5f9be2c3e3
Let's use -nostdlib++ rather than -nodefaultlibs when building libc++/libc++abi/libunwind libraries. The default is -nostdlib++ if supported by a build compiler like it is the case with clang, otherwise -nodefaultlibs is used as before. This change is needed to avoid additional changes at the link step and not to increase the maintenance costs. If clang with -nodefaultlibs is used all the libraries which are removed but required would have to be manually added in. This set of libraries are unique and will send out. The propose change will allow to make the link step simple for other platforms as well. Reviewed By: #libc, #libc_abi, ldionne Differential Revision: https://reviews.llvm.org/D95875
119 lines
4.5 KiB
CMake
119 lines
4.5 KiB
CMake
include(CMakePushCheckState)
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include(CheckLibraryExists)
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include(CheckCCompilerFlag)
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include(CheckCXXCompilerFlag)
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include(CheckCSourceCompiles)
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if(WIN32 AND NOT MINGW)
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# NOTE(compnerd) this is technically a lie, there is msvcrt, but for now, lets
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# let the default linking take care of that.
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set(LIBCXX_HAS_C_LIB NO)
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else()
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check_library_exists(c fopen "" LIBCXX_HAS_C_LIB)
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endif()
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if (NOT LIBCXX_USE_COMPILER_RT)
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if(WIN32 AND NOT MINGW)
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set(LIBCXX_HAS_GCC_S_LIB NO)
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else()
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if(ANDROID)
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check_library_exists(gcc __gcc_personality_v0 "" LIBCXX_HAS_GCC_LIB)
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else()
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check_library_exists(gcc_s __gcc_personality_v0 "" LIBCXX_HAS_GCC_S_LIB)
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endif()
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endif()
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endif()
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# libc++ is using -nostdlib++ at the link step when available,
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# otherwise -nodefaultlibs is used. We want all our checks to also
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# use one of these options, otherwise we may end up with an inconsistency between
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# the flags we think we require during configuration (if the checks are
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# performed without one of those options) and the flags that are actually
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# required during compilation (which has the -nostdlib++ or -nodefaultlibs). libc is
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# required for the link to go through. We remove sanitizers from the
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# configuration checks to avoid spurious link errors.
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check_c_compiler_flag(-nostdlib++ LIBCXX_SUPPORTS_NOSTDLIBXX_FLAG)
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if (LIBCXX_SUPPORTS_NOSTDLIBXX_FLAG)
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set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -nostdlib++")
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else()
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check_c_compiler_flag(-nodefaultlibs LIBCXX_SUPPORTS_NODEFAULTLIBS_FLAG)
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if (LIBCXX_SUPPORTS_NODEFAULTLIBS_FLAG)
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set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -nodefaultlibs")
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endif()
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endif()
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if (LIBCXX_SUPPORTS_NOSTDLIBXX_FLAG OR LIBCXX_SUPPORTS_NODEFAULTLIBS_FLAG)
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if (LIBCXX_HAS_C_LIB)
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list(APPEND CMAKE_REQUIRED_LIBRARIES c)
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endif ()
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if (LIBCXX_USE_COMPILER_RT)
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list(APPEND CMAKE_REQUIRED_FLAGS -rtlib=compiler-rt)
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find_compiler_rt_library(builtins LIBCXX_BUILTINS_LIBRARY)
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list(APPEND CMAKE_REQUIRED_LIBRARIES "${LIBCXX_BUILTINS_LIBRARY}")
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elseif (LIBCXX_HAS_GCC_LIB)
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list(APPEND CMAKE_REQUIRED_LIBRARIES gcc)
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elseif (LIBCXX_HAS_GCC_S_LIB)
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list(APPEND CMAKE_REQUIRED_LIBRARIES gcc_s)
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endif ()
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if (MINGW)
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# Mingw64 requires quite a few "C" runtime libraries in order for basic
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# programs to link successfully with -nodefaultlibs.
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if (LIBCXX_USE_COMPILER_RT)
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set(MINGW_RUNTIME ${LIBCXX_BUILTINS_LIBRARY})
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else ()
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set(MINGW_RUNTIME gcc_s gcc)
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endif()
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set(MINGW_LIBRARIES mingw32 ${MINGW_RUNTIME} moldname mingwex msvcrt advapi32
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shell32 user32 kernel32 mingw32 ${MINGW_RUNTIME}
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moldname mingwex msvcrt)
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list(APPEND CMAKE_REQUIRED_LIBRARIES ${MINGW_LIBRARIES})
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endif()
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if (CMAKE_C_FLAGS MATCHES -fsanitize OR CMAKE_CXX_FLAGS MATCHES -fsanitize)
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set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -fno-sanitize=all")
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endif ()
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if (CMAKE_C_FLAGS MATCHES -fsanitize-coverage OR CMAKE_CXX_FLAGS MATCHES -fsanitize-coverage)
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set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -fno-sanitize-coverage=edge,trace-cmp,indirect-calls,8bit-counters")
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endif ()
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endif ()
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# Check compiler pragmas
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if(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
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cmake_push_check_state()
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set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -Werror=unknown-pragmas")
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check_c_source_compiles("
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#pragma comment(lib, \"c\")
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int main() { return 0; }
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" LIBCXX_HAS_COMMENT_LIB_PRAGMA)
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cmake_pop_check_state()
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endif()
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# Check libraries
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if(WIN32 AND NOT MINGW)
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# TODO(compnerd) do we want to support an emulation layer that allows for the
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# use of pthread-win32 or similar libraries to emulate pthreads on Windows?
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set(LIBCXX_HAS_PTHREAD_LIB NO)
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set(LIBCXX_HAS_M_LIB NO)
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set(LIBCXX_HAS_RT_LIB NO)
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set(LIBCXX_HAS_SYSTEM_LIB NO)
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set(LIBCXX_HAS_ATOMIC_LIB NO)
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elseif(APPLE)
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check_library_exists(System write "" LIBCXX_HAS_SYSTEM_LIB)
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set(LIBCXX_HAS_PTHREAD_LIB NO)
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set(LIBCXX_HAS_M_LIB NO)
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set(LIBCXX_HAS_RT_LIB NO)
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set(LIBCXX_HAS_ATOMIC_LIB NO)
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elseif(FUCHSIA)
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set(LIBCXX_HAS_M_LIB NO)
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set(LIBCXX_HAS_PTHREAD_LIB NO)
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set(LIBCXX_HAS_RT_LIB NO)
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set(LIBCXX_HAS_SYSTEM_LIB NO)
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check_library_exists(atomic __atomic_fetch_add_8 "" LIBCXX_HAS_ATOMIC_LIB)
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else()
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check_library_exists(pthread pthread_create "" LIBCXX_HAS_PTHREAD_LIB)
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check_library_exists(m ccos "" LIBCXX_HAS_M_LIB)
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check_library_exists(rt clock_gettime "" LIBCXX_HAS_RT_LIB)
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set(LIBCXX_HAS_SYSTEM_LIB NO)
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check_library_exists(atomic __atomic_fetch_add_8 "" LIBCXX_HAS_ATOMIC_LIB)
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endif()
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