From 8740d5d171fbb2fc9a12e46ecda32a0124badb46 Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Mon, 18 Mar 2019 20:08:32 +0100
Subject: [PATCH 01/11] Add benchmarks for [u8]::make_ascii_uppercase
---
src/libcore/benches/ascii_case.rs | 172 ++++++++++++++++++++++++++++++
src/libcore/benches/lib.rs | 1 +
2 files changed, 173 insertions(+)
create mode 100644 src/libcore/benches/ascii_case.rs
diff --git a/src/libcore/benches/ascii_case.rs b/src/libcore/benches/ascii_case.rs
new file mode 100644
index 0000000000000..43242ca3f364e
--- /dev/null
+++ b/src/libcore/benches/ascii_case.rs
@@ -0,0 +1,172 @@
+// 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 == 0b10011000
+//
+// 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 )+) => {
+ 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[..];
+ $body
+ }
+ vec
+ })
+ }
+ )+
+ }
+ }
+}
+
+use test::black_box;
+use test::Bencher;
+
+benches! {
+ fn bench00_alloc_only(_bytes: &mut [u8]) {}
+
+ fn bench01_black_box_read_each_byte(bytes: &mut [u8]) {
+ for byte in bytes {
+ black_box(*byte);
+ }
+ }
+
+ fn bench02_lookup(bytes: &mut [u8]) {
+ for byte in bytes {
+ *byte = ASCII_UPPERCASE_MAP[*byte as usize]
+ }
+ }
+
+ fn bench03_branch_and_subtract(bytes: &mut [u8]) {
+ for byte in bytes {
+ *byte = if b'a' <= *byte && *byte <= b'z' {
+ *byte - b'a' + b'A'
+ } else {
+ *byte
+ }
+ }
+ }
+
+ fn bench04_branch_and_mask(bytes: &mut [u8]) {
+ for byte in bytes {
+ *byte = if b'a' <= *byte && *byte <= b'z' {
+ *byte & !0x20
+ } else {
+ *byte
+ }
+ }
+ }
+
+ fn bench05_branchless(bytes: &mut [u8]) {
+ for byte in bytes {
+ *byte = branchless_to_ascii_upper_case(*byte)
+ }
+ }
+
+ fn bench06_libcore(bytes: &mut [u8]) {
+ bytes.make_ascii_uppercase()
+ }
+}
+
+macro_rules! repeat {
+ ($s: expr) => { concat!($s, $s, $s, $s, $s, $s, $s, $s, $s, $s) }
+}
+
+const SHORT: &'static str = "Alice's";
+const MEDIUM: &'static str = "Alice's Adventures in Wonderland";
+const LONG: &'static str = repeat!(r#"
+ La Guida di Bragia, a Ballad Opera for the Marionette Theatre (around 1850)
+ Alice's Adventures in Wonderland (1865)
+ Phantasmagoria and Other Poems (1869)
+ Through the Looking-Glass, and What Alice Found There (includes "Jabberwocky" and "The Walrus and the Carpenter") (1871)
+ The Hunting of the Snark (1876)
+ Rhyme? And Reason? (1883) – shares some contents with the 1869 collection, including the long poem "Phantasmagoria"
+ A Tangled Tale (1885)
+ Sylvie and Bruno (1889)
+ Sylvie and Bruno Concluded (1893)
+ Pillow Problems (1893)
+ What the Tortoise Said to Achilles (1895)
+ Three Sunsets and Other Poems (1898)
+ The Manlet (1903)[106]
+"#);
+
+const ASCII_UPPERCASE_MAP: [u8; 256] = [
+ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+ 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+ 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+ 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
+ b' ', b'!', b'"', b'#', b'$', 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,
+];
+
diff --git a/src/libcore/benches/lib.rs b/src/libcore/benches/lib.rs
index 48572af611a5b..b72d035b0ce94 100644
--- a/src/libcore/benches/lib.rs
+++ b/src/libcore/benches/lib.rs
@@ -5,6 +5,7 @@ extern crate core;
extern crate test;
mod any;
+mod ascii_case;
mod char;
mod hash;
mod iter;
From ce933f77c865a15670855ac5941fe200752b739f Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Mon, 18 Mar 2019 20:16:37 +0100
Subject: [PATCH 02/11] Make u8::to_ascii_lowercase and to_ascii_uppercase
branchless
---
src/libcore/benches/ascii_case.rs | 22 +-----
src/libcore/num/mod.rs | 122 ++++++++++--------------------
2 files changed, 43 insertions(+), 101 deletions(-)
diff --git a/src/libcore/benches/ascii_case.rs b/src/libcore/benches/ascii_case.rs
index 43242ca3f364e..1c9691d1ee173 100644
--- a/src/libcore/benches/ascii_case.rs
+++ b/src/libcore/benches/ascii_case.rs
@@ -1,24 +1,4 @@
-// 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 == 0b10011000
-//
-// 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:
+// See comments in `u8::to_ascii_uppercase` in `src/libcore/num/mod.rs`.
