Removing a phi-of-guard, remove nested guards

2 files changed, 9 insertions, 3 deletions

diff --git a/chapter25/src/main/java/com/seaofnodes/simple/node/PhiNode.java b/chapter25/src/main/java/com/seaofnodes/simple/node/PhiNode.java
index 2b6d2666..17868faf 100644
--- a/chapter25/src/main/java/com/seaofnodes/simple/node/PhiNode.java
+++ b/chapter25/src/main/java/com/seaofnodes/simple/node/PhiNode.java
@@ -125,13 +125,19 @@ public class PhiNode extends Node {
 
         // If merging Phi(ZERO, guardNZ(N)) - we are losing the cast JOIN effects, so just remove.
         if( nIns()==3 ) {
-            if( in(1) instanceof GuardNode cast && cast._nonZero && in(2)._type.makeZero()==in(2)._type && cast.in(1)!=this )  return cast.in(1);
-            if( in(2) instanceof GuardNode cast && cast._nonZero && in(1)._type.makeZero()==in(1)._type && cast.in(1)!=this )  return cast.in(1);
+            if( in(1) instanceof GuardNode cast && cast._nonZero && in(2)._type.makeZero()==in(2)._type && cast.in(1)!=this )  return unguard(cast.in(1));
+            if( in(2) instanceof GuardNode cast && cast._nonZero && in(1)._type.makeZero()==in(1)._type && cast.in(1)!=this )  return unguard(cast.in(1));
         }
 
         return null;
     }
 
+    private static Node unguard(Node n) {
+        while( n instanceof GuardNode guard )
+            n = guard.in(1);
+        return n;
+    }
+
     // Same op on all Phi paths; all ops have only the Phi as a use.
     // None have a control input.
     private boolean same_op() {
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Eval2.java b/chapter25/src/test/java/com/seaofnodes/simple/Eval2.java
index f8d8fe18..715c499e 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Eval2.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Eval2.java
@@ -283,7 +283,7 @@ public abstract class Eval2 {
         case GuardNode   guard -> val(guard.in(1));
         case ConstantNode con  -> con(con._con);
         case DivNode      div  -> div.mode()==1
-            ? (Object)(x(div.in(1)) /  x(div.in(2)))
+            ? (Object)(x(div.in(2))==0 ? 0L : x(div.in(1)) / x(div.in(2)))
             : (Object)((d(div.in(2))==0 ? 0D : d(div.in(1))) / d(div.in(2)));
         case EscapeNode   esc  -> esc(esc);
         case FunPtrNode   fptr -> con(fptr._con);