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Diffstat (limited to 'src/libcore/benches/ascii.rs')
| -rw-r--r-- | src/libcore/benches/ascii.rs | 351 |
1 files changed, 0 insertions, 351 deletions
diff --git a/src/libcore/benches/ascii.rs b/src/libcore/benches/ascii.rs deleted file mode 100644 index 05dd7adff1f..00000000000 --- a/src/libcore/benches/ascii.rs +++ /dev/null @@ -1,351 +0,0 @@ -mod is_ascii; - -// Lower-case ASCII 'a' is the first byte that has its highest bit set -// after wrap-adding 0x1F: -// -// b'a' + 0x1F == 0x80 == 0b1000_0000 -// b'z' + 0x1F == 0x98 == 0b1001_1000 -// -// Lower-case ASCII 'z' is the last byte that has its highest bit unset -// after wrap-adding 0x05: -// -// b'a' + 0x05 == 0x66 == 0b0110_0110 -// b'z' + 0x05 == 0x7F == 0b0111_1111 -// -// … except for 0xFB to 0xFF, but those are in the range of bytes -// that have the highest bit unset again after adding 0x1F. -// -// So `(byte + 0x1f) & !(byte + 5)` has its highest bit set -// iff `byte` is a lower-case ASCII letter. -// -// Lower-case ASCII letters all have the 0x20 bit set. -// (Two positions right of 0x80, the highest bit.) -// Unsetting that bit produces the same letter, in upper-case. -// -// Therefore: -fn branchless_to_ascii_upper_case(byte: u8) -> u8 { - byte & !((byte.wrapping_add(0x1f) & !byte.wrapping_add(0x05) & 0x80) >> 2) -} - -macro_rules! benches { - ($( fn $name: ident($arg: ident: &mut [u8]) $body: block )+ @iter $( $is_: ident, )+) => { - benches! {@ - $( fn $name($arg: &mut [u8]) $body )+ - $( fn $is_(bytes: &mut [u8]) { bytes.iter().all(u8::$is_) } )+ - } - }; - - (@$( fn $name: ident($arg: ident: &mut [u8]) $body: block )+) => { - benches!(mod short SHORT $($name $arg $body)+); - benches!(mod medium MEDIUM $($name $arg $body)+); - benches!(mod long LONG $($name $arg $body)+); - }; - - (mod $mod_name: ident $input: ident $($name: ident $arg: ident $body: block)+) => { - mod $mod_name { - use super::*; - - $( - #[bench] - fn $name(bencher: &mut Bencher) { - bencher.bytes = $input.len() as u64; - bencher.iter(|| { - let mut vec = $input.as_bytes().to_vec(); - { - let $arg = &mut vec[..]; - black_box($body); - } - vec - }) - } - )+ - } - } -} - -use test::black_box; -use test::Bencher; - -benches! { - fn case00_alloc_only(_bytes: &mut [u8]) {} - - fn case01_black_box_read_each_byte(bytes: &mut [u8]) { - for byte in bytes { - black_box(*byte); - } - } - - fn case02_lookup_table(bytes: &mut [u8]) { - for byte in bytes { - *byte = ASCII_UPPERCASE_MAP[*byte as usize] - } - } - - fn case03_branch_and_subtract(bytes: &mut [u8]) { - for byte in bytes { - *byte = if b'a' <= *byte && *byte <= b'z' { - *byte - b'a' + b'A' - } else { - *byte - } - } - } - - fn case04_branch_and_mask(bytes: &mut [u8]) { - for byte in bytes { - *byte = if b'a' <= *byte && *byte <= b'z' { - *byte & !0x20 - } else { - *byte - } - } - } - - fn case05_branchless(bytes: &mut [u8]) { - for byte in bytes { - *byte = branchless_to_ascii_upper_case(*byte) - } - } - - fn case06_libcore(bytes: &mut [u8]) { - bytes.make_ascii_uppercase() - } - - fn case07_fake_simd_u32(bytes: &mut [u8]) { - // SAFETY: transmuting a sequence of `u8` to `u32` is always fine - let (before, aligned, after) = unsafe { - bytes.align_to_mut::<u32>() - }; - for byte in before { - *byte = branchless_to_ascii_upper_case(*byte) - } - for word in aligned { - // FIXME: this is incorrect for some byte values: - // addition within a byte can carry/overflow into the next byte. - // Test case: b"\xFFz " - *word &= !