[PATCH] D144608: [InstCombine] Add transforms for `(icmp (xor X, Y), X)`
Noah Goldstein via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Wed Feb 22 17:20:28 PST 2023
goldstein.w.n created this revision.
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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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