fold gep undef, ... -> undef
This comes up many times in perlbmk and probably others.
llvm-svn: 17100
diff --git a/llvm/lib/VMCore/ConstantFolding.cpp b/llvm/lib/VMCore/ConstantFolding.cpp
index b56366e..d224afe 100644
--- a/llvm/lib/VMCore/ConstantFolding.cpp
+++ b/llvm/lib/VMCore/ConstantFolding.cpp
@@ -1011,8 +1011,15 @@
if (IdxList.size() == 0 ||
(IdxList.size() == 1 && cast<Constant>(IdxList[0])->isNullValue()))
return const_cast<Constant*>(C);
- Constant *Idx0 = cast<Constant>(IdxList[0]);
+ if (isa<UndefValue>(C)) {
+ const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), IdxList,
+ true);
+ assert(Ty != 0 && "Invalid indices for GEP!");
+ return UndefValue::get(PointerType::get(Ty));
+ }
+
+ Constant *Idx0 = cast<Constant>(IdxList[0]);
if (C->isNullValue()) {
bool isNull = true;
for (unsigned i = 0, e = IdxList.size(); i != e; ++i)