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Auto merge of #37312 - arthurprs:sip-smaller, r=alexcrichton
Small improvement to SipHasher Very small but constant improvement, the objective is to lower latency for u16, u32 and small strings. CC #35735 ``` ➜ siphash-bench git:(master) ✗ sudo nice -n -20 target/release/foo-648738a54f390643 --bench | tee benches.txt [sudo] password for arthurprs: running 62 tests test _same ... bench: 0 ns/iter (+/- 0) test _warmup ... bench: 0 ns/iter (+/- 0) test rust_siphash13::int_u16 ... bench: 12 ns/iter (+/- 1) test rust_siphash13::int_u32 ... bench: 14 ns/iter (+/- 0) test rust_siphash13::int_u64 ... bench: 11 ns/iter (+/- 1) test rust_siphash13::int_u8 ... bench: 11 ns/iter (+/- 1) test rust_siphash13::slice::_10 ... bench: 18 ns/iter (+/- 1) test rust_siphash13::slice::_100 ... bench: 42 ns/iter (+/- 2) test rust_siphash13::slice::_11 ... bench: 19 ns/iter (+/- 1) test rust_siphash13::slice::_12 ... bench: 21 ns/iter (+/- 3) test rust_siphash13::slice::_2 ... bench: 16 ns/iter (+/- 2) test rust_siphash13::slice::_200 ... bench: 68 ns/iter (+/- 3) test rust_siphash13::slice::_3 ... bench: 17 ns/iter (+/- 3) test rust_siphash13::slice::_4 ... bench: 18 ns/iter (+/- 1) test rust_siphash13::slice::_5 ... bench: 19 ns/iter (+/- 4) test rust_siphash13::slice::_6 ... bench: 19 ns/iter (+/- 1) test rust_siphash13::slice::_7 ... bench: 20 ns/iter (+/- 1) test rust_siphash13::slice::_8 ... bench: 16 ns/iter (+/- 1) test rust_siphash13::slice::_9 ... bench: 18 ns/iter (+/- 2) test rust_siphash13::str_::_10 ... bench: 18 ns/iter (+/- 1) test rust_siphash13::str_::_100 ... bench: 41 ns/iter (+/- 2) test rust_siphash13::str_::_11 ... bench: 19 ns/iter (+/- 1) test rust_siphash13::str_::_12 ... bench: 20 ns/iter (+/- 2) test rust_siphash13::str_::_2 ... bench: 16 ns/iter (+/- 1) test rust_siphash13::str_::_200 ... bench: 68 ns/iter (+/- 3) test rust_siphash13::str_::_3 ... bench: 17 ns/iter (+/- 1) test rust_siphash13::str_::_4 ... bench: 18 ns/iter (+/- 2) test rust_siphash13::str_::_5 ... bench: 19 ns/iter (+/- 6) test rust_siphash13::str_::_6 ... bench: 20 ns/iter (+/- 5) test rust_siphash13::str_::_7 ... bench: 23 ns/iter (+/- 1) test rust_siphash13::str_::_8 ... bench: 15 ns/iter (+/- 1) test rust_siphash13::str_::_9 ... bench: 17 ns/iter (+/- 1) test sip1b::int_u16 ... bench: 10 ns/iter (+/- 1) test sip1b::int_u32 ... bench: 9 ns/iter (+/- 1) test sip1b::int_u64 ... bench: 12 ns/iter (+/- 1) test sip1b::int_u8 ... bench: 7 ns/iter (+/- 0) test sip1b::slice::_10 ... bench: 12 ns/iter (+/- 1) test sip1b::slice::_100 ... bench: 33 ns/iter (+/- 2) test sip1b::slice::_11 ... bench: 13 ns/iter (+/- 0) test sip1b::slice::_12 ... bench: 12 ns/iter (+/- 1) test sip1b::slice::_2 ... bench: 10 ns/iter (+/- 0) test sip1b::slice::_200 ... bench: 62 ns/iter (+/- 2) test sip1b::slice::_3 ... bench: 10 ns/iter (+/- 1) test sip1b::slice::_4 ... bench: 9 ns/iter (+/- 0) test sip1b::slice::_5 ... bench: 