Fix a bug where we would corrupt the offset when evaluating

a non-constant GEP.

I don't have any test case that demonstrates this, Nadav (indirectly)
pointed this out in code review. I'm not sure how possible it is to
contrive a test case for the current users of this code that triggers
the bad issue sadly.

llvm-svn: 189188

1 files changed, 3 insertions, 1 deletions

diff --git a/llvm/lib/IR/Value.cpp b/llvm/lib/IR/Value.cpp
index afa9291c9ef..6698f832b25 100644
--- a/llvm/lib/IR/Value.cpp
+++ b/llvm/lib/IR/Value.cpp
@@ -411,8 +411,10 @@ Value *Value::stripAndAccumulateInBoundsConstantOffsets(const DataLayout &DL,
     if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
       if (!GEP->isInBounds())
         return V;
-      if (!GEP->accumulateConstantOffset(DL, Offset))
+      APInt GEPOffset(Offset);
+      if (!GEP->accumulateConstantOffset(DL, GEPOffset))
         return V;
+      Offset = GEPOffset;
       V = GEP->getPointerOperand();
     } else if (Operator::getOpcode(V) == Instruction::BitCast) {
       V = cast<Operator>(V)->getOperand(0);