mirror of
https://git.proxmox.com/git/rustc
synced 2025-05-04 00:48:10 +00:00
399 lines
12 KiB
Rust
399 lines
12 KiB
Rust
//! An example showing runtime dispatch to an architecture-optimized
|
|
//! implementation.
|
|
//!
|
|
//! This program implements hex encoding a slice into a predetermined
|
|
//! destination using various different instruction sets. This selects at
|
|
//! runtime the most optimized implementation and uses that rather than being
|
|
//! required to be compiled differently.
|
|
//!
|
|
//! You can test out this program via:
|
|
//!
|
|
//! echo test | cargo +nightly run --release hex
|
|
//!
|
|
//! and you should see `746573740a` get printed out.
|
|
|
|
#![feature(stdsimd, wasm_target_feature)]
|
|
#![cfg_attr(test, feature(test))]
|
|
#![allow(
|
|
clippy::unwrap_used,
|
|
clippy::print_stdout,
|
|
clippy::unwrap_used,
|
|
clippy::shadow_reuse,
|
|
clippy::cast_possible_wrap,
|
|
clippy::cast_ptr_alignment,
|
|
clippy::cast_sign_loss,
|
|
clippy::missing_docs_in_private_items
|
|
)]
|
|
|
|
use std::{
|
|
io::{self, Read},
|
|
str,
|
|
};
|
|
|
|
#[cfg(target_arch = "x86")]
|
|
use {core_arch::arch::x86::*, std_detect::is_x86_feature_detected};
|
|
#[cfg(target_arch = "x86_64")]
|
|
use {core_arch::arch::x86_64::*, std_detect::is_x86_feature_detected};
|
|
|
|
fn main() {
|
|
let mut input = Vec::new();
|
|
io::stdin().read_to_end(&mut input).unwrap();
|
|
let mut dst = vec![0; 2 * input.len()];
|
|
let s = hex_encode(&input, &mut dst).unwrap();
|
|
println!("{s}");
|
|
}
|
|
|
|
fn hex_encode<'a>(src: &[u8], dst: &'a mut [u8]) -> Result<&'a str, usize> {
|
|
let len = src.len().checked_mul(2).unwrap();
|
|
if dst.len() < len {
|
|
return Err(len);
|
|
}
|
|
|
|
#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
|
|
{
|
|
if is_x86_feature_detected!("avx2") {
|
|
return unsafe { hex_encode_avx2(src, dst) };
|
|
}
|
|
if is_x86_feature_detected!("sse4.1") {
|
|
return unsafe { hex_encode_sse41(src, dst) };
|
|
}
|
|
}
|
|
#[cfg(target_arch = "wasm32")]
|
|
{
|
|
if true {
|
|
return unsafe { hex_encode_simd128(src, dst) };
|
|
}
|
|
}
|
|
|
|
hex_encode_fallback(src, dst)
|
|
}
|
|
|
|
#[target_feature(enable = "avx2")]
|
|
#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
|
|
unsafe fn hex_encode_avx2<'a>(mut src: &[u8], dst: &'a mut [u8]) -> Result<&'a str, usize> {
|
|
let ascii_zero = _mm256_set1_epi8(b'0' as i8);
|
|
let nines = _mm256_set1_epi8(9);
|
|
let ascii_a = _mm256_set1_epi8((b'a' - 9 - 1) as i8);
|
|
let and4bits = _mm256_set1_epi8(0xf);
|
|
|
|
let mut i = 0_usize;
|
|
while src.len() >= 32 {
|
|
let invec = _mm256_loadu_si256(src.as_ptr() as *const _);
|
|
|
|
let masked1 = _mm256_and_si256(invec, and4bits);
|
|
let masked2 = _mm256_and_si256(_mm256_srli_epi64(invec, 4), and4bits);
|
|
|
|
// return 0xff corresponding to the elements > 9, or 0x00 otherwise
|
|
let cmpmask1 = _mm256_cmpgt_epi8(masked1, nines);
|
|
let cmpmask2 = _mm256_cmpgt_epi8(masked2, nines);
|
|
|
|
// add '0' or the offset depending on the masks
|
|
let masked1 = _mm256_add_epi8(masked1, _mm256_blendv_epi8(ascii_zero, ascii_a, cmpmask1));
|
|
let masked2 = _mm256_add_epi8(masked2, _mm256_blendv_epi8(ascii_zero, ascii_a, cmpmask2));
|
|
|
|
// interleave masked1 and masked2 bytes
|
|
let res1 = _mm256_unpacklo_epi8(masked2, masked1);
|
|
let res2 = _mm256_unpackhi_epi8(masked2, masked1);
