[all-commits] [llvm/llvm-project] 28f12a: [RISCV] Teach ComputeNumSignBitsForTargetNode abou...

Alex Bradbury via All-commits all-commits at lists.llvm.org
Wed Aug 3 05:46:07 PDT 2022

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 28f12a09ae631885410d7524f7c60748a59358c5
  Author: Alex Bradbury <asb at igalia.com>
  Date:   2022-08-03 (Wed, 03 Aug 2022)

  Changed paths:
    M llvm/lib/Target/RISCV/RISCVISelLowering.cpp
    M llvm/test/CodeGen/RISCV/atomic-cmpxchg-branch-on-result.ll
    M llvm/test/CodeGen/RISCV/atomic-signext.ll

  Log Message:
  [RISCV] Teach ComputeNumSignBitsForTargetNode about masked atomic intrinsics

An unnecessary sext.w is generated when masking the result of the
riscv_masked_cmpxchg_i64 intrinsic. Implementing handling of the
intrinsic in ComputeNumSignBitsForTargetNode allows it to be removed.

Although this isn't a particularly important optimisation, removing the
sext.w simplifies implementation of an additional cmpxchg-related
optimisation in D130192.

Although I can't produce a test with different codegen for the other
atomics intrinsics, these are added as well for completeness.

Differential Revision: https://reviews.llvm.org/D130191

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