mirror of https://github.com/systemed/tilemaker
You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
67 lines
1.9 KiB
CMake
67 lines
1.9 KiB
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>
|
|
#include <cstddef>
|
|
#if defined(__SIZEOF_INT128__)
|
|
// Boost needs 16-byte atomics for tagged pointers.
|
|
// These are implemented via inline instructions on the platform
|
|
// if 16-byte alignment can be proven, and are delegated to libatomic
|
|
// library routines otherwise. Whether or not alignment is provably
|
|
// OK for a std::atomic unfortunately depends on compiler version and
|
|
// optimization levels, and also on the details of the expression.
|
|
// We specifically test access via an otherwise unknown pointer here
|
|
// to ensure we get the most complex case. If this access can be
|
|
// done without libatomic, then all accesses can be done.
|
|
struct tagged_ptr {
|
|
int* ptr;
|
|
std::size_t tag;
|
|
};
|
|
void atomic16(std::atomic<tagged_ptr> *ptr)
|
|
{
|
|
tagged_ptr p{nullptr, 1};
|
|
ptr->store(p);
|
|
tagged_ptr f = ptr->load();
|
|
tagged_ptr new_tag{nullptr, 0};
|
|
ptr->compare_exchange_strong(f, new_tag);
|
|
}
|
|
#endif
|
|
int main() {
|
|
#if defined(__SIZEOF_INT128__)
|
|
std::atomic<tagged_ptr> ptr;
|
|
atomic16(&ptr);
|
|
#endif
|
|
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 "-latomic")
|
|
else()
|
|
message(FATAL_ERROR
|
|
"Host compiler ${CMAKE_CXX_COMPILER} requires libatomic, but it is not found")
|
|
endif()
|
|
endif()
|