Improve performance of coherence checks #68966
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bors added a commit that referenced this pull request Feb 8, 2020
Improve performance of coherence checks The biggest perf improvement in here is expected to come from the removal of the remaining #43355 warning code since the effectively runs the expensive parts of coherence *twice* (which can even be visualized by obtaining a flamegraph https://twitter.com/sheevink/status/1225963187511709696).
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This has negligible perf impact, but it does improve the code a bit. * Only query the specialization graph of any trait once instead of once per impl * Loop over impls only once, precomputing impl DefId and TraitRef
This was showing up in profiles. Also deduplicates the code to get just the impl header span.
This was previously a future-compat warning that has since been turned into hard error, but without actually removing all the code. Avoids a call to `traits::overlapping_impls`, which is expensive.
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Dylan-DPC-zz pushed a commit to Dylan-DPC-zz/rust that referenced this pull request Feb 10, 2020
…arkor Improve performance of coherence checks The biggest perf improvement in here is expected to come from the removal of the remaining rust-lang#43355 warning code since that effectively runs the expensive parts of coherence *twice*, which can even be visualized by obtaining a flamegraph: 
bors added a commit that referenced this pull request Feb 10, 2020
Rollup of 6 pull requests Successful merges: - #68694 (Reduce the number of `RefCell`s in `InferCtxt`.) - #68966 (Improve performance of coherence checks) - #68976 (Make `num::NonZeroX::new` an unstable `const fn`) - #68992 (Correctly parse `mut a @ b`) - #69005 (Small graphviz improvements for the new dataflow framework) - #69006 (parser: Keep current and previous tokens precisely) Failed merges: r? @ghost
jonas-schievink added relnotes netbsd-srcmastr pushed a commit to NetBSD/pkgsrc that referenced this pull request May 16, 2020
Pkgsrc changes: * Bump rust bootstrap version to 1.42.0, except for Darwin/i686 where the bootstrap is not (yet?) available. Upstream changes: Version 1.43.0 (2020-04-23) ========================== Language -------- - [Fixed using binary operations with `&{number}` (e.g. `&1.0`) not having the type inferred correctly.][68129] - [Attributes such as `#[cfg()]` can now be used on `if` expressions.][69201] **Syntax only changes** - [Allow `type Foo: Ord` syntactically.][69361] - [Fuse associated and extern items up to defaultness.][69194] - [Syntactically allow `self` in all `fn` contexts.][68764] - [Merge `fn` syntax + cleanup item parsing.][68728] - [`item` macro fragments can be interpolated into `trait`s, `impl`s, and `extern` blocks.][69366] For example, you may now write: ```rust macro_rules! mac_trait { ($i:item) => { trait T { $i } } } mac_trait! { fn foo() {} } ``` These are still rejected *semantically*, so you will likely receive an error but these changes can be seen and parsed by macros and conditional compilation. Compiler -------- - [You can now pass multiple lint flags to rustc to override the previous flags.][67885] For example; `rustc -D unused -A unused-variables` denies everything in the `unused` lint group except `unused-variables` which is explicitly allowed. However, passing `rustc -A unused-variables -D unused` denies everything in the `unused` lint group **including** `unused-variables` since the allow flag is specified before the deny flag (and therefore overridden). - [rustc will now prefer your system MinGW libraries over its bundled libraries if they are available on `windows-gnu`.][67429] - [rustc now buffers errors/warnings printed in JSON.][69227] Libraries --------- - [`Arc<[T; N]>`, `Box<[T; N]>`, and `Rc<[T; N]>`, now implement `TryFrom<Arc<[T]>>`,`TryFrom<Box<[T]>>`, and `TryFrom<Rc<[T]>>` respectively.][69538] **Note** These conversions are only available when `N` is `0..