;
+
+public class PhiNode extends Node {
+
+ final String _label;
+
+ public PhiNode(String label, Node... inputs) { super(inputs); _label = label; }
+
+ @Override public String label() { return "Phi_"+_label; }
+
+ @Override public String glabel() { return "&phi;_"+_label; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ if( region().inProgress() )
+ sb.append("Z");
+ sb.append("Phi(");
+ for( Node in : _inputs ) {
+ if (in == null) sb.append("____");
+ else in._print0(sb, visited);
+ sb.append(",");
+ }
+ sb.setLength(sb.length()-1);
+ sb.append(")");
+ return sb;
+ }
+
+ RegionNode region() { return (RegionNode)in(0); }
+ @Override public boolean isMultiTail() { return true; }
+
+ @Override
+ public Type compute() {
+ if( !(region() instanceof RegionNode r) || r.inProgress() )
+ return Type.BOTTOM;
+ Type t = Type.TOP;
+ for (int i = 1; i < nIns(); i++)
+ t = t.meet(in(i)._type);
+ return t;
+ }
+
+ @Override
+ public Node idealize() {
+ if( !(region() instanceof RegionNode r ) || r.inProgress() )
+ return null;
+
+ // If we have only a single unique input, become it.
+ Node live = singleUniqueInput();
+ if (live != null)
+ return live;
+
+ // Pull "down" a common data op. One less op in the world. One more
+ // Phi, but Phis do not make code.
+ // Phi(op(A,B),op(Q,R),op(X,Y)) becomes
+ // op(Phi(A,Q,X), Phi(B,R,Y)).
+ Node op = in(1);
+ if( op.nIns()==3 && op.in(0)==null && !op.isCFG() && same_op() ) {
+ Node[] lhss = new Node[nIns()];
+ Node[] rhss = new Node[nIns()];
+ lhss[0] = rhss[0] = in(0); // Set Region
+ for( int i=1; i<nIns(); i++ ) {
+ lhss[i] = in(i).in(1);
+ rhss[i] = in(i).in(2);
+ }
+ Node phi_lhs = new PhiNode(_label,lhss).peephole();
+ Node phi_rhs = new PhiNode(_label,rhss).peephole();
+ return op.copy(phi_lhs,phi_rhs);
+ }
+
+ return null;
+ }
+
+ private boolean same_op() {
+ for( int i=2; i<nIns(); i++ )
+ if( in(1).getClass() != in(i).getClass() )
+ return false;
+ return true;
+ }
+
+ /**
+ * If only single unique input, return it
+ */
+ private Node singleUniqueInput() {
+ Node live = null;
+ for( int i=1; i<nIns(); i++ )
+ if( region().in(i)._type != Type.XCONTROL && in(i) != this )
+ if( live == null || live == in(i) ) live = in(i);
+ else return null;
+ return live;
+ }
+
+ @Override
+ boolean all_cons() {
+ if( !(region() instanceof RegionNode r) || r.inProgress() )
+ return false;
+ return super.all_cons();
+ }
+}
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/node/ProjNode.java b/chapter08/src/main/java/com/seaofnodes/simple/node/ProjNode.java
new file mode 100644
index 00000000..79ba9d13
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/node/ProjNode.java
@@ -0,0 +1,49 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeTuple;
+
+import java.util.BitSet;
+
+public class ProjNode extends Node {
+
+ // Which slice of the incoming multi-part value
+ public final int _idx;
+
+ // Debugging label
+ public final String _label;
+
+ public ProjNode(MultiNode ctrl, int idx, String label) {
+ super(ctrl);
+ _idx = idx;
+ _label = label;
+ }
+
+ @Override
+ public String label() { return _label; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) { return sb.append(_label); }
+
+ @Override public boolean isCFG() { return _idx==0 || ctrl() instanceof IfNode; }
+ @Override public boolean isMultiTail() { return in(0).isMultiHead(); }
+
+ public MultiNode ctrl() { return (MultiNode)in(0); }
+
+ @Override
+ public Type compute() {
+ Type t = ctrl()._type;
+ return t instanceof TypeTuple tt ? tt._types[_idx] : Type.BOTTOM;
+ }
+
+ @Override
+ public Node idealize() {
+ if( ctrl()._type instanceof TypeTuple tt ) {
+ if( tt._types[_idx]==Type.XCONTROL )
+ return new ConstantNode(Type.XCONTROL).peephole(); // We are dead
+ if( tt._types[1-_idx]==Type.XCONTROL ) // Only true for IfNodes
+ return ctrl().in(0); // We become our input control
+ }
+ return null;
+ }
+}
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/node/RegionNode.java b/chapter08/src/main/java/com/seaofnodes/simple/node/RegionNode.java
new file mode 100644
index 00000000..3b793758
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/node/RegionNode.java
@@ -0,0 +1,81 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.Utils;
+import com.seaofnodes.simple.type.Type;
+
+import java.util.Collection;
+import java.util.BitSet;
+
+public class RegionNode extends Node {
+ public RegionNode(Node... inputs) { super(inputs); }
+
+ @Override
+ public String label() { return "Region"; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ return sb.append(label()).append(_nid);
+ }
+
+ @Override public boolean isCFG() { return true; }
+ @Override public boolean isMultiHead() { return true; }
+
+ @Override
+ public Type compute() {
+ Type t = Type.XCONTROL;
+ for (int i = 1; i < nIns(); i++)
+ t = t.meet(in(i)._type);
+ return t;
+ }
+
+ @Override
+ public Node idealize() {
+ int path = findDeadInput();
+ if( path != 0 ) {
+ for( Node phi : _outputs )
+ if( phi instanceof PhiNode )
+ phi.delDef(path);
+ delDef(path);
+
+ // If down to a single input, become that input - but also make all
+ // Phis an identity on *their* single input.
+ if( nIns()==2 ) {
+ for( Node phi : _outputs )
+ if( phi instanceof PhiNode )
+ // Currently does not happen, because no loops
+ throw Utils.TODO();
+ return in(1);
+ }
+ return this;
+ }
+ return null;
+ }
+
+ private int findDeadInput() {
+ for( int i=1; i<nIns(); i++ )
+ if( in(i)._type==Type.XCONTROL )
+ return i;
+ return 0; // All inputs alive
+ }
+
+ // Immediate dominator of Region is a little more complicated.
