BTreeMap: admit the existence of leaf edges in comments
The btree code is ambiguous about leaf edges (i.e., edges within leaf nodes). Iteration relies on them heavily, but some of the comments suggest there are no leaf edges (extracted from #77025)
r? @Mark-Simulacrum
Remove trait_selection error message in specific case
In the case that a trait is not implemented for an ADT with type errors, cancel the error.
Fixes#75627
Use more intra-doc-links in `core::fmt`
This is a follow-up to #75819, which encountered some broken links due to #75176, so this PR contains the links that are blocked on #75176.
r? @jyn514
Hint the maximum length permitted by invariant of slices
One of the safety invariants of references, and in particular of references to slices, is that they may not cover more than `isize::MAX` bytes. The unsafe `from_raw_parts` constructors of slices explicitly requires the caller to guarantee this fact. Violating it would also be UB with regards to the semantics of generated llvm code.
This effectively bounds the length of a (non-ZST) slice from above by a compile time constant. But when the length is loaded from a function argument it appears llvm is not aware of this requirement. The additional value range assertions allow some further elision of code branches, including overflow checks, especially in the presence of artithmetic on the indices.
This may have a performance impact, adding more code to a common method but allowing more optimization. I'm not quite sure, is the Rust side of const-prop strong enough to elide the irrelevant match branches?
Fixes: #67186
Uses assume to check the length against a constant upper bound. The
inlined result then informs the optimizer of the sound value range.
This was tried with unreachable_unchecked before which introduces a
branch. This has the advantage of not being executed in sound code but
complicates basic blocks. It resulted in ~2% increased compile time in
some worst cases.
Add a codegen test for the assumption, testing the issue from #67186
There's a cleaner way of doing this, but it involves passing
`WithOptConstParam` around in more places. We're going to try to explore
different approaches before committing to that.
Rollup of 8 pull requests
Successful merges:
- #77072 (Minor `hash_map` doc adjustments + item attribute orderings)
- #77368 (Backport LLVM apfloat commit to rustc_apfloat)
- #77445 (BTreeMap: complete the compile-time test_variance test case)
- #77504 (Support vectors with fewer than 8 elements for simd_select_bitmask)
- #77513 (Change DocFragments from enum variant fields to structs with a nested enum)
- #77518 (Only use Fira Sans for the first `td` in item lists)
- #77521 (Move target feature whitelist from cg_llvm to cg_ssa)
- #77525 (Enable RenameReturnPlace MIR optimization on mir-opt-level >= 2)
Failed merges:
r? `@ghost`
Enable RenameReturnPlace MIR optimization on mir-opt-level >= 2
The destination propagation as currently implemented does not supersede the NRVO, e.g., the destination propagation never applies if either local has an address taken, while NRVO might.
Additionally, the issue with failing assertions had been already resolved.
Continue running both optimizations at mir-opt-level >= 2.
Move target feature whitelist from cg_llvm to cg_ssa
These target features have to be supported or at least emulated by alternative codegen backends anyway as they are used by common crates. By moving this list to cg_ssa, other codegen backends don't have to copy
this code.
Only use Fira Sans for the first `td` in item lists
Fixes#77516.
Fixes an issue where links in the one-line version of an item's docs
would be in Fira Sans, while the rest would be in a serifed font.
Change DocFragments from enum variant fields to structs with a nested enum
This makes the code a lot easier to work with. It also makes it easier
to add new fields without updating each variant and `match`
individually.
- Name the `Kind` variant after `DocFragmentKind` from `collapse_docs`
- Remove unneeded impls
Progress towards https://github.com/rust-lang/rust/issues/77254.
r? @GuillaumeGomez
BTreeMap: complete the compile-time test_variance test case
Some of the items added to the new `test_sync` belonged in the old `test_variance` as well. And fixed inconsistent paths to nearby modules.
r? @Mark-Simulacrum
Minor `hash_map` doc adjustments + item attribute orderings
This PR is really a couple visual changes glued together:
1. Some of the doc comments for items in `std::collections::hash_map` referenced the names of types without escaping their formatting (e.g. using "VacantEntry" instead of "`VacantEntry`") - the ones I could find were changed to the latter
2. The vast majority of pre-item attributes seem to place doc comments as the first attribute (instead of things like `#[feature(...)]`), so the few that had the other order were changed.
3. Also ordering related: the general trend seems to be that `#[feature]` attributes follow `#[inline]`, so I swapped the two lines in places where that ordering was reversed. This is primarily a change based on stylistic continuity and aesthetics - I'm not sure how important that actually is / should be.
I figured this would be pretty uncontroversial, but some of these might have been intentional for reasons I don't know about - if so, I'd be happy to remove the relevant changes. Of these, the final set of changes is probably the most unnecessary, so it also might be better to leave those out (in favor of reducing code churn).
Implement as_ne_bytes() for integers and floats
This is related to issue #64464.
I am pretty sure that these functions are actually const-ify-able, and technically as_bits() can also be implemented for floats, but I might need some comments on both.
These target features have to be supported or at least emulated by
alternative codegen backends anyway as they are used by common crates.
By moving this list to cg_ssa, other codegen backends don't have to copy
this code.
Implement Make `handle_alloc_error` default to panic (for no_std + liballoc)
Related: https://github.com/rust-lang/rust/issues/66741
Guarded with `#![feature(default_alloc_error_handler)]` a default
`alloc_error_handler` is called, if a custom allocator is used and no
other custom `#[alloc_error_handler]` is defined.
Unbox mutexes and condvars on some platforms
Both mutexes and condition variables contained a Box containing the actual os-specific object. This was done because moving these objects may cause undefined behaviour on some platforms.
However, this is not needed on Windows[1], Wasm[2], cloudabi[2], and 'unsupported'[3], were the box was only needlessly making them less efficient.
This change gets rid of the box on those platforms.
On those platforms, `Condvar` can no longer verify it is only used with one `Mutex`, as mutexes no longer have a stable address. This was addressed and considered acceptable in #76932.
[1]\: https://docs.microsoft.com/en-us/windows/win32/api/synchapi/nf-synchapi-initializesrwlock
[2]\: These are just a single atomic integer together with futex wait/wake calls/instructions.
[3]\: The `unsupported` platform doesn't support multiple threads at all.
Improve rustdoc error for failed intra-doc link resolution
The previous error was confusing since it made it sound like you can't
link to items that are defined outside the current module.
Also suggested importing the item.
r? @jyn514
Add some regression tests
Closes#66501Closes#68951Closes#72565Closes#74244Closes#75299
The first issue is fixed in 1.43.0, other issues are fixed in the recent nightly.
Use `tracing` spans to trace the entire MIR interp stack
r? @RalfJung
While being very verbose, this allows really good tracking of what's going on. While I considered schemes like the previous indenter that we had (which we could get by using the `tracing-tree` crate), this will break down horribly with things like multithreaded rustc. Instead, we can now use `RUSTC_LOG` to restrict the things being traced. You could specify a filter in a way that only shows the logging of a specific frame.
If we lower the span's level to `debug`, then in `info` level logging we'd not see the frames, but in `debug` level we would see them. The filtering rules in `tracing` are super powerful, but I'm not sure if we can specify a filter so we do see `debug` level events, but *not* the `frame` spans. The documentation at https://docs.rs/tracing-subscriber/0.2.10/tracing_subscriber/struct.EnvFilter.html makes me think that we can only turn on things, not turn off things at a more precise level.
cc @hawkw
Use less divisions in display u128/i128
This PR is an absolute mess, and I need to test if it improves the speed of fmt::Display for u128/i128, but I think it's correct.
It hopefully is more efficient by cutting u128 into at most 2 u64s, and also chunks by 1e16 instead of just 1e4.
Also I specialized the implementations for uints to always be non-false because it bothered me that it was checked at all
Do not merge until I benchmark it and also clean up the god awful mess of spaghetti.
Based on prior work in #44583
cc: `@Dylan-DPC`
Due to work on `itoa` and suggestion in original issue:
r? `@dtolnay`
Backports LLVM commit:
[APFloat] convert SNaN to QNaN in convert() and raise Invalid signal
149f5b573c
SNaN to QNaN conversion also matches what my Intel x86_64 hardware does.
The destination propagation as currently implemented does not supersede
the NRVO, e.g., the destination propagation never applies if either
local has an address taken, while NRVO might.
Additionally, the issue with failing assertions had been already
resolved.
Continue running both optimizations at mir-opt-level >= 2.
This makes the code a lot easier to work with. It also makes it easier
to add new fields without updating each variant and `match`
individually.
- Name the `Kind` variant after `DocFragmentKind` from `collapse_docs`
- Remove unneeded impls
