[all-commits] [llvm/llvm-project] ffe139: [InstCombine] Fold (A & 2^C1) + A => A & (2^C1 - 1...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: ffe13960b5795b08b574b31720b517c59f26ca2f
      https://github.com/llvm/llvm-project/commit/ffe13960b5795b08b574b31720b517c59f26ca2f
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2022-04-22 (Fri, 22 Apr 2022)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
    M llvm/test/Transforms/InstCombine/add-mask.ll
    M llvm/test/Transforms/InstCombine/modulo.ll

  Log Message:
  -----------
  [InstCombine] Fold (A & 2^C1) + A => A & (2^C1 - 1) iff bit C1 in A is a sign bit (PR21929)

Alive2: https://alive2.llvm.org/ce/z/Ygq26C

This is the final missing fold to handle the modulo2 simplification: https://github.com/llvm/llvm-project/issues/22303

Fixes #22303

Differential Revision: https://reviews.llvm.org/D123374