+ private Node _idom; // Immediate dominator cache
+ @Override Node idom() {
+ if( _idom != null ) return _idom; // Return cached copy
+ if( nIns()!=3 ) return null; // Fails for anything other than 2-inputs
+ // Walk the LHS & RHS idom trees in parallel until they match, or either fails
+ Node lhs = in(1).idom();
+ Node rhs = in(2).idom();
+ while( lhs != rhs ) {
+ if( lhs==null || rhs==null ) return null;
+ var comp = lhs._idepth - rhs._idepth;
+ if( comp >= 0 ) lhs = lhs.idom();
+ if( comp <= 0 ) rhs = rhs.idom();
+ }
+ if( lhs==null ) return null;
+ _idepth = lhs._idepth+1;
+ return (_idom=lhs);
+ }
+
+ public boolean inProgress() { return false; }
+}
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/node/ReturnNode.java b/chapter08/src/main/java/com/seaofnodes/simple/node/ReturnNode.java
new file mode 100644
index 00000000..4dea773a
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/node/ReturnNode.java
@@ -0,0 +1,46 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.*;
+
+import java.util.BitSet;
+
+/**
+ * The Return node has two inputs. The first input is a control node and the
+ * second is the data node that supplies the return value.
+ * <p>
+ * In this presentation, Return functions as a Stop node, since multiple <code>return</code> statements are not possible.
+ * The Stop node will be introduced in Chapter 6 when we implement <code>if</code> statements.
+ * <p>
+ * The Return's output is the value from the data node.
+ */
+public class ReturnNode extends Node {
+
+ public ReturnNode(Node ctrl, Node data) {
+ super(ctrl, data);
+ }
+
+ public Node ctrl() { return in(0); }
+ public Node expr() { return in(1); }
+
+ @Override
+ public String label() { return "Return"; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ return expr()._print0(sb.append("return "), visited).append(";");
+ }
+
+ @Override public boolean isCFG() { return true; }
+
+ @Override
+ public Type compute() {
+ return new TypeTuple(ctrl()._type,expr()._type);
+ }
+
+ @Override
+ public Node idealize() {
+ if( ctrl()._type==Type.XCONTROL )
+ return ctrl();
+ return null;
+ }
+}
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/node/ScopeNode.java b/chapter08/src/main/java/com/seaofnodes/simple/node/ScopeNode.java
new file mode 100644
index 00000000..e486a390
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/node/ScopeNode.java
@@ -0,0 +1,193 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.Parser;
+import com.seaofnodes.simple.type.Type;
+
+import java.util.*;
+
+/**
+ * The Scope node is purely a parser helper - it tracks names to nodes with a
+ * stack of scopes.
+ */
+public class ScopeNode extends Node {
+
+ /**
+ * The control is a name that binds to the currently active control
+ * node in the graph
+ */
+ public static final String CTRL = "$ctrl";
+ public static final String ARG0 = "arg";
+
+ /**
+ * Names for every input edge
+ */
+ public final Stack<HashMap<String, Integer>> _scopes;
+
+
+ // A new ScopeNode
+ public ScopeNode() {
+ _scopes = new Stack<>();
+ _type = Type.BOTTOM;
+ }
+
+
+ @Override public String label() { return "Scope"; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ sb.append("Scope[ ");
+ String[] names = reverse_names();
+ for( int j=0; j<nIns(); j++ ) {
+ sb.append(names[j]).append(":");
+ Node n = in(j);
+ while( n instanceof ScopeNode loop ) {
+ sb.append("Lazy_");
+ n = loop.in(j);
+ }
+ n._print0(sb, visited).append(" ");
+ }
+ sb.setLength(sb.length()-1);
+ return sb.append("]");
+ }
+
+ // Expensive...
+ public String[] reverse_names() {
+ String[] names = new String[nIns()];
+ for( HashMap<String,Integer> syms : _scopes )
+ for( String name : syms.keySet() )
+ names[syms.get(name)] = name;
+ return names;
+ }
+
+ @Override public Type compute() { return Type.BOTTOM; }
+
+ @Override public Node idealize() { return null; }
+
+ public void push() { _scopes.push(new HashMap<>()); }
+ public void pop() { pop_n(_scopes.pop().size()); }
+
+ // Create a new name in the current scope
+ public Node define( String name, Node n ) {
+ HashMap<String,Integer> syms = _scopes.lastElement();
+ if( syms.put(name,nIns()) != null )
+ return null; // Double define
+ return add_def(n);
+ }
+
+ // Lookup a name. It is recursive to support lazy Phis on loops.
+ public Node lookup(String name) { return update(name,null,_scopes.size()-1); }
+ // If the name is present in any scope, then redefine else null
+ public Node update(String name, Node n) { return update(name,n,_scopes.size()-1); }
+ // Both recursive lookup and update. If a Lazy Phi is found at any level,
+ // a concrete Phi is inserted at the loop head and also in the current
+ // scope. The Lazy Phi does a recursive lookup for its input which may
+ // itself be Lazy.
+ private Node update( String name, Node n, int i ) {
+ if( i<0 ) return null; // Missed in all scopes, not found
+ var syms = _scopes.get(i);
+ var idx = syms.get(name);
+ if( idx == null ) return update(name,n,i-1); // Missed in this scope, recursively look
+ Node old = in(idx);
+ if( old instanceof ScopeNode loop ) {
+ // Lazy Phi!
+ old = loop.in(idx) instanceof PhiNode phi && loop.ctrl()==phi.region()
+ // Loop already has a real Phi, use it
+ ? loop.in(idx)
+ // Set real Phi in the loop head
+ // The phi takes its one input (no backedge yet) from a recursive
+ // lookup, which might have insert a Phi in every loop nest.
+ : loop.set_def(idx,new PhiNode(name,loop.ctrl(),loop.update(name,null,i),null).peephole());
+ set_def(idx,old);
+ }
+ return n==null ? old : set_def(idx,n); // Not lazy, so this is the answer
+ }
+
+ public Node ctrl() { return in(0); }
+
+ /**
+ * The ctrl of a ScopeNode is always bound to the currently active
+ * control node in the graph, via a special name '$ctrl' that is not
+ * a valid identifier in the language grammar and hence cannot be
+ * referenced in Simple code.
+ *
+ * @param n The node to be bound to '$ctrl'
+ *
+ * @return Node that was bound
+ */
+ public Node ctrl(Node n) { return set_def(0,n); }
+
+ /**
+ * Duplicate a ScopeNode; including all levels, up to Nodes. So this is
+ * neither shallow (would dup the Scope but not the internal HashMap
+ * tables), nor deep (would dup the Scope, the HashMap tables, but then
+ * also the program Nodes).
+ * <p>
+ * If the {@code loop} flag is set, the edges are filled in as the original
+ * Scope, as a indication of Lazy Phis at loop heads. The goal here is to
+ * not make Phis at loop heads for variables which are never touched in the
+ * loop body.
+ * <p>
+ * The new Scope is a full-fledged Node with proper use<->def edges.
