[PATCH] D106023: [AMDGPU] Mark relevant rematerializable VOP2 instructions

Thu Jul 15 15:23:17 PDT 2021

arsenm added inline comments.

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Comment at: llvm/lib/Target/AMDGPU/VOP2Instructions.td:765
+let SubtargetPredicate = HasFmaakFmamkF32Insts, isReMaterializable = 1 in {
 def V_FMAMK_F32 : VOP2_Pseudo<"v_fmamk_f32", VOP_MADMK_F32, [], "">;

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rampitec wrote:
> arsenm wrote:
> > This and the other fma flavors preserve the high bits on gfx9
> This is f32, both f16 fma shall also zero hi bits because these are VOP2 only.
I wrote inline asm tests a few weeks ago for all of these. The gfx9 manual says it didn't change the existing instruction behavior, but I think this was wrong. mad/mac/fma all seem to preserve (see  GCNSubtarget::zeroesHigh16BitsOfDest)

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  https://reviews.llvm.org/D106023/new/

https://reviews.llvm.org/D106023