10 ns/iter (+/- 1) test sip1b::slice::_6 ... bench: 10 ns/iter (+/- 0) test sip1b::slice::_7 ... bench: 11 ns/iter (+/- 0) test sip1b::slice::_8 ... bench: 11 ns/iter (+/- 1) test sip1b::slice::_9 ... bench: 12 ns/iter (+/- 1) test sip1b::str_::_10 ... bench: 15 ns/iter (+/- 1) test sip1b::str_::_100 ... bench: 37 ns/iter (+/- 3) test sip1b::str_::_11 ... bench: 16 ns/iter (+/- 1) test sip1b::str_::_12 ... bench: 14 ns/iter (+/- 1) test sip1b::str_::_2 ... bench: 13 ns/iter (+/- 1) test sip1b::str_::_200 ... bench: 67 ns/iter (+/- 5) test sip1b::str_::_3 ... bench: 14 ns/iter (+/- 2) test sip1b::str_::_4 ... bench: 12 ns/iter (+/- 1) test sip1b::str_::_5 ... bench: 13 ns/iter (+/- 1) test sip1b::str_::_6 ... bench: 13 ns/iter (+/- 0) test sip1b::str_::_7 ... bench: 16 ns/iter (+/- 1) test sip1b::str_::_8 ... bench: 14 ns/iter (+/- 1) test sip1b::str_::_9 ... bench: 15 ns/iter (+/- 1) test result: ok. 0 passed; 0 failed; 0 ignored; 62 measured ➜ siphash-bench git:(master) ✗ cargo benchcmp rust_siphash13:: sip1b:: benches.txt name rust_siphash13:: ns/iter sip1b:: ns/iter diff ns/iter diff % int_u16 12 10 -2 -16.67% int_u32 14 9 -5 -35.71% int_u64 11 12 1 9.09% int_u8 11 7 -4 -36.36% slice::_10 18 12 -6 -33.33% slice::_100 42 33 -9 -21.43% slice::_11 19 13 -6 -31.58% slice::_12 21 12 -9 -42.86% slice::_2 16 10 -6 -37.50% slice::_200 68 62 -6 -8.82% slice::_3 17 10 -7 -41.18% slice::_4 18 9 -9 -50.00% slice::_5 19 10 -9 -47.37% slice::_6 19 10 -9 -47.37% slice::_7 20 11 -9 -45.00% slice::_8 16 11 -5 -31.25% slice::_9 18 12 -6 -33.33% str_::_10 18 15 -3 -16.67% str_::_100 41 37 -4 -9.76% str_::_11 19 16 -3 -15.79% str_::_12 20 14 -6 -30.00% str_::_2 16 13 -3 -18.75% str_::_200 68 67 -1 -1.47% str_::_3 17 14 -3 -17.65% str_::_4 18 12 -6 -33.33% str_::_5 19 13 -6 -31.58% str_::_6 20 13 -7 -35.00% str_::_7 23 16 -7 -30.43% str_::_8 15 14 -1 -6.67% str_::_9 17 15 -2 -11.76% ``` from a modified hash-rs suite (preallocating maps and adding having slice/str variants) graph version: http://imgur.com/a/DuoI4 ``` ➜ hash-rs git:(rfc-extend-hasher) ✗ cargo benchcmp sip13:: sip13opt:: benches.txt name sip13:: ns/iter sip13opt:: ns/iter diff ns/iter diff % slice::mapcountdense_000000001 27,343 (36 MB/s) 26,401 (37 MB/s) -942 -3.45% slice::mapcountdense_000000002 28,982 (69 MB/s) 26,807 (74 MB/s) -2,175 -7.50% slice::mapcountdense_000000003 29,304 (102 MB/s) 27,360 (109 MB/s) -1,944 -6.63% slice::mapcountdense_000000004 30,411 (131 MB/s) 25,888 (154 MB/s) -4,523 -14.87% slice::mapcountdense_000000005 32,625 (153 MB/s) 27,486 (181 MB/s) -5,139 -15.75% slice::mapcountdense_000000006 34,920 (171 MB/s) 27,204 (220 MB/s) -7,716 -22.10% slice::mapcountdense_000000007 33,497 (208 MB/s) 28,330 (247 MB/s) -5,167 -15.43% slice::mapcountdense_000000008 31,153 (256 MB/s) 28,617 (279 MB/s) -2,536 -8.14% slice::mapcountdense_000000009 30,745 (292 MB/s) 29,666 (303 MB/s) -1,079 -3.51% slice::mapcountdense_000000010 31,509 (317 MB/s) 29,804 (335 