+ */
+ public ScopeNode dup() { return dup(false); }
+ public ScopeNode dup(boolean loop) {
+ ScopeNode dup = new ScopeNode();
+ // Our goals are:
+ // 1) duplicate the name bindings of the ScopeNode across all stack levels
+ // 2) Make the new ScopeNode a user of all the nodes bound
+ // 3) Ensure that the order of defs is the same to allow easy merging
+ for( HashMap<String,Integer> syms : _scopes )
+ dup._scopes.push(new HashMap<>(syms));
+ String[] reverse = Parser.LAZY ? null : reverse_names();
+ dup.add_def(ctrl()); // Control input is just copied
+ for( int i=1; i<nIns(); i++ ) {
+ dup.add_def(loop ? (Parser.LAZY ? this : new PhiNode(reverse[i],ctrl(),in(i),null).peephole()) : in(i));
+ if( loop && !Parser.LAZY ) set_def(i,dup.in(i));
+ }
+ return dup;
+ }
+
+ /**
+ * Merges the names whose node bindings differ, by creating Phi node for such names
+ * The names could occur at all stack levels, but a given name can only differ in the
+ * innermost stack level where the name is bound.
+ *
+ * @param that The ScopeNode to be merged into this
+ * @return A new node representing the merge point
+ */
+ public Node mergeScopes(ScopeNode that) {
+ RegionNode r = (RegionNode) ctrl(new RegionNode(null,ctrl(), that.ctrl()).keep());
+ String[] ns = reverse_names();
+ // Note that we skip i==0, which is bound to '$ctrl'
+ for (int i = 1; i < nIns(); i++) {
+ if( in(i) != that.in(i) ) { // No need for redundant Phis
+ Node n1 = Parser.LAZY ? this.lookup(ns[i]) : in(i); // Must do a lookup to set lazy Phis
+ Node n2 = Parser.LAZY ? that.lookup(ns[i]) : that.in(i); // Must do a lookup to set lazy Phis
+ set_def(i, new PhiNode(ns[i], r, n1, n2).peephole());
+ }
+ }
+ that.kill(); // Kill merged scope
+ return r.unkeep().peephole();
+ }
+
+ // Merge the backedge scope into this loop head scope
+ public void endLoop(ScopeNode back, ScopeNode exit ) {
+ Node ctrl = ctrl();
+ assert ctrl instanceof LoopNode loop && loop.inProgress();
+ ctrl.set_def(2,back.ctrl());
+ for( int i=1; i<nIns(); i++ ) {
+ if( back.in(i) != this ) {
+ PhiNode phi = (PhiNode)in(i);
+ assert phi.region()==ctrl && phi.in(2)==null;
+ phi.set_def(2,back.in(i));
+ // Do an eager useless-phi removal
+ Node in = phi.peephole();
+ if( in != phi )
+ phi.subsume(in);
+ }
+ if( exit.in(i) == this ) // Replace a lazy-phi on the exit path also
+ exit.set_def(i,in(i));
+ }
+ back.kill(); // Loop backedge is dead
+ }
+}
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/node/StartNode.java b/chapter08/src/main/java/com/seaofnodes/simple/node/StartNode.java
new file mode 100644
index 00000000..19d03e0f
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/node/StartNode.java
@@ -0,0 +1,46 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeTuple;
+
+import java.util.BitSet;
+
+/**
+ * The Start node represents the start of the function. For now, we do not
+ * have any inputs to Start because our function does not yet accept
+ * parameters. When we add parameters the value of Start will be a tuple, and
+ * will require Projections to extract the values. We discuss this in detail
+ * in Chapter 9: Functions and Calls.
+ */
+public class StartNode extends MultiNode {
+
+ final TypeTuple _args;
+
+ public StartNode(Type[] args) {
+ super();
+ _args = new TypeTuple(args);
+ _type = _args;
+ }
+
+ @Override
+ public String label() { return "Start"; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ return sb.append(label());
+ }
+
+ @Override public boolean isCFG() { return true; }
+ @Override public boolean isMultiHead() { return true; }
+
+ @Override
+ public TypeTuple compute() { return _args; }
+
+ @Override
+ public Node idealize() { return null; }
+
+ // No immediate dominator, and idepth==0
+ @Override
+ Node idom() { return null; }
+
+}
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/node/StopNode.java b/chapter08/src/main/java/com/seaofnodes/simple/node/StopNode.java
new file mode 100644
index 00000000..c4375771
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/node/StopNode.java
@@ -0,0 +1,53 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+
+import java.util.BitSet;
+
+public class StopNode extends Node {
+ public StopNode(Node... inputs) {
+ super(inputs);
+ }
+
+ @Override
+ public String label() {
+ return "Stop";
+ }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ if( ret()!=null ) return ret()._print0(sb, visited);
+ sb.append("Stop[ ");
+ for( Node ret : _inputs )
+ ret._print0(sb, visited).append(" ");
+ return sb.append("]");
+ }
+
+ @Override public boolean isCFG() { return true; }
+
+ // If a single Return, return it.
+ // Otherwise, null because ambiguous.
+ public ReturnNode ret() {
+ return nIns()==1 ? (ReturnNode)in(0) : null;
+ }
+
+ @Override
+ public Type compute() {
+ return Type.BOTTOM;
+ }
+
+ @Override
+ public Node idealize() {
+ int len = nIns();
+ for( int i=0; i<nIns(); i++ )
+ if( in(i)._type==Type.XCONTROL )
+ delDef(i--);
+ if( len != nIns() ) return this;
+ return null;
+ }
+
+ public Node addReturn(Node node) {
+ return add_def(node);
+ }
+
+}
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/node/SubNode.java b/chapter08/src/main/java/com/seaofnodes/simple/node/SubNode.java
new file mode 100644
index 00000000..1484ab8a
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/node/SubNode.java
@@ -0,0 +1,43 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeInteger;
+
+import java.util.BitSet;
+
+public class SubNode extends Node {
+ public SubNode(Node lhs, Node rhs) { super(null, lhs, rhs); }
+
+ @Override public String label() { return "Sub"; }
+
+ @Override public String glabel() { return "-"; }
+
+ @Override
+ StringBuilder _print1(StringBuilder sb, BitSet visited) {
+ in(1)._print0(sb.append("("), visited);
+ in(2)._print0(sb.append("-"), visited);
+ return sb.append(")");
+ }
+
+ @Override
+ public Type compute() {
+ if (in(1)._type instanceof TypeInteger i0 &&
+ in(2)._type instanceof TypeInteger i1) {
+ if (i0.isConstant() && i1.isConstant())
+ return TypeInteger.constant(i0.value()-i1.value());
+ return i0.meet(i1);
+ }
+ return Type.BOTTOM;
+ }
+
+ @Override
+ public Node idealize() {
+ // Sub of same is 0
+ if( in(1)==in(2) )
+ return new ConstantNode(TypeInteger.constant(0));
+
+ return null;
+ }
+
+ @Override Node copy(Node lhs, Node rhs) { return new SubNode(lhs,rhs); }
+}
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/type/Type.java b/chapter08/src/main/java/com/seaofnodes/simple/type/Type.java
new file mode 100644
index 00000000..f88403a5
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/type/Type.java
@@ -0,0 +1,77 @@
+package com.seaofnodes.simple.type;
+
+
+/**
+ * These types are part of a Monotone Analysis Framework,
+ * @see <a href="https://www.cse.psu.edu/~gxt29/teaching/cse597s21/slides/08monotoneFramework.pdf">see for example this set of slides</a>.
