Fix ConstantFoldShuffleVectorInstruction to properly handle the case

when the result type has a different # elements than the input vectors.

llvm-svn: 149221

1 files changed, 5 insertions, 3 deletions

diff --git a/llvm/lib/VMCore/ConstantFold.cpp b/llvm/lib/VMCore/ConstantFold.cpp
index 36bd4aba4b1..f73e7a76d1a 100644
--- a/llvm/lib/VMCore/ConstantFold.cpp
+++ b/llvm/lib/VMCore/ConstantFold.cpp
@@ -794,15 +794,17 @@ Constant *llvm::ConstantFoldInsertElementInstruction(Constant *Val,
 Constant *llvm::ConstantFoldShuffleVectorInstruction(Constant *V1,
                                                      Constant *V2,
                                                      Constant *Mask) {
+  unsigned MaskNumElts = Mask->getType()->getVectorNumElements();
+  Type *EltTy = V1->getType()->getVectorElementType();
+
   // Undefined shuffle mask -> undefined value.
-  if (isa<UndefValue>(Mask)) return UndefValue::get(V1->getType());
+  if (isa<UndefValue>(Mask))
+    return UndefValue::get(VectorType::get(EltTy, MaskNumElts));
 
   // Don't break the bitcode reader hack.
   if (isa<ConstantExpr>(Mask)) return 0;
   
-  unsigned MaskNumElts = Mask->getType()->getVectorNumElements();
   unsigned SrcNumElts = V1->getType()->getVectorNumElements();
-  Type *EltTy = V1->getType()->getVectorElementType();
 
   // Loop over the shuffle mask, evaluating each element.
   SmallVector<Constant*, 32> Result;