ceph/cmake/modules/CheckCxxAtomic.cmake
Kefu Chai 16976bd42a cmake: should link against libatomic if libcxx/libstdc++ does not offer atomic ops
for instance,  GCC-8 on riscv64 does not offer atomic ops like
__atomic_fetch_or_1, so we need to link against libatomic to get access
to these symbols.

Signed-off-by: Kefu Chai <kchai@redhat.com>
2018-07-10 01:37:00 +08:00

39 lines
1014 B
CMake

# some platforms do not offer support for atomic primitive for all integer
# types, in that case we need to link against libatomic
include(CheckCXXSourceCompiles)
include(CMakePushCheckState)
function(check_cxx_atomics var)
set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -std=c++11")
check_cxx_source_compiles("
#include <atomic>
#include <cstdint>
int main() {
std::atomic<uint8_t> w1;
std::atomic<uint16_t> w2;
std::atomic<uint32_t> w4;
std::atomic<uint64_t> w8;
return w1 + w2 + w4 + w8;
}
" ${var})
endfunction(check_cxx_atomics)
cmake_push_check_state()
check_cxx_atomics(HAVE_CXX11_ATOMIC)
cmake_pop_check_state()
if(NOT HAVE_CXX11_ATOMIC)
cmake_push_check_state()
set(CMAKE_REQUIRED_LIBRARIES "atomic")
check_cxx_atomics(HAVE_LIBATOMIC)
cmake_pop_check_state()
if(HAVE_LIBATOMIC)
set(LIBATOMIC_LINK_FLAGS "-Wl,--as-needed -latomic")
else()
message(FATAL_ERROR
"Host compiler ${CMAKE_CXX_COMPILER} requires libatomic, but it is not found")
endif()
endif()