( - ( - word.wrapping_add(0x1f1f1f1f) & - !word.wrapping_add(0x05050505) & - 0x80808080 - ) >> 2 - ) - } - for byte in after { - *byte = branchless_to_ascii_upper_case(*byte) - } - } - - fn case08_fake_simd_u64(bytes: &mut [u8]) { - // SAFETY: transmuting a sequence of `u8` to `u64` is always fine - let (before, aligned, after) = unsafe { - bytes.align_to_mut::<u64>() - }; - for byte in before { - *byte = branchless_to_ascii_upper_case(*byte) - } - for word in aligned { - // FIXME: like above, this is incorrect for some byte values. - *word &= !( - ( - word.wrapping_add(0x1f1f1f1f_1f1f1f1f) & - !word.wrapping_add(0x05050505_05050505) & - 0x80808080_80808080 - ) >> 2 - ) - } - for byte in after { - *byte = branchless_to_ascii_upper_case(*byte) - } - } - - fn case09_mask_mult_bool_branchy_lookup_table(bytes: &mut [u8]) { - fn is_ascii_lowercase(b: u8) -> bool { - if b >= 0x80 { return false } - match ASCII_CHARACTER_CLASS[b as usize] { - L | Lx => true, - _ => false, - } - } - for byte in bytes { - *byte &= !(0x20 * (is_ascii_lowercase(*byte) as u8)) - } - } - - fn case10_mask_mult_bool_lookup_table(bytes: &mut [u8]) { - fn is_ascii_lowercase(b: u8) -> bool { - match ASCII_CHARACTER_CLASS[b as usize] { - L | Lx => true, - _ => false - } - } - for byte in bytes { - *byte &= !(0x20 * (is_ascii_lowercase(*byte) as u8)) - } - } - - fn case11_mask_mult_bool_match_range(bytes: &mut [u8]) { - fn is_ascii_lowercase(b: u8) -> bool { - match b { - b'a'..=b'z' => true, - _ => false - } - } - for byte in bytes { - *byte &= !(0x20 * (is_ascii_lowercase(*byte) as u8)) - } - } - - fn case12_mask_shifted_bool_match_range(bytes: &mut [u8]) { - fn is_ascii_lowercase(b: u8) -> bool { - match b { - b'a'..=b'z' => true, - _ => false - } - } - for byte in bytes { - *byte &= !((is_ascii_lowercase(*byte) as u8) << 5) - } - } - - fn case13_subtract_shifted_bool_match_range(bytes: &mut [u8]) { - fn is_ascii_lowercase(b: u8) -> bool { - match b { - b'a'..=b'z' => true, - _ => false - } - } - for byte in bytes { - *byte -= (is_ascii_lowercase(*byte) as u8) << 5 - } - } - - fn case14_subtract_multiplied_bool_match_range(bytes: &mut [u8]) { - fn is_ascii_lowercase(b: u8) -> bool { - match b { - b'a'..=b'z' => true, - _ => false - } - } - for byte in bytes { - *byte -= (b'a' - b'A') * is_ascii_lowercase(*byte) as u8 - } - } - - @iter - - is_ascii, - is_ascii_alphabetic, - is_ascii_uppercase, - is_ascii_lowercase, - is_ascii_alphanumeric, - is_ascii_digit, - is_ascii_hexdigit, - is_ascii_punctuation, - is_ascii_graphic, - is_ascii_whitespace, - is_ascii_control, -} - -macro_rules! repeat { - ($s: expr) => { - concat!($s, $s, $s, $s, $s, $s, $s, $s, $s, $s) - }; -} - -const SHORT: &'static str = "Alice's"; -const MEDIUM: &'static str = "Alice's Adventures in Wonderland"; -const LONG: &'static str = repeat!