fn branchless_to_ascii_upper_case(byte: u8) -> u8 {
byte &
!(
diff --git a/src/libcore/num/mod.rs b/src/libcore/num/mod.rs
index d93cfbc2a28ac..977e21e0dc89a 100644
--- a/src/libcore/num/mod.rs
+++ b/src/libcore/num/mod.rs
@@ -3794,7 +3794,39 @@ impl u8 {
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
#[inline]
pub fn to_ascii_uppercase(&self) -> u8 {
- ASCII_UPPERCASE_MAP[*self as usize]
+ // See benchmarks in src/libcore/benches/ascii_case.rs
+
+ // 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 == 0b10011000
+ //
+ // 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:
+ *self &
+ !(
+ (
+ self.wrapping_add(0x1f) &
+ !self.wrapping_add(0x05) &
+ 0x80
+ ) >> 2
+ )
}
/// Makes a copy of the value in its ASCII lower case equivalent.
@@ -3816,7 +3848,15 @@ impl u8 {
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
#[inline]
pub fn to_ascii_lowercase(&self) -> u8 {
- ASCII_LOWERCASE_MAP[*self as usize]
+ // See comments in to_ascii_uppercase above.
+ *self |
+ (
+ (
+ self.wrapping_add(0x3f) &
+ !self.wrapping_add(0x25) &
+ 0x80
+ ) >> 2
+ )
}
/// Checks that two values are an ASCII case-insensitive match.
@@ -4940,84 +4980,6 @@ impl_from! { u32, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0"
// Float -> Float
impl_from! { f32, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
-static ASCII_LOWERCASE_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'$', b'%', b'&', b'\'',
- b'(', b')', b'*', b'+', b',', b'-', b'.', b'/',
- b'0', b'1', b'2', b'3', b'4', b'5', b'6', b'7',
- b'8', b'9', b':', b';', b'<', b'=', b'>', b'?',
- b'@',
-
- b'a', b'b', b'c', b'd', b'e', b'f', b'g',
- b'h', b'i', b'j', b'k', b'l', b'm', b'n', b'o',
- b'p', b'q', b'r', b's', b't', b'u', b'v', b'w',
- b'x', b'y', b'z',
-
- b'[', b'\\', b']', b'^', b'_',
- b'`', b'a', b'b', b'c', b'd', b'e', b'f', b'g',
- b'h', b'i', b'j', b'k', b'l', b'm', b'n', b'o',
- b'p', b'q', b'r', b's', b't', b'u', b'v', b'w',
- b'x', b'y', b'z', b'{', b'|', b'}', b'~', 0x7f,
- 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
- 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
- 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
- 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,
- 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
- 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
- 0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7,
- 0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,
- 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
- 0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,
- 0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7,
- 0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
- 0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7,
- 0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,
- 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
- 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff,
-];
-
-static ASCII_UPPERCASE_MAP: [u8; 256] = [
- 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
