From d8405f46790d85f5d18f8b04dbd4fd8116af08ea Mon Sep 17 00:00:00 2001
From: Cliff Click <cliffc@acm.org>
Date: Sat, 28 Oct 2023 14:23:48 -0700
Subject: Dont make redundant phis

---
 chapter05/src/main/java/com/seaofnodes/simple/node/ScopeNode.java | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

(limited to 'chapter05')

diff --git a/chapter05/src/main/java/com/seaofnodes/simple/node/ScopeNode.java b/chapter05/src/main/java/com/seaofnodes/simple/node/ScopeNode.java
index 60d2bd43..ba4758e4 100644
--- a/chapter05/src/main/java/com/seaofnodes/simple/node/ScopeNode.java
+++ b/chapter05/src/main/java/com/seaofnodes/simple/node/ScopeNode.java
@@ -116,7 +116,8 @@ public class ScopeNode extends Node {
     public RegionNode mergeScopes(ScopeNode that) {
         RegionNode r = (RegionNode)ctrl(new RegionNode(ctrl(), that.ctrl()).peephole());
         for( int i=1; i<nIns(); i++ )
-            set_def(i,new PhiNode(r, in(i), that.in(i)).peephole());
+            if( in(1) != that.in(i) ) // No need for redundant Phis
+                set_def(i,new PhiNode(r, in(i), that.in(i)).peephole());
         that.kill();            // Kill merged scope
         return r;
     }
-- 
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