[llvm-branch-commits] [llvm] [AMDGPU][GlobalISel] Add COPY_SCC_VCC combine for VCC-SGPR-VGPR pattern (PR #179352)

[Petar Avramovic via llvm-branch-commits]

https://github.com/petar-avramovic commented:

RegbankLegalize was meant to clean up just simplest cases of vgpr->sgpr->back-to-vgpr, but ended up with having quite a few combines.

However think this one is way to complex for RegbankLegalize.
Could do:
  %vcc_orig:vcc(s1) = ...
  %sgpr:sgpr(s32) = G_AMDGPU_COPY_SCC_VCC %vcc_orig
  %vcc(s1) = G_AMDGPU_COPY_VCC_SCC %sgpr
  ->
  %vcc = COPY %vcc_orig
if it appears somewhere

https://github.com/llvm/llvm-project/pull/179352