[llvm] [DAGCombiner] Require same type of splat & element for build_vector (PR #88284)

[Feng Zou via llvm-commits]

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@@ -23429,17 +23429,21 @@ SDValue DAGCombiner::visitBUILD_VECTOR(SDNode *N) {
   // TODO: Maybe this is useful for non-splat too?
   if (!LegalOperations) {
     if (SDValue Splat = cast<BuildVectorSDNode>(N)->getSplatValue()) {
-      Splat = peekThroughBitcasts(Splat);
-      EVT SrcVT = Splat.getValueType();
-      if (SrcVT.isVector()) {
-        unsigned NumElts = N->getNumOperands() * SrcVT.getVectorNumElements();
-        EVT NewVT = EVT::getVectorVT(*DAG.getContext(),
-                                     SrcVT.getVectorElementType(), NumElts);
-        if (!LegalTypes || TLI.isTypeLegal(NewVT)) {
-          SmallVector<SDValue, 8> Ops(N->getNumOperands(), Splat);
-          SDValue Concat = DAG.getNode(ISD::CONCAT_VECTORS, SDLoc(N),
-                                       NewVT, Ops);
-          return DAG.getBitcast(VT, Concat);
+      // Only change build_vector to a concat_vector if the splat value type is
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fzou1 wrote:

Right. Updated.

https://github.com/llvm/llvm-project/pull/88284