[all-commits] [llvm/llvm-project] 8c0483: RegisterCoalescer: Fix assert on remat to copy-to-...

[Matt Arsenault via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 8c0483bba2d25ae7e4b6cac150dba9447dfed59c
      https://github.com/llvm/llvm-project/commit/8c0483bba2d25ae7e4b6cac150dba9447dfed59c
  Author: Matt Arsenault <Matthew.Arsenault at amd.com>
  Date:   2025-01-07 (Tue, 07 Jan 2025)

  Changed paths:
    M llvm/lib/CodeGen/RegisterCoalescer.cpp
    A llvm/test/CodeGen/AMDGPU/remat-physreg-copy-subreg-extract-already-live-at-def-issue120970.mir

  Log Message:
  -----------
  RegisterCoalescer: Fix assert on remat to copy-to-physreg with subregs (#121734)

Do not try to rematerialize a super-register def used by a subregister
extract copy into a copy to a physical register if the other pieces of
the
full physreg are live at the rematerialization point. It would insert
the
super-register def at the rematerialization point, and assert since the
other half of the register was already live.

This is analagous to the undef subregister def handling above,
which handled the virtual register case.

Fixes #120970



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