[PATCH] D136442: [GISel] Add (fsub +-0.0, X) -> fneg combine

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added inline comments.


================
Comment at: llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp:5251
+  const auto LHSCst = getFConstantVRegValWithLookThrough(LHS, MRI);
+  return LHSCst && LHSCst->Value.isZero();
+}
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arsenm wrote:
> Doing this for -0 is only valid with nsz: [[ https://alive2.llvm.org/ce/z/SK2Bs9 ]]
I mean +0 


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D136442/new/

https://reviews.llvm.org/D136442