Improve codegen for mixing in length#112
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tkaitchuck merged 1 commit intotkaitchuck:masterfrom Feb 27, 2022
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tkaitchuck
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Feb 26, 2022
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| #[inline(always)] | ||
| pub(crate) fn add_in_length(enc: &mut u128, len: u64) { | ||
| #[cfg(all(target_feature = "sse2", not(miri)))] |
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This refers to sse2 and below it refers to sss3, but it looks like these were both meant to be the same so as to provide two alternative paths.
tkaitchuck
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Feb 26, 2022
| use core::arch::x86_64::*; | ||
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| unsafe { | ||
| let enc = std::ptr::addr_of_mut!(*enc); |
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| unsafe { | ||
| let enc = std::ptr::addr_of_mut!(*enc); | ||
| let len = _mm_cvtsi64_si128(len as i64); |
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Is this 64 bit only? It is giving a compile error on i686.
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Yep, 64-bit. I've added target_arch to the cfg on this branch.
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@tkaitchuck Thanks for the review, I've just pushed updated diff with the fixes. |
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Minor detail, but produces +17% speed improvement for small strings/byte slices (x86-64).
Measured on Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz (Skylake).
Before (relevant part):
In order to add the length it extracts enc[0] into general-purpose register, adds there and then moves it back to vector register (and uses blend).
After:
LLVM able to recognize there is no need to go through GRP and blend.