( - r#" - La Guida di Bragia, a Ballad Opera for the Marionette Theatre (around 1850) - Alice's Adventures in Wonderland (1865) - Phantasmagoria and Other Poems (1869) - Through the Looking-Glass, and What Alice Found There - (includes "Jabberwocky" and "The Walrus and the Carpenter") (1871) - The Hunting of the Snark (1876) - Rhyme? And Reason? (1883) – shares some contents with the 1869 collection, - including the long poem "Phantasmagoria" - A Tangled Tale (1885) - Sylvie and Bruno (1889) - Sylvie and Bruno Concluded (1893) - Pillow Problems (1893) - What the Tortoise Said to Achilles (1895) - Three Sunsets and Other Poems (1898) - The Manlet (1903)[106] -"# -); - -#[rustfmt::skip] -const ASCII_UPPERCASE_MAP: [u8; 256] = [ - 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, - 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, - 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, - 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, - b' ', b'!', b'"', b'#', b'$', b'%', b'&', b'\'', - b'(', b')', b'*', b'+', b',', b'-', b'.', b'/', - b'0', b'1', b'2', b'3', b'4', b'5', b'6', b'7', - b'8', b'9', b':', b';', b'<', b'=', b'>', b'?', - b'@', b'A', b'B', b'C', b'D', b'E', b'F', b'G', - b'H', b'I', b'J', b'K', b'L', b'M', b'N', b'O', - b'P', b'Q', b'R', b'S', b'T', b'U', b'V', b'W', - b'X', b'Y', b'Z', b'[', b'\\', b']', b'^', b'_', - b'`', - - b'A', b'B', b'C', b'D', b'E', b'F', b'G', - b'H', b'I', b'J', b'K', b'L', b'M', b'N', b'O', - b'P', b'Q', b'R', b'S', b'T', b'U', b'V', b'W', - b'X', b'Y', b'Z', - - b'{', b'|', b'}', b'~', 0x7f, - 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, - 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f, - 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, - 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f, - 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7, - 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf, - 0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, - 0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf, - 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, - 0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf, - 0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, - 0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf, - 0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, - 0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef, - 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, - 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff, -]; - -enum AsciiCharacterClass { - C, // control - Cw, // control whitespace - W, // whitespace - D, // digit - L, // lowercase - Lx, // lowercase hex digit - U, // uppercase - Ux, // uppercase hex digit - P, // punctuation - N, // Non-ASCII -} -use self::AsciiCharacterClass::*; - -#[rustfmt::skip] -static ASCII_CHARACTER_CLASS: [AsciiCharacterClass; 256] = [ -// _0 _1 _2 _3 _4 _5 _6 _7 _8 _9 _a _b _c _d _e _f - C, C, C, C, C, C, C, C, C, Cw,Cw,C, Cw,Cw,C, C, // 0_ - C, C, C, C, C, C, C, C, C, C, C, C, C, C, C, C, // 1_ - W, P, P, P, P, P, P, P, P, P, P, P, P, P, P, P, // 2_ - D, D, D, D, D, D, D, D, D, D, P, P, P, P, P, P, // 3_ - P, Ux,Ux,Ux,Ux,Ux,Ux,U, U, U, U, U, U, U, U, U, // 4_ - U, U, U, U, U, U, U, U, U, U, U, P, P, P, P, P, // 5_ - P, Lx,Lx,Lx,Lx,Lx,Lx,L, L, L, L, L, L, L, L, L, // 6_ - L, L, L, L, L, L, L, L, L, L, L, P, P, P, P, C, // 7_ - N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, - N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, - N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, - N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, - N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, - N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, - N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, - N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, -]; |