[PATCH] D108725: [AArch64][GlobalISel] Implement custom legalization for s32/s64 G_FCOPYSIGN

[Jessica Paquette via Phabricator via llvm-commits]

paquette created this revision.
paquette added reviewers: aemerson, jroelofs.
Herald added subscribers: hiraditya, kristof.beyls, rovka.
paquette requested review of this revision.
Herald added a project: LLVM.

This is intended to be equivalent to the s32 + s64 cases in `AArch64TargetLowering::LowerFCOPYSIGN`.

Widen everything and then use G_BIT + a mask to handle the actual copysign operation. Then, narrow back down to s32/s64.

I wasn't sure about what the best/most canonical INSERT_SUBREG-selectable pattern is. I chose G_INSERT_VECTOR_ELT + an undef vector because it produces reasonably okay codegen. (It doesn't produce INSERT_SUBREG right now though.) If there's a better way to do this then I'm happy to change it.

We also have a couple codegen deficiencies with how we emit vector constants right now. (We need a GISel equivalent to the `tryAdvSIMDModImm64` stuff)


https://reviews.llvm.org/D108725

Files:
  llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
  llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.h
  llvm/test/CodeGen/AArch64/GlobalISel/legalize-fcopysign.mir
  llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir

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