=32`. - [You can now use associated constants on floats and integers directly, rather than having to import the module.][68952] e.g. You can now write `u32::MAX` or `f32::NAN` with no imports. - [`u8::is_ascii` is now `const`.][68984] - [`String` now implements `AsMut<str>`.][68742] - [Added the `primitive` module to `std` and `core`.][67637] This module reexports Rust's primitive types. This is mainly useful in macros where you want avoid these types being shadowed. - [Relaxed some of the trait bounds on `HashMap` and `HashSet`.][67642] - [`string::FromUtf8Error` now implements `Clone + Eq`.][68738] Stabilized APIs --------------- - [`Once::is_completed`] - [`f32::LOG10_2`] - [`f32::LOG2_10`] - [`f64::LOG10_2`] - [`f64::LOG2_10`] - [`iter::once_with`] Cargo ----- - [You can now set config `[profile]`s in your `.cargo/config`, or through your environment.][cargo/7823] - [Cargo will now set `CARGO_BIN_EXE_<name>` pointing to a binary's executable path when running integration tests or benchmarks.][cargo/7697] `<name>` is the name of your binary as-is e.g. If you wanted the executable path for a binary named `my-program`you would use `env!("CARGO_BIN_EXE_my-program")`. Misc ---- - [Certain checks in the `const_err` lint were deemed unrelated to const evaluation][69185], and have been moved to the `unconditional_panic` and `arithmetic_overflow` lints. Compatibility Notes ------------------- - [Having trailing syntax in the `assert!` macro is now a hard error.][69548] This has been a warning since 1.36.0. - [Fixed `Self` not having the correctly inferred type.][69340] This incorrectly led to some instances being accepted, and now correctly emits a hard error. [69340]: rust-lang/rust#69340 Internal Only ------------- These changes provide no direct user facing benefits, but represent significant improvements to the internals and overall performance of `rustc` and related tools. - [All components are now built with `opt-level=3` instead of `2`.][67878] - [Improved how rustc generates drop code.][67332] - [Improved performance from `#[inline]`-ing certain hot functions.][69256] - [traits: preallocate 2 Vecs of known initial size][69022] - [Avoid exponential behaviour when relating types][68772] - [Skip `Drop` terminators for enum variants without drop glue][68943] - [Improve performance of coherence checks][68966] - [Deduplicate types in the generator witness][68672] - [Invert control in struct_lint_level.][68725] [67332]: rust-lang/rust#67332 [67429]: rust-lang/rust#67429 [67637]: rust-lang/rust#67637 [67642]: rust-lang/rust#67642 [67878]: rust-lang/rust#67878 [67885]: rust-lang/rust#67885 [68129]: rust-lang/rust#68129 [68672]: rust-lang/rust#68672 [68725]: rust-lang/rust#68725 [68728]: rust-lang/rust#68728 [68738]: rust-lang/rust#68738 [68742]: rust-lang/rust#68742 [68764]: rust-lang/rust#68764 [68772]: rust-lang/rust#68772 [68943]: rust-lang/rust#68943 [68952]: rust-lang/rust#68952 [68966]: rust-lang/rust#68966 [68984]: rust-lang/rust#68984 [69022]: rust-lang/rust#69022 [69185]: rust-lang/rust#69185 [69194]: rust-lang/rust#69194 [69201]: rust-lang/rust#69201 [69227]: rust-lang/rust#69227 [69548]: rust-lang/rust#69548 [69256]: rust-lang/rust#69256 [69361]: rust-lang/rust#69361 [69366]: rust-lang/rust#69366 [69538]: rust-lang/rust#69538 [cargo/7823]: rust-lang/cargo#7823 [cargo/7697]: rust-lang/cargo#7697 [`Once::is_completed`]: https://doc.rust-lang.org/std/sync/struct.Once.html#method.is_completed [`f32::LOG10_2`]: https://doc.rust-lang.org/std/f32/consts/constant.LOG10_2.html [`f32::LOG2_10`]: https://doc.rust-lang.org/std/f32/consts/constant.LOG2_10.html [`f64::LOG10_2`]: https://doc.rust-lang.org/std/f64/consts/constant.LOG10_2.html [`f64::LOG2_10`]: https://doc.rust-lang.org/std/f64/consts/constant.LOG2_10.html [`iter::once_with`]: https://doc.rust-lang.org/std/iter/fn.once_with.html Sign up for free to join this conversation on GitHub. 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The biggest perf improvement in here is expected to come from the removal of the remaining #43355 warning code since that effectively runs the expensive parts of coherence twice, which can even be visualized by obtaining a flamegraph: