[PATCH] D108086: [DAGCombiner] Stop visitEXTRACT_SUBVECTOR creating illegal BITCASTs post legalisation.

[Paul Walker via Phabricator via llvm-commits]

paulwalker-arm created this revision.
Herald added subscribers: ecnelises, hiraditya.
paulwalker-arm requested review of this revision.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D108086

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


Index: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -20583,8 +20583,12 @@
     //    otherwise => (extract_subvec V1, ExtIdx)
     uint64_t InsIdx = V.getConstantOperandVal(2);
     if (InsIdx * SmallVT.getScalarSizeInBits() ==
-        ExtIdx * NVT.getScalarSizeInBits())
+        ExtIdx * NVT.getScalarSizeInBits()) {
+      if (LegalOperations && !TLI.isOperationLegal(ISD::BITCAST, NVT))
+        return SDValue();
+
       return DAG.getBitcast(NVT, V.getOperand(1));
+    }
     return DAG.getNode(
         ISD::EXTRACT_SUBVECTOR, SDLoc(N), NVT,
         DAG.getBitcast(N->getOperand(0).getValueType(), V.getOperand(0)),


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