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Benchmark more possibles impls of [u8]::make_ascii_uppercase

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SimonSapin committed Mar 18, 2019
1 parent b4faa9b commit 4a3241a815e951dfa87e9be7133e8265bc945e57
Showing with 83 additions and 1 deletion.
  1. +83 −1 src/libcore/benches/ascii.rs
@@ -59,7 +59,7 @@ benches! {
}
}

fn case02_lookup(bytes: &mut [u8]) {
fn case02_lookup_table(bytes: &mut [u8]) {
for byte in bytes {
*byte = ASCII_UPPERCASE_MAP[*byte as usize]
}
@@ -141,6 +141,55 @@ benches! {
}
}

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)
}
}

@iter

is_ascii,
@@ -219,3 +268,36 @@ const ASCII_UPPERCASE_MAP: [u8; 256] = [
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::*;

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,
];

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