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

[WangLian via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rGfc2b4dfef2f1: [DAGCombiner] Add use check for VSCALE in visitSUB. (authored by Jimerlife).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D132115/new/

https://reviews.llvm.org/D132115

Files:
  llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  llvm/test/CodeGen/AArch64/sve-vscale-combine.ll


Index: llvm/test/CodeGen/AArch64/sve-vscale-combine.ll
===================================================================
--- llvm/test/CodeGen/AArch64/sve-vscale-combine.ll
+++ llvm/test/CodeGen/AArch64/sve-vscale-combine.ll
@@ -76,10 +76,8 @@
 define i64 @multiple_uses_sub_vscale_i64(i64 %x, i64 %y) nounwind {
 ; CHECK-LABEL: multiple_uses_sub_vscale_i64:
 ; CHECK-NEXT:  rdvl	x8, #1
-; CHECK-NEXT:  rdvl	x9, #-1
 ; CHECK-NEXT:  lsr	x8, x8, #4
-; CHECK-NEXT:  asr	x9, x9, #4
-; CHECK-NEXT:  add	x9, x0, x9
+; CHECK-NEXT:  sub	x9, x0, x8
 ; CHECK-NEXT:  add	x8, x1, x8
 ; CHECK-NEXT:  mul	x0, x9, x8
 ; CHECK-NEXT:  ret
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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