[all-commits] [llvm/llvm-project] abc27e: [MachineCopyPropagation] Fix debug info referring ...

[Eli Friedman via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: abc27e39ab4d0d17820159329ee3faeaf31261ae
      https://github.com/llvm/llvm-project/commit/abc27e39ab4d0d17820159329ee3faeaf31261ae
  Author: Eli Friedman <efriedma at qti.qualcomm.com>
  Date:   2026-07-08 (Wed, 08 Jul 2026)

  Changed paths:
    M llvm/include/llvm/CodeGen/MachineRegisterInfo.h
    M llvm/lib/CodeGen/MachineRegisterInfo.cpp
    A llvm/test/DebugInfo/AArch64/machine-cp-updates-dbg-reg-subreg.mir

  Log Message:
  -----------
  [MachineCopyPropagation] Fix debug info referring to subregisters. (#207861)

When copy propagation removes a copy, it fixes debug info that refers to
the old register to instead refer to the new register. This logic didn't
really deal with subregisters; it took any DBG_VALUE that pointed to a
subregister of the old register, and replaced it with the full new
register.

This patch adds logic for subregisters: if a DBG_VALUE refers to a
subregister of the source register, find the corresponding subregister
of the destination register.

Fixes #207682



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