DisDis / clang_toolchain

CMake script to build LLVM, Clang, lld, compiler-rt, libunwind, libc++abi, libc++. Default sysroot used is Raspbian.

clang_toolchain

This repo is used to build a Clang toolchain, sysroot, compiler-rt, libcxxabi, and libcxx.

The default sysroot created is the latest Raspbian rootfs.

The default triple is arm-linux-gnueabihf.

These defaults are overridable, for use with other sysroots, such as a Yocto SDK.

Project Status

Tested with GCC (Trusty, Xenial, and Bionic), and Clang (macOS Mojave). Sysroot install step will fail on Windows native, should work on Cygwin or Mingw.

Travis-CI

Note: If you don't have a commercial account, your travis build will fail due to the build time exceeding max. If you do have a commercial account, you will need to request a max build time setting of 180 minutes.

Build Prerequisites

1. CMake 3.11 or greater

2. Host capable of building something

    sudo apt-get update
    sudo apt install gcc clang build-essentials make subversion texinfo bison flex
   

   Alternatively install LLVM/Clang

3. sysroot generation uses rsync, or ln, tar, and curl.

Build Example

mkdir -p ~/git && cd ~/git
git clone https://github.com/jwinarske/clang_toolchain.git
cd clang_toolchain && mkdir build && cd build
cmake .. -DTARGET_TRIPLE=arm-none-eabi -DTARGET_SYSROOT=/home/joel/sdk/gcc-arm-none-eabi-8-2018-q4-major
make -j$(numproc)

Notes

When passing path values to CMake use aboslute paths

If you want to force a rebuild of a sub-project, either delete the specific folder from your build folder, or delete to appropriate flags from the sub projects build folder.

Cross compiling for RaspberryPi (armhf raspbian)

Build 7.0.1 Toolchain, populate sysroot from target via rsync, and build MRAA

-DLLVM_TARGETS_TO_BUILD="ARM"
-DBUILD_PLATFORM_RPI=ON
-DTARGET_HOSTNAME=[e-mail]
-DBUILD_MRAA=ON

Build 8.0.0 rc2 Toolchain, create sysroot from official rootfs, build MRAA, and specify sdk folder

-DLLVM_VERSION=tags/RELEASE_800/rc2/
-DLLVM_VER_DIR=8.0.0
-DBUILD_PLATFORM_RPI=ON
-DBUILD_PLATFORM_SYSROOT=ON
-DBUILD_MRAA=ON
-DSDK_ROOT_DIR=/home/joel/rpi
-DTOOLCHAIN_FILE_DIR=/home/joel/rpi/sdk/build/cmake

Build 8.0.0 rc2 Toolchain, populate sysroot from target via rsync, and build MRAA

-DLLVM_TARGETS_TO_BUILD="ARM"
-DBUILD_PLATFORM_RPI=ON
-DTARGET_HOSTNAME=[e-mail]
-DBUILD_MRAA=ON
-DLLVM_VERSION=tags/RELEASE_800/rc2/
-DLLVM_VER_DIR=8.0.0

Cross compiling for AtomicPi (x86_64 lubuntu)

Build 7.0.1 Toolchain, populate sysroot from target via rsync, and build MRAA

-DTARGET_ARCH=x86_64
-DTARGET_TRIPLE=x86_64-linux-gnu
-DLLVM_TARGETS_TO_BUILD="X86" -DTARGET_HOSTNAME=[e-mail]
-DBUILD_MRAA=ON

Build 8.0.0 rc2 Toolchain, populate sysroot from target via rsync, and build MRAA

-DTARGET_ARCH=x86_64
-DTARGET_TRIPLE=x86_64-linux-gnu
-DLLVM_TARGETS_TO_BUILD="X86" -DTARGET_HOSTNAME=[e-mail]
-DBUILD_MRAA=ON
-DLLVM_VERSION=tags/RELEASE_800/rc2/
-DLLVM_VER_DIR=8.0.0

Sequence to build 7.0.1 Toolchain, populate sysroot from target, build hello-wayland, push to target, and execute

ssh [e-mail]
sudo apt-get install wayland-protocols libwayland-dev
exit
mkdir -p ~/git && cd ~/git
git clone https://github.com/jwinarske/clang_toolchain.git
cd clang_toolchain && mkdir build && cd build
cmake .. -DTARGET_ARCH=x86_64 -DTARGET_TRIPLE=x86_64-linux-gnu -DTARGET_HOSTNAME=[e-mail] -DBUILD_WAYLAND=ON
make -j$(nproc)
scp ./target/bin/hello_wayland [e-mail]:/home/atomicpi
ssh [e-mail]
./hello-wayland

CMake Build options

BUILD_PLATFORM_RPI

Build Platform Raspberry Pi

BUILD_PLATFORM_SYSROOT

Build Platform sysroot. This currently only affects RPI. You either provide your own, or create from scratch.