- 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
- 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
- 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
- b' ', b'!', b'"', b'#', b'$', 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
From fbe34cc521a5d0f04dd6afadb5b200f0338f41d9 Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Mon, 18 Mar 2019 20:40:32 +0100
Subject: [PATCH 03/11] =?UTF-8?q?Add=20benchmark=20for=20not-quite-correct?=
=?UTF-8?q?=20=E2=80=9Cfake=20SIMD=E2=80=9D=20make=5Fascii=5Fuppercase?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
---
src/libcore/benches/ascii_case.rs | 46 +++++++++++++++++++++++++++++++
1 file changed, 46 insertions(+)
diff --git a/src/libcore/benches/ascii_case.rs b/src/libcore/benches/ascii_case.rs
index 1c9691d1ee173..df82a8cb1d537 100644
--- a/src/libcore/benches/ascii_case.rs
+++ b/src/libcore/benches/ascii_case.rs
@@ -87,6 +87,52 @@ benches! {
fn bench06_libcore(bytes: &mut [u8]) {
bytes.make_ascii_uppercase()
}
+
+ fn bench07_fake_simd_u32(bytes: &mut [u8]) {
+ 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 bench08_fake_simd_u64(bytes: &mut [u8]) {
+ 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)
+ }
+ }
}
macro_rules! repeat {
From e3fb6f89fef4fea94deeac572b0373843560c2d6 Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Mon, 18 Mar 2019 21:28:33 +0100
Subject: [PATCH 04/11] Tidy
---
src/libcore/benches/ascii_case.rs | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/src/libcore/benches/ascii_case.rs b/src/libcore/benches/ascii_case.rs
index df82a8cb1d537..dcc87cc45b1e3 100644
--- a/src/libcore/benches/ascii_case.rs
+++ b/src/libcore/benches/ascii_case.rs
@@ -145,9 +145,11 @@ 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)
+ 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"
+ 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)
From 525a043c6bc8a220b7dbdde3eb10bb79f8e99506 Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Mon, 18 Mar 2019 23:32:36 +0100
Subject: [PATCH 05/11] Rename src/libcore/benches/ascii_case.rs to ascii.rs
---
src/libcore/benches/{ascii_case.rs => ascii.rs} | 6 ++++++
src/libcore/benches/lib.rs | 2 +-
2 files changed, 7 insertions(+), 1 deletion(-)
rename src/libcore/benches/{ascii_case.rs => ascii.rs} (97%)
diff --git a/src/libcore/benches/ascii_case.rs b/src/libcore/benches/ascii.rs
similarity index 97%
rename from src/libcore/benches/ascii_case.rs
rename to src/libcore/benches/ascii.rs
index dcc87cc45b1e3..2714a8a5c278e 100644
--- a/src/libcore/benches/ascii_case.rs
+++ b/src/libcore/benches/ascii.rs
@@ -84,6 +84,12 @@ benches! {
}
}
+ fn bench05_multiply_by_bool(bytes: &mut [u8]) {
+ for byte in bytes {
+ *byte &= !(0x20 * (b'a' <= *byte && *byte <= b'z') as u8)
+ }
+ }
+
fn bench06_libcore(bytes: &mut [u8]) {
bytes.make_ascii_uppercase()
}
diff --git a/src/libcore/benches/lib.rs b/src/libcore/benches/lib.rs
index b72d035b0ce94..707cdd5f450ea 100644
--- a/src/libcore/benches/lib.rs
