[LoopUnroll] Use undef for phis with no value live

We would create a phi node with a zero initialized operand instead of
undef in the case where no value was originally available.  This was
problematic for x86_mmx which has no null value.

llvm-svn: 241143

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp b/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp
index 919b45d3c7b..add5432aa27 100644
--- a/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp
@@ -86,7 +86,7 @@ static void ConnectProlog(Loop *L, Value *BECount, unsigned Count,
       if (L->contains(PN)) {
         NewPN->addIncoming(PN->getIncomingValueForBlock(NewPH), OrigPH);
       } else {
-        NewPN->addIncoming(Constant::getNullValue(PN->getType()), OrigPH);
+        NewPN->addIncoming(UndefValue::get(PN->getType()), OrigPH);
       }
 
       Value *V = PN->getIncomingValueForBlock(Latch);