[llvm-dev] bug: cross-compile Clang/LLVM for ARM using Clang/LLVM

[李阳 via llvm-dev]

Hi renato,

1. The command above is followed by the guide[ HowToCrossCompileLLVM.rst ]
and I specify some path(ex. <path-to-host-bin>).

2. The including x86_64 libraries is added because of  some missing
libraries(ex. "error:  Host compiler appears to require libatomic, but
cannot find it"). As I have found that the bugs needed to dealt with is
some ARM-dependent libraries, I cannot download them on Ubuntu14, could you
share them or some available links?

Thanks very much!

Best,
Liyang

2016-04-25 18:33 GMT+08:00 Renato Golin <renato.golin at linaro.org>:

> On 25 April 2016 at 10:39, 李阳 via llvm-dev <llvm-dev at lists.llvm.org>
> wrote:
>
>> CC='clang' CXX='clang++' cmake -G Ninja ../llvm-source-code
>> -DCMAKE_CROSSCOMPILING=True
>> -DCMAKE_INSTALL_PREFIX=./llvm
>> -DLLVM_TABLEGEN=/home/lab/workspace/llvm/build4x86/bin/llvm-tblgen
>> -DCLANG_TABLEGEN=/home/lab/workspace/llvm/build4x86/bin/clang-tblgen
>> -DLLVM_DEFAULT_TARGET_TRIPLE=arm-linux-gnueabihf
>> -DLLVM_TARGET_ARCH=ARM
>> -DLLVM_TARGETS_TO_BUILD=ARM
>> -DCMAKE_CXX_FLAGS='-target armv7a-linux-gnueabihf -mcpu=cortex-a9
>> -I/usr/arm-linux-gnueabihf/include/c++/4.7.3/arm-linux-gnueabihf/
>> -I/usr/arm-linux-gnueabihf/include/
>> -I/home/lab/workspace/llvm/llvm-source-code/lib4arm/
>> -I/home/lab/workspace/llvm/llvm-source-code/lib2ubuntu/
>> -I/usr/lib/gcc/x86_64-linux-gnu/4.8/libatomic.so
>> -I/usr/lib/gcc/x86_64-linux-gnu/4.8/libatomic.so
>> -L/usr/lib/gcc/x86_64-linux-gnu/4.8/libatomic.so
>> -L/usr/lib/gcc/x86_64-linux-gnu/4.8/libatomic.a -mfloat-abi=hard
>> -ccc-gcc-name arm-linux-gnueabihf-gcc'
>> -DLLVM_ENABLE_LIBCXX=ON
>> -DLLVM_ENABLE_PIC=False
>>
>
> Hi Liyang,
>
> You have "LLVM_DEFAULT_TARGET_TRIPLE=arm-linux-gnueabihf"  and
> "CMAKE_CXX_FLAGS='-target armv7a-linux-gnueabihf" which are different, and
> may confuse Clang when finding tools and libraries. Use whatever is the ARM
> triple in your system (looks like it's "arm-linux-gnueabihf") and make both
> target triple and "-target" to be that exact same string.
>
> Also, you're including x86_64 libraries
> (ex. -L/usr/lib/gcc/x86_64-linux-gnu/4.8/libatomic.so) to an ARM
> compilation job, that won't work. You have to find the ARM version (maybe
> /usr/lib/gcc/arm-linux-gnueabihf/ ?).
>
> Finally, the include paths with -I are only necessary if Clang cannot find
> it. The first three should be ok, but using -I on a DSO object
> (libatomic.so) makes no sense.
>
> cheers,
> --renato
>
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