Zig LLVM-MOS Bootstrap

This project is a fork of zig-bootstrap, originally created by Andrew Kelley, the creator of Zig programming language. The aim of this fork, zig-mos-bootstrap, is to switch the LLVM upstream dependency over to LLVM-mos in order to add support for a new target based on mos6502 architecture.

Project Objective

The primary goal of this project is to minimize system dependencies while achieving a fully functional Zig compiler for various targets.

Acknowledgements

This project owes its existence to the invaluable contributions of several individuals and communities:

• Andrew Kelley: The original creator of zig-bootstrap, which serves as the foundation for this project.
• Zig Developers: For helping to maintain the Zig.
• LLVM-MOS Developers: For their work on llvm-mos, enabling support for the mos6502 architecture.

Version Information

This repository copies sources from upstream. Patches listed below. Use git to find and inspect the patch diffs.

• LLVM-MOS (LLVM 20.0.0)
• zlib 1.3.1
• zstd 1.5.2
• zig 0.14.0-dev

For other versions, check the git tags of this repository.

Patches

• all: Deleted unused files.
• LLVM: Support .lib extension for static zstd.
• LLVM: Portable handling of .def linker flag
• Clang: Disable building of libclang-cpp.so.
• LLD: Added additional include directory to Zig's libunwind.
• LLD: Respect LLD_BUILD_TOOLS=OFF
• zlib: Delete the ability to build a shared library.

Host System Dependencies

• C++ compiler capable of building LLVM, Clang, and LLD from source (GCC 5.1+ or Clang)
• CMake 3.19 or later
• make, ninja, or any other build system supported by CMake
• POSIX system (bash, mkdir, cd)
• Python 3

Build Instructions

./build <arch>-<os>-<abi> <mcpu>

All parameters are required:

• <arch>-<os>-<abi>: Replace with one of the Supported Triples below, or use native for the <arch> value (e.g. native-linux-gnu) to use the native architecture.
• <mcpu>: Replace with a -mcpu parameter of Zig. baseline is recommended and means it will target a generic CPU for the target. native means it will target the native CPU. See the Zig documentation for more details.

Please be aware of the following two CMake environment variables that can significantly affect how long it takes to build:

• CMAKE_GENERATOR can be used to select a different generator instead of the default. For example, CMAKE_GENERATOR=Ninja.
• CMAKE_BUILD_PARALLEL_LEVEL can be used to introduce parallelism to build systems (such as make) which do not default to parallel builds. This option is irrelevant when using Ninja.

When it succeeds, output can be found in out/zig-<triple>-<cpu>/.

Windows Build Instructions

Bootstrapping on Windows with MSVC is also possible via build.bat, which takes the same arguments as build above.

This script requires that the "C++ CMake tools for Windows" component be installed via the Visual Studio installer.

The script must be run within the Developer Command Prompt for VS 2019 shell:

build.bat <arch>-<os>-<abi> <mcpu>

To build for x86 Windows, run the script within the x86 Native Tools Command Prompt for VS 2019.

Supported Triples

If you try a "not tested" one and find a problem please file an issue, and a pull request linking to the issue in the table.

If you try a "not tested" one and find that it works, please file a pull request changing the status to "OK".

If you try an "OK" one and it does not work, please check if there is an existing issue, and if not, file an issue.

Note: Generally, for Linux targets, we prefer the musl libc builds over the glibc builds here, because musl builds end up producing a static binary, which is more portable across Linux distributions.

Other Notable Targets Known to Work

• arm-linux-musleabi with mcpu value of generic+v6kz. This produces a build of Zig that runs on the RPi 1 and RPi Zero.
  • If you want to produce a build for this CPU exactly, use arm1176jzf_s.