llvm/libunwind/cmake/config-ix.cmake
Zbigniew Sarbinowski 5f9be2c3e3 [SystemZ][ZOS] Prefer -nostdlib++ as opposed to -nodefaultlibs when building c++ libraries
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
2021-02-16 18:42:14 +00:00

106 lines
4 KiB
CMake

include(CMakePushCheckState)
include(CheckCCompilerFlag)
include(CheckCXXCompilerFlag)
include(CheckLibraryExists)
include(CheckSymbolExists)
include(CheckCSourceCompiles)
check_library_exists(c fopen "" LIBUNWIND_HAS_C_LIB)
if (NOT LIBUNWIND_USE_COMPILER_RT)
if (ANDROID)
check_library_exists(gcc __gcc_personality_v0 "" LIBUNWIND_HAS_GCC_LIB)
else ()
check_library_exists(gcc_s __gcc_personality_v0 "" LIBUNWIND_HAS_GCC_S_LIB)
check_library_exists(gcc __absvdi2 "" LIBUNWIND_HAS_GCC_LIB)
endif ()
endif()
# libunwind is using -nostdlib++ at the link step when available,
# otherwise -nodefaultlibs is used. We want all our checks to also
# use one of these options, otherwise we may end up with an inconsistency between
# the flags we think we require during configuration (if the checks are
# performed without one of those options) and the flags that are actually
# required during compilation (which has the -nostdlib++ or -nodefaultlibs). libc is
# required for the link to go through. We remove sanitizers from the
# configuration checks to avoid spurious link errors.
check_c_compiler_flag(-nostdlib++ LIBUNWIND_SUPPORTS_NOSTDLIBXX_FLAG)
if (LIBUNWIND_SUPPORTS_NOSTDLIBXX_FLAG)
set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -nostdlib++")
else()
check_c_compiler_flag(-nodefaultlibs LIBUNWIND_SUPPORTS_NODEFAULTLIBS_FLAG)
if (LIBUNWIND_SUPPORTS_NODEFAULTLIBS_FLAG)
set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -nodefaultlibs")
endif()
endif()
if (LIBUNWIND_SUPPORTS_NOSTDLIBXX_FLAG OR LIBUNWIND_SUPPORTS_NODEFAULTLIBS_FLAG)
if (LIBUNWIND_HAS_C_LIB)
list(APPEND CMAKE_REQUIRED_LIBRARIES c)
endif ()
if (LIBUNWIND_USE_COMPILER_RT)
find_compiler_rt_library(builtins LIBUNWIND_BUILTINS_LIBRARY)
list(APPEND CMAKE_REQUIRED_LIBRARIES "${LIBUNWIND_BUILTINS_LIBRARY}")
else ()
if (LIBUNWIND_HAS_GCC_S_LIB)
list(APPEND CMAKE_REQUIRED_LIBRARIES gcc_s)
endif ()
if (LIBUNWIND_HAS_GCC_LIB)
list(APPEND CMAKE_REQUIRED_LIBRARIES gcc)
endif ()
endif ()
if (MINGW)
# Mingw64 requires quite a few "C" runtime libraries in order for basic
# programs to link successfully with -nodefaultlibs.
if (LIBUNWIND_USE_COMPILER_RT)
set(MINGW_RUNTIME ${LIBUNWIND_BUILTINS_LIBRARY})
else ()
set(MINGW_RUNTIME gcc_s gcc)
endif()
set(MINGW_LIBRARIES mingw32 ${MINGW_RUNTIME} moldname mingwex msvcrt advapi32
shell32 user32 kernel32 mingw32 ${MINGW_RUNTIME}
moldname mingwex msvcrt)
list(APPEND CMAKE_REQUIRED_LIBRARIES ${MINGW_LIBRARIES})
endif()
if (CMAKE_C_FLAGS MATCHES -fsanitize OR CMAKE_CXX_FLAGS MATCHES -fsanitize)
set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -fno-sanitize=all")
endif ()
if (CMAKE_C_FLAGS MATCHES -fsanitize-coverage OR CMAKE_CXX_FLAGS MATCHES -fsanitize-coverage)
set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -fno-sanitize-coverage=edge,trace-cmp,indirect-calls,8bit-counters")
endif ()
endif ()
# Check compiler pragmas
if(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
cmake_push_check_state()
set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -Werror=unknown-pragmas")
check_c_source_compiles("
#pragma comment(lib, \"c\")
int main() { return 0; }
" LIBUNWIND_HAS_COMMENT_LIB_PRAGMA)
cmake_pop_check_state()
endif()
# Check compiler flags
check_cxx_compiler_flag(-nostdinc++ LIBUNWIND_HAS_NOSTDINCXX_FLAG)
# Check symbols
check_symbol_exists(__arm__ "" LIBUNWIND_TARGET_ARM)
check_symbol_exists(__USING_SJLJ_EXCEPTIONS__ "" LIBUNWIND_USES_SJLJ_EXCEPTIONS)
check_symbol_exists(__ARM_DWARF_EH__ "" LIBUNWIND_USES_DWARF_EH)
if(LIBUNWIND_TARGET_ARM AND NOT LIBUNWIND_USES_SJLJ_EXCEPTIONS AND NOT LIBUNWIND_USES_DWARF_EH)
# This condition is copied from __libunwind_config.h
set(LIBUNWIND_USES_ARM_EHABI ON)
endif()
# Check libraries
if(FUCHSIA)
set(LIBUNWIND_HAS_DL_LIB NO)
set(LIBUNWIND_HAS_PTHREAD_LIB NO)
else()
check_library_exists(dl dladdr "" LIBUNWIND_HAS_DL_LIB)
check_library_exists(pthread pthread_once "" LIBUNWIND_HAS_PTHREAD_LIB)
endif()