+++ b/src/libcore/benches/lib.rs
@@ -5,7 +5,7 @@ extern crate core;
extern crate test;
mod any;
-mod ascii_case;
+mod ascii;
mod char;
mod hash;
mod iter;
From 6d3840b23a185d057cc9792a2516e6a71887f277 Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Mon, 18 Mar 2019 23:56:50 +0100
Subject: [PATCH 06/11] Add benchmarks for `u8::is_ascii*`
---
src/libcore/benches/ascii.rs | 49 +++++++++++++++++++++++-------------
1 file changed, 32 insertions(+), 17 deletions(-)
diff --git a/src/libcore/benches/ascii.rs b/src/libcore/benches/ascii.rs
index 2714a8a5c278e..e20b1b9bf3136 100644
--- a/src/libcore/benches/ascii.rs
+++ b/src/libcore/benches/ascii.rs
@@ -12,7 +12,14 @@ fn branchless_to_ascii_upper_case(byte: u8) -> u8 {
macro_rules! benches {
- ($( fn $name: ident($arg: ident: &mut [u8]) $body: block )+) => {
+ ($( 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)+);
@@ -30,7 +37,7 @@ macro_rules! benches {
let mut vec = $input.as_bytes().to_vec();
{
let $arg = &mut vec[..];
- $body
+ black_box($body);
}
vec
})
@@ -44,21 +51,21 @@ use test::black_box;
use test::Bencher;
benches! {
- fn bench00_alloc_only(_bytes: &mut [u8]) {}
+ fn case00_alloc_only(_bytes: &mut [u8]) {}
- fn bench01_black_box_read_each_byte(bytes: &mut [u8]) {
+ fn case01_black_box_read_each_byte(bytes: &mut [u8]) {
for byte in bytes {
black_box(*byte);
}
}
- fn bench02_lookup(bytes: &mut [u8]) {
+ fn case02_lookup(bytes: &mut [u8]) {
for byte in bytes {
*byte = ASCII_UPPERCASE_MAP[*byte as usize]
}
}
- fn bench03_branch_and_subtract(bytes: &mut [u8]) {
+ 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'
@@ -68,7 +75,7 @@ benches! {
}
}
- fn bench04_branch_and_mask(bytes: &mut [u8]) {
+ fn case04_branch_and_mask(bytes: &mut [u8]) {
for byte in bytes {
*byte = if b'a' <= *byte && *byte <= b'z' {
*byte & !0x20
@@ -78,23 +85,17 @@ benches! {
}
}
- fn bench05_branchless(bytes: &mut [u8]) {
+ fn case05_branchless(bytes: &mut [u8]) {
for byte in bytes {
*byte = branchless_to_ascii_upper_case(*byte)
}
}
- fn bench05_multiply_by_bool(bytes: &mut [u8]) {
- for byte in bytes {
- *byte &= !(0x20 * (b'a' <= *byte && *byte <= b'z') as u8)
- }
- }
-
- fn bench06_libcore(bytes: &mut [u8]) {
+ fn case06_libcore(bytes: &mut [u8]) {
bytes.make_ascii_uppercase()
}
- fn bench07_fake_simd_u32(bytes: &mut [u8]) {
+ fn case07_fake_simd_u32(bytes: &mut [u8]) {
let (before, aligned, after) = unsafe {
bytes.align_to_mut::<u32>()
};
@@ -118,7 +119,7 @@ benches! {
}
}
- fn bench08_fake_simd_u64(bytes: &mut [u8]) {
+ fn case08_fake_simd_u64(bytes: &mut [u8]) {
let (before, aligned, after) = unsafe {
bytes.align_to_mut::<u64>()
};
@@ -139,6 +140,20 @@ benches! {
*byte = branchless_to_ascii_upper_case(*byte)
}
}
+
+ @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 {
From b4faa9b45635ae5185d562701d7429e5fbb08c8b Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Mon, 18 Mar 2019 23:57:09 +0100
Subject: [PATCH 07/11] Remove ASCII_CHARACTER_CLASS table, use `match` with
range patterns instead.
