[PATCH] D117032: GlobalIsel: Fix fma combine when one of the uses comes from unmerge

[Petar Avramovic via Phabricator via llvm-commits]

Petar.Avramovic created this revision.
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Fma combine assumes that MRI.getVRegDef(Reg)->getOperand(0).getReg() = Reg
which is not true when Reg is defined by instruction with multiple defs
e.g. G_UNMERGE_VALUES.
Fix is to keep register and the instruction that defines register in
DefinitionAndSourceRegister and use when needed.


https://reviews.llvm.org/D117032

Files:
  llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
  llvm/test/CodeGen/AMDGPU/GlobalISel/combine-fma-add-mul-post-legalize.mir
  llvm/test/CodeGen/AMDGPU/GlobalISel/combine-fma-add-mul.ll

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