|
|
|
|
// Store everything into the right destination now
|
|
let base = dst.as_mut_ptr().add(i * 2);
|
|
let base1 = base.add(0) as *mut _;
|
|
let base2 = base.add(16) as *mut _;
|
|
let base3 = base.add(32) as *mut _;
|
|
let base4 = base.add(48) as *mut _;
|
|
_mm256_storeu2_m128i(base3, base1, res1);
|
|
_mm256_storeu2_m128i(base4, base2, res2);
|
|
src = &src[32..];
|
|
i += 32;
|
|
}
|
|
|
|
let _ = hex_encode_sse41(src, &mut dst[i * 2..]);
|
|
|
|
Ok(str::from_utf8_unchecked(&dst[..src.len() * 2 + i * 2]))
|
|
}
|
|
|
|
// copied from https://github.com/Matherunner/bin2hex-sse/blob/master/base16_sse4.cpp
|
|
#[target_feature(enable = "sse4.1")]
|
|
#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
|
|
unsafe fn hex_encode_sse41<'a>(mut src: &[u8], dst: &'a mut [u8]) -> Result<&'a str, usize> {
|
|
let ascii_zero = _mm_set1_epi8(b'0' as i8);
|
|
let nines = _mm_set1_epi8(9);
|
|
let ascii_a = _mm_set1_epi8((b'a' - 9 - 1) as i8);
|
|
let and4bits = _mm_set1_epi8(0xf);
|
|
|
|
let mut i = 0_usize;
|
|
while src.len() >= 16 {
|
|
let invec = _mm_loadu_si128(src.as_ptr() as *const _);
|
|
|
|
let masked1 = _mm_and_si128(invec, and4bits);
|
|
let masked2 = _mm_and_si128(_mm_srli_epi64(invec, 4), and4bits);
|
|
|
|
// return 0xff corresponding to the elements > 9, or 0x00 otherwise
|
|
let cmpmask1 = _mm_cmpgt_epi8(masked1, nines);
|
|
let cmpmask2 = _mm_cmpgt_epi8(masked2, nines);
|
|
|
|
// add '0' or the offset depending on the masks
|
|
let masked1 = _mm_add_epi8(masked1, _mm_blendv_epi8(ascii_zero, ascii_a, cmpmask1));
|
|
let masked2 = _mm_add_epi8(masked2, _mm_blendv_epi8(ascii_zero, ascii_a, cmpmask2));
|
|
|
|
// interleave masked1 and masked2 bytes
|
|
let res1 = _mm_unpacklo_epi8(masked2, masked1);
|
|
let res2 = _mm_unpackhi_epi8(masked2, masked1);
|
|
|
|
_mm_storeu_si128(dst.as_mut_ptr().add(i * 2) as *mut _, res1);
|
|
_mm_storeu_si128(dst.as_mut_ptr().add(i * 2 + 16) as *mut _, res2);
|
|
src = &src[16..];
|
|
i += 16;
|
|
}
|
|
|
|
let _ = hex_encode_fallback(src, &mut dst[i * 2..]);
|
|
|
|
Ok(str::from_utf8_unchecked(&dst[..src.len() * 2 + i * 2]))
|
|
}
|
|
|
|
#[cfg(target_arch = "wasm32")]
|
|
#[target_feature(enable = "simd128")]
|
|
unsafe fn hex_encode_simd128<'a>(mut src: &[u8], dst: &'a mut [u8]) -> Result<&'a str, usize> {
|
|
use core_arch::arch::wasm32::*;
|
|
|
|
let ascii_zero = u8x16_splat(b'0');
|
|
let nines = u8x16_splat(9);
|
|
let ascii_a = u8x16_splat(b'a' - 9 - 1);
|
|
let and4bits = u8x16_splat(0xf);
|
|
|
|
let mut i = 0_usize;
|
|
while src.len() >= 16 {
|
|
let invec = v128_load(src.as_ptr() as *const _);
|
|
|
|
let masked1 = v128_and(invec, and4bits);
|
|
let masked2 = v128_and(u8x16_shr(invec, 4), and4bits);
|
|
|
|
// return 0xff corresponding to the elements > 9, or 0x00 otherwise
|
|
let cmpmask1 = u8x16_gt(masked1, nines);
|
|
let cmpmask2 = u8x16_gt(masked2, nines);
|
|
|
|
// add '0' or the offset depending on the masks
|
|
let masked1 = u8x16_add(masked1, v128_bitselect(ascii_a, ascii_zero, cmpmask1));
|
|
let masked2 = u8x16_add(masked2, v128_bitselect(ascii_a, ascii_zero, cmpmask2));
|
|
|
|
// Next we need to shuffle around masked{1,2} to get back to the
|
|
// original source text order. The first element (res1) we'll store uses
|
|
// all the low bytes from the 2 masks and the second element (res2) uses
|
|
// all the upper bytes.
