llvm-project

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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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check_library_exists(c fopen "" LIBCXXABI_HAS_C_LIB)
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if (NOT LIBCXXABI_USE_COMPILER_RT)
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  if (ANDROID)
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    check_library_exists(gcc __gcc_personality_v0 "" LIBCXXABI_HAS_GCC_LIB)
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  else ()
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    check_library_exists(gcc_s __gcc_personality_v0 "" LIBCXXABI_HAS_GCC_S_LIB)
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    check_library_exists(gcc __aeabi_uldivmod "" LIBCXXABI_HAS_GCC_LIB)
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  endif ()
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endif ()
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# libc++abi 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 -nodefaultlibs) and the flags that are actually
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# required during compilation (which has the -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_cxx_compiler_flag(-nostdlib++ CXX_SUPPORTS_NOSTDLIBXX_FLAG)
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if (CXX_SUPPORTS_NOSTDLIBXX_FLAG)
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  set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -nostdlib++")
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else()
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  check_c_compiler_flag(-nodefaultlibs C_SUPPORTS_NODEFAULTLIBS_FLAG)
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  if (C_SUPPORTS_NODEFAULTLIBS_FLAG)
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    set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -nodefaultlibs")
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  endif()
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endif()
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# Only link against compiler-rt manually if we use -nodefaultlibs, since
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# otherwise the compiler will do the right thing on its own.
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if (NOT CXX_SUPPORTS_NOSTDLIBXX_FLAG AND C_SUPPORTS_NODEFAULTLIBS_FLAG)
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  if (LIBCXXABI_HAS_C_LIB)
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    list(APPEND CMAKE_REQUIRED_LIBRARIES c)
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  endif ()
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  if (LIBCXXABI_USE_COMPILER_RT)
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    include(HandleCompilerRT)
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    find_compiler_rt_library(builtins LIBCXXABI_BUILTINS_LIBRARY
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                             FLAGS "${LIBCXXABI_COMPILE_FLAGS}")
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    if (LIBCXXABI_BUILTINS_LIBRARY)
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      list(APPEND CMAKE_REQUIRED_LIBRARIES "${LIBCXXABI_BUILTINS_LIBRARY}")
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    else()
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      message(WARNING "Could not find builtins library from libc++abi")
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    endif()
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  else ()
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    if (LIBCXXABI_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 (LIBCXXABI_HAS_GCC_LIB)
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      list(APPEND CMAKE_REQUIRED_LIBRARIES gcc)
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    endif ()
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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 (LIBCXXABI_USE_COMPILER_RT)
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      set(MINGW_RUNTIME ${LIBCXXABI_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 ${MINGW_LIBRARIES})
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  endif()
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endif()
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if (CXX_SUPPORTS_NOSTDLIBXX_FLAG OR C_SUPPORTS_NODEFAULTLIBS_FLAG)
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  if (CMAKE_C_FLAGS MATCHES -fsanitize OR CMAKE_CXX_FLAGS MATCHES -fsanitize)
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    set(CMAKE_REQUIRED_FLAGS "${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 "${CMAKE_REQUIRED_FLAGS} -fsanitize-coverage=0")
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  endif ()
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endif ()
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# Check compiler pragmas
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if(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
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  cmake_push_check_state()
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  set(CMAKE_REQUIRED_FLAGS "${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(void) { return 0; }
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" C_SUPPORTS_COMMENT_LIB_PRAGMA)
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  cmake_pop_check_state()
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endif()
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# Check compiler flags
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check_cxx_compiler_flag(-nostdinc++ CXX_SUPPORTS_NOSTDINCXX_FLAG)
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# Check libraries
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if(FUCHSIA)
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  set(LIBCXXABI_HAS_DL_LIB NO)
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  set(LIBCXXABI_HAS_PTHREAD_LIB NO)
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  check_library_exists(c __cxa_thread_atexit_impl ""
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    LIBCXXABI_HAS_CXA_THREAD_ATEXIT_IMPL)
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elseif(ANDROID)
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  set(LIBCXXABI_HAS_DL_LIB YES)
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  set(LIBCXXABI_HAS_PTHREAD_LIB NO)
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  check_library_exists(c __cxa_thread_atexit_impl ""
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    LIBCXXABI_HAS_CXA_THREAD_ATEXIT_IMPL)
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else()
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  check_library_exists(dl dladdr "" LIBCXXABI_HAS_DL_LIB)
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  check_library_exists(pthread pthread_once "" LIBCXXABI_HAS_PTHREAD_LIB)
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  check_library_exists(c __cxa_thread_atexit_impl ""
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    LIBCXXABI_HAS_CXA_THREAD_ATEXIT_IMPL)
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endif()
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