xref: /libuv/m4/ax_pthread.m4 (revision b4fe4f6a)
1# ===========================================================================
2#        https://www.gnu.org/software/autoconf-archive/ax_pthread.html
3# ===========================================================================
4#
5# SYNOPSIS
6#
7#   AX_PTHREAD([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])
8#
9# DESCRIPTION
10#
11#   This macro figures out how to build C programs using POSIX threads. It
12#   sets the PTHREAD_LIBS output variable to the threads library and linker
13#   flags, and the PTHREAD_CFLAGS output variable to any special C compiler
14#   flags that are needed. (The user can also force certain compiler
15#   flags/libs to be tested by setting these environment variables.)
16#
17#   Also sets PTHREAD_CC to any special C compiler that is needed for
18#   multi-threaded programs (defaults to the value of CC otherwise). (This
19#   is necessary on AIX to use the special cc_r compiler alias.)
20#
21#   NOTE: You are assumed to not only compile your program with these flags,
22#   but also to link with them as well. For example, you might link with
23#   $PTHREAD_CC $CFLAGS $PTHREAD_CFLAGS $LDFLAGS ... $PTHREAD_LIBS $LIBS
24#
25#   If you are only building threaded programs, you may wish to use these
26#   variables in your default LIBS, CFLAGS, and CC:
27#
28#     LIBS="$PTHREAD_LIBS $LIBS"
29#     CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
30#     CC="$PTHREAD_CC"
31#
32#   In addition, if the PTHREAD_CREATE_JOINABLE thread-attribute constant
33#   has a nonstandard name, this macro defines PTHREAD_CREATE_JOINABLE to
34#   that name (e.g. PTHREAD_CREATE_UNDETACHED on AIX).
35#
36#   Also HAVE_PTHREAD_PRIO_INHERIT is defined if pthread is found and the
37#   PTHREAD_PRIO_INHERIT symbol is defined when compiling with
38#   PTHREAD_CFLAGS.
39#
40#   ACTION-IF-FOUND is a list of shell commands to run if a threads library
41#   is found, and ACTION-IF-NOT-FOUND is a list of commands to run it if it
42#   is not found. If ACTION-IF-FOUND is not specified, the default action
43#   will define HAVE_PTHREAD.
44#
45#   Please let the authors know if this macro fails on any platform, or if
46#   you have any other suggestions or comments. This macro was based on work
47#   by SGJ on autoconf scripts for FFTW (http://www.fftw.org/) (with help
48#   from M. Frigo), as well as ac_pthread and hb_pthread macros posted by
49#   Alejandro Forero Cuervo to the autoconf macro repository. We are also
50#   grateful for the helpful feedback of numerous users.
51#
52#   Updated for Autoconf 2.68 by Daniel Richard G.
53#
54# LICENSE
55#
56#   Copyright (c) 2008 Steven G. Johnson <stevenj@alum.mit.edu>
57#   Copyright (c) 2011 Daniel Richard G. <skunk@iSKUNK.ORG>
58#
59#   This program is free software: you can redistribute it and/or modify it
60#   under the terms of the GNU General Public License as published by the
61#   Free Software Foundation, either version 3 of the License, or (at your
62#   option) any later version.
63#
64#   This program is distributed in the hope that it will be useful, but
65#   WITHOUT ANY WARRANTY; without even the implied warranty of
66#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
67#   Public License for more details.
68#
69#   You should have received a copy of the GNU General Public License along
70#   with this program. If not, see <https://www.gnu.org/licenses/>.
71#
72#   As a special exception, the respective Autoconf Macro's copyright owner
73#   gives unlimited permission to copy, distribute and modify the configure
74#   scripts that are the output of Autoconf when processing the Macro. You
75#   need not follow the terms of the GNU General Public License when using
76#   or distributing such scripts, even though portions of the text of the
77#   Macro appear in them. The GNU General Public License (GPL) does govern
78#   all other use of the material that constitutes the Autoconf Macro.
79#
80#   This special exception to the GPL applies to versions of the Autoconf
81#   Macro released by the Autoconf Archive. When you make and distribute a
82#   modified version of the Autoconf Macro, you may extend this special
83#   exception to the GPL to apply to your modified version as well.