BUILD_WAYLAND

Build hello-wayland app

BUILD_LLD

Checkout and build LLVM Linker for host. Defaults to ON

BUILD_BINUTILS

Download and build binutils for host. Defaults to OFF

BUILD_LLDB

Checkout and build LLVM Debugger for host. Defaults to OFF. Enables use of -fuse-ld=gold

BUILD_COMPILER_RT

Checkout and build compiler-rt. Defaults to ON

BUILD_LIBCXXABI

Checkout and build libcxxabi for target. Defaults to ON

BUILD_LIBCXXABI_ENABLE_EXCEPTIONS

Build c++abi with exception support Defaults to ON

BUILD_LIBUNWIND

Checkout and build libunwind for target. Defaults to ON

BUILD_LIBCXX

Checkout and build libcxx for target. Defaults to ON

CMake variables

RASPBIAN_ROOTFS_URL

Defaults to http://director.downloads.raspberrypi.org/raspbian/archive/

RASPBIAN_ROOTFS_VERSION

Defaults to 2018-11-15-21:02

Note: When changing this you may need to adjust dangling/missing symlinks specific to selected version. See cmake/rpi/sysroot.cmake

THIRD_PARTY_DIR

Defaults to ${CMAKE_SOURCE_DIR}/third_party

SDK_ROOT_DIR

Defaults to ${CMAKE_SOURCE_DIR}

TOOLCHAIN_FILE_DIR

Defaults to ${CMAKE_BINARY_DIR}

TOOLCHAIN_DIR

Defaults to ${SDK_ROOT_DIR}/sdk/toolchain

TARGET_SYSROOT

Defaults to ${SDK_ROOT_DIR}/sdk/sysroot

TARGET_TRIPLE

Defaults to arm-linux-gnueabihf

CMAKE_VERBOSE_MAKEFILE

Defaults to OFF. This variable affects all subprojects. Alternatively use:

make VERBOSE=1

LLVM_TARGETS_TO_BUILD

Defaults to X86|ARM|AArch64. One example setting would be

-DLLVM_TARGETS_TO_BUILD="ARM"

Note: This only affects LLVM/Clang (host), not target builds; compiler-rt, libunwind, libcxxabi, and libcxx.

Regardless of this value, the LLVM/Clang build as a minimum will build support for the host triple.

LLVM_VERSION

Defaults to tags/RELEASE_701/final/

Some examples

-DLLVM_VERSION=trunk/
-DLLVM_VERSION=tags/RELEASE_800/rc1/
-DLLVM_VERSION=branches/release_80/

Note: LLVM_VER_DIR needs to match selected version, in order for compiler-rt to install into the proper location.

LLVM_VER_DIR

Defaults to 7.0.1. This must match LLVM version, or use of compiler-rt will fail, as library will not be found. This variable is only used for installation of compiler-rt libraries.

Target Triple (1)

The triple has the general format <arch><sub>-<vendor>-<sys>-<abi>, where:

    arch = x86_64, i386, arm, thumb, mips, etc.
    sub = for ex. on ARM: v5, v6m, v7a, v7m, etc.
    vendor = pc, apple, nvidia, ibm, etc.
    sys = none, linux, win32, darwin, cuda, etc.
    abi = eabi, gnu, android, macho, elf, etc.

The sub-architecture options are available for their own architectures, of course, so "x86v7a" doesn’t make sense. The vendor needs to be specified only if there’s a relevant change, for instance between PC and Apple. Most of the time it can be omitted (and Unknown) will be assumed, which sets the defaults for the specified architecture. The system name is generally the OS (linux, darwin), but could be special like the bare-metal “none”.

When a parameter is not important, it can be omitted, or you can choose unknown and the defaults will be used. If you choose a parameter that Clang doesn’t know, like blerg, it’ll ignore and assume unknown, which is not always desired, so be careful.

References

(1) https://clang.llvm.org/docs/CrossCompilation.html