-Z linker-flavor (Please read the commit message first) This PR is an alternative to rust-lang/rust#36120 (internal lld linker). The main goal of this PR is to make it *possible* to use LLD as a linker to allow out of tree experimentation. Now that LLD is going to be shipped with LLVM 4.0, it should become easier to get a hold of LLD (hopefully, it will be packaged by Linux distros soon). Since LLD is a multiarch linker, it has the potential to make cross compilation easier (less tools need to be installed). Supposedly, LLD is also faster than the gold linker so LLD may improve build times where link times are significant (e.g. 100% incremental compilation reuse). The place where LLD shines is at linking Rust programs that don't depend on system libraries. For example, here's how you would link a bare metal ARM Cortex-M program: ``` $ xargo rustc --target thumbv7m-none-eabi -- -Z linker-flavor=ld -C linker=ld.lld -Z print-link-args "ld.lld" \ "-L" \ "$XARGO_HOME/lib/rustlib/thumbv7m-none-eabi/lib" \ "$PWD/target/thumbv7m-none-eabi/debug/deps/app-de1f86df314ad68c.0.o" \ "-o" \ "$PWD/target/thumbv7m-none-eabi/debug/deps/app-de1f86df314ad68c" \ "--gc-sections" \ "-L" \ "$PWD/target/thumbv7m-none-eabi/debug/deps" \ "-L" \ "$PWD/target/debug/deps" \ "-L" \ "$XARGO_HOME/lib/rustlib/thumbv7m-none-eabi/lib" \ "-Bstatic" \ "-Bdynamic" \ "$XARGO_HOME/lib/rustlib/thumbv7m-none-eabi/lib/libcore-11670d2bd4951fa7.rlib" $ file target/thumbv7m-none-eabi/debug/app app: ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV), statically linked, not stripped, with debug_info ``` This doesn't require installing the `arm-none-eabi-gcc` toolchain. Even cooler (but I'm biased) is that you can link Rust programs that use [`steed`] (`steed` is a `std` re-implementation free of C dependencies for Linux systems) instead of `std` for a bunch of different architectures without having to install a single cross toolchain. [`steed`]: https://github.com/japaric/steed ``` $ xargo rustc --target aarch64-unknown-linux-steed --example hello --release -- -Z print-link-args "ld.lld" \ "-L" \ "$XARGO_HOME/lib/rustlib/aarch64-unknown-linux-steed/lib" \ "$PWD/target/aarch64-unknown-linux-steed/release/examples/hello-80c130ad884c0f8f.0.o" \ "-o" \ "$PWD/target/aarch64-unknown-linux-steed/release/examples/hello-80c130ad884c0f8f" \ "--gc-sections" \ "-L" \ "$PWD/target/aarch64-unknown-linux-steed/release/deps" \ "-L" \ "$PWD/target/release/deps" \ "-L" \ "$XARGO_HOME/lib/rustlib/aarch64-unknown-linux-steed/lib" \ "-Bstatic" \ "-Bdynamic" \ "/tmp/rustc.lAybk9Ltx93Q/libcompiler_builtins-589aede02de78434.rlib" $ file target/aarch64-unknown-linux-steed/release/examples/hello hello: ELF 64-bit LSB executable, ARM aarch64, version 1 (SYSV), statically linked, not stripped, with debug_info ``` All these targets (architectures) worked with LLD: - [aarch64-unknown-linux-steed](https://github.com/japaric/steed/blob/lld/docker/aarch64-unknown-linux-steed.json) - [arm-unknown-linux-steedeabi](https://github.com/japaric/steed/blob/lld/docker/arm-unknown-linux-steedeabi.json) - [arm-unknown-linux-steedeabihf](https://github.com/japaric/steed/blob/lld/docker/arm-unknown-linux-steedeabihf.json) - [armv7-unknown-linux-steedeabihf](https://github.com/japaric/steed/blob/lld/docker/armv7-unknown-linux-steedeabihf.json) - [i686-unknown-linux-steed](https://github.com/japaric/steed/blob/lld/docker/i686-unknown-linux-steed.json) - [mips-unknown-linux-steed](https://github.com/japaric/steed/blob/lld/docker/mips-unknown-linux-steed.json) - [mipsel-unknown-linux-steed](https://github.com/japaric/steed/blob/lld/docker/mipsel-unknown-linux-steed.json) - [powerpc-unknown-linux-steed](https://github.com/japaric/steed/blob/lld/docker/powerpc-unknown-linux-steed.json) - [powerpc64-unknown-linux-steed](https://github.com/japaric/steed/blob/lld/docker/powerpc64-unknown-linux-steed.json) - [x86_64-unknown-linux-steed](https://github.com/japaric/steed/blob/lld/docker/x86_64-unknown-linux-steed.json) --- The case where lld is unergonomic is linking binaries that depend on system libraries. Like "Hello, world" for `x86_64-unknown-linux-gnu`. Because you have to pass as linker arguments: the path to the startup objects, the path to the dynamic linker and the library search paths. And all those are system specific so they can't be encoded in the target itself. ``` $ cargo \ rustc \ --release \ -- \ -C \ linker=ld.lld \ -Z \ linker-flavor=ld \ -C \ link-args='-dynamic-linker /lib64/ld-linux-x86-64.so.2 -L/usr/lib -L/usr/lib/gcc/x86_64-pc-linux-gnu/6.3.1 /usr/lib/Scrt1.o /usr/lib/crti.o /usr/lib/gcc/x86_64-pc-linux-gnu/6.3.1/crtbeginS.o /usr/lib/gcc/x86_64-pc-linux-gnu/6.3.1/crtendS.o /usr/lib/crtn.o' ``` --- Another case where `-Z linker-flavor` may come in handy is directly calling Solaris' linker which is also a multiarch linker (or so I have heard). cc @binarycrusader cc @alexcrichton Heads up: [breaking-change] due to changes in the target specification format.
