[all-commits] [llvm/llvm-project] e39e8c: PeepholeOpt: Do not add subregister indexes to reg...

[Matt Arsenault via All-commits]

  Branch: refs/heads/users/arsenm/peephole-opt-do-not-introduce-subregister-uses-on-reg-sequence
  Home:   https://github.com/llvm/llvm-project
  Commit: e39e8c040c822970462f1f67f9cde09c0379c8c7
      https://github.com/llvm/llvm-project/commit/e39e8c040c822970462f1f67f9cde09c0379c8c7
  Author: Matt Arsenault <Matthew.Arsenault at amd.com>
  Date:   2025-01-24 (Fri, 24 Jan 2025)

  Changed paths:
    M llvm/lib/CodeGen/PeepholeOptimizer.cpp
    M llvm/test/CodeGen/AMDGPU/GlobalISel/sdivrem.ll
    M llvm/test/CodeGen/AMDGPU/amdgpu-codegenprepare-idiv.ll
    M llvm/test/CodeGen/AMDGPU/atomic_optimizations_global_pointer.ll
    M llvm/test/CodeGen/AMDGPU/atomic_optimizations_local_pointer.ll
    M llvm/test/CodeGen/AMDGPU/div-rem-by-constant-64.ll
    M llvm/test/CodeGen/AMDGPU/div_v2i128.ll
    M llvm/test/CodeGen/AMDGPU/fptoi.i128.ll
    M llvm/test/CodeGen/AMDGPU/fptrunc.ll
    M llvm/test/CodeGen/AMDGPU/idot2.ll
    M llvm/test/CodeGen/AMDGPU/idot4u.ll
    M llvm/test/CodeGen/AMDGPU/integer-mad-patterns.ll
    M llvm/test/CodeGen/AMDGPU/llvm.mulo.ll
    M llvm/test/CodeGen/AMDGPU/load-constant-i1.ll
    M llvm/test/CodeGen/AMDGPU/load-constant-i32.ll
    M llvm/test/CodeGen/AMDGPU/load-global-i16.ll
    M llvm/test/CodeGen/AMDGPU/load-global-i32.ll
    M llvm/test/CodeGen/AMDGPU/lower-buffer-fat-pointers-nontemporal-metadata.ll
    M llvm/test/CodeGen/AMDGPU/mad_64_32.ll
    M llvm/test/CodeGen/AMDGPU/move-to-valu-atomicrmw-system.ll
    M llvm/test/CodeGen/AMDGPU/mul.ll
    M llvm/test/CodeGen/AMDGPU/rem_i128.ll
    M llvm/test/CodeGen/AMDGPU/sdiv.ll
    M llvm/test/CodeGen/AMDGPU/spill-scavenge-offset.ll
    M llvm/test/CodeGen/AMDGPU/spill-vgpr.ll
    M llvm/test/CodeGen/AMDGPU/sra.ll
    M llvm/test/CodeGen/AMDGPU/udiv.ll
    M llvm/test/CodeGen/AMDGPU/v_cndmask.ll

  Log Message:
  -----------
  PeepholeOpt: Do not add subregister indexes to reg_sequence operands

Given the rest of the pass just gives up when it needs to compose
subregisters, folding a subregister extract directly into a reg_sequence
is counterproductive. Later fold attempts in the function will give up
on the subregister operand, preventing looking up through the reg_sequence.

It may still be profitable to do these folds if we start handling
the composes. There are some test regressions, but this mostly
looks better.



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