Edit: threadlib.m4
# threadlib.m4 serial 11 (gettext-0.18.2) dnl Copyright (C) 2005-2016 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, dnl with or without modifications, as long as this notice is preserved. dnl From Bruno Haible. dnl gl_THREADLIB dnl ------------ dnl Tests for a multithreading library to be used. dnl If the configure.ac contains a definition of the gl_THREADLIB_DEFAULT_NO dnl (it must be placed before the invocation of gl_THREADLIB_EARLY!), then the dnl default is 'no', otherwise it is system dependent. In both cases, the user dnl can change the choice through the options --enable-threads=choice or dnl --disable-threads. dnl Defines at most one of the macros USE_POSIX_THREADS, USE_SOLARIS_THREADS, dnl USE_PTH_THREADS, USE_WINDOWS_THREADS dnl Sets the variables LIBTHREAD and LTLIBTHREAD to the linker options for use dnl in a Makefile (LIBTHREAD for use without libtool, LTLIBTHREAD for use with dnl libtool). dnl Sets the variables LIBMULTITHREAD and LTLIBMULTITHREAD similarly, for dnl programs that really need multithread functionality. The difference dnl between LIBTHREAD and LIBMULTITHREAD is that on platforms supporting weak dnl symbols, typically LIBTHREAD is empty whereas LIBMULTITHREAD is not. dnl Adds to CPPFLAGS the flag -D_REENTRANT or -D_THREAD_SAFE if needed for dnl multithread-safe programs. AC_DEFUN([gl_THREADLIB_EARLY], [ AC_REQUIRE([gl_THREADLIB_EARLY_BODY]) ]) dnl The guts of gl_THREADLIB_EARLY. Needs to be expanded only once. AC_DEFUN([gl_THREADLIB_EARLY_BODY], [ dnl Ordering constraints: This macro modifies CPPFLAGS in a way that dnl influences the result of the autoconf tests that test for *_unlocked dnl declarations, on AIX 5 at least. Therefore it must come early. AC_BEFORE([$0], [gl_FUNC_GLIBC_UNLOCKED_IO])dnl AC_BEFORE([$0], [gl_ARGP])dnl AC_REQUIRE([AC_CANONICAL_HOST]) dnl _GNU_SOURCE is needed for pthread_rwlock_t on glibc systems. dnl AC_USE_SYSTEM_EXTENSIONS was introduced in autoconf 2.60 and obsoletes dnl AC_GNU_SOURCE. m4_ifdef([AC_USE_SYSTEM_EXTENSIONS], [AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])], [AC_REQUIRE([AC_GNU_SOURCE])]) dnl Check for multithreading. m4_ifdef([gl_THREADLIB_DEFAULT_NO], [m4_divert_text([DEFAULTS], [gl_use_threads_default=no])], [m4_divert_text([DEFAULTS], [gl_use_threads_default=])]) AC_ARG_ENABLE([threads], AC_HELP_STRING([--enable-threads={posix|solaris|pth|windows}], [specify multithreading API])m4_ifdef([gl_THREADLIB_DEFAULT_NO], [], [ AC_HELP_STRING([--disable-threads], [build without multithread safety])]), [gl_use_threads=$enableval], [if test -n "$gl_use_threads_default"; then gl_use_threads="$gl_use_threads_default" else changequote(,)dnl case "$host_os" in dnl Disable multithreading by default on OSF/1, because it interferes dnl with fork()/exec(): When msgexec is linked with -lpthread, its dnl child process gets an endless segmentation fault inside execvp(). dnl Disable multithreading by default on Cygwin 1.5.x, because it has dnl bugs that lead to endless loops or crashes. See dnl <http://cygwin.com/ml/cygwin/2009-08/msg00283.html>. osf*) gl_use_threads=no ;; cygwin*) case `uname -r` in 1.