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cmake/Modules/FindThreads.cmake

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7.3 KiB

# Distributed under the OSI-approved BSD 3-Clause License. See accompanying
# file Copyright.txt or https://cmake.org/licensing for details.
#[=======================================================================[.rst:
FindThreads
-----------
This module determines the thread library of the system.
The following variables are set
::
CMAKE_THREAD_LIBS_INIT - the thread library
CMAKE_USE_WIN32_THREADS_INIT - using WIN32 threads?
CMAKE_USE_PTHREADS_INIT - are we using pthreads
CMAKE_HP_PTHREADS_INIT - are we using hp pthreads
The following import target is created
::
Threads::Threads
If the use of the -pthread compiler and linker flag is preferred then the
caller can set
::
THREADS_PREFER_PTHREAD_FLAG
The compiler flag can only be used with the imported
target. Use of both the imported target as well as this switch is highly
recommended for new code.
#]=======================================================================]
include (CheckLibraryExists)
set(Threads_FOUND FALSE)
set(CMAKE_REQUIRED_QUIET_SAVE ${CMAKE_REQUIRED_QUIET})
set(CMAKE_REQUIRED_QUIET ${Threads_FIND_QUIETLY})
if(CMAKE_C_COMPILER_LOADED)
include (CheckIncludeFile)
include (CheckCSourceCompiles)
elseif(CMAKE_CXX_COMPILER_LOADED)
include (CheckIncludeFileCXX)
include (CheckCXXSourceCompiles)
else()
message(FATAL_ERROR "FindThreads only works if either C or CXX language is enabled")
endif()
# simple pthread test code
set(PTHREAD_C_CXX_TEST_SOURCE [====[
#include <pthread.h>
void* test_func(void* data)
{
return data;
}
int main(void)
{
pthread_t thread;
pthread_create(&thread, NULL, test_func, NULL);
pthread_detach(thread);
pthread_join(thread, NULL);
pthread_atfork(NULL, NULL, NULL);
pthread_exit(NULL);
return 0;
}
]====])
# Internal helper macro.
# Do NOT even think about using it outside of this file!
macro(_check_threads_lib LIBNAME FUNCNAME VARNAME)
if(NOT Threads_FOUND)
CHECK_LIBRARY_EXISTS(${LIBNAME} ${FUNCNAME} "" ${VARNAME})
if(${VARNAME})
set(CMAKE_THREAD_LIBS_INIT "-l${LIBNAME}")
set(CMAKE_HAVE_THREADS_LIBRARY 1)
set(Threads_FOUND TRUE)
endif()
endif ()
endmacro()
# Internal helper macro.
# Do NOT even think about using it outside of this file!
macro(_check_pthreads_flag)
if(NOT Threads_FOUND)
# If we did not found -lpthread, -lpthread, or -lthread, look for -pthread
if(NOT DEFINED THREADS_HAVE_PTHREAD_ARG)
message(STATUS "Check if compiler accepts -pthread")
if(CMAKE_C_COMPILER_LOADED)
set(_threads_src ${CMAKE_CURRENT_LIST_DIR}/CheckForPthreads.c)
elseif(CMAKE_CXX_COMPILER_LOADED)
set(_threads_src ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/FindThreads/CheckForPthreads.cxx)
configure_file(${CMAKE_CURRENT_LIST_DIR}/CheckForPthreads.c "${_threads_src}" COPYONLY)
endif()
try_compile(THREADS_HAVE_PTHREAD_ARG
${CMAKE_BINARY_DIR}
${_threads_src}
CMAKE_FLAGS -DLINK_LIBRARIES:STRING=-pthread
OUTPUT_VARIABLE OUTPUT)
unset(_threads_src)
if(THREADS_HAVE_PTHREAD_ARG)
set(Threads_FOUND TRUE)
message(STATUS "Check if compiler accepts -pthread - yes")
else()
message(STATUS "Check if compiler accepts -pthread - no")
file(APPEND
${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
"Determining if compiler accepts -pthread failed with the following output:\n${OUTPUT}\n\n")
endif()
endif()
if(THREADS_HAVE_PTHREAD_ARG)
set(Threads_FOUND TRUE)
set(CMAKE_THREAD_LIBS_INIT "-pthread")
endif()
endif()
endmacro()
# Do we have pthreads?
if(CMAKE_C_COMPILER_LOADED)
CHECK_INCLUDE_FILE("pthread.h" CMAKE_HAVE_PTHREAD_H)
else()
CHECK_INCLUDE_FILE_CXX("pthread.h" CMAKE_HAVE_PTHREAD_H)
endif()
if(CMAKE_HAVE_PTHREAD_H)
#
# We have pthread.h
# Let's check for the library now.
#
set(CMAKE_HAVE_THREADS_LIBRARY)
if(NOT THREADS_HAVE_PTHREAD_ARG)
