llvm dev - May 2016 - facing issue for building llvm-clang cross tool chain for arm target

Hi All,

I am building llvm-clang cross tool chain for arm target and getting below
error message when I tried to execute below command :

*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 :*

*-- Performing Test HAVE_CXX_ATOMICS_WITHOUT_LIB - Failed*
-- Looking for __atomic_fetch_add_4 in atomic
-- Looking for __atomic_fetch_add_4 in atomic - found
*-- Performing Test HAVE_CXX_ATOMICS_WITH_LIB*
*-- Performing Test HAVE_CXX_ATOMICS_WITH_LIB - Failed*
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 this build issue because of external library not installed or LLVM
itself has issue with arm support?*


Thanks,
Bala
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On 8 May 2016 at 15:13, Balasaheb Dabhade via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> Does this build issue because of external library not installed or LLVM
> itself has issue with arm support?
Hi Bala,

LLVM does not have issues with ARM support. Cross compilation is not a
trivial matter. I'm trying to help you on the other thread, let's keep
the discussion there.

cheers,
--renato