[0-5].*) gl_use_threads=no ;; *) gl_use_threads=yes ;; esac ;; *) gl_use_threads=yes ;; esac changequote([,])dnl fi ]) if test "$gl_use_threads" = yes || test "$gl_use_threads" = posix; then # For using <pthread.h>: case "$host_os" in osf*) # On OSF/1, the compiler needs the flag -D_REENTRANT so that it # groks <pthread.h>. cc also understands the flag -pthread, but # we don't use it because 1. gcc-2.95 doesn't understand -pthread, # 2. putting a flag into CPPFLAGS that has an effect on the linker # causes the AC_LINK_IFELSE test below to succeed unexpectedly, # leading to wrong values of LIBTHREAD and LTLIBTHREAD. CPPFLAGS="$CPPFLAGS -D_REENTRANT" ;; esac # Some systems optimize for single-threaded programs by default, and # need special flags to disable these optimizations. For example, the # definition of 'errno' in <errno.h>. case "$host_os" in aix* | freebsd*) CPPFLAGS="$CPPFLAGS -D_THREAD_SAFE" ;; solaris*) CPPFLAGS="$CPPFLAGS -D_REENTRANT" ;; esac fi ]) dnl The guts of gl_THREADLIB. Needs to be expanded only once. AC_DEFUN([gl_THREADLIB_BODY], [ AC_REQUIRE([gl_THREADLIB_EARLY_BODY]) gl_threads_api=none LIBTHREAD= LTLIBTHREAD= LIBMULTITHREAD= LTLIBMULTITHREAD= if test "$gl_use_threads" != no; then dnl Check whether the compiler and linker support weak declarations. AC_CACHE_CHECK([whether imported symbols can be declared weak], [gl_cv_have_weak], [gl_cv_have_weak=no dnl First, test whether the compiler accepts it syntactically. AC_LINK_IFELSE( [AC_LANG_PROGRAM( [[extern void xyzzy (); #pragma weak xyzzy]], [[xyzzy();]])], [gl_cv_have_weak=maybe]) if test $gl_cv_have_weak = maybe; then dnl Second, test whether it actually works. On Cygwin 1.7.2, with dnl gcc 4.3, symbols declared weak always evaluate to the address 0. AC_RUN_IFELSE( [AC_LANG_SOURCE([[ #include <stdio.h> #pragma weak fputs int main () { return (fputs == NULL); }]])], [gl_cv_have_weak=yes], [gl_cv_have_weak=no], [dnl When cross-compiling, assume that only ELF platforms support dnl weak symbols. AC_EGREP_CPP([Extensible Linking Format], [#ifdef __ELF__ Extensible Linking Format #endif ], [gl_cv_have_weak="guessing yes"], [gl_cv_have_weak="guessing no"]) ]) fi ]) if test "$gl_use_threads" = yes || test "$gl_use_threads" = posix; then # On OSF/1, the compiler needs the flag -pthread or -D_REENTRANT so that # it groks <pthread.h>. It's added above, in gl_THREADLIB_EARLY_BODY. AC_CHECK_HEADER([pthread.h], [gl_have_pthread_h=yes], [gl_have_pthread_h=no]) if test "$gl_have_pthread_h" = yes; then # Other possible tests: # -lpthreads (FSU threads, PCthreads) # -lgthreads gl_have_pthread= # Test whether both pthread_mutex_lock and pthread_mutexattr_init exist # in libc. IRIX 6.5 has the first one in both libc and libpthread, but # the second one only in libpthread, and lock.c needs it. # # If -pthread works, prefer it to -lpthread, since Ubuntu 14.04 # needs -pthread for some reason. See: # http://lists.gnu.org/archive/html/bug-gnulib/2014-09/msg00023.html