[PATCH] D78908: [RISCV] Add patterns for checking isnan

[Sam Elliott via Phabricator via llvm-commits]

lenary created this revision.
lenary added a reviewer: luismarques.
Herald added subscribers: llvm-commits, evandro, apazos, sameer.abuasal, pzheng, s.egerton, Jim, benna, psnobl, jocewei, PkmX, rkruppe, the_o, brucehoult, MartinMosbeck, rogfer01, edward-jones, zzheng, MaskRay, jrtc27, shiva0217, kito-cheng, niosHD, sabuasal, simoncook, johnrusso, rbar, asb, hiraditya.
Herald added a project: LLVM.
lenary added a parent revision: D78907: [RISCV] Add tests for checking isnan patterns.

This patch addresses some weird assembly sequences we were seeing during
comparing floats. In particular, comparing a float to itself tells you whether
it is NaN or not, which we were doing correctly, but with an extra unneeded
`and` instruction.

This patch specialises the existing patterns to remove the `and` instruction
when both their operands are the same.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D78908

Files:
  llvm/lib/Target/RISCV/RISCVInstrInfoD.td
  llvm/lib/Target/RISCV/RISCVInstrInfoF.td
  llvm/test/CodeGen/RISCV/double-isnan.ll
  llvm/test/CodeGen/RISCV/float-isnan.ll

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