1 dnl @synopsis ACX_PTHREAD([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])
3 dnl This macro figures out how to build C programs using POSIX threads.
4 dnl It sets the PTHREAD_LIBS output variable to the threads library and
5 dnl linker flags, and the PTHREAD_CFLAGS output variable to any special
6 dnl C compiler flags that are needed. (The user can also force certain
7 dnl compiler flags/libs to be tested by setting these environment
10 dnl Also sets PTHREAD_CC to any special C compiler that is needed for
11 dnl multi-threaded programs (defaults to the value of CC otherwise).
12 dnl (This is necessary on AIX to use the special cc_r compiler alias.)
14 dnl NOTE: You are assumed to not only compile your program with these
15 dnl flags, but also link it with them as well. e.g. you should link
16 dnl with $PTHREAD_CC $CFLAGS $PTHREAD_CFLAGS $LDFLAGS ... $PTHREAD_LIBS
19 dnl If you are only building threads programs, you may wish to use
20 dnl these variables in your default LIBS, CFLAGS, and CC:
22 dnl LIBS="$PTHREAD_LIBS $LIBS"
23 dnl CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
26 dnl In addition, if the PTHREAD_CREATE_JOINABLE thread-attribute
27 dnl constant has a nonstandard name, defines PTHREAD_CREATE_JOINABLE to
28 dnl that name (e.g. PTHREAD_CREATE_UNDETACHED on AIX).
30 dnl ACTION-IF-FOUND is a list of shell commands to run if a threads
31 dnl library is found, and ACTION-IF-NOT-FOUND is a list of commands to
32 dnl run it if it is not found. If ACTION-IF-FOUND is not specified, the
33 dnl default action will define HAVE_PTHREAD.
35 dnl Please let the authors know if this macro fails on any platform, or
36 dnl if you have any other suggestions or comments. This macro was based
37 dnl on work by SGJ on autoconf scripts for FFTW (www.fftw.org) (with
38 dnl help from M. Frigo), as well as ac_pthread and hb_pthread macros
39 dnl posted by Alejandro Forero Cuervo to the autoconf macro repository.
40 dnl We are also grateful for the helpful feedback of numerous users.
42 dnl @category InstalledPackages
43 dnl @author Steven G. Johnson <stevenj@alum.mit.edu>
44 dnl @version 2005-01-14
45 dnl @license GPLWithACException
47 dnl Checks for GCC shared/pthread inconsistency based on work by
48 dnl Marcin Owsiany <marcin@owsiany.pl>
51 AC_DEFUN([ACX_PTHREAD], [
52 AC_REQUIRE([AC_CANONICAL_HOST])
57 # We used to check for pthread.h first, but this fails if pthread.h
58 # requires special compiler flags (e.g. on True64 or Sequent).
59 # It gets checked for in the link test anyway.
61 # First of all, check if the user has set any of the PTHREAD_LIBS,
62 # etcetera environment variables, and if threads linking works using
64 if test x"$PTHREAD_LIBS$PTHREAD_CFLAGS" != x; then
66 CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
68 LIBS="$PTHREAD_LIBS $LIBS"
69 AC_MSG_CHECKING([for pthread_join in LIBS=$PTHREAD_LIBS with CFLAGS=$PTHREAD_CFLAGS])
70 AC_TRY_LINK_FUNC(pthread_join, acx_pthread_ok=yes)
71 AC_MSG_RESULT($acx_pthread_ok)
72 if test x"$acx_pthread_ok" = xno; then
80 # We must check for the threads library under a number of different
81 # names; the ordering is very important because some systems
82 # (e.g. DEC) have both -lpthread and -lpthreads, where one of the
83 # libraries is broken (non-POSIX).
85 # Create a list of thread flags to try. Items starting with a "-" are
86 # C compiler flags, and other items are library names, except for "none"
87 # which indicates that we try without any flags at all, and "pthread-config"
88 # which is a program returning the flags for the Pth emulation library.
