1 # threadlib.m4 serial 13
2 dnl Copyright (C) 2005-2018 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 <https://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 $gl_cv_have_weak = maybe; then
128 dnl Second, test whether it actually works. On Cygwin 1.7.2, with
129 dnl gcc 4.3, symbols declared weak always evaluate to the address 0.
136 return (fputs == NULL);
138 [gl_cv_have_weak=yes],
139 [gl_cv_have_weak=no],
140 [dnl When cross-compiling, assume that only ELF platforms support
142 AC_EGREP_CPP([Extensible Linking Format],
144 Extensible Linking Format
147 [gl_cv_have_weak="guessing yes"],
148 [gl_cv_have_weak="guessing no"])
151 dnl But when linking statically, weak symbols don't work.
153 *" -static "*) gl_cv_have_weak=no ;;
156 if test "$gl_use_threads" = yes || test "$gl_use_threads" = posix; then
157 # On OSF/1, the compiler needs the flag -pthread or -D_REENTRANT so that
158 # it groks <pthread.h>. It's added above, in gl_THREADLIB_EARLY_BODY.
159 AC_CHECK_HEADER([pthread.h],
160 [gl_have_pthread_h=yes], [gl_have_pthread_h=no])
161 if test "$gl_have_pthread_h" = yes; then
162 # Other possible tests:
163 # -lpthreads (FSU threads, PCthreads)
166 # Test whether both pthread_mutex_lock and pthread_mutexattr_init exist
167 # in libc. IRIX 6.5 has the first one in both libc and libpthread, but
168 # the second one only in libpthread, and lock.c needs it.
170 # If -pthread works, prefer it to -lpthread, since Ubuntu 14.04
171 # needs -pthread for some reason. See:
172 # https://lists.gnu.org/r/bug-gnulib/2014-09/msg00023.html
174 for gl_pthread in '' '-pthread'; do
175 LIBS="$LIBS $gl_pthread"
178 [[#include <pthread.h>
180 pthread_mutexattr_t ma;
182 [[pthread_mutex_lock (&m);
183 pthread_mutexattr_init (&ma);]])],
185 LIBTHREAD=$gl_pthread LTLIBTHREAD=$gl_pthread
186 LIBMULTITHREAD=$gl_pthread LTLIBMULTITHREAD=$gl_pthread])
188 test -n "$gl_have_pthread" && break
191 # Test for libpthread by looking for pthread_kill. (Not pthread_self,
192 # since it is defined as a macro on OSF/1.)
193 if test -n "$gl_have_pthread" && test -z "$LIBTHREAD"; then
194 # The program links fine without libpthread. But it may actually
195 # need to link with libpthread in order to create multiple threads.
196 AC_CHECK_LIB([pthread], [pthread_kill],
197 [LIBMULTITHREAD=-lpthread LTLIBMULTITHREAD=-lpthread
198 # On Solaris and HP-UX, most pthread functions exist also in libc.
199 # Therefore pthread_in_use() needs to actually try to create a
200 # thread: pthread_create from libc will fail, whereas
201 # pthread_create will actually create a thread.
202 # On Solaris 10 or newer, this test is no longer needed, because
203 # libc contains the fully functional pthread functions.
205 solaris | solaris2.[1-9] | solaris2.[1-9].* | hpux*)
206 AC_DEFINE([PTHREAD_IN_USE_DETECTION_HARD], [1],
207 [Define if the pthread_in_use() detection is hard.])
210 elif test -z "$gl_have_pthread"; then
211 # Some library is needed. Try libpthread and libc_r.
212 AC_CHECK_LIB([pthread], [pthread_kill],
214 LIBTHREAD=-lpthread LTLIBTHREAD=-lpthread
215 LIBMULTITHREAD=-lpthread LTLIBMULTITHREAD=-lpthread])
216 if test -z "$gl_have_pthread"; then
218 AC_CHECK_LIB([c_r], [pthread_kill],
220 LIBTHREAD=-lc_r LTLIBTHREAD=-lc_r
221 LIBMULTITHREAD=-lc_r LTLIBMULTITHREAD=-lc_r])
224 if test -n "$gl_have_pthread"; then
226 AC_DEFINE([USE_POSIX_THREADS], [1],
227 [Define if the POSIX multithreading library can be used.])
228 if test -n "$LIBMULTITHREAD" || test -n "$LTLIBMULTITHREAD"; then
229 if case "$gl_cv_have_weak" in *yes) true;; *) false;; esac; then
230 AC_DEFINE([USE_POSIX_THREADS_WEAK], [1],
231 [Define if references to the POSIX multithreading library should be made weak.])
