1 # threadlib.m4 serial 12
2 dnl Copyright (C) 2005-2017 Free Software Foundation, Inc.
3 dnl This file is free software; the Free Software Foundation
4 dnl gives unlimited permission to copy and/or distribute it,
5 dnl with or without modifications, as long as this notice is preserved.
11 dnl Tests for a multithreading library to be used.
12 dnl If the configure.ac contains a definition of the gl_THREADLIB_DEFAULT_NO
13 dnl (it must be placed before the invocation of gl_THREADLIB_EARLY!), then the
14 dnl default is 'no', otherwise it is system dependent. In both cases, the user
15 dnl can change the choice through the options --enable-threads=choice or
16 dnl --disable-threads.
17 dnl Defines at most one of the macros USE_POSIX_THREADS, USE_SOLARIS_THREADS,
18 dnl USE_PTH_THREADS, USE_WINDOWS_THREADS
19 dnl Sets the variables LIBTHREAD and LTLIBTHREAD to the linker options for use
20 dnl in a Makefile (LIBTHREAD for use without libtool, LTLIBTHREAD for use with
22 dnl Sets the variables LIBMULTITHREAD and LTLIBMULTITHREAD similarly, for
23 dnl programs that really need multithread functionality. The difference
24 dnl between LIBTHREAD and LIBMULTITHREAD is that on platforms supporting weak
25 dnl symbols, typically LIBTHREAD is empty whereas LIBMULTITHREAD is not.
26 dnl Adds to CPPFLAGS the flag -D_REENTRANT or -D_THREAD_SAFE if needed for
27 dnl multithread-safe programs.
29 AC_DEFUN([gl_THREADLIB_EARLY],
31 AC_REQUIRE([gl_THREADLIB_EARLY_BODY])
34 dnl The guts of gl_THREADLIB_EARLY. Needs to be expanded only once.
36 AC_DEFUN([gl_THREADLIB_EARLY_BODY],
38 dnl Ordering constraints: This macro modifies CPPFLAGS in a way that
39 dnl influences the result of the autoconf tests that test for *_unlocked
40 dnl declarations, on AIX 5 at least. Therefore it must come early.
41 AC_BEFORE([$0], [gl_FUNC_GLIBC_UNLOCKED_IO])dnl
42 AC_BEFORE([$0], [gl_ARGP])dnl
44 AC_REQUIRE([AC_CANONICAL_HOST])
45 dnl _GNU_SOURCE is needed for pthread_rwlock_t on glibc systems.
46 dnl AC_USE_SYSTEM_EXTENSIONS was introduced in autoconf 2.60 and obsoletes
48 m4_ifdef([AC_USE_SYSTEM_EXTENSIONS],
49 [AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])],
50 [AC_REQUIRE([AC_GNU_SOURCE])])
51 dnl Check for multithreading.
52 m4_ifdef([gl_THREADLIB_DEFAULT_NO],
53 [m4_divert_text([DEFAULTS], [gl_use_threads_default=no])],
54 [m4_divert_text([DEFAULTS], [gl_use_threads_default=])])
55 AC_ARG_ENABLE([threads],
56 AC_HELP_STRING([--enable-threads={posix|solaris|pth|windows}], [specify multithreading API])m4_ifdef([gl_THREADLIB_DEFAULT_NO], [], [
57 AC_HELP_STRING([--disable-threads], [build without multithread safety])]),
58 [gl_use_threads=$enableval],
59 [if test -n "$gl_use_threads_default"; then
60 gl_use_threads="$gl_use_threads_default"
64 dnl Disable multithreading by default on OSF/1, because it interferes
65 dnl with fork()/exec(): When msgexec is linked with -lpthread, its
66 dnl child process gets an endless segmentation fault inside execvp().
67 dnl Disable multithreading by default on Cygwin 1.5.x, because it has
68 dnl bugs that lead to endless loops or crashes. See
69 dnl <http://cygwin.com/ml/cygwin/2009-08/msg00283.html>.
70 osf*) gl_use_threads=no ;;
73 1.[0-5].*) gl_use_threads=no ;;
74 *) gl_use_threads=yes ;;
77 *) gl_use_threads=yes ;;
82 if test "$gl_use_threads" = yes || test "$gl_use_threads" = posix; then
83 # For using <pthread.h>:
86 # On OSF/1, the compiler needs the flag -D_REENTRANT so that it
87 # groks <pthread.h>. cc also understands the flag -pthread, but
88 # we don't use it because 1. gcc-2.95 doesn't understand -pthread,
89 # 2. putting a flag into CPPFLAGS that has an effect on the linker
90 # causes the AC_LINK_IFELSE test below to succeed unexpectedly,
91 # leading to wrong values of LIBTHREAD and LTLIBTHREAD.
92 CPPFLAGS="$CPPFLAGS -D_REENTRANT"
95 # Some systems optimize for single-threaded programs by default, and
96 # need special flags to disable these optimizations. For example, the
97 # definition of 'errno' in <errno.h>.