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.x or laterpython
2.7 (but not 3.x)- GNU
make
3.81 or later cmake
3.4.3 or latercurl
git
-
Clone the source with
git
:$ git clone https://github.com/rust-lang/rust.git $ cd rust
-
Build and install:
$ ./x.py build && sudo ./x.py dist --install
Note: Install locations can be adjusted by copying the config file from
./src/bootstrap/config.toml.example
to./config.toml
, and adjusting theprefix
option under[install]
. Various other options are also supported, and are documented in the config file.When complete,
sudo ./x.py dist --install
will 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.
-
Run
mingw32_shell.bat
ormingw64_shell.bat
from wherever you installed MSYS2 (i.e.C:\msys64
), depending on whether you want 32-bit or 64-bit Rust. (As of the latest version of MSYS2 you have to runmsys2_shell.cmd -mingw32
ormsys2_shell.cmd -mingw64
from the command line instead) -
From this terminal, install the required tools:
# Update package mirrors (may be needed if you have a fresh install of MSYS2) $ pacman -Sy pacman-mirrors # Install build tools needed for Rust. If you're building a 32-bit compiler, # then replace "x86_64" below with "i686". If you've already got git, python, # or CMake installed and in PATH you can remove them from this list. Note # that it is important that you do **not** use the 'python2' and 'cmake' # packages from the 'msys2' subsystem. The build has historically been known # to fail with these packages. $ pacman -S git \ make \ diffutils \ tar \ mingw-w64-x86_64-python2 \ mingw-w64-x86_64-cmake \ mingw-w64-x86_64-gcc
-
Navigate to Rust's source code (or clone it), then build it:
$ ./x.py build && ./x.py dist --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.
With these dependencies installed, you can build the compiler in a cmd.exe
shell with:
> python x.py build
Currently building Rust only works with some known versions of Visual Studio. If you have a more recent version installed the build system doesn't understand then you may need to force rustbuild to use an older version. This can be done by manually calling the appropriate vcvars file before running the bootstrap.
CALL "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\bin\amd64\vcvars64.bat"
python x.py build
Specifying an ABI
Each specific ABI can also be used from either environment (for example, using the GNU ABI in powershell) by using an explicit build triple. The available Windows build triples are:
- GNU ABI (using GCC)
i686-pc-windows-gnu
x86_64-pc-windows-gnu
- The MSVC ABI
i686-pc-windows-msvc
x86_64-pc-windows-msvc
The build triple can be specified by either specifying --build=ABI
when
invoking x.py
commands, or by copying the config.toml
file (as described
in Building From Source), and modifying the build
option under the [build]
section.
Configure and Make
While it's not the recommended build system, this project also provides a
configure script and makefile (the latter of which just invokes x.py
).
$ ./configure
$ make && sudo make install
When using the configure script, the generated config.mk
file may override the
config.toml
file. To go back to the config.toml
file, delete the generated
config.mk
file.
Building Documentation
If you’d like to build the documentation, it’s almost the same:
$ ./x.py doc
The generated documentation will appear under doc
in the build
directory for
the ABI used. I.e., if the ABI was x86_64-pc-windows-msvc
, the directory will be
build\x86_64-pc-windows-msvc\doc
.
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.