LLVM Cross Toolchain

A cross toolchain collection based on LLVM with multi architecture and platform support.

Supported target platforms:

• Linux: musl-libc, glibc

• Android

• Windows: MinGW, MSVC(Experiment)

• Darwin: MacOSX, Mac-Catalyst, iOS, tvOS, watchOS

• BSD: FreeBSD

• WebAssembly(WASM): Emscripten, WAMR(with custom extensions)

The toolchain itself works on Linux, Windows and MacOSX now.

Build

1. Prerequisite tools and libs

• GCC or Clang that supports C++17 and later

• CMake >= 3.15

• Ninja

  It can be installed via pip:

  pip install ninja

• Python 3 >= 3.7

  Python >= 3.8 is required on Windows to support unelevated symlinks with developer mode

• Golang(latest version recommended)

• Some development libs:

Lib	CentOS	Ubuntu/Debian
libz	zlib-devel	zlib1g-dev
liblzma	xz-devel	liblzma-dev
libxml2	libxml2-devel	libxml2-dev

• Windows host:

  • MSYS2

  NOTE: To build in MSYS2, you can install the following packages with pacman:

  curl rsync make patch
  mingw-w64-x86_64-gcc mingw-w64-x86_64-cmake mingw-w64-x86_64-ninja mingw-w64-x86_64-python3 mingw-w64-x86_64-zlib mingw-w64-x86_64-xz mingw-w64-x86_64-libxml2 mingw-w64-x86_64-polly
  

  • Windows subsystem for Linux(WSL) with any Linux distribution(Optional)

2. Configure project

The file version contains the versions of some important toolchain components, such as glibc, musl-libc and so on.

The array variable CROSS_TARGETS in the file cross-targets defines all cross target triples to be built.

You can change version and cross-targets based on your need.

3. Prepare stuff

(1) Linux kernel header

NOTE for MacOSX host: Linux kernel header must be built on Linux environment, it's recommended to build in Docker Linux image.

prebuilt-linux-header/build-linux-header.sh

(2) Linux glibc

NOTE: glibc must be built in glibc based Linux environment(eg. CentOS, Debian, Ubuntu).

Prerequisite development libs:

Lib	CentOS	Ubuntu/Debian
libgmp	gmp-devel	libgmp-dev
libmpfr	mpfr-devel	libmpfr-dev
libmpc	libmpc-devel	libmpc-dev

# Build glibc from source, it will take a long time
prebuilt-glibc/build-glibc.sh

(3) Android Bionic libc

Prerequisite: Android NDK >= r21e

# Set the installation path of Android NDK
export ANDROID_NDK_HOME=/path/to/android-ndk
# Extract Bionic headers and libs from NDK
prebuilt-bionic/extract_bionic_from_ndk.sh

(4) Darwin SDKs

Method 1: (recommended)extract SDKs from Xcode.xip package

1. Download Xcode.xip from official Apple Developer website

2. Execute tool:

./prebuilt-darwin-sdk/extract_sdks_from_xcode_archive.sh /path/to/Xcode.xip

3. Check and modify values of MACOSX_VERSION, IOS_VERSION, APPLE_TVOS_VERSION, APPLE_WATCHOS_VERSION in file version to match those of extracted SDKs in dir prebuilt-darwin-sdk.

Method 2: (MacOSX host only)extract SDKs from installed Xcode

1. Install gnu-tar, it can be installed via homebrew:

   brew install gnu-tar

   Check if command gtar is available.

2. Execute tool:

   prebuilt-darwin-sdk/extract_sdks_from_xcode.sh

3. Check and modify values of MACOSX_VERSION, IOS_VERSION, APPLE_TVOS_VERSION, APPLE_WATCHOS_VERSION in file version to match those of extracted SDKs in dir prebuilt-darwin-sdk.

(5) Apple cctools

NOTE for Windows host: cctools must be built in WSL.

Prerequisite:

• clang >= 4
• development libs:

Lib	CentOS	Ubuntu/Debian
llvm	llvm-devel	llvm-dev
llvm(static libs)	llvm-static	llvm-dev
libuuid	libuuid-devel	uuid-dev
openssl	openssl-devel	libssl-dev

Check if the following command works first:

llvm-config --link-static --libs lto

Build cctools:

./prebuilt-cctools/build-cctools.sh

(6) MSVC

1. Enter Visual Studio Developer Command Prompt first, then enter MSYS2/Cygwin shell.

2. Execute the shell script:

./prebuilt-msvc-sdk/extract_sdk_from_msvc.sh

3. Check and modify values of VC_VERSION, WINDOWS_SDK_VERSION in file version to match those of extracted SDKs in dir prebuilt-msvc-sdk.

(7) FreeBSD

./prebuilt-freebsd/prepare_sysroot.sh

(8) Open Harmony OS(OHOS)

# Set the installation path of OHOS SDK
export OHOS_SDK_HOME=/path/to/ohos-sdk
# Extract headers and libs from SDK
prebuilt-ohos/extract_sdk.sh

4. Build and Assemble toolchain

Execute the script build-all.sh to start building.

./build-all.sh

The output directory path is defined by variable OUTPUT_DIR in the file config.

After building has finished successfully, you can use tool strip_toolchain.sh to strip the output toolchain.

Project Reference

• llvm-mingw

• crosstool-ng

• osxcross