Forward Hash::write_iN to Hash::write_uN #73800
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r? @kennytm (rust_highfive has picked a reviewer for you, use r? to override) |
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Forward Hash::write_iN to Hash::write_uN The `Hasher::write_iN()` methods should forward to `Hasher::write_uN()`, because some Hasher implementations implement only the `write_uN()` variants, with the expectation that `write_iN()` will use the same implementation. Most notably, this is the case for the [FxHasher](https://github.com/rust-lang/rustc-hash/blob/5e09ea0a1c7ab7e4f9e27771f5a0e5a36c58d1bb/src/lib.rs#L111) used by rustc itself. This used to be the case previously, but was broken in rust-lang#59982. As the PR description makes no mention of this particular change, I assume it was unintentional. In a local test, this mitigates the regression from rust-lang#73526 on at least one test-case (cc @cuviper), because we're no longer at the mercy of `FxHasher::write()` getting inlined to get reasonable performance.
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@bors retry rollup=never May have perf implications |
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Forward Hash::write_iN to Hash::write_uN The `Hasher::write_iN()` methods should forward to `Hasher::write_uN()`, because some Hasher implementations implement only the `write_uN()` variants, with the expectation that `write_iN()` will use the same implementation. Most notably, this is the case for the [FxHasher](https://github.com/rust-lang/rustc-hash/blob/5e09ea0a1c7ab7e4f9e27771f5a0e5a36c58d1bb/src/lib.rs#L111) used by rustc itself. This used to be the case previously, but was broken in rust-lang#59982. As the PR description makes no mention of this particular change, I assume it was unintentional. In a local test, this mitigates the regression from rust-lang#73526 on at least one test-case (cc @cuviper), because we're no longer at the mercy of `FxHasher::write()` getting inlined to get reasonable performance.
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…arth Rollup of 9 pull requests Successful merges: - rust-lang#73577 (Add partition_point) - rust-lang#73757 (Const prop: erase all block-only locals at the end of every block) - rust-lang#73774 (Make liveness more precise for assignments to fields) - rust-lang#73795 (Add some `const_compare_raw_pointers`-related regression tests) - rust-lang#73800 (Forward Hash::write_iN to Hash::write_uN) - rust-lang#73813 (Rename two `Resolver` traits) - rust-lang#73817 (Rename clashing_extern_decl to clashing_extern_declarations.) - rust-lang#73826 (Fix docstring typo) - rust-lang#73833 (Remove GlobalCtxt::enter_local) Failed merges: r? @ghost
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May I think may have observable change in behaviour, not sure if that means this PR is acceptable or not... |
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In that sense, this is just reverting the observable change in #59982. |
Not really. It was a change from self.write(&unsafe { mem::transmute::<_, [u8; 4]>(i) }) to self.write(&i.to_ne_bytes())In both cases the function called, the data types, and the values supplied were identical. A |
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Oh sorry, I see what you mean, I was looking at the wrong functions ^^ Ignore me. |
It was accidentally rolled up anyway in #73838. |
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The
Hasher::write_iN()methods should forward toHasher::write_uN(), because some Hasher implementations implement only thewrite_uN()variants, with the expectation thatwrite_iN()will use the same implementation. Most notably, this is the case for the FxHasher used by rustc itself.This used to be the case previously, but was broken in #59982. As the PR description makes no mention of this particular change, I assume it was unintentional.
In a local test, this mitigates the regression from #73526 on at least one test-case (cc @cuviper), because we're no longer at the mercy of
FxHasher::write()getting inlined to get reasonable performance.