|
|
let res1 = u8x16_shuffle::<0, 16, 1, 17, 2, 18, 3, 19, 4, 20, 5, 21, 6, 22, 7, 23>(
|
|
masked2, masked1,
|
|
);
|
|
let res2 = u8x16_shuffle::<8, 24, 9, 25, 10, 26, 11, 27, 12, 28, 13, 29, 14, 30, 15, 31>(
|
|
masked2, masked1,
|
|
);
|
|
|
|
v128_store(dst.as_mut_ptr().add(i * 2) as *mut _, res1);
|
|
v128_store(dst.as_mut_ptr().add(i * 2 + 16) as *mut _, res2);
|
|
src = &src[16..];
|
|
i += 16;
|
|
}
|
|
|
|
let _ = hex_encode_fallback(src, &mut dst[i * 2..]);
|
|
|
|
Ok(str::from_utf8_unchecked(&dst[..src.len() * 2 + i * 2]))
|
|
}
|
|
|
|
fn hex_encode_fallback<'a>(src: &[u8], dst: &'a mut [u8]) -> Result<&'a str, usize> {
|
|
fn hex(byte: u8) -> u8 {
|
|
static TABLE: &[u8] = b"0123456789abcdef";
|
|
TABLE[byte as usize]
|
|
}
|
|
|
|
for (byte, slots) in src.iter().zip(dst.chunks_mut(2)) {
|
|
slots[0] = hex((*byte >> 4) & 0xf);
|
|
slots[1] = hex(*byte & 0xf);
|
|
}
|
|
|
|
unsafe { Ok(str::from_utf8_unchecked(&dst[..src.len() * 2])) }
|
|
}
|
|
|
|
// Run these with `cargo +nightly test --example hex -p stdarch`
|
|
#[cfg(test)]
|
|
mod tests {
|
|
use std::iter;
|
|
|
|
use super::*;
|
|
|
|
fn test(input: &[u8], output: &str) {
|
|
let tmp = || vec![0; input.len() * 2];
|
|
|
|
assert_eq!(hex_encode_fallback(input, &mut tmp()).unwrap(), output);
|
|
assert_eq!(hex_encode(input, &mut tmp()).unwrap(), output);
|
|
|
|
#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
|
|
unsafe {
|
|
if self::is_x86_feature_detected!("avx2") {
|
|
assert_eq!(hex_encode_avx2(input, &mut tmp()).unwrap(), output);
|
|
}
|
|
if self::is_x86_feature_detected!("sse4.1") {
|
|
assert_eq!(hex_encode_sse41(input, &mut tmp()).unwrap(), output);
|
|
}
|
|
}
|
|
}
|
|
|
|
#[test]
|
|
fn empty() {
|
|
test(b"", "");
|
|
}
|
|
|
|
#[test]
|
|
fn big() {
|
|
test(
|
|
&[0; 1024],
|
|
&iter::repeat('0').take(2048).collect::<String>(),
|
|
);
|
|
}
|
|
|
|
#[test]
|
|
fn odd() {
|
|
test(
|
|
&[0; 313],
|
|
&iter::repeat('0').take(313 * 2).collect::<String>(),
|
|
);
|
|
}
|
|
|
|
#[test]
|
|
fn avx_works() {
|
|
let mut input = [0; 33];
|
|
input[4] = 3;
|
|
input[16] = 3;
|
|
input[17] = 0x30;
|
|
input[21] = 1;
|
|
input[31] = 0x24;
|
|
test(
|
|
&input,
|
|
"\
|
|
0000000003000000\
|
|
0000000000000000\
|
|
0330000000010000\
|
|
0000000000000024\
|
|
00\
|
|
",
|
|
);
|
|
}
|
|
|
|
quickcheck::quickcheck! {
|
|
fn encode_equals_fallback(input: Vec<u8>) -> bool {
|
|
let mut space1 = vec![0; input.len() * 2];
|
|
let mut space2 = vec![0; input.len() * 2];
|
|
let a = hex_encode(&input, &mut space1).unwrap();
|
|
let b = hex_encode_fallback(&input, &mut space2).unwrap();
|
|
a == b
|
|
}
|
|
|
|
#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
|
|
fn avx_equals_fallback(input: Vec<u8>) -> bool {
