[ConstantFold] Get the correct vector type when folding a getelementptr.

Differential Revision:  https://reviews.llvm.org/D26014

llvm-svn: 285371

2 files changed, 17 insertions, 6 deletions

diff --git a/llvm/lib/IR/ConstantFold.cpp b/llvm/lib/IR/ConstantFold.cpp
index 7bbe9b74cdc..5bfcc274ae9 100644
--- a/llvm/lib/IR/ConstantFold.cpp
+++ b/llvm/lib/IR/ConstantFold.cpp
@@ -2056,12 +2056,8 @@ static Constant *ConstantFoldGetElementPtrImpl(Type *PointeeTy, Constant *C,
     return C;
 
   if (isa<UndefValue>(C)) {
-    PointerType *PtrTy = cast<PointerType>(C->getType()->getScalarType());
-    Type *Ty = GetElementPtrInst::getIndexedType(PointeeTy, Idxs);
-    assert(Ty && "Invalid indices for GEP!");
-    Type *GEPTy = PointerType::get(Ty, PtrTy->getAddressSpace());
-    if (VectorType *VT = dyn_cast<VectorType>(C->getType()))
-      GEPTy = VectorType::get(GEPTy, VT->getNumElements());
+    Type *GEPTy = GetElementPtrInst::getGEPReturnType(C,
+        makeArrayRef((Value * const *)Idxs.data(), Idxs.size()));
     return UndefValue::get(GEPTy);
   }
 
diff --git a/llvm/test/Transforms/InstCombine/gep-vector.ll b/llvm/test/Transforms/InstCombine/gep-vector.ll
new file mode 100644
index 00000000000..ce021bf207f
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/gep-vector.ll
@@ -0,0 +1,15 @@
+; RUN: opt -instcombine %s -S | FileCheck %s
+
+; CHECK-LABEL: patatino
+; CHECK-NEXT: ret <8 x i64*> undef
+define <8 x i64*> @patatino() {
+  %el = getelementptr i64, <8 x i64*> undef, <8 x i64> undef
+  ret <8 x i64*> %el
+}
+
+; CHECK-LABEL: patatino2
+; CHECK-NEXT: ret <8 x i64*> undef
+define <8 x i64*> @patatino2() {
+  %el = getelementptr inbounds i64, i64* undef, <8 x i64> undef
+  ret <8 x i64*> %el
+}