[PATCH] D144608: [InstCombine] Add transforms for `(icmp (xor X, Y), X)`

[Noah Goldstein via Phabricator via llvm-commits]

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There are a variety of cases we can simplify either saving
instructions are creating sequences that are easier to optimize
elsewhere.

`(X ^ Y_NonZero) u>= X` --> `(X ^ Y_NonZero) u> X`

- https://alive2.llvm.org/ce/z/k482NQ

`(X ^ Y_NonZero) u<= X` --> `(X ^ Y_NonZero) u< X`

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

`(X ^ Y_NonZero) s>= X` --> `(X ^ Y_NonZero) s> X`

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

`(X ^ Y_NonZero) s<= X` --> `(X ^ Y_NonZero) s< X    `

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

`(X ^ Y) u> X` --> `X & MSB(Y) == 0`

- https://alive2.llvm.org/ce/z/R63Nq2

`(X ^ Y) u< X` --> `X & MSB(Y) != 0`

- https://alive2.llvm.org/ce/z/5s9SWj

`(X ^ Pos_Y) s> X` --> `X & MSB(Pow2_Y) == 0`

- https://alive2.llvm.org/ce/z/P6VTSm

`(X ^ Pos_Y) s< X` --> `X & MSB(Pow2_Y) != 0`

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

`(X ^ Neg_Y) s> X` --> `X s< 0`

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

`(X ^ Neg_Y) s< X` --> `X s>= 0`

- https://alive2.llvm.org/ce/z/36iZDw


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D144608

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

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