8cbffc5bcf
[MIR] Implement overflow checking The initial set of changes is from @Aatch's #33255 PR, rebased on master, plus: Added an `Assert` terminator to MIR, to simplify working with overflow and bounds checks. With this terminator, error cases can be accounted for directly, instead of looking for lang item calls. It also keeps the MIR slimmer, with no extra explicit blocks for the actual panic calls. Warnings can be produced when the `Assert` is known to always panic at runtime, e.g.: ```rust warning: index out of bounds: the len is 1 but the index is 3 --> <anon>:1:14 1 |> fn main() { &[std::io::stdout()][3]; } |> ^^^^^^^^^^^^^^^^^^^^^^ ``` Generalized the `OperandValue::FatPtr` optimization to any aggregate pair of immediates. This allows us to generate the same IR for overflow checks as old trans, not something worse. For example, addition on `i16` calls `llvm.sadd.with.overflow.i16`, which returns `{i16, i1}`. However, the Rust type `(i16, bool)`, has to be `{i16, i8}`, only an immediate `bool` is `i1`. But if we split the pair into an `i16` and an `i1`, we can pass them around as such for free. The latest addition is a rebase of #34054, updated to work for pairs too. Closes #34054, fixes #33873. Last but not least, the `#[rustc_inherit_overflow_checks]` attribute was introduced to control the overflow checking behavior of generic or `#[inline]` functions, when translated in another crate. It is **not** intended to be used by crates other than `libcore`, which is in the unusual position of being distributed as only an optimized build with no checks, even when used from debug mode. Before MIR-based translation, this worked out fine, as the decision for overflow was made at translation time, in the crate being compiled, but MIR stored in `rlib` has to contain the checks. To avoid always generating the checks and slowing everything down, a decision was made to use an attribute in the few spots of `libcore` that need it (see #33255 for previous discussion): * `core::ops::{Add, Sub, Mul, Neg, Shl, Shr}` implementations for integers, which have `#[inline]` methods and can be used in generic abstractions from other crates * `core::ops::{Add, Sub, Mul, Neg, Shl, Shr}Assign` same as above, for augmented assignment * `pow` and `abs` methods on integers, which intentionally piggy-back on built-in multiplication and negation, respectively, to get overflow checks * `core::iter::{Iterator, Chain, Peek}::count` and `core::iter::Enumerate::{next, nth}`, also documented as panicking on overflow, from addition, counting elements of an iterator in an `usize` |
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| .travis.yml | ||
| COMPILER_TESTS.md | ||
| configure | ||
| CONTRIBUTING.md | ||
| COPYRIGHT | ||
| LICENSE-APACHE | ||
| LICENSE-MIT | ||
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| README.md | ||
| RELEASES.md | ||
The Rust Programming Language
This is the main source code repository for Rust. It contains the compiler, standard library, and documentation.
Quick Start
Read "Installing Rust" from The Book.
Building from Source
-
Make sure you have installed the dependencies:
g++4.7 or later orclang++3.xpython2.7 (but not 3.x)- GNU
make3.81 or later curlgit
-
Clone the source with
git:$ git clone https://github.com/rust-lang/rust.git $ cd rust
-
Build and install:
$ ./configure $ make && make installNote: You may need to use
sudo make installif you do not normally have permission to modify the destination directory. The install locations can be adjusted by passing a--prefixargument toconfigure. Various other options are also supported – pass--helpfor more information on them.When complete,
make installwill place several programs into/usr/local/bin:rustc, the Rust compiler, andrustdoc, the API-documentation tool. This install does not include Cargo, Rust's package manager, which you may also want to build.
Building on Windows
There are two prominent ABIs in use on Windows: the native (MSVC) ABI used by Visual Studio, and the GNU ABI used by the GCC toolchain. Which version of Rust you need depends largely on what C/C++ libraries you want to interoperate with: for interop with software produced by Visual Studio use the MSVC build of Rust; for interop with GNU software built using the MinGW/MSYS2 toolchain use the GNU build.
MinGW
MSYS2 can be used to easily build Rust on Windows:
-
Grab the latest MSYS2 installer and go through the installer.
-
From the MSYS2 terminal, install the
mingw64toolchain and other required tools.# Update package mirrors (may be needed if you have a fresh install of MSYS2) $ pacman -Sy pacman-mirrors
Download MinGW from
here, and choose the
version=4.9.x,threads=win32,exceptions=dwarf/seh flavor when installing. Also, make sure to install to a path without spaces in it. After installing,
add its bin directory to your PATH. This is due to #28260, in the future,
installing from pacman should be just fine.
# Make git available in MSYS2 (if not already available on path)
$ pacman -S git
$ pacman -S base-devel
-
Run
mingw32_shell.batormingw64_shell.batfrom wherever you installed MSYS2 (i.e.C:\msys), depending on whether you want 32-bit or 64-bit Rust. -
Navigate to Rust's source code, configure and build it:
$ ./configure $ make && make install
MSVC
MSVC builds of Rust additionally require an installation of Visual Studio 2013
(or later) so rustc can use its linker. Make sure to check the “C++ tools”
option. In addition, cmake needs to be installed to build LLVM.
With these dependencies installed, the build takes two steps:
$ ./configure
$ make && make install
Building Documentation
If you’d like to build the documentation, it’s almost the same:
./configure
$ make docs
Building the documentation requires building the compiler, so the above details will apply. Once you have the compiler built, you can
$ make docs NO_REBUILD=1
To make sure you don’t re-build the compiler because you made a change to some documentation.
The generated documentation will appear in a top-level doc directory,
created by the make rule.
Notes
Since the Rust compiler is written in Rust, it must be built by a precompiled "snapshot" version of itself (made in an earlier state of development). As such, source builds require a connection to the Internet, to fetch snapshots, and an OS that can execute the available snapshot binaries.
Snapshot binaries are currently built and tested on several platforms:
| Platform \ Architecture | x86 | x86_64 |
|---|---|---|
| Windows (7, 8, Server 2008 R2) | ✓ | ✓ |
| Linux (2.6.18 or later) | ✓ | ✓ |
| OSX (10.7 Lion or later) | ✓ | ✓ |
You may find that other platforms work, but these are our officially supported build environments that are most likely to work.
Rust currently needs between 600MiB and 1.5GiB to build, depending on platform. If it hits swap, it will take a very long time to build.
There is more advice about hacking on Rust in CONTRIBUTING.md.
Getting Help
The Rust community congregates in a few places:
- Stack Overflow - Direct questions about using the language.
- users.rust-lang.org - General discussion and broader questions.
- /r/rust - News and general discussion.
Contributing
To contribute to Rust, please see CONTRIBUTING.
Rust has an IRC culture and most real-time collaboration happens in a variety of channels on Mozilla's IRC network, irc.mozilla.org. The most popular channel is #rust, a venue for general discussion about Rust. And a good place to ask for help would be #rust-beginners.
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.