[all-commits] [llvm/llvm-project] 16e059: [AArch64] Use isKnownNonZero to optimize eligible ...

[AtariDreams via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 16e05919d94888e222d4954086f6d860839117dd
      https://github.com/llvm/llvm-project/commit/16e05919d94888e222d4954086f6d860839117dd
  Author: AtariDreams <gfunni234 at gmail.com>
  Date:   2024-07-22 (Mon, 22 Jul 2024)

  Changed paths:
    M llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
    M llvm/test/CodeGen/AArch64/cmp-chains.ll
    M llvm/test/CodeGen/AArch64/cmp-select-sign.ll

  Log Message:
  -----------
  [AArch64] Use isKnownNonZero to optimize eligible compares to cmn and ccmn (#96349)

The problematic case for unsigned comparisons occurs only when the
second argument is zero.

The problematic case for signed comparisons occurs only when the second
argument is the signed minimum value.

We can use KnownBits to know when we don't have to worry about this.

Source: https://devblogs.microsoft.com/oldnewthing/20210607-00/?p=105288



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