MB/s) -1,705 -5.41% slice::mapcountdense_000000011 32,526 (338 MB/s) 30,520 (360 MB/s) -2,006 -6.17% slice::mapcountdense_000000012 32,981 (363 MB/s) 28,739 (417 MB/s) -4,242 -12.86% slice::mapcountdense_000000013 34,713 (374 MB/s) 30,348 (428 MB/s) -4,365 -12.57% slice::mapcountdense_000000014 34,635 (404 MB/s) 29,974 (467 MB/s) -4,661 -13.46% slice::mapcountdense_000000015 35,924 (417 MB/s) 30,584 (490 MB/s) -5,340 -14.86% slice::mapcountdense_000000016 31,939 (500 MB/s) 30,564 (523 MB/s) -1,375 -4.31% slice::mapcountdense_000000032 36,545 (875 MB/s) 34,833 (918 MB/s) -1,712 -4.68% slice::mapcountdense_000000064 44,691 (1432 MB/s) 43,912 (1457 MB/s) -779 -1.74% slice::mapcountdense_000000128 67,210 (1904 MB/s) 64,630 (1980 MB/s) -2,580 -3.84% slice::mapcountdense_000000256 110,320 (2320 MB/s) 108,713 (2354 MB/s) -1,607 -1.46% slice::mapcountsparse_000000001 29,686 (33 MB/s) 28,673 (34 MB/s) -1,013 -3.41% slice::mapcountsparse_000000002 32,073 (62 MB/s) 30,519 (65 MB/s) -1,554 -4.85% slice::mapcountsparse_000000003 33,184 (90 MB/s) 31,208 (96 MB/s) -1,976 -5.95% slice::mapcountsparse_000000004 34,344 (116 MB/s) 30,242 (132 MB/s) -4,102 -11.94% slice::mapcountsparse_000000005 34,536 (144 MB/s) 30,552 (163 MB/s) -3,984 -11.54% slice::mapcountsparse_000000006 35,791 (167 MB/s) 30,813 (194 MB/s) -4,978 -13.91% slice::mapcountsparse_000000007 36,773 (190 MB/s) 31,362 (223 MB/s) -5,411 -14.71% slice::mapcountsparse_000000008 33,101 (241 MB/s) 32,399 (246 MB/s) -702 -2.12% slice::mapcountsparse_000000009 34,025 (264 MB/s) 33,065 (272 MB/s) -960 -2.82% slice::mapcountsparse_000000010 34,755 (287 MB/s) 33,152 (301 MB/s) -1,603 -4.61% slice::mapcountsparse_000000011 35,682 (308 MB/s) 33,631 (327 MB/s) -2,051 -5.75% slice::mapcountsparse_000000012 36,422 (329 MB/s) 32,604 (368 MB/s) -3,818 -10.48% slice::mapcountsparse_000000013 37,561 (346 MB/s) 32,978 (394 MB/s) -4,583 -12.20% slice::mapcountsparse_000000014 38,476 (363 MB/s) 33,376 (419 MB/s) -5,100 -13.26% slice::mapcountsparse_000000015 39,202 (382 MB/s) 33,750 (444 MB/s) -5,452 -13.91% slice::mapcountsparse_000000016 34,898 (458 MB/s) 33,621 (475 MB/s) -1,277 -3.66% slice::mapcountsparse_000000032 39,767 (804 MB/s) 38,013 (841 MB/s) -1,754 -4.41% slice::mapcountsparse_000000064 47,810 (1338 MB/s) 46,332 (1381 MB/s) -1,478 -3.09% slice::mapcountsparse_000000128 64,519 (1983 MB/s) 63,322 (2021 MB/s) -1,197 -1.86% slice::mapcountsparse_000000256 101,042 (2533 MB/s) 99,754 (2566 MB/s) -1,288 -1.27% str_::mapcountdense_000000001 27,183 (36 MB/s) 24,007 (41 MB/s) -3,176 -11.68% str_::mapcountdense_000000002 28,940 (69 MB/s) 24,574 (81 MB/s) -4,366 -15.09% str_::mapcountdense_000000003 29,000 (103 MB/s) 24,687 (121 MB/s) -4,313 -14.87% str_::mapcountdense_000000004 29,822 (134 MB/s) 24,377 (164 MB/s) -5,445 -18.26% str_::mapcountdense_000000005 31,962 (156 MB/s) 25,184 (198 MB/s) -6,778 -21.21% str_::mapcountdense_000000006 32,218 (186 MB/s) 25,020 (239 MB/s) -7,198 -22.34% str_::mapcountdense_000000007 