ARM/RaspberryPi 的 LLVM 构建选项 [英] LLVM build options for ARM / RaspberryPi

问题描述

我正在寻求澄清 Raspbian 上 LLVM 3.2 的最佳构建选项

I'm seeking clarification of what the best build options are for LLVM 3.2 on Raspbian

我已经获取了 3.2 的 LLVM 源代码，我的配置是:

I've fetched the LLVM source of 3.2, and my config is:

cd llvm-3.2.src
./configure --build=armv6-unknown-linux-gnueabi 
--host=armv6-unknown-linux-gnueabi 
--target=armv6-unknown-linux-gnueabi --with-cpu=arm1176jzf-s 
--with-float=hard --with-abi=aapcs-vfp --with-fpu=neon 
--enable-targets=arm --enable-optimized --enable-assertions
make REQUIRES_RTTI=1
sudo make install

我听说构建需要花费相当多的时间.它已经运行了几个小时，但很高兴让它运行.

I've heard it takes quite a number of hours to build. It's been running a few hours now, happy to just let it run though.

这是一个长期的构建项目，所以如果需要，我可以毫不犹豫地重做构建:)

It's a long term build project so I have no qualms about redoing the build if needed :)

推荐答案

我建议为 Raspbian 交叉编译 LLVM.在 Pi 本身上构建它需要很长时间.

I'd recommend cross-compiling LLVM for Raspbian. Building it on Pi itself takes ages.

首先，使用 debootstrap 获得一个可用的根 fs(或者，只需克隆现有的 Raspbian 安装或解压下载的映像).您可能需要将一些绝对符号链接替换为相对符号链接，注意构建错误.

First, get a working root fs using debootstrap (alternatively, just clone your existing Raspbian installation or unpack a downloaded image). You may need to replace some absolute symlinks with relative, watch out for build errors.

确保您有一个可用且足够新的 clang 安装(不要忘记使用 ARM 目标支持来构建它).

Make sure you have a working and recent enough installation of clang (don't forget to build it with ARM target support).

然后，使用以下 CMake 工具链定义交叉编译 LLVM(在此阶段您不应 chroot 到您的根 fs！):

Then, cross-compile LLVM with the following CMake toolchain definition (you should not chroot into your root fs at this stage!):

set(toolchain_dir /path/to/your/chroot-raspbian-armhf/ )
set(toolchain_bin_dir ${toolchain_dir}/usr/bin)
set(toolchain_inc_dir ${toolchain_dir}/usr/include) # was /include
set(toolchain_lib_dir ${toolchain_dir}/usr/lib)

set(CMAKE_SYSTEM_NAME Linux CACHE INTERNAL "system name")
set(CMAKE_SYSTEM_PROCESSOR arm CACHE INTERNAL "processor")
set(CMAKE_C_COMPILER clang)
set(CMAKE_CXX_COMPILER clang++)
set(CMAKE_C_FLAGS "-O2 -integrated-as -target armv6-linux-gnueabihf -mfloat-abi=hard --sysroot=${toolchain_dir}" CACHE INTERNAL "c compiler flags")
set(CMAKE_CXX_FLAGS "-O2 -integrated-as -target armv6-linux-gnueabihf -mfloat-abi=hard --sysroot=${toolchain_dir}" CACHE INTERNAL "cxx compiler flags")

set(link_flags "-L${toolchain_lib_dir} -ldl")

set(CMAKE_EXE_LINKER_FLAGS ${link_flags} CACHE INTERNAL "exe link flags")
set(CMAKE_MODULE_LINKER_FLAGS ${link_flags} CACHE INTERNAL "module link flags")
set(CMAKE_SHARED_LINKER_FLAGS ${link_flags} CACHE INTERNAL "shared link flags")
set(CMAKE_FIND_ROOT_PATH ${toolchain_lib_dir} CACHE INTERNAL "cross root directory")
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM BOTH CACHE INTERNAL "")
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY CACHE INTERNAL "")
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY CACHE INTERNAL "")

(使用cmake -DCMAKE_TOOLCHAIN_FILE=/path/to/the/file/above.txt)

请注意目标应该是armv6-linux-gnueabihf，而不是armv6-linux-gnueabi.

Please note that target should be armv6-linux-gnueabihf, not armv6-linux-gnueabi.

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