From 8ef3ad049d5a38af2ba03504e264d0aa650abe01 Mon Sep 17 00:00:00 2001
From: Andrew Trick <atrick@apple.com>
Date: Wed, 1 Jun 2011 19:14:56 +0000
Subject: [PATCH] SCEV: missing null check fix for r132360, dragonegg crash.

llvm-svn: 132416
---
 llvm/lib/Analysis/ScalarEvolution.cpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index ef390c5a3ee9..025718e09feb 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -1081,9 +1081,8 @@ static const SCEV *getPreStartForSignExtend(const SCEVAddRecExpr *AR,
   const SCEVAddRecExpr *PreAR = dyn_cast<SCEVAddRecExpr>(
     SE->getAddRecExpr(PreStart, Step, L, SCEV::FlagAnyWrap));
 
-  if (PreAR && PreAR->getNoWrapFlags(SCEV::FlagNSW)) {
+  if (PreAR && PreAR->getNoWrapFlags(SCEV::FlagNSW))
     return PreStart;
-  }
 
   // 2. Direct overflow check on the step operation's expression.
   unsigned BitWidth = SE->getTypeSizeInBits(AR->getType());
@@ -1104,7 +1103,8 @@ static const SCEV *getPreStartForSignExtend(const SCEVAddRecExpr *AR,
   ICmpInst::Predicate Pred;
   const SCEV *OverflowLimit = getOverflowLimitForStep(Step, &Pred, SE);
 
-  if (SE->isLoopEntryGuardedByCond(L, Pred, PreStart, OverflowLimit)) {
+  if (OverflowLimit &&
+      SE->isLoopEntryGuardedByCond(L, Pred, PreStart, OverflowLimit)) {
     return PreStart;
   }
   return 0;