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Guillaume Gomez b917753d79 Rollup merge of #120116 - the8472:only-same-alignments, r=cuviper Remove alignment-changing in-place collect This removes the alignment-changing in-place collect optimization introduced in #110353 Currently stable users can't benefit from the optimization because GlobaAlloc doesn't support alignment-changing realloc and neither do most posix allocators. So in practice it has a negative impact on performance. Explanation from https://github.com/rust-lang/rust/issues/120091#issuecomment-1899071681: > > You mention that in case of alignment mismatch -- when the new alignment is less than the old -- the implementation calls `mremap`. > > I was trying to note that this isn't really the case in practice, due to the semantics of Rust's allocator APIs. The only use of the allocator within the `in_place_collect` implementation itself is [a call to `Allocator::shrink()`](`db7125f008/library/alloc/src/vec/in_place_collect.rs (L299-L303)`), which per its documentation [allows decreasing the required alignment](https://doc.rust-lang.org/1.75.0/core/alloc/trait.Allocator.html). However, in stable Rust, the only available `Allocator` is [`Global`](https://doc.rust-lang.org/1.75.0/alloc/alloc/struct.Global.html), which delegates to the registered `GlobalAlloc`. Since `GlobalAlloc::realloc()` [cannot change the required alignment](https://doc.rust-lang.org/1.75.0/core/alloc/trait.GlobalAlloc.html#method.realloc), the implementation of [`<Global as Allocator>::shrink()`](`db7125f008/library/alloc/src/alloc.rs (L280-L321)`) must fall back to creating a brand-new allocation, `memcpy`ing the data into it, and freeing the old allocation, whenever the alignment doesn't remain exactly the same. > > Therefore, the underlying allocator, provided by libc or some other source, has no opportunity to internally `mremap()` the data when the alignment is changed, since it has no way of knowing that the allocation is the same.		2024-01-20 20:06:35 +01:00
.github	Ask for rustc version in diagnostic reports, remind users to update their toolchain	2024-01-07 02:09:55 +00:00
.reuse	Rollup merge of #119189 - henrispriet:move-installing-from-source, r=Mark-Simulacrum	2024-01-13 22:35:08 +01:00
compiler	Rollup merge of #120063 - clubby789:remove-box-handling, r=Nilstrieb	2024-01-20 20:06:34 +01:00
library	Rollup merge of #120116 - the8472:only-same-alignments, r=cuviper	2024-01-20 20:06:35 +01:00
LICENSES	Add missing CC-BY-SA-4.0.	2023-11-27 11:03:53 +00:00
src	Rollup merge of #120000 - smoelius:fix-clippy, r=fee1-dead	2024-01-20 20:06:34 +01:00
tests	Rollup merge of #120063 - clubby789:remove-box-handling, r=Nilstrieb	2024-01-20 20:06:34 +01:00
.editorconfig	Only use max_line_length = 100 for *.rs	2023-07-10 15:18:36 -07:00
.git-blame-ignore-revs	Ignore let-chains formatting	2023-10-15 18:30:34 +00:00
.gitattributes	Rename `config.toml.example` to `config.example.toml`	2023-03-11 14:10:00 -08:00
.gitignore	don't globally ignore rustc-ice files	2023-09-16 09:44:44 +02:00
.gitmodules	Update to LLVM 17.0.6	2023-12-14 09:54:14 +01:00
.mailmap	Add my work email to the mailmap	2023-11-26 18:39:38 +01:00
Cargo.lock	Auto merge of #108359 - Zoxc:side-effects-tweak, r=cjgillot	2024-01-20 15:20:15 +00:00
Cargo.toml	Bump salsa	2024-01-10 08:47:26 +01:00
CODE_OF_CONDUCT.md	Remove the code of conduct; instead link https://www.rust-lang.org/conduct.html	2019-10-05 22:55:19 +02:00
config.example.toml	add a new `optimized_compiler_builtins` option	2024-01-07 13:04:40 +03:00
configure	Enforce Python 3 as much as possible	2020-04-10 09:09:58 -04:00
CONTRIBUTING.md	fix: Update CONTRIBUTING.md recommend -> recommended	2023-11-16 23:57:09 +05:30
COPYRIGHT	Update copyright year for Clippy (2024 edition)	2024-01-03 19:36:44 +01:00
INSTALL.md	Move section "Installing from Source" to seperate file	2024-01-13 17:22:55 +01:00
LICENSE-APACHE	Update copyright year for Clippy (2024 edition)	2024-01-03 19:36:44 +01:00
LICENSE-MIT	Update copyright year for Clippy (2024 edition)	2024-01-03 19:36:44 +01:00
README.md	Move section "Installing from Source" to seperate file	2024-01-13 17:22:55 +01:00
RELEASES.md	apply last suggestions from code review	2023-12-21 13:26:15 +01:00
rust-bors.toml	Add integration for new bors	2023-09-28 10:43:24 +02:00
rustfmt.toml	rustfmt.toml: don't ignore just any `tests` path, only root one	2024-01-11 14:59:59 +03:00
triagebot.toml	Rollup merge of #120122 - Nilstrieb:Diagnosticstriage, r=oli-obk	2024-01-19 19:27:02 +01:00
x	Make x capable of resolving symlinks	2023-10-14 17:53:33 +03:00
x.ps1	use `&` instead of start-process in x.ps1	2023-12-09 09:46:16 -05:00
x.py	Fix recent python linting errors	2023-08-02 04:40:28 -04:00

README.md

The Rust Programming Language

This is the main source code repository for Rust. It contains the compiler, standard library, and documentation.

Note: this README is for users rather than contributors. If you wish to contribute to the compiler, you should read CONTRIBUTING.md instead.

Table of Contents

Quick Start
Getting Help
Contributing
License
Trademark

Quick Start

Read "Installation" from The Book.

Installing from source

If you really want to install from source (though this is not recommended), see INSTALL.md.

Getting Help

See https://www.rust-lang.org/community for a list of chat platforms and forums.

Contributing

See CONTRIBUTING.md.

License

Rust is primarily distributed under the terms of both the MIT license and the Apache License (Version 2.0), with portions covered by various BSD-like licenses.

See LICENSE-APACHE, LICENSE-MIT, and COPYRIGHT for details.

Trademark

The Rust Foundation owns and protects the Rust and Cargo trademarks and logos (the "Rust Trademarks").

If you want to use these names or brands, please read the media guide.

Third-party logos may be subject to third-party copyrights and trademarks. See Licenses for details.