[all-commits] [llvm/llvm-project] f88436: [InstCombine] Fold signbit test of a pow2 or zero

[Jun Zhang via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: f88436c3f3b01a04aff4a129245a8a1b1124e7f1
      https://github.com/llvm/llvm-project/commit/f88436c3f3b01a04aff4a129245a8a1b1124e7f1
  Author: Jun Zhang <jun at junz.org>
  Date:   2023-02-28 (Tue, 28 Feb 2023)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
    M llvm/test/Transforms/InstCombine/fold-signbit-test-power2.ll
    M llvm/test/Transforms/InstCombine/minmax-of-xor-x.ll

  Log Message:
  -----------
  [InstCombine] Fold signbit test of a pow2 or zero

(X & X) <  0 --> X == MinSignedC
(X & X) > -1 --> X != MinSignedC

Alive2: https://alive2.llvm.org/ce/z/_J5q3S
Closes: https://github.com/llvm/llvm-project/issues/60957

Signed-off-by: Jun Zhang <jun at junz.org>

Differential Revision: https://reviews.llvm.org/D144777