35,482 (197 MB/s) 27,705 (252 MB/s) -7,777 -21.92% str_::mapcountdense_000000008 28,643 (279 MB/s) 25,563 (312 MB/s) -3,080 -10.75% str_::mapcountdense_000000009 30,112 (298 MB/s) 26,773 (336 MB/s) -3,339 -11.09% str_::mapcountdense_000000010 31,554 (316 MB/s) 27,607 (362 MB/s) -3,947 -12.51% str_::mapcountdense_000000011 32,062 (343 MB/s) 27,770 (396 MB/s) -4,292 -13.39% str_::mapcountdense_000000012 32,258 (372 MB/s) 25,612 (468 MB/s) -6,646 -20.60% str_::mapcountdense_000000013 33,544 (387 MB/s) 26,908 (483 MB/s) -6,636 -19.78% str_::mapcountdense_000000014 34,681 (403 MB/s) 27,267 (513 MB/s) -7,414 -21.38% str_::mapcountdense_000000015 37,883 (395 MB/s) 30,226 (496 MB/s) -7,657 -20.21% str_::mapcountdense_000000016 30,299 (528 MB/s) 27,960 (572 MB/s) -2,339 -7.72% str_::mapcountdense_000000032 34,372 (930 MB/s) 32,736 (977 MB/s) -1,636 -4.76% str_::mapcountdense_000000048 38,610 (1243 MB/s) 36,437 (1317 MB/s) -2,173 -5.63% str_::mapcountdense_000000064 43,052 (1486 MB/s) 41,269 (1550 MB/s) -1,783 -4.14% str_::mapcountdense_000000128 64,059 (1998 MB/s) 62,007 (2064 MB/s) -2,052 -3.20% str_::mapcountdense_000000256 109,608 (2335 MB/s) 107,184 (2388 MB/s) -2,424 -2.21% str_::mapcountsparse_000000001 29,155 (34 MB/s) 26,151 (38 MB/s) -3,004 -10.30% str_::mapcountsparse_000000002 31,536 (63 MB/s) 27,787 (71 MB/s) -3,749 -11.89% str_::mapcountsparse_000000003 32,524 (92 MB/s) 27,861 (107 MB/s) -4,663 -14.34% str_::mapcountsparse_000000004 33,535 (119 MB/s) 27,585 (145 MB/s) -5,950 -17.74% str_::mapcountsparse_000000005 34,239 (146 MB/s) 27,520 (181 MB/s) -6,719 -19.62% str_::mapcountsparse_000000006 35,485 (169 MB/s) 27,437 (218 MB/s) -8,048 -22.68% str_::mapcountsparse_000000007 39,098 (179 MB/s) 30,465 (229 MB/s) -8,633 -22.08% str_::mapcountsparse_000000008 30,882 (259 MB/s) 29,215 (273 MB/s) -1,667 -5.40% str_::mapcountsparse_000000009 33,375 (269 MB/s) 29,301 (307 MB/s) -4,074 -12.21% str_::mapcountsparse_000000010 33,531 (298 MB/s) 29,008 (344 MB/s) -4,523 -13.49% str_::mapcountsparse_000000011 34,607 (317 MB/s) 29,800 (369 MB/s) -4,807 -13.89% str_::mapcountsparse_000000012 35,700 (336 MB/s) 28,380 (422 MB/s) -7,320 -20.50% str_::mapcountsparse_000000013 36,692 (354 MB/s) 29,350 (442 MB/s) -7,342 -20.01% str_::mapcountsparse_000000014 37,326 (375 MB/s) 29,285 (478 MB/s) -8,041 -21.54% str_::mapcountsparse_000000015 41,098 (364 MB/s) 33,073 (453 MB/s) -8,025 -19.53% str_::mapcountsparse_000000016 33,046 (484 MB/s) 30,717 (520 MB/s) -2,329 -7.05% str_::mapcountsparse_000000032 37,471 (853 MB/s) 35,542 (900 MB/s) -1,929 -5.15% str_::mapcountsparse_000000048 41,324 (1161 MB/s) 39,332 (1220 MB/s) -1,992 -4.82% str_::mapcountsparse_000000064 45,858 (1395 MB/s) 43,802 (1461 MB/s) -2,056 -4.48% str_::mapcountsparse_000000128 62,471 (2048 MB/s) 60,683 (2109 MB/s) -1,788 -2.86% str_::mapcountsparse_000000256 101,283 (2527 MB/s) 97,655 (2621 MB/s) -3,628 -3.58% ```
2 parents a6b3b01 + a319d13 commit a5b6a9f