239 if test -z "$gl_have_pthread"; then
240 if test "$gl_use_threads" = yes || test "$gl_use_threads" = solaris; then
241 gl_have_solaristhread=
243 LIBS="$LIBS -lthread"
251 [gl_have_solaristhread=yes])
253 if test -n "$gl_have_solaristhread"; then
254 gl_threads_api=solaris
257 LIBMULTITHREAD="$LIBTHREAD"
258 LTLIBMULTITHREAD="$LTLIBTHREAD"
259 AC_DEFINE([USE_SOLARIS_THREADS], [1],
260 [Define if the old Solaris multithreading library can be used.])
261 if case "$gl_cv_have_weak" in *yes) true;; *) false;; esac; then
262 AC_DEFINE([USE_SOLARIS_THREADS_WEAK], [1],
263 [Define if references to the old Solaris multithreading library should be made weak.])
270 if test "$gl_use_threads" = pth; then
271 gl_save_CPPFLAGS="$CPPFLAGS"
272 AC_LIB_LINKFLAGS([pth])
277 [AC_LANG_PROGRAM([[#include <pth.h>]], [[pth_self();]])],
280 if test -n "$gl_have_pth"; then
283 LTLIBTHREAD="$LTLIBPTH"
284 LIBMULTITHREAD="$LIBTHREAD"
285 LTLIBMULTITHREAD="$LTLIBTHREAD"
286 AC_DEFINE([USE_PTH_THREADS], [1],
287 [Define if the GNU Pth multithreading library can be used.])
288 if test -n "$LIBMULTITHREAD" || test -n "$LTLIBMULTITHREAD"; then
289 if case "$gl_cv_have_weak" in *yes) true;; *) false;; esac; then
290 AC_DEFINE([USE_PTH_THREADS_WEAK], [1],
291 [Define if references to the GNU Pth multithreading library should be made weak.])
297 CPPFLAGS="$gl_save_CPPFLAGS"
300 if test -z "$gl_have_pthread"; then
301 case "$gl_use_threads" in
302 yes | windows | win32) # The 'win32' is for backward compatibility.
303 if { case "$host_os" in
308 gl_threads_api=windows
309 AC_DEFINE([USE_WINDOWS_THREADS], [1],
310 [Define if the native Windows multithreading API can be used.])
316 AC_MSG_CHECKING([for multithread API to use])
317 AC_MSG_RESULT([$gl_threads_api])
318 AC_SUBST([LIBTHREAD])
319 AC_SUBST([LTLIBTHREAD])
320 AC_SUBST([LIBMULTITHREAD])
321 AC_SUBST([LTLIBMULTITHREAD])
324 AC_DEFUN([gl_THREADLIB],
326 AC_REQUIRE([gl_THREADLIB_EARLY])
327 AC_REQUIRE([gl_THREADLIB_BODY])
331 dnl gl_DISABLE_THREADS
332 dnl ------------------
333 dnl Sets the gl_THREADLIB default so that threads are not used by default.
334 dnl The user can still override it at installation time, by using the
335 dnl configure option '--enable-threads'.
337 AC_DEFUN([gl_DISABLE_THREADS], [
338 m4_divert_text([INIT_PREPARE], [gl_use_threads_default=no])
342 dnl Survey of platforms:
344 dnl Platform Available Compiler Supports test-lock
345 dnl flavours option weak result
346 dnl --------------- --------- --------- -------- ---------
347 dnl Linux 2.4/glibc posix -lpthread Y OK
349 dnl GNU Hurd/glibc posix
351 dnl Ubuntu 14.04 posix -pthread Y OK
353 dnl FreeBSD 5.3 posix -lc_r Y
355 dnl posix -lpthread ? Y
358 dnl FreeBSD 5.2 posix -lc_r Y
362 dnl FreeBSD 4.0,4.10 posix -lc_r Y OK
366 dnl OpenBSD 3.4 posix -lpthread Y OK
368 dnl Mac OS X 10.[123] posix -lpthread Y OK
370 dnl Solaris 7,8,9 posix -lpthread Y Sol 7,8: 0.0; Sol 9: OK
371 dnl solaris -lthread Y Sol 7,8: 0.0; Sol 9: OK
373 dnl HP-UX 11 posix -lpthread N (cc) OK
376 dnl IRIX 6.5 posix -lpthread Y 0.5
378 dnl AIX 4.3,5.1 posix -lpthread N AIX 4: 0.5; AIX 5: OK
380 dnl OSF/1 4.0,5.1 posix -pthread (cc) N OK
381 dnl -lpthread (gcc) Y
383 dnl Cygwin posix -lpthread Y OK
385 dnl Any of the above pth -lpth 0.0
387 dnl Mingw windows N OK
391 dnl The test-lock result shows what happens if in test-lock.c EXPLICIT_YIELD is
393 dnl OK if all three tests terminate OK,
394 dnl 0.5 if the first test terminates OK but the second one loops endlessly,
395 dnl 0.0 if the first test already loops endlessly.