[PATCH] D107442: [AMDGPU] Improve regbankselect for 64-bit VGPR ctlz/cttz_zero_undef

[Jay Foad via Phabricator via llvm-commits]

foad created this revision.
foad added reviewers: arsenm, hliao, Petar.Avramovic.
Herald added subscribers: kerbowa, hiraditya, t-tye, tpr, dstuttard, yaxunl, nhaehnle, jvesely, kzhuravl.
foad requested review of this revision.
Herald added subscribers: llvm-commits, wdng.
Herald added a project: LLVM.

We can improve on the generic splitting by using ffbh/ffbl, which have a
defined result when the input is zero.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D107442

Files:
  llvm/lib/Target/AMDGPU/AMDGPURegisterBankInfo.cpp
  llvm/test/CodeGen/AMDGPU/GlobalISel/cvt_f32_ubyte.ll
  llvm/test/CodeGen/AMDGPU/GlobalISel/regbankselect-ctlz-zero-undef.mir
  llvm/test/CodeGen/AMDGPU/GlobalISel/regbankselect-cttz-zero-undef.mir

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