[all-commits] [llvm/llvm-project] 7a5b04: [RISCV] Add initial support of memcmp expansion

[Pengcheng Wang via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 7a5b040e20394a4794b4360a56de8a172b5e27f4
      https://github.com/llvm/llvm-project/commit/7a5b040e20394a4794b4360a56de8a172b5e27f4
  Author: Pengcheng Wang <wangpengcheng.pp at bytedance.com>
  Date:   2024-11-06 (Wed, 06 Nov 2024)

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

  Log Message:
  -----------
  [RISCV] Add initial support of memcmp expansion

There are two passes that have dependency on the implementation
of `TargetTransformInfo::enableMemCmpExpansion` : `MergeICmps` and
`ExpandMemCmp`.

This PR adds the initial implementation of `enableMemCmpExpansion`
so that we can have some basic benefits from these two passes.

We don't enable expansion when there is no unaligned access support
currently because there are some issues about unaligned loads and
stores in `ExpandMemcmp` pass. We should fix these issues and enable
the expansion later.

Vector case hasn't been tested as we don't generate inlined vector
instructions for memcmp currently.

Reviewers: preames, arcbbb, topperc, asb, dtcxzyw

Reviewed By: topperc, preames

Pull Request: https://github.com/llvm/llvm-project/pull/107548



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