# Check if pthread functions are in normal C library.
# We list some pthread functions in PTHREAD_C_CXX_TEST_SOURCE test code.
# If the pthread functions already exist in C library, we could just use
# them instead of linking to the additional pthread library.
if(CMAKE_C_COMPILER_LOADED)
CHECK_C_SOURCE_COMPILES("${PTHREAD_C_CXX_TEST_SOURCE}" CMAKE_HAVE_LIBC_PTHREAD)
elseif(CMAKE_CXX_COMPILER_LOADED)
CHECK_CXX_SOURCE_COMPILES("${PTHREAD_C_CXX_TEST_SOURCE}" CMAKE_HAVE_LIBC_PTHREAD)
endif()
if(CMAKE_HAVE_LIBC_PTHREAD)
set(CMAKE_THREAD_LIBS_INIT "")
set(CMAKE_HAVE_THREADS_LIBRARY 1)
set(Threads_FOUND TRUE)
else()
# Check for -pthread first if enabled. This is the recommended
# way, but not backwards compatible as one must also pass -pthread
# as compiler flag then.
if (THREADS_PREFER_PTHREAD_FLAG)
_check_pthreads_flag()
endif ()
if(CMAKE_SYSTEM MATCHES "GHS-MULTI")
_check_threads_lib(posix pthread_create CMAKE_HAVE_PTHREADS_CREATE)
endif()
_check_threads_lib(pthreads pthread_create CMAKE_HAVE_PTHREADS_CREATE)
_check_threads_lib(pthread pthread_create CMAKE_HAVE_PTHREAD_CREATE)
if(CMAKE_SYSTEM_NAME MATCHES "SunOS")
# On sun also check for -lthread
_check_threads_lib(thread thr_create CMAKE_HAVE_THR_CREATE)
endif()
endif()
endif()
_check_pthreads_flag()
endif()
if(CMAKE_THREAD_LIBS_INIT OR CMAKE_HAVE_LIBC_PTHREAD)
set(CMAKE_USE_PTHREADS_INIT 1)
set(Threads_FOUND TRUE)
endif()
if(CMAKE_SYSTEM_NAME MATCHES "Windows")
set(CMAKE_USE_WIN32_THREADS_INIT 1)
set(Threads_FOUND TRUE)
endif()
if(CMAKE_USE_PTHREADS_INIT)
if(CMAKE_SYSTEM_NAME MATCHES "HP-UX")
# Use libcma if it exists and can be used. It provides more
# symbols than the plain pthread library. CMA threads
# have actually been deprecated:
# http://docs.hp.com/en/B3920-90091/ch12s03.html#d0e11395
# http://docs.hp.com/en/947/d8.html
# but we need to maintain compatibility here.
# The CMAKE_HP_PTHREADS setting actually indicates whether CMA threads
# are available.
CHECK_LIBRARY_EXISTS(cma pthread_attr_create "" CMAKE_HAVE_HP_CMA)
if(CMAKE_HAVE_HP_CMA)
set(CMAKE_THREAD_LIBS_INIT "-lcma")
set(CMAKE_HP_PTHREADS_INIT 1)
set(Threads_FOUND TRUE)
endif()
set(CMAKE_USE_PTHREADS_INIT 1)
endif()
if(CMAKE_SYSTEM MATCHES "OSF1-V")
set(CMAKE_USE_PTHREADS_INIT 0)
set(CMAKE_THREAD_LIBS_INIT )
endif()
if(CMAKE_SYSTEM MATCHES "CYGWIN_NT")
set(CMAKE_USE_PTHREADS_INIT 1)
set(Threads_FOUND TRUE)
set(CMAKE_THREAD_LIBS_INIT )
set(CMAKE_USE_WIN32_THREADS_INIT 0)
endif()
endif()
set(CMAKE_REQUIRED_QUIET ${CMAKE_REQUIRED_QUIET_SAVE})
include(${CMAKE_CURRENT_LIST_DIR}/FindPackageHandleStandardArgs.cmake)
FIND_PACKAGE_HANDLE_STANDARD_ARGS(Threads DEFAULT_MSG Threads_FOUND)
if(THREADS_FOUND AND NOT TARGET Threads::Threads)
add_library(Threads::Threads INTERFACE IMPORTED)
if(THREADS_HAVE_PTHREAD_ARG)
set_property(TARGET Threads::Threads
PROPERTY INTERFACE_COMPILE_OPTIONS "$<$<COMPILE_LANGUAGE:CUDA>:SHELL:-Xcompiler -pthread>"
"$<$<NOT:$<COMPILE_LANGUAGE:CUDA>>:-pthread>")
endif()
if(CMAKE_THREAD_LIBS_INIT)
set_property(TARGET Threads::Threads PROPERTY INTERFACE_LINK_LIBRARIES "${CMAKE_THREAD_LIBS_INIT}")
endif()
endif()