[SelectionDAG] soften assertion when legalizing narrow vector FP ops

The test based on PR42010:
https://bugs.llvm.org/show_bug.cgi?id=42010
...may show an inaccuracy for PPC's target defs, but we should not
be so aggressive with an assert here. There's no telling what out-of-tree
targets look like.

llvm-svn: 361696

1 files changed, 4 insertions, 6 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
index 8570f57616e..379ee00c90f 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
@@ -2743,13 +2743,11 @@ void DAGTypeLegalizer::WidenVectorResult(SDNode *N, unsigned ResNo) {
     // We're going to widen this vector op to a legal type by padding with undef
     // elements. If the wide vector op is eventually going to be expanded to
     // scalar libcalls, then unroll into scalar ops now to avoid unnecessary
-    // libcalls on the undef elements. We are assuming that if the scalar op
-    // requires expanding, then the vector op needs expanding too.
+    // libcalls on the undef elements.
     EVT VT = N->getValueType(0);
-    if (TLI.isOperationExpand(N->getOpcode(), VT.getScalarType())) {
-      EVT WideVecVT = TLI.getTypeToTransformTo(*DAG.getContext(), VT);
-      assert(!TLI.isOperationLegalOrCustom(N->getOpcode(), WideVecVT) &&
-             "Target supports vector op, but scalar requires expansion?");
+    EVT WideVecVT = TLI.getTypeToTransformTo(*DAG.getContext(), VT);
+    if (!TLI.isOperationLegalOrCustom(N->getOpcode(), WideVecVT) &&
+        TLI.isOperationExpand(N->getOpcode(), VT.getScalarType())) {
       Res = DAG.UnrollVectorOp(N, WideVecVT.getVectorNumElements());
       break;
     }