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‎src/libcore/hash/sip.rs‎

Lines changed: 97 additions & 50 deletions
Original file line numberDiff line numberDiff line change
@@ -14,6 +14,8 @@
1414

1515
use marker::PhantomData;
1616
use ptr;
17+
use cmp;
18+
use mem;
1719

1820
/// An implementation of SipHash 1-3.
1921
///
@@ -78,45 +80,6 @@ struct State {
7880
v3: u64,
7981
}
8082

81-
// sadly, these macro definitions can't appear later,
82-
// because they're needed in the following defs;
83-
// this design could be improved.
84-
85-
macro_rules! u8to64_le {
86-
($buf:expr, $i:expr) =>
87-
($buf[0+$i] as u64 |
88-
($buf[1+$i] as u64) << 8 |
89-
($buf[2+$i] as u64) << 16 |
90-
($buf[3+$i] as u64) << 24 |
91-
($buf[4+$i] as u64) << 32 |
92-
($buf[5+$i] as u64) << 40 |
93-
($buf[6+$i] as u64) << 48 |
94-
($buf[7+$i] as u64) << 56);
95-
($buf:expr, $i:expr, $len:expr) =>
96-
({
97-
let mut t = 0;
98-
let mut out = 0;
99-
while t < $len {
100-
out |= ($buf[t+$i] as u64) << t*8;
101-
t += 1;
102-
}
103-
out
104-
});
105-
}
106-
107-
/// Load a full u64 word from a byte stream, in LE order. Use
108-
/// `copy_nonoverlapping` to let the compiler generate the most efficient way
109-
/// to load u64 from a possibly unaligned address.
110-
///
111-
/// Unsafe because: unchecked indexing at i..i+8
112-
#[inline]
113-
unsafe fn load_u64_le(buf: &[u8], i: usize) -> u64 {
114-
debug_assert!(i + 8 <= buf.len());
115-
let mut data = 0u64;
116-
ptr::copy_nonoverlapping(buf.get_unchecked(i), &mut data as *mut _ as *mut u8, 8);
117-
data.to_le()
118-
}
119-
12083
macro_rules! compress {
12184
($state:expr) => ({
12285
compress!($state.v0, $state.v1, $state.v2, $state.v3)
@@ -132,6 +95,47 @@ macro_rules! compress {
13295
});
13396
}
13497

