[PATCH] D126774: [InstCombine] Use +0.0 instead of -0.0 as the FP identity for some folds

[David Sherwood via Phabricator via llvm-commits]

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In foldSelectIntoOp we sometimes transform a select of a fadd into a
fadd of a select, where we select between data and an identity value.
For both fadd and fsub the identity is always -0.0, but if the nsz
flag is set on the select instruction we can use +0.0 instead. Doing
so then triggers other optimisations, such as when folding the select
of masked load into a new masked load.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D126774

Files:
  llvm/include/llvm/IR/Constants.h
  llvm/lib/IR/Constants.cpp
  llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
  llvm/test/Transforms/InstCombine/select-binop-foldable-floating-point.ll

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