Remove the dependency based IterPeeps and replace it with simple iterative version. Also bug fixes

optvm/src/test/java/com/compilerprogramming/ezlang/interpreter/TestInterpreter.java

@@ -1008,7 +1008,7 @@ func quicksort(arr: [Float], low: Int, high: Int) {
     }
 }
 
-func eq(a: [Int], b: [Int], n: Int)->Int
+func eq(a: [Float], b: [Float], n: Int)->Int
 {
     var result = 1
     var i = 0

seaofnodes/src/main/java/com/compilerprogramming/ezlang/compiler/Compiler.java

@@ -364,9 +364,13 @@ private ReturnNode generateFunctionBody(Symbol.FunctionTypeSymbol functionTypeSy
         // Parse the body
         Node last = compileStatement(funcDecl.block);
 
-        // Last expression is the return
-        if( ctrl()._type== Type.CONTROL )
-            fun.addReturn(ctrl(), _scope.mem().merge(), last);
+        // Add an implicit return only for reachable fall-through. Void functions
+        // use an integer sentinel in the backend signature.
+        if( ctrl()._type== Type.CONTROL ) {
+            EZType.EZTypeFunction functionType = (EZType.EZTypeFunction) functionTypeSymbol.type;
+            Node result = functionType.returnType instanceof EZType.EZTypeVoid ? ZERO : last;
+            fun.addReturn(ctrl(), _scope.mem().merge(), result);
+        }
 
         // Pop off the inProgress node on the multi-exit Region merge
         assert r.inProgress();

seaofnodes/src/main/java/com/compilerprogramming/ezlang/compiler/IterPeeps2.java

@@ -0,0 +1,62 @@
+package com.compilerprogramming.ezlang.compiler;
+
+import com.compilerprogramming.ezlang.compiler.codegen.CodeGen;
+import com.compilerprogramming.ezlang.compiler.node.Node;
+import com.compilerprogramming.ezlang.compiler.node.StopNode;
+
+import java.util.ArrayList;
+import java.util.BitSet;
+import java.util.List;
+import java.util.function.Consumer;
+
+public class IterPeeps2 {
+
+    static void dfs(Node root, Consumer<Node> consumer, BitSet visited) {
+        visited.set(root._nid);
+        /* For each successor node */
+        for (int i = 0; i < root.nOuts(); i++) {
+            Node S = root.out(i);
+            if (S == null)
+                continue;
+            if (!visited.get(S._nid))
+                dfs(S, consumer, visited);
+        }
+        consumer.accept(root);
+    }
+
+    public static List<Node> rpo(Node root) {
+        List<Node> nodes = new ArrayList<>();
+        // note add below prepends
+        dfs(root, (n)->nodes.add(0,n), new BitSet());
+        return nodes;
+    }
+
+    public void iterate(CodeGen code) {
+        final Node startNode = code._start;    // We need the start node to get to the full graph
+        int iter = 1;
+        int count = 0;  // Count of nodes we peepholed
+        for (;;iter++) {
+            List<Node> rpos = rpo(startNode);
+            count += rpos.size();
+            boolean progress = false;
+            for (int i = 0; i < rpos.size(); i++) {
+                Node n = rpos.get(i);
+                if (n.isDead()) continue;
+                Node x = n.peepholeOpt();
+                if (x != null) {
+                    progress = true;
+                    if (x.isDead()) continue;
+                    // peepholeOpt can return brand-new nodes, needing an initial type set
+                    if( x._type==null ) x.setType(x.compute());
+                    if (x != n) n.subsume(x);
+                }
+                if( n.isUnused() && !(n instanceof StopNode) )
+                    n.kill();       // Just plain dead
+            }
+            if (!progress) break;
+        }
+        System.out.println("Completed in " + iter + " iterations; peepholed " + count + " nodes");
+//        if( show )
+//            System.out.println(new GraphVisualizer().generateDotOutput(stopNode,null,null));
+    }
+}

seaofnodes/src/main/java/com/compilerprogramming/ezlang/compiler/codegen/CodeGen.java

@@ -51,7 +51,7 @@ public CodeGen( String src, TypeInteger arg, long workListSeed ) {
         _stop = new StopNode(src);
         _src = src;
         _arg = arg;
-        _iter = new IterPeeps(workListSeed);
+        _iter = new IterPeeps2();
         _main = makeFun(TypeTuple.MAIN, Type.BOTTOM);
         P = new Compiler(this,arg);
     }
@@ -180,7 +180,7 @@ public CodeGen parse() {
 
