CMake/Modules/FindThreads.cmake
Steffen Dettmer d4e551a90b FindThreads: Drop try_run to improve cross-compiling support
Use `try_compile` instead of `try_run`.  It is not clear why `try_run`
was ever needed, and it does not work during cross-compiling.

Update the check's source file to remove code associated with actually
running things.  Also remove the ancient `__CLASSIC_C__` code path and
use a simple `int main(void)` as in `Modules/CheckIncludeFile.c.in`.

Fixes: #16920
2017-08-30 11:15:26 -04:00

218 lines
6.7 KiB
CMake

# 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_SPROC_INIT - are we using sproc?
# 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
#
# For systems with multiple thread libraries, caller can set
#
# ::
#
# CMAKE_THREAD_PREFER_PTHREAD
#
# If the use of the -pthread compiler and linker flag is preferred then the
# caller can set
#
# ::
#
# THREADS_PREFER_PTHREAD_FLAG
#
# Please note that 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)
include (CheckSymbolExists)
set(Threads_FOUND FALSE)
set(CMAKE_REQUIRED_QUIET_SAVE ${CMAKE_REQUIRED_QUIET})
set(CMAKE_REQUIRED_QUIET ${Threads_FIND_QUIETLY})
if(CMAKE_C_COMPILER_LOADED)
include (CheckIncludeFile)
elseif(CMAKE_CXX_COMPILER_LOADED)
include (CheckIncludeFileCXX)
else()
message(FATAL_ERROR "FindThreads only works if either C or CXX language is enabled")
endif()
# Do we have sproc?
if(CMAKE_SYSTEM_NAME MATCHES IRIX AND NOT CMAKE_THREAD_PREFER_PTHREAD)
include (CheckIncludeFiles)
CHECK_INCLUDE_FILES("sys/types.h;sys/prctl.h" CMAKE_HAVE_SPROC_H)
endif()
# Internal helper macro.
# Do NOT even think about using it outside of this file!
macro(_check_threads_lib LIBNAME FUNCNAME VARNAME)
if(NOT Threads_FOUND)
CHECK_LIBRARY_EXISTS(${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()
if(CMAKE_HAVE_SPROC_H AND NOT CMAKE_THREAD_PREFER_PTHREAD)
# We have sproc
set(CMAKE_USE_SPROC_INIT 1)
else()
# 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
CHECK_SYMBOL_EXISTS(pthread_create pthread.h CMAKE_HAVE_LIBC_CREATE)
if(CMAKE_HAVE_LIBC_CREATE)
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 ()
_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()
endif()
if(CMAKE_THREAD_LIBS_INIT OR CMAKE_HAVE_LIBC_CREATE)
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 "-pthread")
endif()
if(CMAKE_THREAD_LIBS_INIT)
set_property(TARGET Threads::Threads PROPERTY INTERFACE_LINK_LIBRARIES "${CMAKE_THREAD_LIBS_INIT}")
endif()
endif()