2018-10-19 00:03:01 +00:00
|
|
|
# The LLVM Compiler Infrastructure
|
2017-10-19 21:09:49 +00:00
|
|
|
|
|
|
|
This directory and its subdirectories contain source code for LLVM,
|
|
|
|
a toolkit for the construction of highly optimized compilers,
|
|
|
|
optimizers, and runtime environments.
|
2019-10-24 01:03:37 +00:00
|
|
|
|
2019-12-02 15:46:47 +00:00
|
|
|
The README briefly describes how to get started with building LLVM.
|
|
|
|
For more information on how to contribute to the LLVM project, please
|
|
|
|
take a look at the
|
|
|
|
[Contributing to LLVM](https://llvm.org/docs/Contributing.html) guide.
|
|
|
|
|
2019-10-24 01:03:37 +00:00
|
|
|
## Getting Started with the LLVM System
|
|
|
|
|
|
|
|
Taken from https://llvm.org/docs/GettingStarted.html.
|
|
|
|
|
|
|
|
### Overview
|
|
|
|
|
|
|
|
Welcome to the LLVM project!
|
|
|
|
|
|
|
|
The LLVM project has multiple components. The core of the project is
|
|
|
|
itself called "LLVM". This contains all of the tools, libraries, and header
|
|
|
|
files needed to process intermediate representations and converts it into
|
|
|
|
object files. Tools include an assembler, disassembler, bitcode analyzer, and
|
|
|
|
bitcode optimizer. It also contains basic regression tests.
|
|
|
|
|
|
|
|
C-like languages use the [Clang](http://clang.llvm.org/) front end. This
|
|
|
|
component compiles C, C++, Objective C, and Objective C++ code into LLVM bitcode
|
|
|
|
-- and from there into object files, using LLVM.
|
|
|
|
|
|
|
|
Other components include:
|
|
|
|
the [libc++ C++ standard library](https://libcxx.llvm.org),
|
|
|
|
the [LLD linker](https://lld.llvm.org), and more.
|
|
|
|
|
|
|
|
### Getting the Source Code and Building LLVM
|
|
|
|
|
|
|
|
The LLVM Getting Started documentation may be out of date. The [Clang
|
|
|
|
Getting Started](http://clang.llvm.org/get_started.html) page might have more
|
|
|
|
accurate information.
|
|
|
|
|
|
|
|
This is an example workflow and configuration to get and build the LLVM source:
|
|
|
|
|
|
|
|
1. Checkout LLVM (including related subprojects like Clang):
|
|
|
|
|
|
|
|
* ``git clone https://github.com/llvm/llvm-project.git``
|
|
|
|
|
|
|
|
* Or, on windows, ``git clone --config core.autocrlf=false
|
|
|
|
https://github.com/llvm/llvm-project.git``
|
|
|
|
|
|
|
|
2. Configure and build LLVM and Clang:
|
|
|
|
|
|
|
|
* ``cd llvm-project``
|
|
|
|
|
|
|
|
* ``mkdir build``
|
|
|
|
|
|
|
|
* ``cd build``
|
|
|
|
|
|
|
|
* ``cmake -G <generator> [options] ../llvm``
|
|
|
|
|
|
|
|
Some common generators are:
|
|
|
|
|
|
|
|
* ``Ninja`` --- for generating [Ninja](https://ninja-build.org)
|
|
|
|
build files. Most llvm developers use Ninja.
|
|
|
|
* ``Unix Makefiles`` --- for generating make-compatible parallel makefiles.
|
|
|
|
* ``Visual Studio`` --- for generating Visual Studio projects and
|
|
|
|
solutions.
|
|
|
|
* ``Xcode`` --- for generating Xcode projects.
|
|
|
|
|
|
|
|
Some Common options:
|
|
|
|
|
|
|
|
* ``-DLLVM_ENABLE_PROJECTS='...'`` --- semicolon-separated list of the LLVM
|
|
|
|
subprojects you'd like to additionally build. Can include any of: clang,
|
|
|
|
clang-tools-extra, libcxx, libcxxabi, libunwind, lldb, compiler-rt, lld,
|
|
|
|
polly, or debuginfo-tests.
|
|
|
|
|
|
|
|
For example, to build LLVM, Clang, libcxx, and libcxxabi, use
|
|
|
|
``-DLLVM_ENABLE_PROJECTS="clang;libcxx;libcxxabi"``.
|
|
|
|
|
|
|
|
* ``-DCMAKE_INSTALL_PREFIX=directory`` --- Specify for *directory* the full
|
|
|
|
pathname of where you want the LLVM tools and libraries to be installed
|
|
|
|
(default ``/usr/local``).
|
|
|
|
|
|
|
|
* ``-DCMAKE_BUILD_TYPE=type`` --- Valid options for *type* are Debug,
|
|
|
|
Release, RelWithDebInfo, and MinSizeRel. Default is Debug.
|
|
|
|
|
|
|
|
* ``-DLLVM_ENABLE_ASSERTIONS=On`` --- Compile with assertion checks enabled
|
|
|
|
(default is Yes for Debug builds, No for all other build types).
|
|
|
|
|
|
|
|
* Run your build tool of choice!
|
|
|
|
|
|
|
|
* The default target (i.e. ``ninja`` or ``make``) will build all of LLVM.
|
|
|
|
|
|
|
|
* The ``check-all`` target (i.e. ``ninja check-all``) will run the
|
|
|
|
regression tests to ensure everything is in working order.
|
|
|
|
|
|
|
|
* CMake will generate build targets for each tool and library, and most
|
|
|
|
LLVM sub-projects generate their own ``check-<project>`` target.
|
|
|
|
|
|
|
|
* Running a serial build will be *slow*. To improve speed, try running a
|
|
|
|
parallel build. That's done by default in Ninja; for ``make``, use
|
|
|
|
``make -j NNN`` (NNN is the number of parallel jobs, use e.g. number of
|
|
|
|
CPUs you have.)
|
|
|
|
|
|
|
|
* For more information see [CMake](https://llvm.org/docs/CMake.html)
|
|
|
|
|
|
|
|
Consult the
|
|
|
|
[Getting Started with LLVM](https://llvm.org/docs/GettingStarted.html#getting-started-with-llvm)
|
|
|
|
page for detailed information on configuring and compiling LLVM. You can visit
|
|
|
|
[Directory Layout](https://llvm.org/docs/GettingStarted.html#directory-layout)
|
|
|
|
to learn about the layout of the source code tree.
|