90 acx_pthread_flags="pthreads none -Kthread -kthread lthread -pthread -pthreads -mthreads pthread --thread-safe -mt pthread-config"
92 # The ordering *is* (sometimes) important. Some notes on the
93 # individual items follow:
95 # pthreads: AIX (must check this before -lpthread)
96 # none: in case threads are in libc; should be tried before -Kthread and
97 # other compiler flags to prevent continual compiler warnings
98 # -Kthread: Sequent (threads in libc, but -Kthread needed for pthread.h)
99 # -kthread: FreeBSD kernel threads (preferred to -pthread since SMP-able)
100 # lthread: LinuxThreads port on FreeBSD (also preferred to -pthread)
101 # -pthread: Linux/gcc (kernel threads), BSD/gcc (userland threads)
102 # -pthreads: Solaris/gcc
103 # -mthreads: Mingw32/gcc, Lynx/gcc
104 # -mt: Sun Workshop C (may only link SunOS threads [-lthread], but it
105 # doesn't hurt to check since this sometimes defines pthreads too;
106 # also defines -D_REENTRANT)
107 # pthread: Linux, etcetera
108 # --thread-safe: KAI C++
109 # pthread-config: use pthread-config program (for GNU Pth library)
111 case "${host_cpu}-${host_os}" in
114 # On Solaris (at least, for some versions), libc contains stubbed
115 # (non-functional) versions of the pthreads routines, so link-based
116 # tests will erroneously succeed. (We need to link with -pthread or
117 # -lpthread.) (The stubs are missing pthread_cleanup_push, or rather
118 # a function called by this macro, so we could check for that, but
119 # who knows whether they'll stub that too in a future libc.) So,
120 # we'll just look for -pthreads and -lpthread first:
122 acx_pthread_flags="-pthread -pthreads pthread -mt $acx_pthread_flags"
126 if test x"$acx_pthread_ok" = xno; then
127 for flag in $acx_pthread_flags; do
131 AC_MSG_CHECKING([whether pthreads work without any flags])
135 AC_MSG_CHECKING([whether pthreads work with $flag])
136 PTHREAD_CFLAGS="$flag"
140 AC_CHECK_PROG(acx_pthread_config, pthread-config, yes, no)
141 if test x"$acx_pthread_config" = xno; then continue; fi
142 PTHREAD_CFLAGS="`pthread-config --cflags`"
143 PTHREAD_LIBS="`pthread-config --ldflags` `pthread-config --libs`"
147 AC_MSG_CHECKING([for the pthreads library -l$flag])
148 PTHREAD_LIBS="-l$flag"
153 save_CFLAGS="$CFLAGS"
154 LIBS="$PTHREAD_LIBS $LIBS"
155 CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
157 # Check for various functions. We must include pthread.h,
158 # since some functions may be macros. (On the Sequent, we
159 # need a special flag -Kthread to make this header compile.)
160 # We check for pthread_join because it is in -lpthread on IRIX
161 # while pthread_create is in libc. We check for pthread_attr_init
162 # due to DEC craziness with -lpthreads. We check for
163 # pthread_cleanup_push because it is one of the few pthread
164 # functions on Solaris that doesn't have a non-functional libc stub.
165 # We try pthread_create on general principles.
166 AC_TRY_LINK([#include <pthread.h>],
167 [pthread_t th; pthread_join(th, 0);
168 pthread_attr_init(0); pthread_cleanup_push(0, 0);
169 pthread_create(0,0,0,0); pthread_cleanup_pop(0); ],
170 [acx_pthread_ok=yes])
173 CFLAGS="$save_CFLAGS"
175 AC_MSG_RESULT($acx_pthread_ok)
176 if test "x$acx_pthread_ok" = xyes; then
185 # Various other checks:
186 if test "x$acx_pthread_ok" = xyes; then
188 LIBS="$PTHREAD_LIBS $LIBS"
189 save_CFLAGS="$CFLAGS"
190 CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
192 # Detect AIX lossage: JOINABLE attribute is called UNDETACHED.
193 AC_MSG_CHECKING([for joinable pthread attribute])
195 for attr in PTHREAD_CREATE_JOINABLE PTHREAD_CREATE_UNDETACHED; do
196 AC_TRY_LINK([#include <pthread.h>], [int attr=$attr;],
197 [attr_name=$attr; break])
199 AC_MSG_RESULT($attr_name)
200 if test "$attr_name" != PTHREAD_CREATE_JOINABLE; then
201 AC_DEFINE_UNQUOTED(PTHREAD_CREATE_JOINABLE, $attr_name,
202 [Define to necessary symbol if this constant
203 uses a non-standard name on your system.])
