[PATCH] D98049: [AMDGPU][GlobalISel] Transform (fsub (fpext (fmul x, y)), z) -> (fma (fpext x), (fpext y), (fneg z))

[Mateja Marjanovic via Phabricator via llvm-commits]

matejam created this revision.
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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 case that has one multiplication, which gets extended, and
from that the third argument is subtracted. This combiner will transform
that into two extends and one negation within the fma/fmad instruction.


https://reviews.llvm.org/D98049

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-ext-mul.ll

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