+ * <p>
+ * The types form a lattice; @see <a href="https://en.wikipedia.org/wiki/Lattice_(order)">a symmetric complete bounded (ranked) lattice.</a>
+ * <p>
+ * This wild lattice theory will be needed later to allow us to easily beef up
+ * the analysis and optimization of the Simple compiler... but we don't need it
+ * now, just know that it is coming along in a later Chapter.
+ * <p>g
+ * One of the fun things here is that while the theory is deep and subtle, the
+ * actual implementation is darn near trivial and is generally really obvious
+ * what we're doing with it. Right now, it's just simple integer math to do
+ * simple constant folding e.g. 1+2 == 3 stuff.
+ */
+
+public class Type {
+
+ // ----------------------------------------------------------
+ // Simple types are implemented fully here. "Simple" means: the code and
+ // type hierarchy are simple, not that the Type is conceptually simple.
+ static final byte TBOT = 0; // Bottom (ALL)
+ static final byte TTOP = 1; // Top (ANY)
+ static final byte TCTRL = 2; // Ctrl flow bottom
+ static final byte TXCTRL = 3; // Ctrl flow top (mini-lattice: any-xctrl-ctrl-all)
+ static final byte TSIMPLE = 4; // End of the Simple Types
+ static final byte TINT = 5; // All Integers; see TypeInteger
+ static final byte TTUPLE = 6; // Tuples; finite collections of unrelated Types, kept in parallel
+
+ public final byte _type;
+
+ public boolean is_simple() { return _type < TSIMPLE; }
+ private static final String[] STRS = new String[]{"Bot","Top","Ctrl","~Ctrl"};
+ protected Type(byte type) { _type = type; }
+
+ public static final Type BOTTOM = new Type( TBOT ); // ALL
+ public static final Type TOP = new Type( TTOP ); // ANY
+ public static final Type CONTROL = new Type( TCTRL ); // Ctrl
+ public static final Type XCONTROL = new Type( TXCTRL ); // ~Ctrl
+
+ public boolean isConstant() { return _type == TTOP || _type == TXCTRL; }
+
+ public StringBuilder _print(StringBuilder sb) {return is_simple() ? sb.append(STRS[_type]) : sb;}
+
+ public final Type meet(Type t) {
+ // Shortcut for the self case
+ if( t == this ) return this;
+ // Same-type is always safe in the subclasses
+ if( _type==t._type ) return xmeet(t);
+ // Reverse; xmeet 2nd arg is never "is_simple" and never equal to "this".
+ if( is_simple() ) return this.xmeet(t );
+ if( t.is_simple() ) return t .xmeet(this);
+ return BOTTOM; // Mixing 2 unrelated types
+ }
+
+ // Compute meet right now. Overridden in subclasses.
+ // Handle cases where 'this.is_simple()' and unequal to 't'.
+ // Subclassed xmeet calls can assert that '!t.is_simple()'.
+ protected Type xmeet(Type t) {
+ assert is_simple(); // Should be overridden in subclass
+ // ANY meet anything is thing; thing meet ALL is ALL
+ if( _type==TBOT || t._type==TTOP ) return this;
+ if( _type==TTOP || t._type==TBOT ) return t;
+ // 'this' is {TCTRL,TXCTRL}
+ if( !t.is_simple() ) return BOTTOM;
+ // 't' is {TCTRL,TXCTRL}
+ return _type==TCTRL || t._type==TCTRL ? CONTROL : XCONTROL;
+ }
+
+ @Override
+ public final String toString() {
+ return _print(new StringBuilder()).toString();
+ }
+}
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/type/TypeInteger.java b/chapter08/src/main/java/com/seaofnodes/simple/type/TypeInteger.java
new file mode 100644
index 00000000..93f5eae3
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/type/TypeInteger.java
@@ -0,0 +1,63 @@
+package com.seaofnodes.simple.type;
+
+/**
+ * Integer Type
+ */
+public class TypeInteger extends Type {
+
+ public final static TypeInteger TOP = new TypeInteger(false, 0);
+ public final static TypeInteger BOT = new TypeInteger(false, 1);
+ public final static TypeInteger ZERO= new TypeInteger(true, 0);
+
+ private final boolean _is_con;
+
+ /**
+ * The constant value or
+ * if not constant then 0=bottom, 1=top.
+ */
+ private final long _con;
+
+ public TypeInteger(boolean is_con, long con) {
+ super(TINT);
+ _is_con = is_con;
+ _con = con;
+ }
+
+ public static TypeInteger constant(long con) { return new TypeInteger(true, con); }
+
+ public boolean isTop() { return !_is_con && _con==0; }
+ public boolean isBot() { return !_is_con && _con==1; }
+
+ @Override
+ public StringBuilder _print(StringBuilder sb) {
+ if (isTop()) return sb.append("IntTop");
+ if (isBot()) return sb.append("IntBot");
+ return sb.append(_con);
+ }
+
+ @Override
+ public boolean isConstant() { return _is_con; }
+
+ public long value() { return _con; }
+
+ @Override
+ public Type xmeet(Type other) {
+ if( this==other ) return this;
+ if (!(other instanceof TypeInteger i)) return super.meet(other);
+ // BOT wins
+ if ( isBot() ) return this;
+ if ( i.isBot() ) return i ;
+ // TOP loses
+ if ( i.isTop() ) return this;
+ if ( isTop() ) return i ;
+ assert isConstant() && i.isConstant();
+ return _con==i._con ? this : TypeInteger.BOT;
+ }
+
+ @Override
+ public boolean equals( Object o ) {
+ if( o==this ) return true;
+ if( !(o instanceof TypeInteger i) ) return false;
+ return _con==i._con && _is_con==i._is_con;
+ }
+}
diff --git a/chapter08/src/main/java/com/seaofnodes/simple/type/TypeTuple.java b/chapter08/src/main/java/com/seaofnodes/simple/type/TypeTuple.java
new file mode 100644
index 00000000..f8c3b3c8
--- /dev/null
+++ b/chapter08/src/main/java/com/seaofnodes/simple/type/TypeTuple.java
@@ -0,0 +1,32 @@
+package com.seaofnodes.simple.type;
+
+public class TypeTuple extends Type {
+
+ public final Type[] _types;
+
+ public TypeTuple(Type... _types) {
+ super(TTUPLE);
+ this._types = _types;
+ }
+
+ @Override
+ public Type xmeet(Type other) {
+ throw new UnsupportedOperationException("Meet on Tuple Type not yet implemented");
+ }
+
+ @Override
+ public StringBuilder _print(StringBuilder sb) {