|
|
if !self::is_x86_feature_detected!("avx2") {
|
|
return true
|
|
}
|
|
let mut space1 = vec![0; input.len() * 2];
|
|
let mut space2 = vec![0; input.len() * 2];
|
|
let a = unsafe { hex_encode_avx2(&input, &mut space1).unwrap() };
|
|
let b = hex_encode_fallback(&input, &mut space2).unwrap();
|
|
a == b
|
|
}
|
|
|
|
#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
|
|
fn sse41_equals_fallback(input: Vec<u8>) -> bool {
|
|
if !self::is_x86_feature_detected!("avx2") {
|
|
return true
|
|
}
|
|
let mut space1 = vec![0; input.len() * 2];
|
|
let mut space2 = vec![0; input.len() * 2];
|
|
let a = unsafe { hex_encode_sse41(&input, &mut space1).unwrap() };
|
|
let b = hex_encode_fallback(&input, &mut space2).unwrap();
|
|
a == b
|
|
}
|
|
}
|
|
}
|
|
|
|
// Run these with `cargo +nightly bench --example hex -p stdarch`
|
|
#[cfg(test)]
|
|
mod benches {
|
|
extern crate rand;
|
|
extern crate test;
|
|
|
|
use self::rand::Rng;
|
|
|
|
use super::*;
|
|
|
|
const SMALL_LEN: usize = 117;
|
|
const LARGE_LEN: usize = 1 * 1024 * 1024;
|
|
|
|
fn doit(
|
|
b: &mut test::Bencher,
|
|
len: usize,
|
|
f: for<'a> unsafe fn(&[u8], &'a mut [u8]) -> Result<&'a str, usize>,
|
|
) {
|
|
let mut rng = rand::thread_rng();
|
|
let input = std::iter::repeat(())
|
|
.map(|()| rng.gen::<u8>())
|
|
.take(len)
|
|
.collect::<Vec<_>>();
|
|
let mut dst = vec![0; input.len() * 2];
|
|
b.bytes = len as u64;
|
|
b.iter(|| unsafe {
|
|
f(&input, &mut dst).unwrap();
|
|
dst[0]
|
|
});
|
|
}
|
|
|
|
#[bench]
|
|
fn small_default(b: &mut test::Bencher) {
|
|
doit(b, SMALL_LEN, hex_encode);
|
|
}
|
|
|
|
#[bench]
|
|
fn small_fallback(b: &mut test::Bencher) {
|
|
doit(b, SMALL_LEN, hex_encode_fallback);
|
|
}
|
|
|
|
#[bench]
|
|
fn large_default(b: &mut test::Bencher) {
|
|
doit(b, LARGE_LEN, hex_encode);
|
|
}
|
|
|
|
#[bench]
|
|
fn large_fallback(b: &mut test::Bencher) {
|
|
doit(b, LARGE_LEN, hex_encode_fallback);
|
|
}
|
|
|
|
#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
|
|
mod x86 {
|
|
use super::*;
|
|
|
|
#[bench]
|
|
fn small_avx2(b: &mut test::Bencher) {
|
|
if self::is_x86_feature_detected!("avx2") {
|
|
doit(b, SMALL_LEN, hex_encode_avx2);
|
|
}
|
|
}
|
|
|
|
#[bench]
|
|
fn small_sse41(b: &mut test::Bencher) {
|
|
if self::is_x86_feature_detected!("sse4.1") {
|
|
doit(b, SMALL_LEN, hex_encode_sse41);
|
|
}
|
|
}
|
|
|
|
#[bench]
|
|
fn large_avx2(b: &mut test::Bencher) {
|
|
if self::is_x86_feature_detected!("avx2") {
|
|
doit(b, LARGE_LEN, hex_encode_avx2);
|
|
}
|
|
}
|
|
|
|
#[bench]
|
|
fn large_sse41(b: &mut test::Bencher) {
|
|
if self::is_x86_feature_detected!("sse4.1") {
|
|
doit(b, LARGE_LEN, hex_encode_sse41);
|
|
}
|
|
}
|
|
}
|
|
}
|