[all-commits] [llvm/llvm-project] 092de9: [InstCombine] Enable FAdd simplifications when use...

[Vedant Paranjape via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 092de9bb90cbcee445b31e504a4c2a09ecf09714
      https://github.com/llvm/llvm-project/commit/092de9bb90cbcee445b31e504a4c2a09ecf09714
  Author: Vedant Paranjape <vedantparanjape160201 at gmail.com>
  Date:   2025-09-12 (Fri, 12 Sep 2025)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
    A llvm/test/Transforms/InstCombine/fold-fadd-with-zero-gh154238.ll

  Log Message:
  -----------
  [InstCombine] Enable FAdd simplifications when user can ignore sign bit (#157757)

When FAdd result is used by fabs, we can safely ignore the sign bit of
fp zero. This patch enables an instruction simplification optimization
that folds fadd x, 0 ==> x, which would otherwise not work as the
compiler cannot prove that the zero isn't -0. But if the result of the
fadd is used by fabs we can simply ignore this and still do the
optimization.

Fixes #154238



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