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
4 dnl threads. It sets the PTHREAD_LIBS output variable to the threads
5 dnl library and linker flags, and the PTHREAD_CFLAGS output variable
6 dnl to any special C compiler flags that are needed. (The user can also
7 dnl force certain compiler flags/libs to be tested by setting these
8 dnl environment variables.)
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 If you are only building threads programs, you may wish to
15 dnl use these variables in your default LIBS, CFLAGS, and CC:
17 dnl LIBS="$PTHREAD_LIBS $LIBS"
18 dnl CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
21 dnl In addition, if the PTHREAD_CREATE_JOINABLE thread-attribute
22 dnl constant has a nonstandard name, defines PTHREAD_CREATE_JOINABLE
23 dnl to that name (e.g. PTHREAD_CREATE_UNDETACHED on AIX).
25 dnl ACTION-IF-FOUND is a list of shell commands to run if a threads
26 dnl library is found, and ACTION-IF-NOT-FOUND is a list of commands
27 dnl to run it if it is not found. If ACTION-IF-FOUND is not specified,
28 dnl the default action will define HAVE_PTHREAD.
30 dnl Please let the authors know if this macro fails on any platform,
31 dnl or if you have any other suggestions or comments. This macro was
32 dnl based on work by SGJ on autoconf scripts for FFTW (www.fftw.org)
33 dnl (with help from M. Frigo), as well as ac_pthread and hb_pthread
34 dnl macros posted by AFC to the autoconf macro repository. We are also
35 dnl grateful for the helpful feedback of numerous users.
37 dnl @author Steven G. Johnson <stevenj@alum.mit.edu> and Alejandro Forero Cuervo <bachue@bachue.com>
39 AC_DEFUN([ACX_PTHREAD], [
40 AC_REQUIRE([AC_CANONICAL_HOST])
45 # We used to check for pthread.h first, but this fails if pthread.h
46 # requires special compiler flags (e.g. on True64 or Sequent).
47 # It gets checked for in the link test anyway.
49 # First of all, check if the user has set any of the PTHREAD_LIBS,
50 # etcetera environment variables, and if threads linking works using
52 if test x"$PTHREAD_LIBS$PTHREAD_CFLAGS" != x; then
54 CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
56 LIBS="$PTHREAD_LIBS $LIBS"
57 AC_MSG_CHECKING([for pthread_join in LIBS=$PTHREAD_LIBS with CFLAGS=$PTHREAD_CFLAGS])
58 AC_TRY_LINK_FUNC(pthread_join, acx_pthread_ok=yes)
59 AC_MSG_RESULT($acx_pthread_ok)
60 if test x"$acx_pthread_ok" = xno; then
68 # We must check for the threads library under a number of different
69 # names; the ordering is very important because some systems
70 # (e.g. DEC) have both -lpthread and -lpthreads, where one of the
71 # libraries is broken (non-POSIX).
73 # Create a list of thread flags to try. Items starting with a "-" are
74 # C compiler flags, and other items are library names, except for "none"
75 # which indicates that we try without any flags at all.
77 acx_pthread_flags="pthreads none -Kthread -kthread lthread -pthread -pthreads -mthreads pthread --thread-safe -mt"
79 # The ordering *is* (sometimes) important. Some notes on the
80 # individual items follow:
82 # pthreads: AIX (must check this before -lpthread)
83 # none: in case threads are in libc; should be tried before -Kthread and
84 # other compiler flags to prevent continual compiler warnings
85 # -Kthread: Sequent (threads in libc, but -Kthread needed for pthread.h)
86 # -kthread: FreeBSD kernel threads (preferred to -pthread since SMP-able)
87 # lthread: LinuxThreads port on FreeBSD (also preferred to -pthread)
88 # -pthread: Linux/gcc (kernel threads), BSD/gcc (userland threads)
89 # -pthreads: Solaris/gcc
90 # -mthreads: Mingw32/gcc, Lynx/gcc
91 # -mt: Sun Workshop C (may only link SunOS threads [-lthread], but it
92 # doesn't hurt to check since this sometimes defines pthreads too;
93 # also defines -D_REENTRANT)
94 # pthread: Linux, etcetera
95 # --thread-safe: KAI C++
97 case "${host_cpu}-${host_os}" in
100 # On Solaris (at least, for some versions), libc contains stubbed
101 # (non-functional) versions of the pthreads routines, so link-based
102 # tests will erroneously succeed. (We need to link with -pthread or
103 # -lpthread.) (The stubs are missing pthread_cleanup_push, or rather
104 # a function called by this macro, so we could check for that, but
105 # who knows whether they'll stub that too in a future libc.) So,
106 # we'll just look for -pthreads and -lpthread first:
108 acx_pthread_flags="-pthread -pthreads pthread -mt $acx_pthread_flags"
112 if test x"$acx_pthread_ok" = xno; then
113 for flag in $acx_pthread_flags; do
117 AC_MSG_CHECKING([whether pthreads work without any flags])
121 AC_MSG_CHECKING([whether pthreads work with $flag])
122 PTHREAD_CFLAGS="$flag"
126 AC_MSG_CHECKING([for the pthreads library -l$flag])
127 PTHREAD_LIBS="-l$flag"
132 save_CFLAGS="$CFLAGS"
133 LIBS="$PTHREAD_LIBS $LIBS"
134 CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
136 # Check for various functions. We must include pthread.h,
137 # since some functions may be macros. (On the Sequent, we
138 # need a special flag -Kthread to make this header compile.)
