[llvm] 4105305 - [DAG] SimplifyVCastOp - ensure we select the correct value type from an SDValue operand

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2023-04-20T10:38:10+01:00
New Revision: 41053053e37f66fcd4350759b172713c08aa41f0

URL: https://github.com/llvm/llvm-project/commit/41053053e37f66fcd4350759b172713c08aa41f0
DIFF: https://github.com/llvm/llvm-project/commit/41053053e37f66fcd4350759b172713c08aa41f0.diff

LOG: [DAG] SimplifyVCastOp - ensure we select the correct value type from an SDValue operand

As reported on Issue #62234 - we weren't correctly using the SDValue operand to get its value type, resulting in a failure when it came from a SDNode with multiple results

We haven't been able to create a suitable upstream regression test, but its been confirmed by inspection by both myself and @topperc

Fixes #62234

Added: 
    

Modified: 
    llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 4bfb8849f7b47..3828f03bdf630 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -25660,8 +25660,6 @@ SDValue DAGCombiner::SimplifyVCastOp(SDNode *N, const SDLoc &DL) {
   unsigned Opcode = N->getOpcode();
 
   SDValue N0 = N->getOperand(0);
-  EVT SrcVT = N0->getValueType(0);
-  EVT SrcEltVT = SrcVT.getVectorElementType();
   const TargetLowering &TLI = DAG.getTargetLoweringInfo();
 
   // TODO: promote operation might be also good here?
@@ -25672,6 +25670,8 @@ SDValue DAGCombiner::SimplifyVCastOp(SDNode *N, const SDLoc &DL) {
        TLI.isExtractVecEltCheap(VT, Index0)) &&
       TLI.isOperationLegalOrCustom(Opcode, EltVT) &&
       TLI.preferScalarizeSplat(N)) {
+    EVT SrcVT = N0.getValueType();
+    EVT SrcEltVT = SrcVT.getVectorElementType();
     SDValue IndexC = DAG.getVectorIdxConstant(Index0, DL);
     SDValue Elt =
         DAG.getNode(ISD::EXTRACT_VECTOR_ELT, DL, SrcEltVT, Src0, IndexC);