[PATCH] D144606: [InstCombine] Add transforms for `(max/min (xor X, Pow2), X)` -> `(and/or X, Pow2/~Pow2)`

[Noah Goldstein via Phabricator via llvm-commits]

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X ^ Pow2 is guranteed to flip one bit. We can use this to speedup
max/min by just selecting X with/without (or/andnot) the flipped bit
respectively.

Alive2 Links:
smax-neg: https://alive2.llvm.org/ce/z/j3QYFs
smin-neg: https://alive2.llvm.org/ce/z/bFYnQW
smax-pos: https://alive2.llvm.org/ce/z/4xYSxR
smin-pos: https://alive2.llvm.org/ce/z/H3RPKj
umax    : https://alive2.llvm.org/ce/z/P4oRcX
umin    : https://alive2.llvm.org/ce/z/vWZG6p


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D144606

Files:
  llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
  llvm/test/Transforms/InstCombine/minmax-of-xor-x.ll

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