206 AC_MSG_CHECKING([if more special flags are required for pthreads])
208 case "${host_cpu}-${host_os}" in
209 *-aix* | *-freebsd* | *-darwin*) flag="-D_THREAD_SAFE";;
210 *solaris* | *-osf* | *-hpux*) flag="-D_REENTRANT";;
212 AC_MSG_RESULT(${flag})
213 if test "x$flag" != xno; then
214 PTHREAD_CFLAGS="$flag $PTHREAD_CFLAGS"
218 CFLAGS="$save_CFLAGS"
220 # More AIX lossage: must compile with cc_r
221 AC_CHECK_PROG(PTHREAD_CC, cc_r, cc_r, ${CC})
223 # The next part tries to detect GCC inconsistency with -shared on some
224 # architectures and systems. The problem is that in certain
225 # configurations, when -shared is specified, GCC "forgets" to
226 # internally use various flags which are still necessary.
228 # First, check whether caller wants us to skip -shared checks
230 AC_MSG_CHECKING([whether to check for GCC pthread/shared inconsistencies])
231 if test x"$3" = x1; then
236 # In order not to create several levels of indentation, we test
237 # the value of "$ok" until we find out the cure or run out of
244 save_CFLAGS="$CFLAGS"
247 # Try with the flags determined by the earlier checks.
249 # -Wl,-z,defs forces link-time symbol resolution, so that the
250 # linking checks with -shared actually have any value
252 # FIXME: -fPIC is required for -shared on many architectures,
253 # so we specify it here, but the right way would probably be to
254 # properly detect whether it is actually required.
255 CFLAGS="-shared -fPIC -Wl,-z,defs $CFLAGS $PTHREAD_CFLAGS"
256 LIBS="$PTHREAD_LIBS $LIBS"
259 AC_MSG_CHECKING([whether -pthread is sufficient with -shared])
260 AC_TRY_LINK([#include <pthread.h>],
261 [pthread_t th; pthread_join(th, 0);
262 pthread_attr_init(0); pthread_cleanup_push(0, 0);
263 pthread_create(0,0,0,0); pthread_cleanup_pop(0); ],
266 if test "x$ok" = xyes; then
273 # Linux gcc on some architectures such as mips/mipsel forgets
276 if test x"$ok" = xno; then
277 AC_MSG_CHECKING([whether -lpthread fixes that])
278 LIBS="-lpthread $PTHREAD_LIBS $save_LIBS"
279 AC_TRY_LINK([#include <pthread.h>],
280 [pthread_t th; pthread_join(th, 0);
281 pthread_attr_init(0); pthread_cleanup_push(0, 0);
282 pthread_create(0,0,0,0); pthread_cleanup_pop(0); ],
285 if test "x$ok" = xyes; then
287 PTHREAD_LIBS="-lpthread $PTHREAD_LIBS"
293 # FreeBSD 4.10 gcc forgets to use -lc_r instead of -lc
295 if test x"$ok" = xno; then
296 AC_MSG_CHECKING([whether -lc_r fixes that])
297 LIBS="-lc_r $PTHREAD_LIBS $save_LIBS"
298 AC_TRY_LINK([#include <pthread.h>],
299 [pthread_t th; pthread_join(th, 0);
300 pthread_attr_init(0); pthread_cleanup_push(0, 0);
301 pthread_create(0,0,0,0); pthread_cleanup_pop(0); ],
304 if test "x$ok" = xyes; then
306 PTHREAD_LIBS="-lc_r $PTHREAD_LIBS"
311 if test x"$ok" = xno; then
312 # OK, we have run out of ideas
313 AC_MSG_WARN([Impossible to determine how to use pthreads with shared libraries])
315 # so it's not safe to assume that we may use pthreads
319 CFLAGS="$save_CFLAGS"
327 AC_SUBST(PTHREAD_LIBS)
328 AC_SUBST(PTHREAD_CFLAGS)
331 # Finally, execute ACTION-IF-FOUND/ACTION-IF-NOT-FOUND:
332 if test x"$acx_pthread_ok" = xyes; then
333 ifelse([$1],,AC_DEFINE(HAVE_PTHREAD,1,[Define if you have POSIX threads libraries and header files.]),[$1])