[all-commits] [llvm/llvm-project] 7e878a: [PatternMatch] Add support for capture-and-match (...

[Nikita Popov via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 7e878aaf23dd559fa491a0bf6168f15f939c5965
      https://github.com/llvm/llvm-project/commit/7e878aaf23dd559fa491a0bf6168f15f939c5965
  Author: Nikita Popov <npopov at redhat.com>
  Date:   2025-07-23 (Wed, 23 Jul 2025)

  Changed paths:
    M llvm/include/llvm/IR/PatternMatch.h
    M llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
    M llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp

  Log Message:
  -----------
  [PatternMatch] Add support for capture-and-match (NFC) (#149825)

When using PatternMatch, there is a common problem where we want to both
match something against a pattern, but also capture the
value/instruction for various reasons (e.g. to access flags).

Currently the two ways to do that is to either capture using
m_Value/m_Instruction and do a separate match on the result, or to use
the somewhat awkward `m_CombineAnd(m_XYZ, m_Value(V))` pattern.

This PR introduces to add a variant of `m_Value`/`m_Instruction` which
does both a capture and a match. `m_Value(V, m_XYZ)` is basically
equivalent to `m_CombineAnd(m_XYZ, m_Value(V))`.

I've ported two InstCombine files to this pattern as a sample.



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