139 # We check for pthread_join because it is in -lpthread on IRIX
140 # while pthread_create is in libc. We check for pthread_attr_init
141 # due to DEC craziness with -lpthreads. We check for
142 # pthread_cleanup_push because it is one of the few pthread
143 # functions on Solaris that doesn't have a non-functional libc stub.
144 # We try pthread_create on general principles.
145 AC_TRY_LINK([#include <pthread.h>],
146 [pthread_t th; pthread_join(th, 0);
147 pthread_attr_init(0); pthread_cleanup_push(0, 0);
148 pthread_create(0,0,0,0); pthread_cleanup_pop(0); ],
149 [acx_pthread_ok=yes])
152 CFLAGS="$save_CFLAGS"
154 AC_MSG_RESULT($acx_pthread_ok)
155 if test "x$acx_pthread_ok" = xyes; then
164 # Various other checks:
165 if test "x$acx_pthread_ok" = xyes; then
167 LIBS="$PTHREAD_LIBS $LIBS"
168 save_CFLAGS="$CFLAGS"
169 CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
171 # Detect AIX lossage: threads are created detached by default
172 # and the JOINABLE attribute has a nonstandard name (UNDETACHED).
173 AC_MSG_CHECKING([for joinable pthread attribute])
174 AC_TRY_LINK([#include <pthread.h>],
175 [int attr=PTHREAD_CREATE_JOINABLE;],
176 ok=PTHREAD_CREATE_JOINABLE, ok=unknown)
177 if test x"$ok" = xunknown; then
178 AC_TRY_LINK([#include <pthread.h>],
179 [int attr=PTHREAD_CREATE_UNDETACHED;],
180 ok=PTHREAD_CREATE_UNDETACHED, ok=unknown)
182 if test x"$ok" != xPTHREAD_CREATE_JOINABLE; then
183 AC_DEFINE(PTHREAD_CREATE_JOINABLE, $ok,
184 [Define to the necessary symbol if this constant
185 uses a non-standard name on your system.])
188 if test x"$ok" = xunknown; then
189 AC_MSG_WARN([we do not know how to create joinable pthreads])
192 AC_MSG_CHECKING([if more special flags are required for pthreads])
194 case "${host_cpu}-${host_os}" in
195 *-aix* | *-freebsd*) flag="-D_THREAD_SAFE";;
196 *-osf* | *-hpux*) flag="-D_REENTRANT";;
198 if test "$GCC" = "yes"; then
201 flag="-mt -D_REENTRANT"
205 AC_MSG_RESULT(${flag})
206 if test "x$flag" != xno; then
207 PTHREAD_CFLAGS="$flag $PTHREAD_CFLAGS"
211 CFLAGS="$save_CFLAGS"
213 # More AIX lossage: must compile with cc_r
214 AC_CHECK_PROG(PTHREAD_CC, cc_r, cc_r, ${CC})
219 AC_SUBST(PTHREAD_LIBS)
220 AC_SUBST(PTHREAD_CFLAGS)
223 # Finally, execute ACTION-IF-FOUND/ACTION-IF-NOT-FOUND:
224 if test x"$acx_pthread_ok" = xyes; then
225 ifelse([$1],,AC_DEFINE(HAVE_PTHREAD,1,[Define if you have POSIX threads libraries and header files.]),[$1])
234 CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
235 LIBS="$LIBS $PTHREAD_LIBS"
236 AC_CHECK_FUNCS([pthread_rwlock_init])