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refactor(users/edef/refscan): switch to intrinsics

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packed_simd is deprecated, but we don't need very much SIMD:
  * _mm256_set1_epi8 / vpbroadcastb (splat)
  * _mm256_cmpgt_epi8 / vpcmpgtb (comparison)
  * _mm256_movemask_epi8 / vpmovmskb (compress to bitmask)

This also simplifies the code by only vectorising the bare minimum,
since we just get a bitmask and operate in scalar mode as soon as
possible.

We don't need nightly Rust anymore: we're using only stable intrinsics.

Change-Id: Id410b5fef2549f3c97f48049f722f1e643e68553
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7687
Reviewed-by: edef <edef@edef.eu>
Tested-by: BuildkiteCI
This commit is contained in:
edef 2023-01-09 23:16:21 +00:00
parent 0b3c0725a2
commit cb764e87de
3 changed files with 41 additions and 25 deletions
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20
users/edef/refscan/Cargo.lock generated
View file

@ -1,25 +1,7 @@
# This file is automatically @generated by Cargo.
# It is not intended for manual editing.
[[package]]
name = "cfg-if"
version = "0.1.10"
source = "registry+https://github.com/rust-lang/crates.io-index"
[[package]]
name = "packed_simd"
version = "0.3.3"
source = "registry+https://github.com/rust-lang/crates.io-index"
dependencies = [
"cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
]
version = 3
[[package]]
name = "refscan"
version = "0.1.0"
dependencies = [
"packed_simd 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
]
[metadata]
"checksum cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)" = "4785bdd1c96b2a846b2bd7cc02e86b6b3dbf14e7e53446c4f54c92a361040822"
"checksum packed_simd 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)" = "a85ea9fc0d4ac0deb6fe7911d38786b32fc11119afd9e9d38b84ff691ce64220"

3
users/edef/refscan/Cargo.toml
View file

@ -5,6 +5,3 @@ authors = ["edef <edef@edef.eu>"]
edition = "2018"
# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
[dependencies]
packed_simd = "0.3.3"

43
users/edef/refscan/src/lib.rs
View file

@ -1,6 +1,6 @@
use packed_simd::{m8x32, u8x32};
use self::simd::u8x32;
fn prefilter(haystack: u8x32) -> m8x32 {
fn prefilter(haystack: u8x32) -> u32 {
let alp = haystack.gt(u8x32::splat(b'a' - 1)) & haystack.lt(u8x32::splat(b'z' + 1));
let num = haystack.gt(u8x32::splat(b'0' - 1)) & haystack.lt(u8x32::splat(b'9' + 1));
alp | num
@ -16,7 +16,7 @@ pub fn scan_clean(buffer: &[u8]) -> Result<&[u8], &[u8]> {
let mut masks = buffer
.chunks_exact(32)
.map(|chunk| prefilter(u8x32::from_slice_unaligned(chunk)).bitmask())
.map(|chunk| prefilter(u8x32::from_slice_unaligned(chunk)))
.enumerate()
.map(|e| (e.0 * 32, e.1))
.peekable();
@ -51,3 +51,40 @@ mod test {
assert_eq!(crate::scan_clean(buffer), Ok(&buffer[..]));
}
}
mod simd {
#[cfg(target_arch = "x86")]
use std::arch::x86 as arch;
#[cfg(target_arch = "x86_64")]
use std::arch::x86_64 as arch;
use {
arch::{__m256i, _mm256_cmpgt_epi8, _mm256_movemask_epi8, _mm256_set1_epi8},
std::ptr,
};
#[derive(Copy, Clone)]
pub struct u8x32(__m256i);
impl u8x32 {
#[inline(always)]
pub fn from_slice_unaligned(slice: &[u8]) -> Self {
assert_eq!(slice.len(), 32);
u8x32(unsafe { ptr::read_unaligned(slice.as_ptr().cast()) })
}
#[inline(always)]
pub fn splat(x: u8) -> Self {
u8x32(unsafe { _mm256_set1_epi8(x as i8) })
}
#[inline(always)]
pub fn gt(self, b: Self) -> u32 {
unsafe { _mm256_movemask_epi8(_mm256_cmpgt_epi8(self.0, b.0)) as u32 }
}
#[inline(always)]
pub fn lt(self, b: Self) -> u32 {
b.gt(self)
}
}
}