[DAGCombiner] make sure we have a whole-number extract before trying to narrow a vector op (PR39511)

The test causes a crash because we were trying to extract v4f32 to v3f32, and the
narrowing factor was then 4/3 = 1 producing a bogus narrow type.

This should fix:
https://bugs.llvm.org/show_bug.cgi?id=39511

llvm-svn: 345842

1 files changed, 5 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index e6ea4898717..d0c898f2e97 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -16708,10 +16708,14 @@ static SDValue narrowExtractedVectorBinOp(SDNode *Extract, SelectionDAG &DAG) {
   assert(ExtractIndex % NumElems == 0 &&
          "Extract index is not a multiple of the vector length.");
   EVT SrcVT = Extract->getOperand(0).getValueType();
+
+  // Bail out if this is not a proper multiple width extraction.
   unsigned NumSrcElems = SrcVT.getVectorNumElements();
-  unsigned NarrowingRatio = NumSrcElems / NumElems;
+  if (NumSrcElems % NumElems != 0)
+    return SDValue();
 
   // Bail out if the target does not support a narrower version of the binop.
+  unsigned NarrowingRatio = NumSrcElems / NumElems;
   unsigned BOpcode = BinOp.getOpcode();
   unsigned WideNumElts = WideBVT.getVectorNumElements();
   EVT NarrowBVT = EVT::getVectorVT(*DAG.getContext(), WideBVT.getScalarType(),