[all-commits] [llvm/llvm-project] 4903c1: [RISCV] Support memcmp expansion for vectors

[Pengcheng Wang via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 4903c11a7e144d63635b115d97936a7aecf7a2f6
      https://github.com/llvm/llvm-project/commit/4903c11a7e144d63635b115d97936a7aecf7a2f6
  Author: Pengcheng Wang <wangpengcheng.pp at bytedance.com>
  Date:   2025-06-13 (Fri, 13 Jun 2025)

  Changed paths:
    M llvm/lib/Target/RISCV/RISCVISelLowering.cpp
    M llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
    M llvm/test/CodeGen/RISCV/memcmp-optsize.ll
    M llvm/test/CodeGen/RISCV/memcmp.ll

  Log Message:
  -----------
  [RISCV] Support memcmp expansion for vectors

This patch adds the support of generating vector instructions for
`memcmp`. This implementation is inspired by X86's.

We convert integer comparisons (eq/ne only) into vector comparisons
and do a vector reduction and to get the result.

The range of supported load sizes is (XLEN, VLEN * LMUL8] and
non-power-of-2 types are not supported.

Fixes #143294.

Reviewers: lukel97, asb, preames, topperc, dtcxzyw

Reviewed By: topperc, lukel97

Pull Request: https://github.com/llvm/llvm-project/pull/114517



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