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249 lines
7.8 KiB
249 lines
7.8 KiB
# Distributed under the OSI-approved BSD 3-Clause License. See accompanying
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# file Copyright.txt or https://cmake.org/licensing for details.
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#[=======================================================================[.rst:
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FindThreads
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-----------
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This module determines the thread library of the system.
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Imported Targets
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^^^^^^^^^^^^^^^^
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.. versionadded:: 3.1
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This module defines the following :prop_tgt:`IMPORTED` target:
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``Threads::Threads``
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The thread library, if found.
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Result Variables
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^^^^^^^^^^^^^^^^
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The following variables are set:
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``Threads_FOUND``
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If a supported thread library was found.
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``CMAKE_THREAD_LIBS_INIT``
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The thread library to use. This may be empty if the thread functions
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are provided by the system libraries and no special flags are needed
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to use them.
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``CMAKE_USE_WIN32_THREADS_INIT``
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If the found thread library is the win32 one.
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``CMAKE_USE_PTHREADS_INIT``
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If the found thread library is pthread compatible.
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``CMAKE_HP_PTHREADS_INIT``
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If the found thread library is the HP thread library.
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Variables Affecting Behavior
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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.. variable:: THREADS_PREFER_PTHREAD_FLAG
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.. versionadded:: 3.1
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If the use of the -pthread compiler and linker flag is preferred then
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the caller can set this variable to TRUE. The compiler flag can only be
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used with the imported target. Use of both the imported target as well
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as this switch is highly recommended for new code.
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This variable has no effect if the system libraries provide the
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thread functions, i.e. when ``CMAKE_THREAD_LIBS_INIT`` will be empty.
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#]=======================================================================]
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include (CheckLibraryExists)
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set(Threads_FOUND FALSE)
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set(CMAKE_REQUIRED_QUIET_SAVE ${CMAKE_REQUIRED_QUIET})
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set(CMAKE_REQUIRED_QUIET ${Threads_FIND_QUIETLY})
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if(CMAKE_C_COMPILER_LOADED)
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include (CheckIncludeFile)
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include (CheckCSourceCompiles)
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elseif(CMAKE_CXX_COMPILER_LOADED)
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include (CheckIncludeFileCXX)
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include (CheckCXXSourceCompiles)
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else()
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message(FATAL_ERROR "FindThreads only works if either C or CXX language is enabled")
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endif()
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# simple pthread test code
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set(PTHREAD_C_CXX_TEST_SOURCE [====[
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#include <pthread.h>
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static void* test_func(void* data)
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{
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return data;
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}
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int main(void)
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{
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pthread_t thread;
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pthread_create(&thread, NULL, test_func, NULL);
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pthread_detach(thread);
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pthread_cancel(thread);
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pthread_join(thread, NULL);
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pthread_atfork(NULL, NULL, NULL);
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pthread_exit(NULL);
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return 0;
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}
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]====])
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# Internal helper macro.
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# Do NOT even think about using it outside of this file!
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macro(_threads_check_libc)
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if(NOT Threads_FOUND)
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if(CMAKE_C_COMPILER_LOADED)
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CHECK_C_SOURCE_COMPILES("${PTHREAD_C_CXX_TEST_SOURCE}" CMAKE_HAVE_LIBC_PTHREAD)
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elseif(CMAKE_CXX_COMPILER_LOADED)
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CHECK_CXX_SOURCE_COMPILES("${PTHREAD_C_CXX_TEST_SOURCE}" CMAKE_HAVE_LIBC_PTHREAD)
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endif()
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if(CMAKE_HAVE_LIBC_PTHREAD)
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set(CMAKE_THREAD_LIBS_INIT "")
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set(Threads_FOUND TRUE)
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endif()
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endif ()
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endmacro()
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# Internal helper macro.
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# Do NOT even think about using it outside of this file!
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macro(_threads_check_lib LIBNAME FUNCNAME VARNAME)
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if(NOT Threads_FOUND)
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CHECK_LIBRARY_EXISTS(${LIBNAME} ${FUNCNAME} "" ${VARNAME})
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if(${VARNAME})
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set(CMAKE_THREAD_LIBS_INIT "-l${LIBNAME}")
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set(Threads_FOUND TRUE)
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endif()
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endif ()
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endmacro()
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# Internal helper macro.
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# Do NOT even think about using it outside of this file!
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macro(_threads_check_flag_pthread)
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if(NOT Threads_FOUND)
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# If we did not find -lpthreads, -lpthread, or -lthread, look for -pthread
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# except on compilers known to not have it.
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if(MSVC)
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# Compilers targeting the MSVC ABI do not have a -pthread flag.