98+
/// Load an integer of the desired type from a byte stream, in LE order. Uses
99+
/// `copy_nonoverlapping` to let the compiler generate the most efficient way
100+
/// to load it from a possibly unaligned address.
101+
///
102+
/// Unsafe because: unchecked indexing at i..i+size_of(int_ty)
103+
macro_rules! load_int_le {
104+
($buf:expr, $i:expr, $int_ty:ident) =>
105+
({
106+
debug_assert!($i + mem::size_of::<$int_ty>() <= $buf.len());
107+
let mut data = 0 as $int_ty;
108+
ptr::copy_nonoverlapping($buf.get_unchecked($i),
109+
&mut data as *mut _ as *mut u8,
110+
mem::size_of::<$int_ty>());
111+
data.to_le()
112+
});
113+
}
114+
115+
/// Load an u64 using up to 7 bytes of a byte slice.
116+
///
117+
/// Unsafe because: unchecked indexing at start..start+len
118+
#[inline]
119+
unsafe fn u8to64_le(buf: &[u8], start: usize, len: usize) -> u64 {
120+
debug_assert!(len < 8);
121+
let mut i = 0; // current byte index (from LSB) in the output u64
122+
let mut out = 0;
123+
if i + 3 < len {
124+
out = load_int_le!(buf, start + i, u32) as u64;
125+
i += 4;
126+
}
127+
if i + 1 < len {
128+
out |= (load_int_le!(buf, start + i, u16) as u64) << (i * 8);
129+
i += 2
130+
}
131+
if i < len {
132+
out |= (*buf.get_unchecked(start + i) as u64) << (i * 8);
133+
i += 1;
134+
}
135+
debug_assert_eq!(i, len);
136+
out
137+
}
138+
135139
impl SipHasher {
136140
/// Creates a new `SipHasher` with the two initial keys set to 0.
137141
#[inline]
@@ -220,6 +224,37 @@ impl<S: Sip> Hasher<S> {
220224
self.state.v3 = self.k1 ^ 0x7465646279746573;
221225
self.ntail = 0;
222226
}
227+
228+
// Specialized write function that is only valid for buffers with len <= 8.
229+
// It's used to force inlining of write_u8 and write_usize, those would normally be inlined
230+
// except for composite types (that includes slices and str hashing because of delimiter).
231+
// Without this extra push the compiler is very reluctant to inline delimiter writes,
232+
// degrading performance substantially for the most common use cases.
233+
#[inline(always)]
234+
fn short_write(&mut self, msg: &[u8]) {
235+
debug_assert!(msg.len() <= 8);
236+
let length = msg.len();
237+
self.length += length;
238+
239+
let needed = 8 - self.ntail;
240+
let fill = cmp::min(length, needed);
241+
if fill == 8 {
242+
self.tail = unsafe { load_int_le!(msg, 0, u64) };
243+
} else {
244+
self.tail |= unsafe { u8to64_le(msg, 0, fill) } << (8 * self.ntail);
245+
if length < needed {
246+
self.ntail += length;
247+
return;
248+
}
249+
}
250+
self.state.v3 ^= self.tail;
251+
S::c_rounds(&mut self.state);
252+
self.state.v0 ^= self.tail;
253+
254+
// Buffered tail is now flushed, process new input.
255+
self.ntail = length - needed;
256+
self.tail = unsafe { u8to64_le(msg, needed, self.ntail) };
257+
}
223258
}
224259

225260
#[stable(feature = "rust1", since = "1.0.0")]
@@ -262,6 +297,21 @@ impl super::Hasher for SipHasher24 {
262297
}
263298

