chenglin.bi 6703290361 [InstCombine] fold sub + and pattern with specific const value ...

`C1 - ((C3 - X) & C2) --> (X & C2) + (C1 - (C2 & C3))`
when:
    (C3 - ((C2 & C3) - 1)) is pow2 &&
    ((C2 + C3) & ((C2 & C3) - 1)) == ((C2 & C3) - 1) &&
    C2 is negative pow2 || (C3 - X) is nuw

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

Fix: #58523

Reviewed By: spatel

Differential Revision: https://reviews.llvm.org/D136582

2022-11-05 12:58:45 +08:00

92 KiB

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