+ sb.append("[");
+ for( Type t : _types )
+ t._print(sb).append(",");
+ sb.setLength(sb.length()-1);
+ sb.append("]");
+ return sb;
+ }
+
+ public static final TypeTuple IF_BOTH = new TypeTuple(new Type[]{Type.CONTROL, Type.CONTROL});
+ public static final TypeTuple IF_NEITHER = new TypeTuple(new Type[]{Type.XCONTROL,Type.XCONTROL});
+ public static final TypeTuple IF_TRUE = new TypeTuple(new Type[]{Type.CONTROL, Type.XCONTROL});
+ public static final TypeTuple IF_FALSE = new TypeTuple(new Type[]{Type.XCONTROL,Type.CONTROL});
+
+}
diff --git a/chapter08/src/test/java/com/seaofnodes/simple/Chapter08Test.java b/chapter08/src/test/java/com/seaofnodes/simple/Chapter08Test.java
new file mode 100644
index 00000000..00178a64
--- /dev/null
+++ b/chapter08/src/test/java/com/seaofnodes/simple/Chapter08Test.java
@@ -0,0 +1,1028 @@
+package com.seaofnodes.simple;
+
+import com.seaofnodes.simple.node.*;
+import com.seaofnodes.simple.type.TypeInteger;
+import org.junit.Test;
+
+import java.util.ArrayList;
+
+import static org.junit.Assert.*;
+
+public class Chapter08Test {
+
+ @Test
+ public void testChapter7Example() {
+ Parser parser = new Parser(
+ """
+ while(arg < 10) {
+ arg = arg + 1;
+ #showGraph;
+ }
+ return arg;
+ """);
+ Node._disablePeephole = true;
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Loop6,arg,(Phi_arg+1));", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ Node._disablePeephole = false;
+ }
+
+ @Test
+ public void testChapter7Regression() {
+ Parser parser = new Parser(
+
+"""
+int a = 1;
+if(arg){}else{
+ while(a < 10) {
+ a = a + 1;
+ }
+}
+return a;
+""");
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Region23,1,Phi(Loop11,1,(Phi_a+1)));", stop.toString());
+ }
+
+ @Test
+ public void testChapter7WhileNested() {
+ Parser parser = new Parser(
+
+"""
+int sum = 0;
+int i = 0;
+while(i < arg) {
+ i = i + 1;
+ int j = 0;
+ while( j < arg ) {
+ sum = sum + j;
+ j = j + 1;
+ }
+}
+return sum;
+""");
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Loop8,0,Phi(Loop21,Phi_sum,(Phi(Loop,0,(Phi_j+1))+Phi_sum)));", stop.toString());
+ System.out.println(IRPrinter.prettyPrint(stop,99));
+ }
+
+ @Test
+ public void testChapter7WhileScope() {
+ Parser parser = new Parser(
+"""
+int a = 1;
+int b = 2;
+while(a < 10) {
+ if (a == 2) a = 3;
+ else b = 4;
+}
+return b;
+""");
+ Node._disablePeephole = true;
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Loop8,2,Phi(Region27,Phi_b,4));", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ Node._disablePeephole = false;
+ System.out.println(IRPrinter.prettyPrint(stop,99));
+ }
+
+ @Test
+ public void testChapter7WhileNestedIfAndInc() {
+ Parser parser = new Parser(
+"""
+int a = 1;
+int b = 2;
+while(a < 10) {
+ if (a == 2) a = 3;
+ else b = 4;
+ b = b + 1;
+ a = a + 1;
+}
+return b;
+""");
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Loop8,2,(Phi(Region27,Phi_b,4)+1));", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ System.out.println(IRPrinter.prettyPrint(stop,99));
+ }
+
+
+ @Test
+ public void testChapter7While() {
+ Parser parser = new Parser(
+"""
+int a = 1;
+while(a < 10) {
+ a = a + 1;
+ a = a + 2;
+}
+return a;
+""");
+ Node._disablePeephole = true;
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Loop7,1,((Phi_a+1)+2));", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ Node._disablePeephole = false;
+ }
+
+ @Test
+ public void testChapter7WhilePeep() {
+ Parser parser = new Parser(
+"""
+int a = 1;
+while(a < 10) {
+ a = a + 1;
+ a = a + 2;
+}
+return a;
+""");
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Loop7,1,(Phi_a+3));", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ }
+
+ @Test
+ public void testChapter7While2() {
+ Parser parser = new Parser(
+"""
+int a = 1;
+while(arg) a = 2;
+return a;
+""");
+ Node._disablePeephole = true;
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Loop7,1,2);", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ Node._disablePeephole = false;
+ System.out.println(IRPrinter.prettyPrint(stop,99));
+ }
+
+ @Test
+ public void testChapter7While2Peep() {
+ Parser parser = new Parser(
+"""
+int a = 1;
+while(arg) a = 2;
+return a;
+""");
+ StopNode stop = parser.parse(false);
+ assertEquals("return Phi(Loop7,1,2);", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ System.out.println(IRPrinter.prettyPrint(stop, 99));
+ }
+
+ @Test
+ public void testChapter7While3() {
+ Parser parser = new Parser(
+"""
+int a = 1;
+while(a < 10) {
+ int b = a + 1;
+ a = b + 2;
+}
+return a;
+""");
+ Node._disablePeephole = true;
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Loop7,1,((Phi_a+1)+2));", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ Node._disablePeephole = false;
+ }
+
+ @Test
+ public void testChapter7While3Peep() {
+ Parser parser = new Parser(
+"""
+int a = 1;
+while(a < 10) {
+ int b = a + 1;
+ a = b + 2;
+}
+return a;
+""");
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Loop7,1,(Phi_a+3));", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ }
+
+ @Test
+ public void testChapter7While4() {
+ Parser parser = new Parser(
+"""
+int a = 1;
+int b = 2;
+while(a < 10) {
+ int b = a + 1;
+ a = b + 2;
+}
+return a;
+""");
+ Node._disablePeephole = true;
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Loop8,1,((Phi_a+1)+2));", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ Node._disablePeephole = false;
+ }
+
+ @Test
+ public void testChapter7While4Peep() {
+ Parser parser = new Parser(
+"""
+int a = 1;
+int b = 2;
+while(a < 10) {
+ int b = a + 1;
+ a = b + 2;
+}
+return a;
+""");
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Loop8,1,(Phi_a+3));", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ }
+
+ @Test
+ public void testChapter6PeepholeReturn() {
+ Parser parser = new Parser(
+"""
+if( true ) return 2;
+return 1;
+""");
+ StopNode stop = parser.parse(true);
+ assertEquals("return 2;", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ }
+
+ @Test
+ public void testChapter6PeepholeRotate() {
+ Parser parser = new Parser(
+"""
+int a = 1;
+if (arg)
+ a = 2;
+return (arg < a) < 3;
+""");
+ StopNode stop = parser.parse(false);
+ assertEquals("return ((arg<Phi(Region12,2,1))<3);", stop.toString());
+ }
+
+ @Test
+ public void testChapter6PeepholeCFG() {
+ Parser parser = new Parser(
+"""
+int a=1;
+if( true )
+ a=2;
+else
+ a=3;
+return a;
+""");
+ StopNode stop = parser.parse(true);
+ assertEquals("return 2;", stop.toString());
+ assertTrue(stop.ret().ctrl() instanceof ProjNode);
+ }
+
+ @Test
+ public void testChapter6IfIf() {
+ Parser parser = new Parser(
+"""
+int a=1;
+if( arg!=1 )
+ a=2;
+else
+ a=3;
+int b=4;
+if( a==2 )
+ b=42;
+else
+ b=5;
+return b;""", TypeInteger.BOT);
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Region32,42,5);", stop.toString());
+ }
+
+ @Test
+ public void testChapter6IfArgIf() {
+ Parser parser = new Parser(
+"""
+int a=1;
+if( 1==1 )
+ a=2;
+else
+ a=3;
+int b=4;
+if( arg==2 )
+ b=a;
+else
+ b=5;
+return b;""", TypeInteger.BOT);
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Region28,2,5);", stop.toString());
+ }
+
+ @Test
+ public void testChapter6Merge3With2() {
+ Parser parser = new Parser(
+"""
+int a=1;
+if( arg==1 )
+ if( arg==2 )
+ a=2;
+ else
+ a=3;
+else if( arg==3 )
+ a=4;
+else
+ a=5;
+return a;
+#showGraph;""", TypeInteger.constant(2));
+ StopNode stop = parser.parse();
+ assertEquals("return 5;", stop.toString());
+ }
+
+ @Test
+ public void testChapter6Merge3With1() {
+ Parser parser = new Parser(
+"""
+int a=1;
+if( arg==1 )
+ if( arg==2 )
+ a=2;
+ else
+ a=3;
+else if( arg==3 )
+ a=4;
+else
+ a=5;
+return a;
+""", TypeInteger.constant(1));
+ StopNode stop = parser.parse(true);
+ assertEquals("return 3;", stop.toString());
+ }
+
+ @Test
+ public void testChapter6Merge3Peephole() {
+ Parser parser = new Parser(
+"""
+int a=1;
+if( arg==1 )
+ if( 1==2 )
+ a=2;
+ else
+ a=3;
+else if( arg==3 )
+ a=4;
+else
+ a=5;
+return a;
+""", TypeInteger.BOT);
+ StopNode stop = parser.parse(true);
+ assertEquals("return Phi(Region36,3,Phi(Region34,4,5));", stop.toString());
+ }
+
+ @Test
+ public void testChapter6Merge3Peephole1() {
+ Parser parser = new Parser(
+"""
+int a=1;
+if( arg==1 )
+ if( 1==2 )
+ a=2;
+ else
+ a=3;
+else if( arg==3 )
+ a=4;
+else
+ a=5;
+return a;
+""", TypeInteger.constant(1));
+ StopNode stop = parser.parse(true);
+ assertEquals("return 3;", stop.toString());
+ }
+
+ @Test
+ public void testChapter6Merge3Peephole3() {
+ Parser parser = new Parser(
+"""
+int a=1;
+if( arg==1 )
+ if( 1==2 )
+ a=2;
+ else
+ a=3;
+else if( arg==3 )
+ a=4;
+else
+ a=5;
+return a;
+""", TypeInteger.constant(3));
+ StopNode stop = parser.parse(true);
+ assertEquals("return 4;", stop.toString());
+ }
+
+ @Test
+ public void testChapter6Demo1NonConst() {
+ Parser parser = new Parser("""
+int a = 0;
+int b = 1;
+if( arg ) {
+ a = 2;
+ if( arg ) { b = 2; }
+ else b = 3;
+}
+return a+b;
+""");
+ StopNode ret = parser.parse(true);
+ assertEquals("return Phi(Region22,4,1);", ret.toString());
+ }
+
+
+ @Test
+ public void testChapter6Demo1True() {
+ Parser parser = new Parser("""
+int a = 0;
+int b = 1;
+if( arg ) {
+ a = 2;
+ if( arg ) { b = 2; }
+ else b = 3;
+}
+return a+b;
+""", TypeInteger.constant(1));
+ StopNode ret = parser.parse(true);
+ assertEquals("return 4;", ret.toString());
+ }
+
+ @Test
+ public void testChapter6Demo1False() {
+ Parser parser = new Parser("""
+int a = 0;
+int b = 1;
+if( arg ) {
+ a = 2;
+ if( arg ) { b = 2; }
+ else b = 3;
+}
+return a+b;
+""", TypeInteger.constant(0));
+ StopNode ret = parser.parse(true);
+ assertEquals("return 1;", ret.toString());
+ }
+
+ @Test
+ public void testChapter6Demo2NonConst() {
+ Parser parser = new Parser("""
+int a = 0;
+int b = 1;
+int c = 0;
+if( arg ) {
+ a = 1;
+ if( arg==2 ) { c=2; } else { c=3; }
+ if( arg ) { b = 2; }
+ else b = 3;
+}
+return a+b+c;
+""");
+ StopNode ret = parser.parse(true);
+ assertEquals("return (Phi(Region33,Phi(Region22,2,3),0)+Phi(Region,3,1));", ret.toString());
+ }
+
+
+ @Test
+ public void testChapter6Demo2True() {
+ Parser parser = new Parser("""
+int a = 0;
+int b = 1;
+int c = 0;
+if( arg ) {
+ a = 1;
+ if( arg==2 ) { c=2; } else { c=3; }
+ if( arg ) { b = 2; }
+ else b = 3;
+}
+return a+b+c;
+""", TypeInteger.constant(1));
+ StopNode ret = parser.parse(true);
+ assertEquals("return 6;", ret.toString());
+ }
+
+ @Test
+ public void testChapter6Demo2arg2() {
+ Parser parser = new Parser("""
+int a = 0;
+int b = 1;
+int c = 0;
+if( arg ) {
+ a = 1;
+ if( arg==2 ) { c=2; } else { c=3; }
+ if( arg ) { b = 2; }
+ else b = 3;
+}
+return a+b+c;
+""", TypeInteger.constant(2));
+ StopNode ret = parser.parse(true);
+ assertEquals("return 5;", ret.toString());
+ }
+
+
+
+ @Test
+ public void testChapter5IfStmt() {
+ Parser parser = new Parser(
+"""
+int a = 1;
+if (arg == 1)
+ a = arg+2;
+else {
+ a = arg-3;
+ #showGraph;
+}
+#showGraph;
+return a;""");
+ StopNode ret = parser.parse(true);
+ assertEquals("return Phi(Region17,(arg+2),(arg-3));", ret.toString());
+ }
+
+ @Test
+ public void testChapter5Test() {
+ Parser parser = new Parser(
+"""
+int c = 3;
+int b = 2;
+if (arg == 1) {
+ b = 3;
+ c = 4;
+}
+return c;""", TypeInteger.BOT);
+ StopNode ret = parser.parse(true);
+ assertEquals("return Phi(Region16,4,3);", ret.toString());
+ }
+
+ @Test
+ public void testChapter5Return2() {
+ Parser parser = new Parser(
+"""
+if( arg==1 )
+ return 3;
