remove support for congruence closure computation #6
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sgrif
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Feb 9, 2018
src/lib.rs
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| pub mod unify; | ||
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src/unify/mod.rs
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| self.rank = rank; | ||
| self.child = child; | ||
| // self.child = child; |
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Maybe just kill it instead of commenting it out?
src/unify/mod.rs
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| @@ -397,7 +370,7 @@ impl<S: UnificationStore> UnificationTable<S> { | |||
| } | |||
| } | |||
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| /// Internal method to redirect `old_root_key` (which is currently | |||
| /// Internal method tox redirect `old_root_key` (which is currently | |||
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you...are right
nikomatsakis
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Supporting congruence closure requires the `unioned_keys` iterator, which in turn requires maintaining the parent/sibling pointers. This grows the size of nodes, which in turn leads to a 2% slowdown in various rustc test cases (e.g., the `coercions` benchmark in perf.rust-lang.org). Given that this feature is not used in chalk or anywhere else, no reason to support it.
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Grr travis you take too long |
lorenzleutgeb
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Apr 26, 2022
Removes just the declaration and the corresponding dependency from `Cargo.toml`. The code that was once guarded by this feature was removed years ago. See 52cd081 See rust-lang#6
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Supporting congruence closure requires the
unioned_keysiterator,which in turn requires maintaining the parent/sibling pointers. This
grows the size of nodes, which in turn leads to a 2% slowdown in
various rustc test cases (e.g., the
coercionsbenchmark inperf.rust-lang.org). Given that this feature is not used in chalk or
anywhere else, no reason to support it.
Cargo bench measurements (3 runs each):
before
test unify::tests::big_array_bench_InPlace ... bench: 1,335,817 ns/iter
test unify::tests::big_array_bench_InPlace ... bench: 1,030,749 ns/iter
test unify::tests::big_array_bench_InPlace ... bench: 1,339,391 ns/iter
after
test unify::tests::big_array_bench_InPlace ... bench: 918,518 ns/iter
test unify::tests::big_array_bench_InPlace ... bench: 1,190,575 ns/iter
test unify::tests::big_array_bench_InPlace ... bench: 918,214 ns/iter
A bit uneven but clearly a win.