commit 5e735294bf5d8df67b8947016c675ca899d4fb79
author Chris Lattner <sabre@nondot.org> Fri Jun 17 01:45:53 2005 +0000
committer Chris Lattner <sabre@nondot.org> Fri Jun 17 01:45:53 2005 +0000
tree ddc2e00ff1150f7379b3d52e8f6e0c59a2396152
parent 29ae6f6ed964d060f22ff7d63a02406240c749fc

Don't crash on:  X = phi (X, X).

This fixes PR584 and Transforms/SimplifyCFG/2005-06-16-PHICrash.ll

llvm-svn: 22232

llvm/lib/Transforms/Utils/SimplifyCFG.cpp

diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index ad78506..6a3b803 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -1461,12 +1461,15 @@
         BasicBlock::iterator AfterPHIIt = BB->begin();
         while (isa<PHINode>(AfterPHIIt)) {
           PHINode *PN = cast<PHINode>(AfterPHIIt++);
-          if (PN->getIncomingValue(0) == PN->getIncomingValue(1))
-            PN->replaceAllUsesWith(PN->getIncomingValue(0));
-          else if (!DominatesMergePoint(PN->getIncomingValue(0), BB,
-                                        &AggressiveInsts) ||
-                   !DominatesMergePoint(PN->getIncomingValue(1), BB,
-                                        &AggressiveInsts)) {
+          if (PN->getIncomingValue(0) == PN->getIncomingValue(1)) {
+            if (PN->getIncomingValue(0) != PN)
+              PN->replaceAllUsesWith(PN->getIncomingValue(0));
+            else
+              PN->replaceAllUsesWith(UndefValue::get(PN->getType()));
+          } else if (!DominatesMergePoint(PN->getIncomingValue(0), BB,
+                                          &AggressiveInsts) ||
+                     !DominatesMergePoint(PN->getIncomingValue(1), BB,
+                                          &AggressiveInsts)) {
             CanPromote = false;
             break;
           }