Sync changes to previous chapters (#57)

Also fix broken links in README

5 files changed, 27 insertions, 29 deletions

diff --git a/chapter07/src/main/java/com/seaofnodes/simple/Parser.java b/chapter07/src/main/java/com/seaofnodes/simple/Parser.java
index 3bc532c2..7cc52e78 100644
--- a/chapter07/src/main/java/com/seaofnodes/simple/Parser.java
+++ b/chapter07/src/main/java/com/seaofnodes/simple/Parser.java
@@ -13,6 +13,7 @@ import java.util.*;
  * 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
@@ -154,24 +155,24 @@ public class Parser {
         // point, and second 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.
+        // associated phis; see {@code inProgress()}.
 
-        ctrl(new LoopNode(ctrl(),null).peephole()); // Note we set back edge to null here
+        ctrl(new LoopNode(ctrl()).peephole()); // Note we set back edge to null here
 
         // At loop head, we clone the current Scope (this includes all
         // names in every nesting level within the Scope).
         // We create phis eagerly for all the names we find, see dup().
 
         // Save the current scope as the loop head
-        ScopeNode head = _xScopes.push(_scope).keep();
+        ScopeNode head = _scope.keep();
         // Clone the head Scope to create a new Scope for the body.
         // Create phis eagerly as part of cloning
-        _scope = _scope.dup(true); // The true argument triggers creating phis
+        _xScopes.push(_scope = _scope.dup(true)); // The true argument triggers creating phis
 
         // Parse predicate
         var pred = require(parseExpression(), ")");
         // IfNode takes current control and predicate
-        IfNode ifNode = (IfNode)new IfNode(ctrl(), pred).<IfNode>keep().peephole();
+        IfNode ifNode = (IfNode)new IfNode(ctrl(), pred).keep().peephole();
         // Setup projection nodes
         Node ifT = new ProjNode(ifNode, 0, "True" ).peephole();
         ifNode.unkeep();
@@ -337,10 +338,10 @@ public class Parser {
         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.LT(lhs, parseComparison()).peephole();
         if (match(">=")) return new BoolNode.LE(parseComparison(), lhs).peephole();
+        if (match(">" )) return new BoolNode.LT(parseComparison(), lhs).peephole();
         return lhs;
     }
 
@@ -437,7 +438,7 @@ public class Parser {
 
     // Require an exact match
     private void require(String syntax) { require(null, syntax); }
-    private Node require(Node n, String syntax) {
+    private <N extends Node> N require(N n, String syntax) {
         if (match(syntax)) return n;
         throw errorSyntax(syntax);
     }
@@ -446,7 +447,7 @@ public class Parser {
         return error("Syntax error, expected " + syntax + ": " + _lexer.getAnyNextToken());
     }
 
-    static RuntimeException error(String errorMessage) {
+    public static RuntimeException error( String errorMessage ) {
         return new RuntimeException(errorMessage);
     }
 
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/node/LoopNode.java b/chapter07/src/main/java/com/seaofnodes/simple/node/LoopNode.java
index eaf19199..aeb8a7f9 100644
--- a/chapter07/src/main/java/com/seaofnodes/simple/node/LoopNode.java
+++ b/chapter07/src/main/java/com/seaofnodes/simple/node/LoopNode.java
@@ -6,7 +6,7 @@ import java.util.BitSet;
 
 public class LoopNode extends RegionNode {
 
-    public LoopNode( Node entry, Node back) { super(null,entry,back); }
+    public LoopNode( Node entry ) { super(null,entry,null); }
 
     Node entry() { return in(1); }
     Node back () { return in(2); }
@@ -15,21 +15,14 @@ public class LoopNode extends RegionNode {
     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; }    
+    @Override Node idom() { return entry(); }    
 }
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/node/Node.java b/chapter07/src/main/java/com/seaofnodes/simple/node/Node.java
index 4cd1b3d2..d9d9366f 100644
--- a/chapter07/src/main/java/com/seaofnodes/simple/node/Node.java
+++ b/chapter07/src/main/java/com/seaofnodes/simple/node/Node.java
@@ -229,11 +229,11 @@ public abstract class Node {
     // 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;
+        return _outputs.isEmpty();
     }
 
     // Shortcut for "popping" n nodes.  A "pop" is basically a
-    // set_def(last,null) followed by lowering the nIns() count.
+    // setDef(last,null) followed by lowering the nIns() count.
     void popN(int n) {
         for( int i=0; i<n; i++ ) {
             Node old_def = _inputs.removeLast();
diff --git a/chapter07/src/main/java/com/seaofnodes/simple/node/RegionNode.java b/chapter07/src/main/java/com/seaofnodes/simple/node/RegionNode.java
index 7113f5c4..00c010b2 100644
--- a/chapter07/src/main/java/com/seaofnodes/simple/node/RegionNode.java
+++ b/chapter07/src/main/java/com/seaofnodes/simple/node/RegionNode.java
@@ -3,11 +3,13 @@ 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); }
 
+    public RegionNode(Node... nodes) { super(nodes); }
+    
     @Override
     public String label() { return "Region"; }
 
@@ -21,6 +23,7 @@ public class RegionNode extends Node {
 
     @Override
     public Type compute() {
+        if( inProgress() ) return Type.CONTROL;
         Type t = Type.XCONTROL;
         for (int i = 1; i < nIns(); i++)
             t = t.meet(in(i)._type);
@@ -29,6 +32,7 @@ public class RegionNode extends Node {
 
     @Override
     public Node idealize() {
+        if( inProgress() ) return null;
         int path = findDeadInput();
         if( path != 0 ) {
             for( Node phi : _outputs )
@@ -76,5 +80,8 @@ public class RegionNode extends Node {
         return (_idom=lhs);
     }
 
-    public boolean inProgress() { return false; }
+    // True if last input is null
+    public final boolean inProgress() {
+        return in(nIns()-1) == 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
index a83ae1a7..80a09ff4 100644
--- a/chapter07/src/main/java/com/seaofnodes/simple/node/ScopeNode.java
+++ b/chapter07/src/main/java/com/seaofnodes/simple/node/ScopeNode.java
@@ -170,12 +170,9 @@ public class ScopeNode extends Node {
         RegionNode r = (RegionNode) ctrl(new RegionNode(null,ctrl(), that.ctrl()).keep());
         String[] ns = reverseNames();
         // 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 phi = new PhiNode(ns[i], r, in(i), that.in(i)).peephole();
-                setDef(i, phi);
-            }
-        }
+        for (int i = 1; i < nIns(); i++)
+            if( in(i) != that.in(i) ) // No need for redundant Phis
+                setDef(i, new PhiNode(ns[i], r, in(i), that.in(i)).peephole());
         that.kill();            // Kill merged scope
         return r.unkeep().peephole();
     }