diff options
Diffstat (limited to 'libcxx/cmake')
| -rw-r--r-- | libcxx/cmake/Modules/CheckLibcxxAtomic.cmake | 41 | ||||
| -rw-r--r-- | libcxx/cmake/config-ix.cmake | 5 |
2 files changed, 46 insertions, 0 deletions
diff --git a/libcxx/cmake/Modules/CheckLibcxxAtomic.cmake b/libcxx/cmake/Modules/CheckLibcxxAtomic.cmake new file mode 100644 index 00000000000..d3b9fa466ed --- /dev/null +++ b/libcxx/cmake/Modules/CheckLibcxxAtomic.cmake @@ -0,0 +1,41 @@ +INCLUDE(CheckCXXSourceCompiles) + +# Sometimes linking against libatomic is required for atomic ops, if +# the platform doesn't support lock-free atomics. +# +# We could modify LLVM's CheckAtomic module and have it check for 64-bit +# atomics instead. However, we would like to avoid careless uses of 64-bit +# atomics inside LLVM over time on 32-bit platforms. + +function(check_cxx_atomics varname) + set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS}) + set(CMAKE_REQUIRED_FLAGS "-std=c++11") + if (${LIBCXX_GCC_TOOLCHAIN}) + set(CMAKE_REQUIRED_FLAGS "-std=c++11 --gcc-toolchain=${LIBCXX_GCC_TOOLCHAIN}") + endif() + check_cxx_source_compiles(" +#include <cstdint> +#include <atomic> +std::atomic<uintptr_t> x; +std::atomic<uintmax_t> y; +int main() { + return x + y; +} +" ${varname}) + set(CMAKE_REQUIRED_FLAGS ${OLD_CMAKE_REQUIRED_FLAGS}) +endfunction(check_cxx_atomics) + +check_cxx_atomics(LIBCXX_HAVE_CXX_ATOMICS_WITH_LIB) +# If not, check if the library exists, and atomics work with it. +if(NOT LIBCXX_HAVE_CXX_ATOMICS_WITH_LIB) + check_library_exists(atomic __atomic_fetch_add_8 "" HAVE_LIBATOMIC) + if(HAVE_LIBATOMIC) + list(APPEND CMAKE_REQUIRED_LIBRARIES "atomic") + check_cxx_atomics(HAVE_CXX_ATOMICS_WITH_LIB) + if (NOT HAVE_CXX_ATOMICS_WITH_LIB) + message(FATAL_ERROR "Host compiler must support std::atomic!") + endif() + else() + message(FATAL_ERROR "Host compiler appears to require libatomic, but cannot find it.") + endif() +endif() diff --git a/libcxx/cmake/config-ix.cmake b/libcxx/cmake/config-ix.cmake index c05597ea73d..1bfa23fadd8 100644 --- a/libcxx/cmake/config-ix.cmake +++ b/libcxx/cmake/config-ix.cmake @@ -1,5 +1,6 @@ include(CheckLibraryExists) include(CheckCXXCompilerFlag) +include(CheckLibcxxAtomic) # Check compiler flags @@ -17,3 +18,7 @@ check_library_exists(c fopen "" LIBCXX_HAS_C_LIB) check_library_exists(m ccos "" LIBCXX_HAS_M_LIB) check_library_exists(rt clock_gettime "" LIBCXX_HAS_RT_LIB) check_library_exists(gcc_s __gcc_personality_v0 "" LIBCXX_HAS_GCC_S_LIB) + +if (NOT HAVE_CXX_ATOMICS_WITHOUT_LIB) + set(LIBCXX_HAS_ATOMIC_LIB True) +endif() |
