[PATCH] D153859: RegisterCoalescer: Fix verifier error on redef of subregister for live out implicit_defs

[Matt Arsenault via Phabricator via llvm-commits]

arsenm created this revision.
arsenm added reviewers: qcolombet, MatzeB, kparzysz, foad.
Herald added subscribers: StephenFan, kerbowa, tpr, hiraditya, jvesely.
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arsenm requested review of this revision.
Herald added a subscriber: wdng.
Herald added a project: LLVM.

A live out implicit_def wasn't deleted, but the subranges weren't
correctly updated. The main range was correct but the def
corresponding to the initial main range def instruction was missing
from the lanes redefined in another block.

      

The written lanes are not quite the same as the valid lanes in the
case of an implicit_def.

      

Fixes verifier error in blender. There is an additional verifier in
some of the testcase variants where an empty subrange remains.


https://reviews.llvm.org/D153859

Files:
  llvm/lib/CodeGen/RegisterCoalescer.cpp
  llvm/test/CodeGen/AMDGPU/blender-coalescer-verifier-error-empty-subrange.mir
  llvm/test/CodeGen/AMDGPU/blender-no-live-segment-at-def-implicit-def.ll
  llvm/test/CodeGen/AMDGPU/liveout-implicit-def-subreg-redef-blender-verifier-error.mir

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