Cache hir_owner_nodes in ParentHirIterator.
Lint level computation may traverse deep HIR trees using that iterator. This calls `hir_owner_nodes` many times for the same HIR owner, which is wasterful.
This PR caches the value to allow a more efficient iteration scheme.
r? ghost for perf
coverage: Rename `mir::coverage::BranchInfo` to `CoverageInfoHi`
This opens the door to collecting and storing coverage information that is unrelated to branch coverage or MC/DC, during MIR building.
There is no change to the output of coverage instrumentation, but one deliberate change is that functions now *always* have an attached `CoverageInfoHi` (if coverage is enabled and they are eligible), even if they didn't collect any interesting branch information.
---
`@rustbot` label +A-code-coverage
DependencyList: removed outdated comment
Comment was outdated. Didn't updated description, as `Linkage` enum have descriptive names.
Also added fixme about moving this file to rustc_metadata.
Miri function identity hack: account for possible inlining
Having a non-lifetime generic is not the only reason a function can be duplicated. Another possibility is that the function may be eligible for cross-crate inlining. So also take into account the inlining attribute in this Miri hack for function pointer identity.
That said, `cross_crate_inlinable` will still sometimes return true even for `inline(never)` functions:
- when they are `DefKind::Ctor(..) | DefKind::Closure` -- I assume those cannot be `InlineAttr::Never` anyway?
- when `cross_crate_inline_threshold == InliningThreshold::Always`
so maybe this is still not quite the right criterion to use for function pointer identity.
cache type sizes in type-size limit visitor
This is basically https://github.com/rust-lang/rust/pull/125507#issuecomment-2206813779 as lcnr can't open the PR now.
Locally it reduces the `itertools` regression by quite a bit, to "only +50%" compared to nightly (that includes overhead from the local lack of artifact post-processing, and is just a data point to compare to the 10-20x timings without the cache).
```console
Benchmark 1: cargo +stage1 build --release
Time (mean ± σ): 2.721 s ± 0.009 s [User: 2.446 s, System: 0.325 s]
Range (min … max): 2.710 s … 2.738 s 10 runs
Benchmark 2: cargo +nightly build --release
Time (mean ± σ): 1.784 s ± 0.005 s [User: 1.540 s, System: 0.279 s]
Range (min … max): 1.778 s … 1.792 s 10 runs
Summary
cargo +nightly build --release ran
1.52 ± 0.01 times faster than cargo +stage1 build --release
```
On master, it's from 34s to the 2.7s above.
r? compiler-errors
Add `as_lang_item` to `LanguageItems`, new trait solver
Add `as_lang_item` which turns `DefId` into a `TraitSolverLangItem` in the new trait solver, so we can turn the large chain of if statements in `assemble_builtin_impl_candidates` into a match instead.
r? lcnr
Re-implement a type-size based limit
r? lcnr
This PR reintroduces the type length limit added in #37789, which was accidentally made practically useless by the caching changes to `Ty::walk` in #72412, which caused the `walk` function to no longer walk over identical elements.
Hitting this length limit is not fatal unless we are in codegen -- so it shouldn't affect passes like the mir inliner which creates potentially very large types (which we observed, for example, when the new trait solver compiles `itertools` in `--release` mode).
This also increases the type length limit from `1048576 == 2 ** 20` to `2 ** 24`, which covers all of the code that can be reached with craterbot-check. Individual crates can increase the length limit further if desired.
Perf regression is mild and I think we should accept it -- reinstating this limit is important for the new trait solver and to make sure we don't accidentally hit more type-size related regressions in the future.
Fixes#125460
Rewrite handling of universe-leaking placeholder regions into outlives constraints
This commit prepares for Polonius by moving handling of leak check/universe errors out of the inference step by rewriting any universe error into an outlives-static constraint.
This variant is a work in progress but seems to pass most tests.