     // ---------------------------
     // Iterator peepholes.
-    public final IterPeeps _iter;
+    public final IterPeeps2 _iter;
     // Stop tracking deps while assertin
     public boolean _midAssert;
     // Statistics on peepholes
@@ -206,8 +206,6 @@ public CodeGen opto() {
         // loop unroll, peel, RCE, etc
         return this;
     }
-    public <N extends Node> N add( N n ) { return _iter.add(n); }
-    public void addAll( Ary<Node> ary ) { _iter.addAll(ary); }
 
 
     // ---------------------------

seaofnodes/src/main/java/com/compilerprogramming/ezlang/compiler/codegen/GlobalCodeMotion.java

@@ -1,7 +1,7 @@
 package com.compilerprogramming.ezlang.compiler.codegen;
 
 import com.compilerprogramming.ezlang.compiler.util.Ary;
-import com.compilerprogramming.ezlang.compiler.IterPeeps.WorkList;
+import com.compilerprogramming.ezlang.compiler.util.WorkList;
 import com.compilerprogramming.ezlang.compiler.util.Utils;
 import com.compilerprogramming.ezlang.compiler.node.*;
 import com.compilerprogramming.ezlang.compiler.type.*;

seaofnodes/src/main/java/com/compilerprogramming/ezlang/compiler/codegen/RegAlloc.java

@@ -397,7 +397,7 @@ boolean splitByLoop( byte round, LRG lrg ) {
         // If the minLoopDepth is less than the maxLoopDepth: for-all defs and
         // uses, if at minLoopDepth or lower, split after def and before use.
         for( Node n : _ns ) {
-            if( n instanceof SplitNode && min!=max ) continue; // Ignoring splits; since spilling need to split in a deeper loop
+            if( n instanceof SplitNode ) continue; // Ignoring splits; since spilling need to split in a deeper loop
             if( n.isDead() ) continue; // Some Cloneable went dead by other spill changes
             // If this is a 2-address commutable op (e.g. AddX86, MulX86) and the rhs has only a single user,
             // commute the inputs... which chops the LHS live ranges' upper bound to just the RHS.

seaofnodes/src/main/java/com/compilerprogramming/ezlang/compiler/node/CallEndNode.java

@@ -89,11 +89,6 @@ public Node idealize() {
                         fun.setDef(1, Compiler.XCTRL); // No default/unknown StartNode caller
                         fun.setDef(2,call.ctrl());  // Bypass the Call;
                         fun.ret().setDef(3,null);   // Return is folding also
-                        CodeGen.CODE.addAll(fun._outputs);
-                        // Repeat defs 1 layer down, for users of Parm (Phis)
-                        for( Node parm : fun._outputs )
-                            if( parm instanceof ParmNode )
-                                CodeGen.CODE.addAll(parm._outputs);
 
                         // Inlining immediately blows all cache idepth fields past the inline point.
                         // Bump the global version number invalidating them en-masse.

seaofnodes/src/main/java/com/compilerprogramming/ezlang/compiler/node/CallNode.java

@@ -129,7 +129,7 @@ private Node link( FunNode fun ) {
             if( use instanceof ParmNode parm )
                 parm.addDef(parm._idx==0 ? new ConstantNode(cend()._rpc).peephole() : arg(parm._idx));
         // Call end points to function return
-        CodeGen.CODE.add(cend()).addDef(fun.ret());
+        cend().addDef(fun.ret());
         return this;
     }
 

seaofnodes/src/main/java/com/compilerprogramming/ezlang/compiler/node/FunNode.java

@@ -65,7 +65,6 @@ public ParmNode rpc() {
     public void setSig( TypeFunPtr sig ) {
         assert sig.isa(_sig);
         if( _sig != sig ) {
-            CODE.add(this);
             _sig = sig;
         }
     }
@@ -89,8 +88,6 @@ public Node idealize() {
         // Some linked path dies
         Node progress = deadPath();
         if( progress!=null ) {
-            if( nIns()==3 && in(2) instanceof CallNode call )
-                CODE.add(call.cend()); // If Start and one call, check for inline
             return progress;
         }
 
@@ -114,8 +111,6 @@ public Node idealize() {
 
         // If down to a single input, become that input
         if( nIns()==2 && !hasPhi() ) {
-            CODE.add( CODE._stop ); // Stop will remove dead path
-            CODE.add( _ret );       // Return will compute to TOP control
             return in(1); // Collapse if no Phis; 1-input Phis will collapse on their own
         }
 

seaofnodes/src/main/java/com/compilerprogramming/ezlang/compiler/node/IfNode.java

@@ -9,7 +9,6 @@ public class IfNode extends CFGNode implements MultiNode {
 
     public IfNode(Node ctrl, Node pred) {
         super(ctrl, pred);
-        CodeGen.CODE.add(this); // Because idoms are complex, just add it
     }
     public IfNode(IfNode iff) { super(iff); }