99 aix* | freebsd*) CPPFLAGS="$CPPFLAGS -D_THREAD_SAFE" ;;
100 solaris*) CPPFLAGS="$CPPFLAGS -D_REENTRANT" ;;
105 dnl The guts of gl_THREADLIB. Needs to be expanded only once.
107 AC_DEFUN([gl_THREADLIB_BODY],
109 AC_REQUIRE([gl_THREADLIB_EARLY_BODY])
115 if test "$gl_use_threads" != no; then
116 dnl Check whether the compiler and linker support weak declarations.
117 AC_CACHE_CHECK([whether imported symbols can be declared weak],
120 dnl First, test whether the compiler accepts it syntactically.
123 [[extern void xyzzy ();
124 #pragma weak xyzzy]],
126 [gl_cv_have_weak=maybe])
127 if test $gl_cv_have_weak = maybe; then
128 dnl Second, test whether it actually works. On Cygwin 1.7.2, with
129 dnl gcc 4.3, symbols declared weak always evaluate to the address 0.
136 return (fputs == NULL);
138 [gl_cv_have_weak=yes],
139 [gl_cv_have_weak=no],
140 [dnl When cross-compiling, assume that only ELF platforms support
142 AC_EGREP_CPP([Extensible Linking Format],
144 Extensible Linking Format
147 [gl_cv_have_weak="guessing yes"],
148 [gl_cv_have_weak="guessing no"])
152 if test "$gl_use_threads" = yes || test "$gl_use_threads" = posix; then
153 # On OSF/1, the compiler needs the flag -pthread or -D_REENTRANT so that
154 # it groks <pthread.h>. It's added above, in gl_THREADLIB_EARLY_BODY.
155 AC_CHECK_HEADER([pthread.h],
156 [gl_have_pthread_h=yes], [gl_have_pthread_h=no])
157 if test "$gl_have_pthread_h" = yes; then
158 # Other possible tests:
159 # -lpthreads (FSU threads, PCthreads)
162 # Test whether both pthread_mutex_lock and pthread_mutexattr_init exist
163 # in libc. IRIX 6.5 has the first one in both libc and libpthread, but
164 # the second one only in libpthread, and lock.c needs it.
166 # If -pthread works, prefer it to -lpthread, since Ubuntu 14.04
167 # needs -pthread for some reason. See:
168 # http://lists.gnu.org/archive/html/bug-gnulib/2014-09/msg00023.html
170 for gl_pthread in '' '-pthread'; do
171 LIBS="$LIBS $gl_pthread"
174 [[#include <pthread.h>
176 pthread_mutexattr_t ma;
178 [[pthread_mutex_lock (&m);
179 pthread_mutexattr_init (&ma);]])],
181 LIBTHREAD=$gl_pthread LTLIBTHREAD=$gl_pthread
182 LIBMULTITHREAD=$gl_pthread LTLIBMULTITHREAD=$gl_pthread])
184 test -n "$gl_have_pthread" && break
187 # Test for libpthread by looking for pthread_kill. (Not pthread_self,
188 # since it is defined as a macro on OSF/1.)
189 if test -n "$gl_have_pthread" && test -z "$LIBTHREAD"; then
190 # The program links fine without libpthread. But it may actually
191 # need to link with libpthread in order to create multiple threads.
192 AC_CHECK_LIB([pthread], [pthread_kill],
193 [LIBMULTITHREAD=-lpthread LTLIBMULTITHREAD=-lpthread
194 # On Solaris and HP-UX, most pthread functions exist also in libc.
195 # Therefore pthread_in_use() needs to actually try to create a
196 # thread: pthread_create from libc will fail, whereas
197 # pthread_create will actually create a thread.
198 # On Solaris 10 or newer, this test is no longer needed, because
199 # libc contains the fully functional pthread functions.
201 solaris | solaris2.[1-9] | solaris2.[1-9].* | hpux*)
202 AC_DEFINE([PTHREAD_IN_USE_DETECTION_HARD], [1],
203 [Define if the pthread_in_use() detection is hard.])
206 elif test -z "$gl_have_pthread"; then
207 # Some library is needed. Try libpthread and libc_r.
208 AC_CHECK_LIB([pthread], [pthread_kill],
210 LIBTHREAD=-lpthread LTLIBTHREAD=-lpthread
211 LIBMULTITHREAD=-lpthread LTLIBMULTITHREAD=-lpthread])
212 if test -z "$gl_have_pthread"; then
214 AC_CHECK_LIB([c_r], [pthread_kill],
216 LIBTHREAD=-lc_r LTLIBTHREAD=-lc_r
217 LIBMULTITHREAD=-lc_r LTLIBMULTITHREAD=-lc_r])
220 if test -n "$gl_have_pthread"; then
222 AC_DEFINE([USE_POSIX_THREADS], [1],
223 [Define if the POSIX multithreading library can be used.])
224 if test -n "$LIBMULTITHREAD" || test -n "$LTLIBMULTITHREAD"; then
225 if case "$gl_cv_have_weak" in *yes) true;; *) false;; esac; then
226 AC_DEFINE([USE_POSIX_THREADS_WEAK], [1],
227 [Define if references to the POSIX multithreading library should be made weak.])
