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Use bitwise XOR in to_ascii_uppercase by redzic · Pull Request #95831 · rust-lan...
source link: https://github.com/rust-lang/rust/pull/95831
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This saves an instruction compared to the previous approach, which
was to unset the fifth bit with bitwise OR.
Comparison of generated assembly on x86: https://godbolt.org/z/GdfvdGs39
This can also affect autovectorization, saving SIMD instructions as well: https://godbolt.org/z/cnPcz75T9
Not sure if u8::to_ascii_lowercase should also be changed, since using bitwise OR for that function does not require an extra bitwise negate since the code is setting a bit rather than unsetting a bit. char::to_ascii_uppercase already uses XOR, so no change seems to be required there.
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