[PATCH] D71209: InstCombine: Don't rewrite phi-of-bitcast when the phi has other users

[Connor Abbott via Phabricator via llvm-commits]

cwabbott created this revision.
cwabbott added a reviewer: Carrot.
Herald added subscribers: llvm-commits, hiraditya, tpr.
Herald added a project: LLVM.
spatel added reviewers: nikic, lebedev.ri, spatel.
spatel added a comment.

I'm not sure if these patches conflict, but D71164 <https://reviews.llvm.org/D71164> is also trying to fix a bug in this code.


Judging by the existing comments, this was the intention, but the
transform never actually checked if the existing phi's would be removed.
See https://bugs.llvm.org/show_bug.cgi?id=44242 for an example where
this causes much worse code generation on AMDGPU.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D71209

Files:
  llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
  llvm/test/Transforms/InstCombine/pr44242.ll

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