[PATCH] D101282: [SPE] Support constrained float operations on SPE

[Qiu Chaofan via Phabricator via llvm-commits]

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This patch enables support on SPE for constrained fadd/fsub/fmul/fdiv/fma and compare operations. The motivation is https://bugs.llvm.org/show_bug.cgi?id=50070.

One thing I'm not pretty sure is the `fcmp` versus `fcmps`. On description of SPE float comparing instructions, I saw:

> If either operand contains a NaN, infinity, or a denorm and floating-point invalid exceptions are enabled in the SPEFSCR, the exception is taken. If the exception is not enabled, the comparison treats NaNs, infinities, and denorms as normalized numbers.

So I think `fcmps` should be the enabled one. (LangRef section <https://llvm.org/docs/LangRef.html#llvm-experimental-constrained-fcmp-and-llvm-experimental-constrained-fcmps-intrinsics>) But when I'm targeting SPE using clang, it generates IR with some `fcmp` and some other `fcmps`.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D101282

Files:
  llvm/lib/Target/PowerPC/PPCISelLowering.cpp
  llvm/lib/Target/PowerPC/PPCInstrInfo.td
  llvm/lib/Target/PowerPC/PPCInstrSPE.td
  llvm/test/CodeGen/PowerPC/fp-strict-fcmp-spe.ll
  llvm/test/CodeGen/PowerPC/fp-strict-round.ll
  llvm/test/CodeGen/PowerPC/fp-strict.ll

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