[PATCH] D54615: RegisterCoalescer: Defer clearing implicit_def lanes

[Matt Arsenault via Phabricator via llvm-commits]

arsenm created this revision.
arsenm added reviewers: MatzeB, kparzysz, qcolombet.
Herald added subscribers: tpr, nhaehnle, wdng, jvesely.

We can't go back and recover the lanes if it turns
out the implicit_def really can't be erased.

      

Assume all lanes are valid if an unresolved conflict
is encountered. There aren't any tests where this
seems to matter either way, but this seems like a
safer option.

Fixes bug 39602


https://reviews.llvm.org/D54615

Files:
  lib/CodeGen/RegisterCoalescer.cpp
  test/CodeGen/AMDGPU/regcoalesce-keep-valid-lanes-implicit-def-bug39602.mir

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