+else
+ return 4;
+#showGraph;""", TypeInteger.BOT);
+ StopNode stop = parser.parse();
+ assertEquals("Stop[ return 3; return 4; ]", stop.toString());
+ }
+
+ @Test
+ public void testChapter5IfMergeB() {
+ Parser parser = new Parser(
+"""
+int a=arg+1;
+int b=0;
+if( arg==1 )
+ b=a;
+else
+ b=a+1;
+return a+b;""");
+ StopNode ret = parser.parse(true);
+ assertEquals("return ((arg*2)+Phi(Region20,2,3));", ret.toString());
+ }
+
+ @Test
+ public void testChapter5IfMerge2() {
+ Parser parser = new Parser(
+"""
+int a=arg+1;
+int b=arg+2;
+if( arg==1 )
+ b=b+a;
+else
+ a=b+1;
+return a+b;""");
+ StopNode ret = parser.parse(true);
+ assertEquals("return ((Phi(Region31,(arg*2),arg)+arg)+Phi(Region,4,5));", ret.toString());
+ }
+
+ @Test
+ public void testChapter5Merge3() {
+ Parser parser = new Parser(
+"""
+int a=1;
+if( arg==1 )
+ if( arg==2 )
+ a=2;
+ else
+ a=3;
+else if( arg==3 )
+ a=4;
+else
+ a=5;
+return a;
+#showGraph;""", TypeInteger.BOT);
+ StopNode stop = parser.parse();
+ assertEquals("return Phi(Region33,Phi(Region21,2,3),Phi(Region31,4,5));", stop.toString());
+ }
+
+ @Test
+ public void testChapter5Merge4() {
+ Parser parser = new Parser(
+"""
+int a=0;
+int b=0;
+if( arg )
+ a=1;
+if( arg==0 )
+ b=2;
+return arg+a+b;
+#showGraph;""", TypeInteger.BOT);
+ StopNode stop = parser.parse();
+ assertEquals("return ((arg+Phi(Region13,1,0))+Phi(Region22,2,0));", stop.toString());
+ }
+
+ @Test
+ public void testChapter5Merge5() {
+ Parser parser = new Parser(
+"""
+int a=arg==2;
+if( arg==1 )
+{
+ a=arg==3;
+}
+return a;""");
+ StopNode ret = parser.parse(true);
+ assertEquals("return (arg==Phi(Region16,3,2));", ret.toString());
+ }
+
+ @Test
+ public void testChapter5True() {
+ StopNode stop = new Parser("return true;").parse();
+ assertEquals("return 1;",stop.toString());
+ }
+
+ @Test
+ public void testChapter5HalfDef() {
+ try {
+ new Parser("if( arg==1 ) int b=2; return b;").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Cannot define a new name on one arm of an if",e.getMessage());
+ }
+ }
+
+ @Test
+ public void testChapter5HalfDef2() {
+ try {
+ new Parser("if( arg==1 ) { int b=2; } else { int b=3; } return b;").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Undefined name 'b'",e.getMessage());
+ }
+ }
+
+ @Test
+ public void testChapter5BadNum() {
+ try {
+ new Parser("return 1-;").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Syntax error, expected an identifier or expression: ;",e.getMessage());
+ }
+ }
+
+ @Test
+ public void testChapter5Keyword1() {
+ try {
+ new Parser("int true=0; return true;").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Expected an identifier, found 'true'",e.getMessage());
+ }
+ }
+
+ @Test
+ public void testChapter5Keyword2() {
+ try {
+ new Parser("int else=arg; if(else) else=2; else else=1; return else;").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Expected an identifier, found 'else'",e.getMessage());
+ }
+ }
+
+ @Test
+ public void testChapter5Keyword3() {
+ try {
+ new Parser("int a=1; ififif(arg)inta=2;return a;").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Syntax error, expected =: (",e.getMessage());
+ }
+ }
+
+ @Test
+ public void testChapter4Peephole() {
+ Parser parser = new Parser("return 1+arg+2; #showGraph;");
+ StopNode ret = parser.parse();
+ assertEquals("return (arg+3);", ret.print());
+ }
+
+ @Test
+ public void testChapter4Peephole2() {
+ Parser parser = new Parser("return (1+arg)+2;");
+ StopNode ret = parser.parse();
+ assertEquals("return (arg+3);", ret.print());
+ }
+
+ @Test
+ public void testChapter4Add0() {
+ Parser parser = new Parser("return 0+arg;");
+ StopNode ret = parser.parse();
+ assertEquals("return arg;", ret.print());
+ }
+
+ @Test
+ public void testChapter4AddAddMul() {
+ Parser parser = new Parser("return arg+0+arg;");
+ StopNode ret = parser.parse();
+ assertEquals("return (arg*2);", ret.print());
+ }
+
+ @Test
+ public void testChapter4Peephole3() {
+ Parser parser = new Parser("return 1+arg+2+arg+3; #showGraph;");
+ StopNode ret = parser.parse();
+ assertEquals("return ((arg*2)+6);", ret.print());
+ }
+
+ @Test
+ public void testChapter4Mul1() {
+ Parser parser = new Parser("return 1*arg;");
+ StopNode ret = parser.parse();
+ assertEquals("return arg;", ret.print());
+ }
+
+ @Test
+ public void testChapter4VarArg() {
+ Parser parser = new Parser("return arg; #showGraph;");
+ StopNode stop = parser.parse();
+ ReturnNode ret = stop.ret();
+ assertTrue(ret.in(0) instanceof ProjNode);
+ assertTrue(ret.in(1) instanceof ProjNode);
+ }
+
+ @Test
+ public void testChapter4ConstantArg() {
+ Parser parser = new Parser("return arg; #showGraph;", TypeInteger.constant(2));
+ StopNode ret = parser.parse();
+ assertEquals("return 2;", ret.print());
+ }
+
+ @Test
+ public void testChapter4CompEq() {
+ Parser parser = new Parser("return 3==3; #showGraph;");
+ StopNode ret = parser.parse();
+ assertEquals("return 1;", ret.print());
+ }
+
+ @Test
+ public void testChapter4CompEq2() {
+ Parser parser = new Parser("return 3==4; #showGraph;");
+ StopNode ret = parser.parse();
+ assertEquals("return 0;", ret.print());
+ }
+
+ @Test
+ public void testChapter4CompNEq() {
+ Parser parser = new Parser("return 3!=3; #showGraph;");
+ StopNode ret = parser.parse();
+ assertEquals("return 0;", ret.print());
+ }
+
+ @Test
+ public void testChapter4CompNEq2() {
+ Parser parser = new Parser("return 3!=4; #showGraph;");
+ StopNode ret = parser.parse();
+ assertEquals("return 1;", ret.print());
+ }
+
+ @Test
+ public void testChapter4Bug1() {
+ Parser parser = new Parser("int a=arg+1; int b=a; b=1; return a+2; #showGraph;");
+ StopNode ret = parser.parse();
+ assertEquals("return (arg+3);", ret.print());
