The LLVM Compiler Infrastructure

This directory and its sub-directories contain a forked source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and run-time environments.

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 guide.

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 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, the LLD linker, and more.

Getting the Source Code and Building LLVM

The LLVM Getting Started documentation may be out of date. The Clang Getting Started page might have more accurate information.

This is an example work-flow and configuration to get and build the LLVM source:

1. Checkout LLVM (including related sub-projects 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 build system generators are:

     • Ninja --- for generating Ninja 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 sub-projects 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 path name 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).

   • cmake --build . [-- [options] <target>] or your build system specified above directly.

     • 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 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 the option -j NNN, where NNN is the number of parallel jobs, e.g. the number of CPUs you have.

   • For more information see CMake

Consult the Getting Started with LLVM page for detailed information on configuring and compiling LLVM. You can visit Directory Layout to learn about the layout of the source code tree.

iOS version specific information

This is a very experimental port. It's is designed to work inside ios_system (https://github.com/holzschu/ios_system), which itself is supposed to be embedded inside shell applications such as OpenTerm, a-Shell or Blink:

• https://github.com/louisdh/terminal
• https://github.com/holzschu/a-Shell

Compilation of the entire package takes several hours (divided by the number of cores you can give to the compiler).

The steps for compilation are:

• compile LLVM, clang, lld, libcxx and libcxxabi for OSX
• make sure ios_system has been compiled, and if not compile it.
• compile LLVM and clang for iOS and the Simulator (that's the long step)

"bootstrap.sh" in this directory takes care of all these steps. Remember, you have time for a long walk in the woods while it compiles.

You can also embed the precompiled Swift binary packages from the release, using Xcode -> Swift Packages -> Add package dependency for Xcode 12 and above.

Once you have compiled everything, add the binaries you want (at least clang) to the list of embedded binaries, along with libLLVM.dylib and libclang.dylib.

Once you have the binaries inside your app, you need to provide the header files. I copied them from wasi-sdk: https://github.com/holzschu/wasi-sdk since the focus is on creating webAssembly files, but you can also copy from the Xcode iPhone SDK if you plan on compiling for iOS (you will not be able to execute files compiled for iOS without signing them, which requires moving them to a Mac, but still).

I welcome all help on this project, including on this README file.