264299
impl<S: Sip> super::Hasher for Hasher<S> {
300+
// see short_write comment for explanation
301+
#[inline]
302+
fn write_usize(&mut self, i: usize) {
303+
let bytes = unsafe {
304+
::slice::from_raw_parts(&i as *const usize as *const u8, mem::size_of::<usize>())
305+
};
306+
self.short_write(bytes);
307+
}
308+
309+
// see short_write comment for explanation
310+
#[inline]
311+
fn write_u8(&mut self, i: u8) {
312+
self.short_write(&[i]);
313+
}
314+
265315
#[inline]
266316
fn write(&mut self, msg: &[u8]) {
267317
let length = msg.len();
@@ -271,19 +321,16 @@ impl<S: Sip> super::Hasher for Hasher<S> {
271321

272322
if self.ntail != 0 {
273323
needed = 8 - self.ntail;
324+
self.tail |= unsafe { u8to64_le(msg, 0, cmp::min(length, needed)) } << 8 * self.ntail;
274325
if length < needed {
275-
self.tail |= u8to64_le!(msg, 0, length) << 8 * self.ntail;
276326
self.ntail += length;
277327
return
328+
} else {
329+
self.state.v3 ^= self.tail;
330+
S::c_rounds(&mut self.state);
331+
self.state.v0 ^= self.tail;
332+
self.ntail = 0;
278333
}
279-
280-
let m = self.tail | u8to64_le!(msg, 0, needed) << 8 * self.ntail;
281-
282-
self.state.v3 ^= m;
283-
S::c_rounds(&mut self.state);
284-
self.state.v0 ^= m;
285-
286-
self.ntail = 0;
287334
}
288335

289336
// Buffered tail is now flushed, process new input.
@@ -292,7 +339,7 @@ impl<S: Sip> super::Hasher for Hasher<S> {
292339

293340
let mut i = needed;
294341
while i < len - left {
295-
let mi = unsafe { load_u64_le(msg, i) };
342+
let mi = unsafe { load_int_le!(msg, i, u64) };
296343

297344
self.state.v3 ^= mi;
298345
S::c_rounds(&mut self.state);
@@ -301,7 +348,7 @@ impl<S: Sip> super::Hasher for Hasher<S> {
301348
i += 8;
302349
}
303350

304-
self.tail = u8to64_le!(msg, i, left);
351+
self.tail = unsafe { u8to64_le(msg, i, left) };
305352
self.ntail = left;
306353
}
307354

‎src/libcoretest/hash/sip.rs‎

Lines changed: 21 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -14,6 +14,7 @@ use test::{Bencher, black_box};
1414

1515
use core::hash::{Hash, Hasher};
1616
use core::hash::{SipHasher, SipHasher13, SipHasher24};
17+
use core::{slice, mem};
1718

1819
// Hash just the bytes of the slice, without length prefix
1920
struct Bytes<'a>(&'a [u8]);
@@ -327,6 +328,26 @@ fn test_hash_no_concat_alias() {
327328
assert!(hash(&v) != hash(&w));
328329
}
329330

331+
#[test]
332+
fn test_write_short_works() {
333+
let test_usize = 0xd0c0b0a0usize;
334+
let mut h1 = SipHasher24::new();
335+
h1.write_usize(test_usize);
336+
h1.write(b"bytes");
337+
h1.write(b"string");
338+
h1.write_u8(0xFFu8);
339+
h1.write_u8(0x01u8);
340+
let mut h2 = SipHasher24::new();
341+
h2.write(unsafe {
342+
slice::from_raw_parts(&test_usize as *const _ as *const u8,
343+
mem::size_of::<usize>())
344+
});
345+
h2.write(b"bytes");
346+
h2.write(b"string");
347+
h2.write(&[0xFFu8, 0x01u8]);
348+
assert_eq!(h1.finish(), h2.finish());
349+
}
350+
330351
#[bench]
331352
fn bench_str_under_8_bytes(b: &mut Bencher) {
332353
let s = "foo";

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