[all-commits] [llvm/llvm-project] 4220ef: [InstCombine] Add fold for redundant sign bits cou...

[Alexander Shaposhnikov via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 4220ef2be1c911f92b48a895fdd18e4077b322f5
      https://github.com/llvm/llvm-project/commit/4220ef2be1c911f92b48a895fdd18e4077b322f5
  Author: Alexander Shaposhnikov <ashaposhnikov at google.com>
  Date:   2022-07-30 (Sat, 30 Jul 2022)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
    M llvm/lib/Transforms/InstCombine/InstCombineInternal.h
    M llvm/test/Transforms/InstCombine/icmp.ll

  Log Message:
  -----------
  [InstCombine] Add fold for redundant sign bits count comparison

For power-of-2 C:
((X s>> ShiftC) ^ X) u< C --> (X + C) u< (C << 1)
((X s>> ShiftC) ^ X) u> (C - 1) --> (X + C) u> ((C << 1) - 1)

(https://github.com/llvm/llvm-project/issues/56479)

Test plan:
0/ ninja check-llvm check-clang + bootstrap LLVM/Clang
1/ https://alive2.llvm.org/ce/z/eEUfx3

Differential revision: https://reviews.llvm.org/D130433