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set(THREADS_HAVE_PTHREAD_ARG FALSE)
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elseif(NOT DEFINED THREADS_HAVE_PTHREAD_ARG)
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message(CHECK_START "Check if compiler accepts -pthread")
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if(CMAKE_C_COMPILER_LOADED)
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set(_threads_src CheckForPthreads.c)
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elseif(CMAKE_CXX_COMPILER_LOADED)
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set(_threads_src CheckForPthreads.cxx)
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endif()
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try_compile(THREADS_HAVE_PTHREAD_ARG
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SOURCE_FROM_FILE "${_threads_src}" "${CMAKE_CURRENT_LIST_DIR}/CheckForPthreads.c"
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CMAKE_FLAGS -DLINK_LIBRARIES:STRING=-pthread
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OUTPUT_VARIABLE _cmake_check_pthreads_output)
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string(APPEND _cmake_find_threads_output "${_cmake_check_pthreads_output}")
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unset(_cmake_check_pthreads_output)
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unset(_threads_src)
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if(THREADS_HAVE_PTHREAD_ARG)
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set(Threads_FOUND TRUE)
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message(CHECK_PASS "yes")
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else()
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message(CHECK_FAIL "no")
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endif()
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endif()
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if(THREADS_HAVE_PTHREAD_ARG)
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set(Threads_FOUND TRUE)
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set(CMAKE_THREAD_LIBS_INIT "-pthread")
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endif()
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endif()
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endmacro()
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# Check if pthread functions are in normal C library.
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# We list some pthread functions in PTHREAD_C_CXX_TEST_SOURCE test code.
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# If the pthread functions already exist in C library, we could just use
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# them instead of linking to the additional pthread library.
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_threads_check_libc()
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# Check for -pthread first if enabled. This is the recommended
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# way, but not backwards compatible as one must also pass -pthread
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# as compiler flag then.
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if (THREADS_PREFER_PTHREAD_FLAG)
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_threads_check_flag_pthread()
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endif ()
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if(CMAKE_SYSTEM MATCHES "GHS-MULTI")
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_threads_check_lib(posix pthread_create CMAKE_HAVE_PTHREADS_CREATE)
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endif()
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_threads_check_lib(pthreads pthread_create CMAKE_HAVE_PTHREADS_CREATE)
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_threads_check_lib(pthread pthread_create CMAKE_HAVE_PTHREAD_CREATE)
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if (NOT THREADS_PREFER_PTHREAD_FLAG)
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_threads_check_flag_pthread()
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endif()
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if(CMAKE_THREAD_LIBS_INIT OR CMAKE_HAVE_LIBC_PTHREAD)
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set(CMAKE_USE_PTHREADS_INIT 1)
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set(Threads_FOUND TRUE)
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endif()
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if(CMAKE_SYSTEM_NAME MATCHES "Windows")
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set(CMAKE_USE_WIN32_THREADS_INIT 1)
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set(Threads_FOUND TRUE)
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endif()
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if(CMAKE_USE_PTHREADS_INIT)
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if(CMAKE_SYSTEM_NAME MATCHES "HP-UX")
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# Use libcma if it exists and can be used. It provides more
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# symbols than the plain pthread library. CMA threads
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# have actually been deprecated:
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# http://docs.hp.com/en/B3920-90091/ch12s03.html#d0e11395
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# http://docs.hp.com/en/947/d8.html
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# but we need to maintain compatibility here.
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# The CMAKE_HP_PTHREADS setting actually indicates whether CMA threads
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# are available.
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CHECK_LIBRARY_EXISTS(cma pthread_attr_create "" CMAKE_HAVE_HP_CMA)
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if(CMAKE_HAVE_HP_CMA)
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set(CMAKE_THREAD_LIBS_INIT "-lcma")
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set(CMAKE_HP_PTHREADS_INIT 1)
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set(Threads_FOUND TRUE)
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endif()
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set(CMAKE_USE_PTHREADS_INIT 1)
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endif()
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if(CMAKE_SYSTEM MATCHES "OSF1-V")
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set(CMAKE_USE_PTHREADS_INIT 0)
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set(CMAKE_THREAD_LIBS_INIT )
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endif()
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if(CMAKE_SYSTEM MATCHES "CYGWIN_NT" OR CMAKE_SYSTEM MATCHES "MSYS_NT")
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set(CMAKE_USE_PTHREADS_INIT 1)
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set(Threads_FOUND TRUE)
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set(CMAKE_THREAD_LIBS_INIT )
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set(CMAKE_USE_WIN32_THREADS_INIT 0)
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endif()
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endif()
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set(CMAKE_REQUIRED_QUIET ${CMAKE_REQUIRED_QUIET_SAVE})
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include(${CMAKE_CURRENT_LIST_DIR}/FindPackageHandleStandardArgs.cmake)
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FIND_PACKAGE_HANDLE_STANDARD_ARGS(Threads DEFAULT_MSG Threads_FOUND)
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if(THREADS_FOUND AND NOT TARGET Threads::Threads)
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add_library(Threads::Threads INTERFACE IMPORTED)
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if(THREADS_HAVE_PTHREAD_ARG)
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set_property(TARGET Threads::Threads
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PROPERTY INTERFACE_COMPILE_OPTIONS "$<$<COMPILE_LANG_AND_ID:CUDA,NVIDIA>:SHELL:-Xcompiler -pthread>"
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"$<$<NOT:$<COMPILE_LANG_AND_ID:CUDA,NVIDIA>>:-pthread>")
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endif()
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if(CMAKE_THREAD_LIBS_INIT)
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set_property(TARGET Threads::Threads PROPERTY INTERFACE_LINK_LIBRARIES "${CMAKE_THREAD_LIBS_INIT}")
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endif()
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elseif(NOT THREADS_FOUND AND _cmake_find_threads_output)
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file(APPEND
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${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
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"Determining if compiler accepts -pthread failed with the following output:\n${_cmake_find_threads_output}\n\n")
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endif()
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unset(_cmake_find_threads_output)
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