From d247ac44cc9d52d7dfa15cb3d1785c554ea66e81 Mon Sep 17 00:00:00 2001 From: Vasileios Kalintiris Date: Thu, 11 Feb 2016 12:43:04 +0000 Subject: [PATCH] Re-commit "Introduce a cmake module to figure out whether we need to link with libatomic." This re-applies commit r260235. However, this time we add -gcc-toolchain to the compiler's flags when the user has specified the LIBCXX_GCC_TOOLCHAIN variable. llvm-svn: 260515 --- libcxx/cmake/Modules/CheckLibcxxAtomic.cmake | 41 ++++++++++++++++++++++++++++ libcxx/cmake/config-ix.cmake | 5 ++++ libcxx/lib/CMakeLists.txt | 1 + libcxx/test/CMakeLists.txt | 1 + libcxx/test/libcxx/test/target_info.py | 3 ++ libcxx/test/lit.site.cfg.in | 1 + 6 files changed, 52 insertions(+) create mode 100644 libcxx/cmake/Modules/CheckLibcxxAtomic.cmake diff --git a/libcxx/cmake/Modules/CheckLibcxxAtomic.cmake b/libcxx/cmake/Modules/CheckLibcxxAtomic.cmake new file mode 100644 index 0000000..d3b9fa46 --- /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 +#include +std::atomic x; +std::atomic 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 c05597e..1bfa23f 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() diff --git a/libcxx/lib/CMakeLists.txt b/libcxx/lib/CMakeLists.txt index d6a35f8..3e3c47f 100644 --- a/libcxx/lib/CMakeLists.txt +++ b/libcxx/lib/CMakeLists.txt @@ -79,6 +79,7 @@ add_library_flags_if(LIBCXX_HAS_C_LIB c) add_library_flags_if(LIBCXX_HAS_M_LIB m) add_library_flags_if(LIBCXX_HAS_RT_LIB rt) add_library_flags_if(LIBCXX_HAS_GCC_S_LIB gcc_s) +add_library_flags_if(LIBCXX_HAS_ATOMIC_LIB atomic) # Setup flags. add_flags_if_supported(-fPIC) diff --git a/libcxx/test/CMakeLists.txt b/libcxx/test/CMakeLists.txt index b67b3b4..8814553 100644 --- a/libcxx/test/CMakeLists.txt +++ b/libcxx/test/CMakeLists.txt @@ -15,6 +15,7 @@ pythonize_bool(LIBCXX_ENABLE_SHARED) pythonize_bool(LIBCXX_BUILD_32_BITS) pythonize_bool(LIBCXX_GENERATE_COVERAGE) pythonize_bool(LIBCXXABI_USE_LLVM_UNWINDER) +pythonize_bool(LIBCXX_HAS_ATOMIC_LIB) # The tests shouldn't link to any ABI library when it has been linked into # libc++ statically or via a linker script. diff --git a/libcxx/test/libcxx/test/target_info.py b/libcxx/test/libcxx/test/target_info.py index 7ca08be..dc37f71 100644 --- a/libcxx/test/libcxx/test/target_info.py +++ b/libcxx/test/libcxx/test/target_info.py @@ -172,6 +172,9 @@ class LinuxLocalTI(DefaultTargetInfo): flags += ['-lunwind', '-ldl'] else: flags += ['-lgcc_s', '-lgcc'] + use_libatomic = self.full_config.get_lit_bool('use_libatomic', False) + if use_libatomic: + flags += ['-latomic'] san = self.full_config.get_lit_conf('use_sanitizer', '').strip() if san: # The libraries and their order are taken from the diff --git a/libcxx/test/lit.site.cfg.in b/libcxx/test/lit.site.cfg.in index fa25834..9eb2b20 100644 --- a/libcxx/test/lit.site.cfg.in +++ b/libcxx/test/lit.site.cfg.in @@ -20,6 +20,7 @@ config.generate_coverage = "@LIBCXX_GENERATE_COVERAGE@" config.target_info = "@LIBCXX_TARGET_INFO@" config.executor = "@LIBCXX_EXECUTOR@" config.llvm_unwinder = "@LIBCXXABI_USE_LLVM_UNWINDER@" +config.use_libatomic = "@LIBCXX_HAS_ATOMIC_LIB@" # Let the main config do the real work. lit_config.load_config(config, "@LIBCXX_SOURCE_DIR@/test/lit.cfg") -- 2.7.4