plain_hasher/uint: remove some unsafe code and don't assume endianness #407
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knarz
changed the title
ordian
approved these changes
Jul 25, 2020
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Thank you!
What I found surprising is that the performance of uint::from_little_endian and uint::from_big_endian has improved according to our benches! And plain_hasher::write has not regressed. Amazing!
Will need to look at the generated code to confirm.
I'll submit a PR to fix the benches from optimizing away.
dvdplm
approved these changes
Jul 27, 2020
| @@ -30,17 +30,18 @@ impl Hasher for PlainHasher { | |||
| fn write(&mut self, bytes: &[u8]) { | |||
| debug_assert!(bytes.len() == 32); | |||
| let mut bytes_ptr = bytes.as_ptr(); | |||
| let mut prefix_ptr = &mut self.prefix as *mut u64 as *mut u8; | |||
| let mut prefix_bytes = self.prefix.to_le_bytes(); | |||
|
|
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| unroll! { | |||
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I wonder if the unroll! is still needed here – did you try without it? :)
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I did, it's stll needed :(
write_plain_hasher time: [1.9603 us 1.9624 us 1.9647 us]
change: [+381.78% +382.63% +383.51%] (p = 0.00 < 0.05)
Performance has regressed.
Found 12 outliers among 100 measurements (12.00%)
1 (1.00%) low severe
7 (7.00%) high mild
4 (4.00%) high severe
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Tests for
plain_hasheranduintboth fail on big endian architectures because they assume a certain byte layout. With these patches tests for both pass on big and small endian systems.