Allow pre-inc/dec on variables

3 files changed, 33 insertions, 16 deletions

diff --git a/chapter17/src/main/java/com/seaofnodes/simple/IterPeeps.java b/chapter17/src/main/java/com/seaofnodes/simple/IterPeeps.java
index 81b89513..36f053f9 100644
--- a/chapter17/src/main/java/com/seaofnodes/simple/IterPeeps.java
+++ b/chapter17/src/main/java/com/seaofnodes/simple/IterPeeps.java
@@ -1,25 +1,24 @@
 package com.seaofnodes.simple;
 
 import com.seaofnodes.simple.node.*;
-import com.seaofnodes.simple.type.Type;
 
-import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.BitSet;
 import java.util.Random;
 
 /**
- * The IterOptim runs after parsing. It iterates the peepholes to a fixed point
+ * The IterPeeps runs after parsing. It iterates the peepholes to a fixed point
  * so that no more peepholes apply.  This should be linear because peepholes rarely
  * (never?)  increase code size.  The graph should monotonically reduce in some
  * dimension, which is usually size.  It might also reduce in e.g. number of
  * MulNodes or Load/Store nodes, swapping out more "expensive" Nodes for cheaper
  * ones.
- *
+ * <br>
  * The theoretical overall worklist is mindless just grabbing the next thing and
- * doing it.  If the graph changes, put the neighbors on the worklist.  Lather,
- * Rinse, Repeat until the worklist runs dry.
- *
+ * doing it.  If the graph changes, put the neighbors on the worklist.
+ * <br>
+ * Lather, Rinse, Repeat until the worklist runs dry.
+ * <p>
  * The main issues we have to deal with:
  *
  * <ul>
@@ -29,7 +28,7 @@ import java.util.Random;
  *   is stable and correct between peepholes.  In our case `Node.subsume` does
  *   most of the munging, building on our prior stable Node utilities.</li>
  *
- * <li>Changing a Node also changes the graph "neighborhood".  The neigbors need to
+ * <li>Changing a Node also changes the graph "neighborhood".  The neighbors need to
  *   be checked to see if THEY can also peephole, and so on.  After any peephole
  *   or graph update we put a Nodes uses and defs on the worklist.</li>
  *
@@ -39,7 +38,7 @@ import java.util.Random;
  *   check is linear at each peephole step... so quadratic overall.  Its a useful
  *   assert, but one we can disable once the overall algorithm is stable - and
  *   then turn it back on again when some new set of peepholes is misbehaving.
- *   The code for this is turned on in `IterOptim.iterate` as `assert
+ *   The code for this is turned on in `IterPeeps.iterate` as `assert
  *   progressOnList(stop);`</li>
  * </ul>
  */
@@ -115,7 +114,7 @@ public abstract class IterPeeps {
         int old_cnt = Node.ITER_CNT, old_nop = Node.ITER_NOP_CNT;
         Node changed = stop.walk( n -> {
                 Node m = n;
-                if( n.compute().isa(n._type) ) { // Types must be forwards, even if on worklist
+                if( n.compute().isa(n._type) && (!n.iskeep() || n._nid<=5) ) { // Types must be forwards, even if on worklist
                     if( WORK.on(n) ) return null;
                     m = n.peepholeOpt();
                     if( m==null ) return null;
diff --git a/chapter17/src/main/java/com/seaofnodes/simple/Parser.java b/chapter17/src/main/java/com/seaofnodes/simple/Parser.java
index a4f7462e..e2f8ad32 100644
--- a/chapter17/src/main/java/com/seaofnodes/simple/Parser.java
+++ b/chapter17/src/main/java/com/seaofnodes/simple/Parser.java
@@ -476,7 +476,7 @@ public class Parser {
         _xScopes.pop();       // Discard pushed from graph display
 
         RegionNode r = ctrl(tScope.mergeScopes(fScope));
-        Node ret = stmt ? r : peep(new PhiNode("",lhs._type.meet(rhs._type),r,lhs,rhs));
+        Node ret = stmt ? r : peep(new PhiNode("",lhs._type.meet(rhs._type),r,lhs.unkeep(),rhs));
         r.peephole();
         return ret;
     }
@@ -838,11 +838,29 @@ public class Parser {
      * Parse a unary minus expression.
      *
      * <pre>
-     *     unaryExpr : ('-') | '!') unaryExpr | postfixExpr | primaryExpr
+     *     unaryExpr : ('-') unaryExpr | '!') unaryExpr | postfixExpr | primaryExpr | '--' Id | '++' Id
      * </pre>
      * @return a unary expression {@link Node}, never {@code null}
      */
     private Node parseUnary() {
+        // Pre-dec/pre-inc
+        int old = pos();
+        if( match("--") || match("++") ) {
+            int delta = _lexer.peek(-1)=='+' ? 1 : -1; // Pre vs post
+            String name = _lexer.matchId();
+            if( name!=null ) {
+                ScopeMinNode.Var n = _scope.lookup(name);
+                if( n != null ) {
+                    if( n._final )
+                        throw error("Cannot reassign final '"+n._name+"'");
+                    Node expr = peep(new AddNode(_scope.in(n),con(delta)));
+                    _scope.update(n,expr);
+                    return expr;
+                }
+            }
+            // Reset, try again
+            pos(old);
+        }
         if (match("-")) return peep(new MinusNode(parseUnary()).widen());
         if (match("!")) return peep(new   NotNode(parseUnary()));
         return parsePostfix(parsePrimary());
@@ -892,7 +910,7 @@ public class Parser {
         if( t==null ) throw error("Expected a type");
         // Parse ary[ length_expr ]
         if( match("[") ) {
-            Node len = parseExpression().keep();
+            Node len = parseExpression();
             if( !(len._type instanceof TypeInteger) )
                 throw error("Cannot allocate an array with length "+len._type);
             require("]");
@@ -964,8 +982,8 @@ public class Parser {
     private Node newArray(TypeStruct ary, Node len) {
         int base = ary.aryBase ();
         int scale= ary.aryScale();
-        Node size = peep(new AddNode(con(base),peep(new ShlNode(len,con(scale)))));
-        ALTMP.clear();  ALTMP.add(len); ALTMP.add(con(ary._fields[1]._type.makeInit()));
+        Node size = peep(new AddNode(con(base),peep(new ShlNode(len.keep(),con(scale)))));
+        ALTMP.clear();  ALTMP.add(len.unkeep()); ALTMP.add(con(ary._fields[1]._type.makeInit()));
         return newStruct(ary,size,0,ALTMP);
     }
 
diff --git a/chapter17/src/main/java/com/seaofnodes/simple/node/PhiNode.java b/chapter17/src/main/java/com/seaofnodes/simple/node/PhiNode.java
index f0140ce6..58ce6b47 100644
--- a/chapter17/src/main/java/com/seaofnodes/simple/node/PhiNode.java
+++ b/chapter17/src/main/java/com/seaofnodes/simple/node/PhiNode.java
@@ -101,7 +101,7 @@ public class PhiNode extends Node {
             if( in(2)._type == in(2)._type.makeInit() ) nullx = 2;
             if( nullx != -1 ) {
                 Node val = in(3-nullx);
-                if( r.idom(this) instanceof IfNode iff && iff.pred().addDep(this)==val ) {
+                if( r.idom(this).addDep(this) instanceof IfNode iff && iff.pred().addDep(this)==val ) {
                     // Must walk the idom on the null side to make sure we hit False.
                     CFGNode idom = (CFGNode)r.in(nullx);
                     while( idom.nIns() > 0 && idom.in(0) != iff ) idom = idom.idom();