+ }
+
+ @Test
+ public void testChapter4Bug2() {
+ Parser parser = new Parser("int a=arg+1; a=a; return a; #showGraph;");
+ StopNode ret = parser.parse();
+ assertEquals("return (arg+1);", ret.print());
+ }
+
+ @Test
+ public void testChapter4Bug3() {
+ try {
+ new Parser("inta=1; return a;").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Undefined name 'inta'",e.getMessage());
+ }
+ }
+
+ @Test
+ public void testChapter4Bug4() {
+ Parser parser = new Parser("return -arg;");
+ StopNode ret = parser.parse();
+ assertEquals("return (-arg);", ret.print());
+ }
+
+ @Test
+ public void testVarDecl() {
+ Parser parser = new Parser("int a=1; return a;");
+ StopNode ret = parser.parse();
+ assertEquals("return 1;", ret.print());
+ }
+
+ @Test
+ public void testVarAdd() {
+ Parser parser = new Parser("int a=1; int b=2; return a+b;");
+ StopNode ret = parser.parse();
+ assertEquals("return 3;", ret.print());
+ }
+
+ @Test
+ public void testVarScope() {
+ Parser parser = new Parser("int a=1; int b=2; int c=0; { int b=3; c=a+b; } return c;");
+ StopNode ret = parser.parse();
+ assertEquals("return 4;", ret.print());
+ }
+
+ @Test
+ public void testVarScopeNoPeephole() {
+ Parser parser = new Parser("int a=1; int b=2; int c=0; { int b=3; c=a+b; #showGraph; } return c; #showGraph;");
+ Node._disablePeephole = true;
+ StopNode ret = parser.parse();
+ Node._disablePeephole = false;
+ assertEquals("return (1+3);", ret.print());
+ }
+
+ @Test
+ public void testVarDist() {
+ Parser parser = new Parser("int x0=1; int y0=2; int x1=3; int y1=4; return (x0-x1)*(x0-x1) + (y0-y1)*(y0-y1); #showGraph;");
+ StopNode ret = parser.parse();
+ assertEquals("return 8;", ret.print());
+ }
+
+ @Test
+ public void testSelfAssign() {
+ try {
+ new Parser("int a=a; return a;").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Undefined name 'a'",e.getMessage());
+ }
+ }
+
+ @Test
+ public void testChapter2ParseGrammar() {
+ Parser parser = new Parser("return 1+2*3+-5;");
+ Node._disablePeephole = true; // disable peephole so we can observe full graph
+ StopNode ret = parser.parse();
+ assertEquals("return (1+((2*3)+(-5)));", ret.print());
+ GraphVisualizer gv = new GraphVisualizer();
+ System.out.println(gv.generateDotOutput(parser));
+ Node._disablePeephole = false;
+ }
+
+ @Test
+ public void testChapter2AddPeephole() {
+ Parser parser = new Parser("return 1+2;");
+ StopNode ret = parser.parse();
+ assertEquals("return 3;", ret.print());
+ }
+
+ @Test
+ public void testChapter2SubPeephole() {
+ Parser parser = new Parser("return 1-2;");
+ StopNode ret = parser.parse();
+ assertEquals("return -1;", ret.print());
+ }
+
+ @Test
+ public void testChapter2MulPeephole() {
+ Parser parser = new Parser("return 2*3;");
+ StopNode ret = parser.parse();
+ assertEquals("return 6;", ret.print());
+ }
+
+ @Test
+ public void testChapter2DivPeephole() {
+ Parser parser = new Parser("return 6/3;");
+ StopNode ret = parser.parse();
+ assertEquals("return 2;", ret.print());
+ }
+
+ @Test
+ public void testChapter2MinusPeephole() {
+ Parser parser = new Parser("return 6/-3;");
+ StopNode ret = parser.parse();
+ assertEquals("return -2;", ret.print());
+ }
+
+ @Test
+ public void testChapter2Example() {
+ Parser parser = new Parser("return 1+2*3+-5;");
+ StopNode ret = parser.parse();
+ assertEquals("return 2;", ret.print());
+ GraphVisualizer gv = new GraphVisualizer();
+ System.out.println(gv.generateDotOutput(parser));
+ }
+
+ @Test
+ public void testSimpleProgram() {
+ Parser parser = new Parser("return 1;");
+ StopNode stop = parser.parse();
+ StartNode start = Parser.START;
+ ReturnNode ret = (ReturnNode)stop.in(0);
+
+ assertTrue(ret.ctrl() instanceof ProjNode);
+ Node expr = ret.expr();
+ if( expr instanceof ConstantNode con ) {
+ assertEquals(start,con.in(0));
+ assertEquals(TypeInteger.constant(1), con._type);
+ } else {
+ fail();
+ }
+ }
+
+ @Test
+ public void testZero() {
+ Parser parser = new Parser("return 0;");
+ parser.parse();
+ StartNode start = Parser.START;
+ for( Node use : start._outputs )
+ if( use instanceof ConstantNode con )
+ assertEquals(TypeInteger.constant(0),con._type);
+ }
+
+ @Test
+ public void testBad1() {
+ try {
+ new Parser("ret").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Syntax error, expected =: ",e.getMessage());
+ }
+ }
+
+ @Test
+ public void testBad2() {
+ try {
+ new Parser("return 0123;").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Syntax error: integer values cannot start with '0'",e.getMessage());
+ }
+ }
+
+ @Test
+ public void testNotBad3() {
+ // this test used to fail in chapter 1
+ assertEquals("return 12;", new Parser("return --12;").parse().print());
+ }
+
+ @Test
+ public void testBad4() {
+ try {
+ new Parser("return 100").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Syntax error, expected ;: ",e.getMessage());
+ }
+ }
+
+ @Test
+ public void testNotBad5() {
+ // this test used to fail in chapter 1
+ assertEquals("return -100;", new Parser("return -100;").parse().print());
+ }
+
+ @Test
+ public void testBad6() {
+ try {
+ new Parser("int a=1; int b=2; int c=0; { int b=3; c=a+b;").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Syntax error, expected }: ",e.getMessage());
+ }
+ }
+
+ @Test
+ public void testBad7() {
+ try {
+ new Parser("return 1;}").parse();
+ fail();
+ } catch( RuntimeException e ) {
+ assertEquals("Syntax error, unexpected }",e.getMessage());
+ }
+ }
+
+}
diff --git a/pom.xml b/pom.xml
index 30022404..4557af32 100644
--- a/pom.xml
+++ b/pom.xml
@@ -25,6 +25,8 @@
<module>chapter04</module>
<module>chapter05</module>
<module>chapter06</module>
+ <module>chapter07</module>
+ <module>chapter08</module>
</modules>
<properties>