---
src/libcore/num/mod.rs | 75 +++++++++++-------------------------------
1 file changed, 20 insertions(+), 55 deletions(-)
diff --git a/src/libcore/num/mod.rs b/src/libcore/num/mod.rs
index 977e21e0dc89a..64469a4b7e43c 100644
--- a/src/libcore/num/mod.rs
+++ b/src/libcore/num/mod.rs
@@ -3958,9 +3958,8 @@ impl u8 {
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
#[inline]
pub fn is_ascii_alphabetic(&self) -> bool {
- if *self >= 0x80 { return false; }
- match ASCII_CHARACTER_CLASS[*self as usize] {
- L | Lx | U | Ux => true,
+ match *self {
+ b'A'...b'Z' | b'a'...b'z' => true,
_ => false
}
}
@@ -3994,9 +3993,8 @@ impl u8 {
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
#[inline]
pub fn is_ascii_uppercase(&self) -> bool {
- if *self >= 0x80 { return false }
- match ASCII_CHARACTER_CLASS[*self as usize] {
- U | Ux => true,
+ match *self {
+ b'A'...b'Z' => true,
_ => false
}
}
@@ -4030,9 +4028,8 @@ impl u8 {
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
#[inline]
pub fn is_ascii_lowercase(&self) -> bool {
- if *self >= 0x80 { return false }
- match ASCII_CHARACTER_CLASS[*self as usize] {
- L | Lx => true,
+ match *self {
+ b'a'...b'z' => true,
_ => false
}
}
@@ -4069,9 +4066,8 @@ impl u8 {
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
#[inline]
pub fn is_ascii_alphanumeric(&self) -> bool {
- if *self >= 0x80 { return false }
- match ASCII_CHARACTER_CLASS[*self as usize] {
- D | L | Lx | U | Ux => true,
+ match *self {
+ b'0'...b'9' | b'A'...b'Z' | b'a'...b'z' => true,
_ => false
}
}
@@ -4105,9 +4101,8 @@ impl u8 {
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
#[inline]
pub fn is_ascii_digit(&self) -> bool {
- if *self >= 0x80 { return false }
- match ASCII_CHARACTER_CLASS[*self as usize] {
- D => true,
+ match *self {
+ b'0'...b'9' => true,
_ => false
}
}
@@ -4144,9 +4139,8 @@ impl u8 {
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
#[inline]
pub fn is_ascii_hexdigit(&self) -> bool {
- if *self >= 0x80 { return false }
- match ASCII_CHARACTER_CLASS[*self as usize] {
- D | Lx | Ux => true,
+ match *self {
+ b'0'...b'9' | b'A'...b'F' | b'a'...b'f' => true,
_ => false
}
}
@@ -4184,9 +4178,8 @@ impl u8 {
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
#[inline]
pub fn is_ascii_punctuation(&self) -> bool {
- if *self >= 0x80 { return false }
- match ASCII_CHARACTER_CLASS[*self as usize] {
- P => true,
+ match *self {
+ b'!'...b'/' | b':'...b'@' | b'['...b'`' | b'{'...b'~' => true,
_ => false
}
}
@@ -4220,9 +4213,8 @@ impl u8 {
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
#[inline]
pub fn is_ascii_graphic(&self) -> bool {
- if *self >= 0x80 { return false; }
- match ASCII_CHARACTER_CLASS[*self as usize] {
- Ux | U | Lx | L | D | P => true,
+ match *self {
+ b'!'...b'~' => true,
_ => false
}
}
@@ -4273,9 +4265,8 @@ impl u8 {
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
#[inline]
pub fn is_ascii_whitespace(&self) -> bool {
- if *self >= 0x80 { return false; }
- match ASCII_CHARACTER_CLASS[*self as usize] {
- Cw | W => true,
+ match *self {
+ b'\t' | b'\n' | b'\x0C' | b'\r' | b' ' => true,
_ => false
}
}
@@ -4311,9 +4302,8 @@ impl u8 {
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
#[inline]
pub fn is_ascii_control(&self) -> bool {
- if *self >= 0x80 { return false; }
- match ASCII_CHARACTER_CLASS[*self as usize] {
- C | Cw => true,
+ match *self {
+ b'\0'...b'\x1F' | b'\x7F' => true,
_ => false
}
}
@@ -4979,28 +4969,3 @@ impl_from! { u32, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0"
// Float -> Float
impl_from! { f32, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
-
-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
-}
-use self::AsciiCharacterClass::*;
-
-static ASCII_CHARACTER_CLASS: [AsciiCharacterClass; 128] = [
