commit 0289929c6212229980c9057853860ccfd3f81678
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 1449dba3d3a97a380575317087a5e5805796455b
parent bff44407e8f371298df3d31dd076a231039a7912

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

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


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22232 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Utils/SimplifyCFG.cpp

diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index ad78506..6a3b803 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/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;
           }