44 lines
1.4 KiB
CMake
44 lines
1.4 KiB
CMake
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# - Try to find if 64-bits atomics need -latomic linking
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# Once done this will define
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# HAVE_CXX_ATOMICS_WITHOUT_LIB - Whether atomic types work without -latomic
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include(CheckCXXSourceCompiles)
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include(CheckLibraryExists)
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# Sometimes linking against libatomic is required for atomic ops, if
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# the platform doesn't support lock-free atomics.
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function(check_working_cxx_atomics VARNAME)
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check_cxx_source_compiles("
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#include <atomic>
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int main() {
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std::atomic<long long> x;
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return std::atomic_is_lock_free(&x);
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}
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" ${VARNAME})
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endfunction()
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# Check for atomic operations.
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if(MSVC)
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# This isn't necessary on MSVC.
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set(HAVE_CXX_ATOMICS_WITHOUT_LIB TRUE)
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else()
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# First check if atomics work without the library.
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check_working_cxx_atomics(HAVE_CXX_ATOMICS_WITHOUT_LIB)
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endif()
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# If not, check if the library exists, and atomics work with it.
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if(NOT HAVE_CXX_ATOMICS_WITHOUT_LIB)
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check_library_exists(atomic __atomic_load_8 "" HAVE_LIBATOMIC)
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if(NOT HAVE_LIBATOMIC)
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message(STATUS "Host compiler appears to require libatomic, but cannot locate it.")
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endif()
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list(APPEND CMAKE_REQUIRED_LIBRARIES "atomic")
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check_working_cxx_atomics(HAVE_CXX_ATOMICS_WITH_LIB)
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list(REMOVE_ITEM CMAKE_REQUIRED_LIBRARIES "atomic")
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if(NOT HAVE_CXX_ATOMICS_WITH_LIB)
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message(FATAL_ERROR "Host compiler must support std::atomic!")
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endif()
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endif()
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