[PATCH] D132115: [DAGCombiner] Add use check for VSCALE in visitSUB.

[WangLian via Phabricator via llvm-commits]

Jimerlife created this revision.
Jimerlife added reviewers: RKSimon, craig.topper, sdesmalen, david-arm, benshi001.
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If there are multiple uses of VSCALE, then it may be more beneficial to keep origin form.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D132115

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
@@ -3720,7 +3720,7 @@
   }
 
   // canonicalize (sub X, (vscale * C)) to (add X, (vscale * -C))
-  if (N1.getOpcode() == ISD::VSCALE) {
+  if (N1.getOpcode() == ISD::VSCALE && N1.hasOneUse()) {
     const APInt &IntVal = N1.getConstantOperandAPInt(0);
     return DAG.getNode(ISD::ADD, DL, VT, N0, DAG.getVScale(DL, VT, -IntVal));
   }


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