This caused several performance regressions because of existing code
which uses `Read::read` and therefore requires full buffer
initialization. This is particularly a problem when the same buffer is
re-used for multiple read calls since this means it needs to be fully
re-initialized each time.
There is still some benefit to landing the API changes, but we will have
to add private APIs so that the existing infrastructure can
track and avoid redundant initialization.
(cherry picked from commit 4b07875505)
Rollup of 9 pull requests
Successful merges:
- rust-lang/rust#147224 (Emscripten: Turn wasm-eh on by default)
- rust-lang/rust#149405 (Recover on misspelled item keyword)
- rust-lang/rust#149443 (Tidying up UI tests [6/N])
- rust-lang/rust#149524 (Move attribute safety checking to attribute parsing)
- rust-lang/rust#149593 (powf, powi: point out SNaN non-determinism)
- rust-lang/rust#149605 (Use branch name instead of HEAD when unshallowing)
- rust-lang/rust#149612 (Apply the `bors` environment also to the `outcome` job)
- rust-lang/rust#149623 (Don't require a normal tool build of clippy/rustfmt when running their test steps)
- rust-lang/rust#149627 (Point to the item that is incorrectly annotated with `#[diagnostic::on_const]`)
r? `@ghost`
`@rustbot` modify labels: rollup
powf, powi: point out SNaN non-determinism
The non-determinism has two sources:
- LLVM reserves the right to treat signaling NaNs as-if they were quiet, so it may fold `powf(x, 0)` to `1` even if `x` might be a signaling NaN.
- Some libm `pow` implementations (e.g. the one in musl) don't implement the signaling NaN special-case. See https://rust.godbolt.org/z/chsbv5v4d.
Cc `@tgross35` `@Amanieu`
Motor OS: fix compile error
[PR 148765](https://github.com/rust-lang/rust/pull/148765) changed the expected signature of Thread::new(), which broke Motor OS target.
Also set thread name while at it.
std: don't call `current_os_id` from signal handler
`current_os_id` is not always async-signal-safe depending on the platform, hence it may not be called from the SIGSEGV handler. Instead, store the thread ID along with the thread name during setup. With rust-lang/rust#144465 merged, this information is available even before the thread main function.
Remove initialized-bytes tracking from `BorrowedBuf` and `BorrowedCursor`
As discussed extensively in libs-api, the initialized-bytes tracking primarily benefits calls to `read_buf` that end up initializing the buffer and calling `read`, at the expense of calls to `read_buf` that *don't* need to initialize the buffer. Essentially, this optimizes for the past at the expense of the future. If people observe performance issues using `read_buf` (or something that calls it) with a given `Read` impl, they can fix those performance issues by implementing `read_buf` for that `Read`.
Update the documentation to stop talking about initialized-but-unfilled bytes.
Remove all functions that just deal with those bytes and their tracking, and remove usage of those methods.
Remove `BorrowedCursor::advance` as there's no longer a safe case for advancing within initialized-but-unfilled bytes. Rename `BorrowedCursor::advance_unchecked` to `advance`.
Update tests.
r? ``@Amanieu``
At least on OVMF, some files copied over from linux file system seem
to have invalid time (year = 1980 and everything else 0). Since Rust
allows time to be optional and we can return error, that seems to be
the way to go for now.
Signed-off-by: Ayush Singh <ayush@beagleboard.org>
As discussed extensively in libs-api, the initialized-bytes tracking
primarily benefits calls to `read_buf` that end up initializing the
buffer and calling `read`, at the expense of calls to `read_buf` that
*don't* need to initialize the buffer. Essentially, this optimizes for
the past at the expense of the future. If people observe performance
issues using `read_buf` (or something that calls it) with a given `Read`
impl, they can fix those performance issues by implementing `read_buf`
for that `Read`.
Update the documentation to stop talking about initialized-but-unfilled
bytes.
Remove all functions that just deal with those bytes and their tracking,
and remove usage of those methods.
Remove `BorrowedCursor::advance` as there's no longer a safe case for
advancing within initialized-but-unfilled bytes. Rename
`BorrowedCursor::advance_unchecked` to `advance`.
