[PATCH] D110070: [AMDGPU] Prefer v_fmac over v_fma only when no source modifiers are used

[Jay Foad via Phabricator via llvm-commits]

foad created this revision.
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v_fmac with source modifiers forces VOP3 encoding, but it is strictly
better to use the VOP3-only v_fma instead, because $dst and $src2 are
not tied so it gives the register allocator more freedom and avoids a
copy in some cases.

This is the same strategy we already use for v_mad vs v_mac and
v_fma_legacy vs v_fmac_legacy.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D110070

Files:
  llvm/lib/Target/AMDGPU/SIInstructions.td
  llvm/test/CodeGen/AMDGPU/GlobalISel/fdiv.f32.ll
  llvm/test/CodeGen/AMDGPU/GlobalISel/fma.ll
  llvm/test/CodeGen/AMDGPU/GlobalISel/inst-select-fma.s32.mir
  llvm/test/CodeGen/AMDGPU/dagcombine-fma-fmad.ll
  llvm/test/CodeGen/AMDGPU/fdiv.ll
  llvm/test/CodeGen/AMDGPU/fma.f64.ll
  llvm/test/CodeGen/AMDGPU/fmad-formation-fmul-distribute-denormal-mode.ll
  llvm/test/CodeGen/AMDGPU/fmuladd.f16.ll
  llvm/test/CodeGen/AMDGPU/frem.ll
  llvm/test/CodeGen/AMDGPU/mad-mix.ll
  llvm/test/CodeGen/AMDGPU/strict_fma.f16.ll
  llvm/test/CodeGen/AMDGPU/strict_fma.f32.ll
  llvm/test/CodeGen/AMDGPU/udiv.ll

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