[PATCH] D158882: RegisterCoalescer: Don't delete IMPLICIT_DEF if it's live into the same block

[Matt Arsenault via Phabricator via llvm-commits]

arsenm created this revision.
arsenm added reviewers: qcolombet, MatzeB, kparzysz, uabelho, wmi, foad, tpr, dstuttard, bjope.
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Live out implicit_defs need to be kept, but the check for this only
checked if the block parent was the same. This doesn't work if the
parent blocks are the same but the value is live. Fixes verifier error
"Instruction ending live segment doesn't read the register", which
would appear at the coalesced non-implicit_def def.

      

Fixes #38788


https://reviews.llvm.org/D158882

Files:
  llvm/lib/CodeGen/RegisterCoalescer.cpp
  llvm/test/CodeGen/X86/pr38795-verifier-error-pr38788.ll
  llvm/test/CodeGen/X86/pr38795-verifier-error-pr38788.mir
  llvm/test/CodeGen/X86/pr38795.ll

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