llvm dev - May 2016 - build issue in llvm-clang cross tool chain for arm target

Hello All,

I am building llvm-clang cross tool chain for arm target, after successful
build for Linux host now I am now building toolchain for *arm target*.
However, I am getting below error message which seems to be confusing and
not getting any idea how to resolve this issue.

*Command :*
#CC='clang' CXX='clang++' cmake -G Ninja
/home/iiita/crossbuild/llvm
-DLLVM_ENABLE_LIBCXX=ON -DCMAKE_CROSSCOMPILING=True
-DCMAKE_INSTALL_PREFIX=/home/iiita/crossbuild/build
-DLLVM_TABLEGEN=/home/iiita/llvm-3.8/build/bin/llvm-tblgen
-DCLANG_TABLEGEN=/home/iiita/llvm-3.8/build/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/ -mfloat-abi=hard -ccc-gcc-name
arm-linux-gnueabihf-gcc'

*Error message:*
CMake Error at cmake/modules/CheckAtomic.cmake:33 (message):
  Host compiler must support std::atomic!
Call Stack (most recent call first):
  cmake/config-ix.cmake:296 (include)
  CMakeLists.txt:407 (include)


-- Configuring incomplete, errors occurred!
See also "/home/iiita/crossbuild/build/CMakeFiles/CMakeOutput.log".
See also "/home/iiita/crossbuild/build/CMakeFiles/CMakeError.log".


Does anyone know how to resolve this issue or any other way to build tool
chain for arm from source code?

Thanks,
Bala
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On 6 May 2016 at 18:28, Balasaheb Dabhade via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> Error message:
> CMake Error at cmake/modules/CheckAtomic.cmake:33 (message):
>   Host compiler must support std::atomic!
Hi,

It's possible that you don't have the required ARM libraries in your
system?

cheers,
--renato

On 6 May 2016 at 18:28, Balasaheb Dabhade via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> -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/ -mfloat-abi=hard -ccc-gcc-name
> arm-linux-gnueabihf-gcc'
I can think of two things:

1. You're using a triple that is different from your gcc name:

'-target armv7a-linux-gnueabihf'

vs

'-ccc-gcc-name arm-linux-gnueabihf-gcc'

You should use the target as "arm-linux-gnueabihf".

2. You're not including the GCC headers or libraries.

You need to find where GCC keeps its libraries (normally
/usr/lib/gcc/arm-linux-gnueabihf) and headers (if necessary).

In your case, just adding -L"where your gcc libs are" should be
enough.

cheers,
--renato

Thanks a lot  Renoto,

I really appreciate your help.

As you mentioned I have modified the command to include gcc libs path(-L )
option in cmake command as below :

cmake -G Ninja /home/iiita/crossbuild/llvm -DLLVM_ENABLE_PIC=False
-DLLVM_ENABLE_LIBCXX=ON -DCMAKE_CROSSCOMPILING=True
-DCMAKE_INSTALL_PREFIX=/home/iiita/crossbuild/build
-DLLVM_TABLEGEN=/home/iiita/llvm-3.8/build/bin/llvm-tblgen
-DCLANG_TABLEGEN=/home/iiita/llvm-3.8/build/bin/clang-tblgen
-DLLVM_DEFAULT_TARGET_TRIPLE=arm-linux-gnueabihf -DLLVM_TARGET_ARCH=ARM
-DLLVM_TARGETS_TO_BUILD=ARM -DCMAKE_CXX_FLAGS='-target
*arm-linux-gnueabihf-gcc* -mcpu=cortex-a9
-I/usr/arm-linux-gnueabihf/include/c++/4.7.3/arm-linux-gnueabihf/
-I/usr/arm-linux-gnueabihf/include/ *-L/usr/lib/gcc/arm-linux-gnueabihf*
-mfloat-abi=hard -ccc-gcc-name arm-linux-gnueabihf-gcc'

However, I am still facing the issue since *cmake not able to find header
file path as per **CMakeError.log (attached for email for reference) error
message*.

Do you have any idea about how to include header file path in cmake command
line or is there any other thing I am missing?


Thanks,
Bala



On Sun, May 8, 2016 at 7:52 PM, Renato Golin <renato.golin at linaro.org>
wrote:
> On 6 May 2016 at 18:28, Balasaheb Dabhade via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
> > -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/ -mfloat-abi=hard -ccc-gcc-name
> > arm-linux-gnueabihf-gcc'
>
> I can think of two things:
>
> 1. You're using a triple that is different from your gcc name:
>
> '-target armv7a-linux-gnueabihf'
>
> vs
>
> '-ccc-gcc-name arm-linux-gnueabihf-gcc'
>
> You should use the target as "arm-linux-gnueabihf".
>
> 2. You're not including the GCC headers or libraries.
>
> You need to find where GCC keeps its libraries (normally
> /usr/lib/gcc/arm-linux-gnueabihf) and headers (if necessary).
>
> In your case, just adding -L"where your gcc libs are" should be
enough.
>
> cheers,
> --renato
>
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