Note that a few debug assertions no longer hold; a few extra eyes on those changes are appreciated!
This version is a squash-rebased version of a series
of exiermental commits, since large parts of them
were broken out into PR #125069.
It explicitly handles universe violations in higher-kinded
outlives constraints by adding extra outlives static constraints.
Implement new effects desugaring
cc `@rust-lang/project-const-traits.` Will write down notes once I have finished.
* [x] See if we want `T: Tr` to desugar into `T: Tr, T::Effects: Compat<true>`
* [x] Fix ICEs on `type Assoc: ~const Tr` and `type Assoc<T: ~const Tr>`
* [ ] add types and traits to minicore test
* [ ] update rustc-dev-guide
Fixes#119717Fixes#123664Fixes#124857Fixes#126148
Rename `super_predicates_of` and similar queries to `explicit_*` to note that they're not elaborated
Rename:
* `super_predicates_of` -> `explicit_super_predicates_of`
* `implied_predicates_of` -> `explicit_implied_predicates_of`
* `supertraits_containing_assoc_item` -> `explicit_supertraits_containing_assoc_item`
This makes it clearer that, unlike (for example) [`TyCtxt::super_traits_of`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/context/struct.TyCtxt.html#method.super_traits_of), we don't automatically elaborate this set of predicates.
r? ``@lcnr`` or ``@oli-obk`` or someone from t-types idc
patchable-function-entry: Add unstable compiler flag and attribute
Tracking issue: #123115
Add the -Z patchable-function-entry compiler flag and the #[patchable_function_entry(prefix_nops = m, entry_nops = n)] attribute.
Rebased and adjusted the canditate implementation to match changes in the RFC.
coverage: Make `#[coverage(..)]` apply recursively to nested functions
This PR makes the (currently-unstable) `#[coverage(off)]` and `#[coverage(on)]` attributes apply recursively to all nested functions/closures, instead of just the function they are directly attached to.
Those attributes can now also be applied to modules and to impl/impl-trait blocks, where they have no direct effect, but will be inherited by all enclosed functions/closures/methods that don't override the inherited value.
---
Fixes#126625.
Remove more `PtrToPtr` casts in GVN
This addresses two things I noticed in MIR:
1. `NonNull::<T>::eq` does `(a as *mut T) == (b as *mut T)`, but it could just compare the `*const T`s, so this removes `PtrToPtr` casts that are on both sides of a pointer comparison, so long as they're not fat-to-thin casts.
2. `NonNull::<T>::addr` does `transmute::<_, usize>(p as *const ())`, but so long as `T: Thin` that cast doesn't do anything, and thus we can directly transmute the `*const T` instead.
r? mir-opt
`-Z patchable-function-entry` works like `-fpatchable-function-entry`
on clang/gcc. The arguments are total nop count and function offset.
See MCP rust-lang/compiler-team#704
transmute size check: properly account for alignment
Fixes another place where ZST alignment was ignored when checking whether something is a newtype. I wonder how many more of these there are...
Fixes https://github.com/rust-lang/rust/issues/101084
Add `SliceLike` to `rustc_type_ir`, use it in the generic solver code (+ some other changes)
First, we split out `TraitRef::new_from_args` which takes *just* `ty::GenericArgsRef` from `TraitRef::new` which takes `impl IntoIterator<Item: Into<GenericArg>>`. I will explain in a minute why.
Second, we introduce `SliceLike`, which allows us to be generic over `List<T>` and `[T]`. This trait has an `as_slice()` and `into_iter()` method, and some other convenience functions. However, importantly, since types like `I::GenericArgs` now implement `SliceLike` rather than `IntoIter<Item = I::GenericArg>`, we can't use `TraitRef::new` on this directly. That's where `new_from_args` comes in.
Finally, we adjust all the code to use these slice operators. Some things get simpler, some things get a bit more annoying since we need to use `as_slice()` in a few places. 🤷
r? lcnr