Update tests.
std: split up the `thread` module
Almost all functionality in `std::thread` is currently implemented in `thread/mod.rs`, resulting in a *huge* file with more than 2000 lines and multiple, interoperating `unsafe` sections. This PR splits the file up into multiple different private modules, each implementing mostly independent parts of the functionality. The only remaining `unsafe` interplay is that of the `lifecycle` and `scope` modules, the `spawn_scoped` implementation relies on the live thread count being updated correctly by the `lifecycle` module.
This PR contains no functional changes and only moves code around for the most part, with a few notable exceptions:
* `with_current_name` is moved to the already existing `current` module and now uses the `name` method instead of calculating the name from private fields. The old code was just a reimplementation of that method anyway.
* The private `JoinInner` type used to implement both join handles now has some more methods (`is_finished`, `thread` and the `AsInner`/`IntoInner` implementations) to avoid having to expose private fields and their invariants.
* The private `spawn_unchecked_` (note the underscore) method of `Builder` is now a freestanding function in `lifecycle`.
The rest of the changes are just visibility annotations.
I realise this PR ended up quite large – let me know if there is anyway I can aid the review process.
Edit: I've simplified the diff by adding an intermediate commit that creates all the new files by duplicating `mod.rs`. The actual changes in the second commit thus appear to delete the non-relevant parts from the respective file.
Remove outdated comment
The comment was added in rust-lang/rust#136897 , but wasn't removed when the feature gate was stabilized (again).
Also, `it's` -> `its` :)
Allow the global allocator to use thread-local storage and std:🧵:current()
Fixes https://github.com/rust-lang/rust/issues/115209.
Currently the thread-local storage implementation uses the `Global` allocator if it needs to allocate memory in some places. This effectively means the global allocator can not use thread-local variables. This is a shame as an allocator is precisely one of the locations where you'd *really* want to use thread-locals. We also see that this lead to hacks such as https://github.com/rust-lang/rust/pull/116402, where we detect re-entrance and abort.
So I've made the places where I could find allocation happening in the TLS implementation use the `System` allocator instead. I also applied this change to the storage allocated for a `Thread` handle so that it may be used care-free in the global allocator as well, for e.g. registering it to a central place or parking primitives.
r? `@joboet`
Show backtrace on allocation failures when possible
And if an allocation while printing the backtrace fails, don't try to print another backtrace as that will never succeed.
Split out of https://github.com/rust-lang/rust/pull/147725 to allow landing this independently of a decision whether or not to remove `-Zoom=panic`.
Remove outdated part of comment claiming thread_local re-enters global allocator
Fix typo in doc comment
Add comments for guarantees given and footnote that System may still be called
Revise mention of using the global allocator
Allow for the possibility that the global allocator is the system allocator.
Co-authored-by: Mark Rousskov <mark.simulacrum@gmail.com>
Stabilize `maybe_uninit_write_slice`
Stabilize feature `maybe_uninit_write_slice` (closes https://github.com/rust-lang/rust/issues/79995).
Note that this also const-stabilizes `<[MaybeUninit<_>]>::write_copy_of_slice`. That method depends on `<[_]>::copy_from_slice`, which is already const-stable, and `<[MaybeUninit<_>]>::assume_init_mut` which is now also stable.
Add `Box::clone_from_ref` and similar under `feature(clone_from_ref)`
Tracking issue: https://github.com/rust-lang/rust/issues/149075
Accepted ACP: https://github.com/rust-lang/libs-team/issues/483
This PR implements `clone_from_ref` (and `try_*` and `_*in` variants), to get a `Box<T>`, `Arc<T>`, or `Rc<T>` by cloning from a `&T` where `T: CloneToUninit`.
The "Implement..." commits replace some ad-hoc conversions with `clone_from_ref` variants, which can be split out to a separate PR if desired.
This PR will conflict with https://github.com/rust-lang/rust/pull/148769 due to usage of `Layout::dangling` (which that PR is renaming to `dangling_ptr`), so they should not be rolled up together, and the one which merges later will need to be amended.
