[PATCH] D50895: [SimplifyLibCalls] Generalize replacePowWithSqrt to handle more cases.

[Florian Hahn via Phabricator via llvm-commits]

fhahn created this revision.
fhahn added reviewers: paulwalker-arm, wmi, efriedma, evandro, spatel.

This patch folds the logic to expand

- pow(x, 0.5) to (x == -infinity ? +infinity : fabs(sqrt(x)))

into replacePowWithSqrt. If the original pow has NoInfs, we do not need
the select, if it has NoSignedZero, we do not need the fabs.

This addresses several FIXMEs in test/Transforms/InstCombine/pow-sqrt.ll.

One thing I am not entirely sure about: did we need isFast() in the original code for anything besides NoInfs and NoUnsignedZeros (e.g. errno behavior)?


https://reviews.llvm.org/D50895

Files:
  lib/Transforms/Utils/SimplifyLibCalls.cpp
  test/Transforms/InstCombine/pow-1.ll
  test/Transforms/InstCombine/pow-sqrt.ll

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