235 if test -z "$gl_have_pthread"; then
236 if test "$gl_use_threads" = yes || test "$gl_use_threads" = solaris; then
237 gl_have_solaristhread=
239 LIBS="$LIBS -lthread"
247 [gl_have_solaristhread=yes])
249 if test -n "$gl_have_solaristhread"; then
250 gl_threads_api=solaris
253 LIBMULTITHREAD="$LIBTHREAD"
254 LTLIBMULTITHREAD="$LTLIBTHREAD"
255 AC_DEFINE([USE_SOLARIS_THREADS], [1],
256 [Define if the old Solaris multithreading library can be used.])
257 if case "$gl_cv_have_weak" in *yes) true;; *) false;; esac; then
258 AC_DEFINE([USE_SOLARIS_THREADS_WEAK], [1],
259 [Define if references to the old Solaris multithreading library should be made weak.])
266 if test "$gl_use_threads" = pth; then
267 gl_save_CPPFLAGS="$CPPFLAGS"
268 AC_LIB_LINKFLAGS([pth])
273 [AC_LANG_PROGRAM([[#include <pth.h>]], [[pth_self();]])],
276 if test -n "$gl_have_pth"; then
279 LTLIBTHREAD="$LTLIBPTH"
280 LIBMULTITHREAD="$LIBTHREAD"
281 LTLIBMULTITHREAD="$LTLIBTHREAD"
282 AC_DEFINE([USE_PTH_THREADS], [1],
283 [Define if the GNU Pth multithreading library can be used.])
284 if test -n "$LIBMULTITHREAD" || test -n "$LTLIBMULTITHREAD"; then
285 if case "$gl_cv_have_weak" in *yes) true;; *) false;; esac; then
286 AC_DEFINE([USE_PTH_THREADS_WEAK], [1],
287 [Define if references to the GNU Pth multithreading library should be made weak.])
293 CPPFLAGS="$gl_save_CPPFLAGS"
296 if test -z "$gl_have_pthread"; then
297 case "$gl_use_threads" in
298 yes | windows | win32) # The 'win32' is for backward compatibility.
299 if { case "$host_os" in
304 gl_threads_api=windows
305 AC_DEFINE([USE_WINDOWS_THREADS], [1],
306 [Define if the native Windows multithreading API can be used.])
312 AC_MSG_CHECKING([for multithread API to use])
313 AC_MSG_RESULT([$gl_threads_api])
314 AC_SUBST([LIBTHREAD])
315 AC_SUBST([LTLIBTHREAD])
316 AC_SUBST([LIBMULTITHREAD])
317 AC_SUBST([LTLIBMULTITHREAD])
320 AC_DEFUN([gl_THREADLIB],
322 AC_REQUIRE([gl_THREADLIB_EARLY])
323 AC_REQUIRE([gl_THREADLIB_BODY])
327 dnl gl_DISABLE_THREADS
328 dnl ------------------
329 dnl Sets the gl_THREADLIB default so that threads are not used by default.
330 dnl The user can still override it at installation time, by using the
331 dnl configure option '--enable-threads'.
333 AC_DEFUN([gl_DISABLE_THREADS], [
334 m4_divert_text([INIT_PREPARE], [gl_use_threads_default=no])
338 dnl Survey of platforms:
340 dnl Platform Available Compiler Supports test-lock
341 dnl flavours option weak result
342 dnl --------------- --------- --------- -------- ---------
343 dnl Linux 2.4/glibc posix -lpthread Y OK
345 dnl GNU Hurd/glibc posix
347 dnl Ubuntu 14.04 posix -pthread Y OK
349 dnl FreeBSD 5.3 posix -lc_r Y
351 dnl posix -lpthread ? Y
354 dnl FreeBSD 5.2 posix -lc_r Y
358 dnl FreeBSD 4.0,4.10 posix -lc_r Y OK
362 dnl OpenBSD 3.4 posix -lpthread Y OK
364 dnl Mac OS X 10.[123] posix -lpthread Y OK
366 dnl Solaris 7,8,9 posix -lpthread Y Sol 7,8: 0.0; Sol 9: OK
367 dnl solaris -lthread Y Sol 7,8: 0.0; Sol 9: OK
369 dnl HP-UX 11 posix -lpthread N (cc) OK
372 dnl IRIX 6.5 posix -lpthread Y 0.5
374 dnl AIX 4.3,5.1 posix -lpthread N AIX 4: 0.5; AIX 5: OK
376 dnl OSF/1 4.0,5.1 posix -pthread (cc) N OK
377 dnl -lpthread (gcc) Y
379 dnl Cygwin posix -lpthread Y OK
381 dnl Any of the above pth -lpth 0.0
383 dnl Mingw windows N OK
387 dnl The test-lock result shows what happens if in test-lock.c EXPLICIT_YIELD is
389 dnl OK if all three tests terminate OK,
390 dnl 0.5 if the first test terminates OK but the second one loops endlessly,
391 dnl 0.0 if the first test already loops endlessly.