[PATCH] D96614: [AMDGPU][GlobalISel] Transform (fsub (fmul x, y), z) -> (fma x, y, -z)

[Mateja Marjanovic via Phabricator via llvm-commits]

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Instead of sub and mul instructions, use v_mad, v_mac or v_fma if fma
instructions are faster and are legal for the given architecture.
Combiner for a simple case that has only one subtraction and one
multiplication instruction and transforms them into some of the fma
instructions depending on the architecture.


https://reviews.llvm.org/D96614

Files:
  llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h
  llvm/include/llvm/Target/GlobalISel/Combine.td
  llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
  llvm/test/CodeGen/AMDGPU/GlobalISel/combine-fma-sub-mul.ll

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