From 772de516b6851e679d3da9e5171712b9c3122019 Mon Sep 17 00:00:00 2001
From: Evan Cheng <evan.cheng@apple.com>
Date: Wed, 12 Dec 2007 00:51:06 +0000
Subject: [PATCH] Bug fix. Only safe to perform extension uses optimization if
 the source of extension is also defined in the same BB as the extension.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@44896 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/CodeGenPrepare.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lib/Transforms/Scalar/CodeGenPrepare.cpp b/lib/Transforms/Scalar/CodeGenPrepare.cpp
index 594c017ba8a..37a645f3ce8 100644
--- a/lib/Transforms/Scalar/CodeGenPrepare.cpp
+++ b/lib/Transforms/Scalar/CodeGenPrepare.cpp
@@ -929,6 +929,11 @@ bool CodeGenPrepare::OptimizeExtUses(Instruction *I) {
   if (Src->hasOneUse())
     return false;
 
+  // Only safe to perform the optimization if the source is also defined in
+  // this block. 
+  if (DefBB != cast<Instruction>(Src)->getParent())
+    return false;
+
   bool DefIsLiveOut = false;
   for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); 
        UI != E; ++UI) {