[PATCH] D145281: [InstCombine] Add transforms for `(icmp spred (xor X, Y), X)`

[Noah Goldstein via Phabricator via llvm-commits]

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If we know the sign of Y or the value of Y we can either evaluate or
simplify the condition.

`icmp (X | MinInt) s> X` --> `false`

- https://alive2.llvm.org/ce/z/mpd-Yj

`icmp (X | MinInt) s<= X` --> `true`

- https://alive2.llvm.org/ce/z/E4aynv

`icmp (X | MinInt) s>= X` --> `X s< 0`

- https://alive2.llvm.org/ce/z/ThZkSV

`icmp (X | MinInt) s< X` --> `X s>= 0`

- https://alive2.llvm.org/ce/z/sNx2VB

`icmp (X | Pos_Y) s> X` --> `(X | Pos_Y) != X`

- https://alive2.llvm.org/ce/z/n-XM6N

`icmp (X | Pos_Y) s<= X` --> `(X | Pos_Y) == X`

- https://alive2.llvm.org/ce/z/1FQZM-


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D145281

Files:
  llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
  llvm/test/Transforms/InstCombine/icmp-of-or-x.ll

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