Correct extractelement constant folding

Summary: Constant folding of extractelement with out-of-bound index produces undef also for indexes bigger than 64bit (instead of crash assert failure as before)

Test Plan: Unit tests included.

Reviewers: majnemer

Reviewed By: majnemer

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D9225

llvm-svn: 235700

1 files changed, 2 insertions, 3 deletions

diff --git a/llvm/lib/IR/ConstantFold.cpp b/llvm/lib/IR/ConstantFold.cpp
index d3caf04..03d7c5e 100644
--- a/llvm/lib/IR/ConstantFold.cpp
+++ b/llvm/lib/IR/ConstantFold.cpp
@@ -789,11 +789,10 @@ Constant *llvm::ConstantFoldExtractElementInstruction(Constant *Val,
     return UndefValue::get(Val->getType()->getVectorElementType());
 
   if (ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx)) {
-    uint64_t Index = CIdx->getZExtValue();
     // ee({w,x,y,z}, wrong_value) -> undef
-    if (Index >= Val->getType()->getVectorNumElements())
+    if (CIdx->uge(Val->getType()->getVectorNumElements()))
       return UndefValue::get(Val->getType()->getVectorElementType());
-    return Val->getAggregateElement(Index);
+    return Val->getAggregateElement(CIdx->getZExtValue());
   }
   return nullptr;
 }