-// _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_
-];
From 4a3241a815e951dfa87e9be7133e8265bc945e57 Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Tue, 19 Mar 2019 00:34:27 +0100
Subject: [PATCH 08/11] Benchmark more possibles impls of
[u8]::make_ascii_uppercase
---
src/libcore/benches/ascii.rs | 84 +++++++++++++++++++++++++++++++++++-
1 file changed, 83 insertions(+), 1 deletion(-)
diff --git a/src/libcore/benches/ascii.rs b/src/libcore/benches/ascii.rs
index e20b1b9bf3136..ce36027394a48 100644
--- a/src/libcore/benches/ascii.rs
+++ b/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,
+];
From 0ad91f73d92c3b8d3978f8f54c04b8efe3d2e673 Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Tue, 19 Mar 2019 00:50:26 +0100
Subject: [PATCH 09/11] Simplify u8::to_ascii_{upp,low}ercase while keeping it
fast
---
src/libcore/benches/ascii.rs | 24 ++++++++++++++++++-
src/libcore/num/mod.rs | 46 ++++--------------------------------
2 files changed, 27 insertions(+), 43 deletions(-)
diff --git a/src/libcore/benches/ascii.rs b/src/libcore/benches/ascii.rs
index ce36027394a48..89e67cca4b754 100644
--- a/src/libcore/benches/ascii.rs
+++ b/src/libcore/benches/ascii.rs
@@ -1,4 +1,26 @@
-// See comments in `u8::to_ascii_uppercase` in `src/libcore/num/mod.rs`.
+// 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 == 0b10011000
+//
+// 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 &
!(
diff --git a/src/libcore/num/mod.rs b/src/libcore/num/mod.rs
index 64469a4b7e43c..3fcae6b94b06d 100644
--- a/src/libcore/num/mod.rs
+++ b/src/libcore/num/mod.rs
@@ -3794,39 +3794,8 @@ impl u8 {
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
#[inline]
pub fn to_ascii_uppercase(&self) -> u8 {
- // See benchmarks in src/libcore/benches/ascii_case.rs
-
- // 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 == 0b10011000
- //
- // 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:
- *self &
- !(
- (
- self.wrapping_add(0x1f) &
- !self.wrapping_add(0x05) &
- 0x80
- ) >> 2
- )
+ // Unset the fith bit if this is a lowercase letter
+ *self & !((self.is_ascii_lowercase() as u8) << 5)
}
/// Makes a copy of the value in its ASCII lower case equivalent.
@@ -3848,15 +3817,8 @@ impl u8 {
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
#[inline]
pub fn to_ascii_lowercase(&self) -> u8 {
- // See comments in to_ascii_uppercase above.
- *self |
- (
- (
- self.wrapping_add(0x3f) &
- !self.wrapping_add(0x25) &
- 0x80
- ) >> 2
- )
+ // Set the fith bit if this is an uppercase letter
+ *self | ((self.is_ascii_uppercase() as u8) << 5)
}
/// Checks that two values are an ASCII case-insensitive match.
From c1ec29ace000ce4c733cde6948c87f9bc2370691 Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Tue, 19 Mar 2019 08:32:15 +0100
Subject: [PATCH 10/11] ASCII uppercase: add "subtract shifted bool" benchmark
---
src/libcore/benches/ascii.rs | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/src/libcore/benches/ascii.rs b/src/libcore/benches/ascii.rs
index 89e67cca4b754..968d28a995897 100644
--- a/src/libcore/benches/ascii.rs
+++ b/src/libcore/benches/ascii.rs
@@ -212,6 +212,18 @@ benches! {
}
}
+ 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
+ }
+ }
+
@iter
is_ascii,
From 7fad370fe9dc000f6f6f497a1939de6196e2c4fc Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Tue, 19 Mar 2019 13:41:59 +0100
Subject: [PATCH 11/11] ASCII uppercase: add "subtract multiplied bool"
benchmark
---
src/libcore/benches/ascii.rs | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/src/libcore/benches/ascii.rs b/src/libcore/benches/ascii.rs
index 968d28a995897..635537e312158 100644
--- a/src/libcore/benches/ascii.rs
+++ b/src/libcore/benches/ascii.rs
@@ -224,6 +224,18 @@ benches! {
}
}
+ 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,