[PATCH] D88217: [GVN] Make propagateEquality look into the operand of freeze

Sat Sep 26 05:21:15 PDT 2020

aqjune added inline comments.

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Comment at: llvm/lib/Transforms/Scalar/GVN.cpp:2000
       if (LVN < RVN) {
         std::swap(LHS, RHS);
         LVN = RVN;
----------------
nikic wrote:
> Won't something fishy happen here if LHS and RHS are swapped, but LHSFr still refers to the old LHS?
Yes, it might have caused a problem; LHSFr should have been updated.
But, allowing this transformation when LHS and RHS were both freeze seemed problematic as well - its benefit wasn't clear. So I fixed this patch to simply be disabled in that case.
Added a few negative tests for such case.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D88217/new/

https://reviews.llvm.org/D88217