save_LIBS=$LIBS for gl_pthread in '' '-pthread'; do LIBS="$LIBS $gl_pthread" AC_LINK_IFELSE( [AC_LANG_PROGRAM( [[#include <pthread.h> pthread_mutex_t m; pthread_mutexattr_t ma; ]], [[pthread_mutex_lock (&m); pthread_mutexattr_init (&ma);]])], [gl_have_pthread=yes LIBTHREAD=$gl_pthread LTLIBTHREAD=$gl_pthread LIBMULTITHREAD=$gl_pthread LTLIBMULTITHREAD=$gl_pthread]) LIBS=$save_LIBS test -n "$gl_have_pthread" && break done # Test for libpthread by looking for pthread_kill. (Not pthread_self, # since it is defined as a macro on OSF/1.) if test -n "$gl_have_pthread" && test -z "$LIBTHREAD"; then # The program links fine without libpthread. But it may actually # need to link with libpthread in order to create multiple threads. AC_CHECK_LIB([pthread], [pthread_kill], [LIBMULTITHREAD=-lpthread LTLIBMULTITHREAD=-lpthread # On Solaris and HP-UX, most pthread functions exist also in libc. # Therefore pthread_in_use() needs to actually try to create a # thread: pthread_create from libc will fail, whereas # pthread_create will actually create a thread. case "$host_os" in solaris* | hpux*) AC_DEFINE([PTHREAD_IN_USE_DETECTION_HARD], [1], [Define if the pthread_in_use() detection is hard.]) esac ]) elif test -z "$gl_have_pthread"; then # Some library is needed. Try libpthread and libc_r. AC_CHECK_LIB([pthread], [pthread_kill], [gl_have_pthread=yes LIBTHREAD=-lpthread LTLIBTHREAD=-lpthread LIBMULTITHREAD=-lpthread LTLIBMULTITHREAD=-lpthread]) if test -z "$gl_have_pthread"; then # For FreeBSD 4. AC_CHECK_LIB([c_r], [pthread_kill], [gl_have_pthread=yes LIBTHREAD=-lc_r LTLIBTHREAD=-lc_r LIBMULTITHREAD=-lc_r LTLIBMULTITHREAD=-lc_r]) fi fi if test -n "$gl_have_pthread"; then gl_threads_api=posix AC_DEFINE([USE_POSIX_THREADS], [1], [Define if the POSIX multithreading library can be used.]) if test -n "$LIBMULTITHREAD" || test -n "$LTLIBMULTITHREAD"; then if case "$gl_cv_have_weak" in *yes) true;; *) false;; esac; then AC_DEFINE([USE_POSIX_THREADS_WEAK], [1], [Define if references to the POSIX multithreading library should be made weak.]) LIBTHREAD= LTLIBTHREAD= fi fi fi fi fi if test -z "$gl_have_pthread"; then if test "$gl_use_threads" = yes || test "$gl_use_threads" = solaris; then gl_have_solaristhread= gl_save_LIBS="$LIBS" LIBS="$LIBS -lthread" AC_LINK_IFELSE( [AC_LANG_PROGRAM( [[ #include <thread.h> #include <synch.h> ]], [[thr_self();]])], [gl_have_solaristhread=yes]) LIBS="$gl_save_LIBS" if test -n "$gl_have_solaristhread"; then gl_threads_api=solaris LIBTHREAD=-lthread LTLIBTHREAD=-lthread LIBMULTITHREAD="$LIBTHREAD" LTLIBMULTITHREAD="$LTLIBTHREAD" AC_DEFINE([USE_SOLARIS_THREADS], [1], [Define if the old Solaris multithreading library can be used.]) if case "$gl_cv_have_weak" in *yes) true;; *) false;; esac; then AC_DEFINE([USE_SOLARIS_THREADS_WEAK], [1], [Define if references to the old Solaris multithreading library should be made weak.]) LIBTHREAD= LTLIBTHREAD= fi fi fi fi if test "$gl_use_threads" = pth; then gl_save_CPPFLAGS="$CPPFLAGS" AC_LIB_LINKFLAGS([pth]) gl_have_pth= gl_save_LIBS="$LIBS" LIBS="$LIBS $LIBPTH" AC_LINK_IFELSE( [AC_LANG_PROGRAM([[#include <pth.h>]], [[pth_self();]])], [gl_have_pth=yes]) LIBS="$gl_save_LIBS" if test -n "$gl_have_pth"; then gl_threads_api=pth LIBTHREAD="$LIBPTH" LTLIBTHREAD="$LTLIBPTH" LIBMULTITHREAD="$LIBTHREAD" LTLIBMULTITHREAD="$LTLIBTHREAD" AC_DEFINE([USE_PTH_THREADS], [1], [Define if the GNU Pth multithreading library can be used.]) if test -n "$LIBMULTITHREAD" || test -n "$LTLIBMULTITHREAD"; then if case "$gl_cv_have_weak" in *yes) true;; *) false;; esac; then AC_DEFINE([USE_PTH_THREADS_WEAK], [1], [Define if references to the GNU Pth multithreading library should be made weak.]) LIBTHREAD= LTLIBTHREAD= fi fi else CPPFLAGS="$gl_save_CPPFLAGS" fi fi if test -z "$gl_have_pthread"; then case "$gl_use_threads" in yes | windows | win32) # The 'win32' is for backward compatibility. if { case "$host_os" in mingw*) true;; *) false;; esac }; then gl_threads_api=windows AC_DEFINE([USE_WINDOWS_THREADS], [1], [Define if the native Windows multithreading API can be used.]) fi ;; esac fi fi AC_MSG_CHECKING([for multithread API to use]) AC_MSG_RESULT([$gl_threads_api]) AC_SUBST([LIBTHREAD]) AC_SUBST([LTLIBTHREAD]) AC_SUBST([LIBMULTITHREAD]) AC_SUBST([LTLIBMULTITHREAD]) ]) AC_DEFUN([gl_THREADLIB], [ AC_REQUIRE([gl_THREADLIB_EARLY]) AC_REQUIRE([gl_THREADLIB_BODY]) ]) dnl gl_DISABLE_THREADS dnl ------------------ dnl Sets the gl_THREADLIB default so that threads are not used by default. dnl The user can still override it at installation time, by using the dnl configure option '--enable-threads'. AC_DEFUN([gl_DISABLE_THREADS], [ m4_divert_text([INIT_PREPARE], [gl_use_threads_default=no]) ]) dnl Survey of platforms: dnl dnl Platform Available Compiler Supports test-lock dnl flavours option weak result dnl --------------- --------- --------- -------- --------- dnl Linux 2.4/glibc posix -lpthread Y OK dnl dnl GNU Hurd/glibc posix dnl dnl Ubuntu 14.04 posix -pthread Y OK dnl dnl FreeBSD 5.3 posix -lc_r Y dnl posix -lkse ? Y dnl posix -lpthread ? Y dnl posix -lthr Y dnl dnl FreeBSD 5.2 posix -lc_r Y dnl posix -lkse Y dnl posix -lthr Y dnl dnl FreeBSD 4.0,4.10 posix -lc_r Y OK dnl dnl NetBSD 1.6 -- dnl dnl OpenBSD 3.4 posix -lpthread Y OK dnl dnl Mac OS X 10.[123] posix -lpthread Y OK dnl dnl Solaris 7,8,9 posix -lpthread Y Sol 7,8: 0.0; Sol 9: OK dnl solaris -lthread Y Sol 7,8: 0.0; Sol 9: OK dnl dnl HP-UX 11 posix -lpthread N (cc) OK dnl Y (gcc) dnl dnl IRIX 6.5 posix -lpthread Y 0.5 dnl dnl AIX 4.3,5.1 posix -lpthread N AIX 4: 0.5; AIX 5: OK dnl dnl OSF/1 4.0,5.1 posix -pthread (cc) N OK dnl -lpthread (gcc) Y dnl dnl Cygwin posix -lpthread Y OK dnl dnl Any of the above pth -lpth 0.0 dnl dnl Mingw windows N OK dnl dnl BeOS 5 -- dnl dnl The test-lock result shows what happens if in test-lock.c EXPLICIT_YIELD is dnl turned off: dnl OK if all three tests terminate OK, dnl 0.5 if the first test terminates OK but the second one loops endlessly, dnl 0.0 if the first test already loops endlessly.
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