84
85#serial 24
86
87AU_ALIAS([ACX_PTHREAD], [AX_PTHREAD])
88AC_DEFUN([AX_PTHREAD], [
89AC_REQUIRE([AC_CANONICAL_HOST])
90AC_REQUIRE([AC_PROG_CC])
91AC_REQUIRE([AC_PROG_SED])
92AC_LANG_PUSH([C])
93ax_pthread_ok=no
94
95# We used to check for pthread.h first, but this fails if pthread.h
96# requires special compiler flags (e.g. on Tru64 or Sequent).
97# It gets checked for in the link test anyway.
98
99# First of all, check if the user has set any of the PTHREAD_LIBS,
100# etcetera environment variables, and if threads linking works using
101# them:
102if test "x$PTHREAD_CFLAGS$PTHREAD_LIBS" != "x"; then
103        ax_pthread_save_CC="$CC"
104        ax_pthread_save_CFLAGS="$CFLAGS"
105        ax_pthread_save_LIBS="$LIBS"
106        AS_IF([test "x$PTHREAD_CC" != "x"], [CC="$PTHREAD_CC"])
107        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
108        LIBS="$PTHREAD_LIBS $LIBS"
109        AC_MSG_CHECKING([for pthread_join using $CC $PTHREAD_CFLAGS $PTHREAD_LIBS])
110        AC_LINK_IFELSE([AC_LANG_CALL([], [pthread_join])], [ax_pthread_ok=yes])
111        AC_MSG_RESULT([$ax_pthread_ok])
112        if test "x$ax_pthread_ok" = "xno"; then
113                PTHREAD_LIBS=""
114                PTHREAD_CFLAGS=""
115        fi
116        CC="$ax_pthread_save_CC"
117        CFLAGS="$ax_pthread_save_CFLAGS"
118        LIBS="$ax_pthread_save_LIBS"
119fi
120
121# We must check for the threads library under a number of different
122# names; the ordering is very important because some systems
123# (e.g. DEC) have both -lpthread and -lpthreads, where one of the
124# libraries is broken (non-POSIX).
125
126# Create a list of thread flags to try.  Items starting with a "-" are
127# C compiler flags, and other items are library names, except for "none"
128# which indicates that we try without any flags at all, and "pthread-config"
129# which is a program returning the flags for the Pth emulation library.
130
131ax_pthread_flags="pthreads none -Kthread -pthread -pthreads -mthreads pthread --thread-safe -mt pthread-config"
132
133# The ordering *is* (sometimes) important.  Some notes on the
134# individual items follow:
135
136# pthreads: AIX (must check this before -lpthread)
137# none: in case threads are in libc; should be tried before -Kthread and
138#       other compiler flags to prevent continual compiler warnings
139# -Kthread: Sequent (threads in libc, but -Kthread needed for pthread.h)
140# -pthread: Linux/gcc (kernel threads), BSD/gcc (userland threads), Tru64
141#           (Note: HP C rejects this with "bad form for `-t' option")
142# -pthreads: Solaris/gcc (Note: HP C also rejects)
143# -mt: Sun Workshop C (may only link SunOS threads [-lthread], but it
144#      doesn't hurt to check since this sometimes defines pthreads and
145#      -D_REENTRANT too), HP C (must be checked before -lpthread, which
146#      is present but should not be used directly; and before -mthreads,
147#      because the compiler interprets this as "-mt" + "-hreads")
148# -mthreads: Mingw32/gcc, Lynx/gcc
149# pthread: Linux, etcetera
150# --thread-safe: KAI C++
151# pthread-config: use pthread-config program (for GNU Pth library)
152
153case $host_os in
154
155        freebsd*)
156
157        # -kthread: FreeBSD kernel threads (preferred to -pthread since SMP-able)
158        # lthread: LinuxThreads port on FreeBSD (also preferred to -pthread)
159
160        ax_pthread_flags="-kthread lthread $ax_pthread_flags"
161        ;;
162
163        hpux*)
164
165        # From the cc(1) man page: "[-mt] Sets various -D flags to enable
166        # multi-threading and also sets -lpthread."
167
168        ax_pthread_flags="-mt -pthread pthread $ax_pthread_flags"
169        ;;
170
171        openedition*)
172
173        # IBM z/OS requires a feature-test macro to be defined in order to
174        # enable POSIX threads at all, so give the user a hint if this is
175        # not set. (We don't define these ourselves, as they can affect
176        # other portions of the system API in unpredictable ways.)
177
178        AC_EGREP_CPP([AX_PTHREAD_ZOS_MISSING],
179            [
180#            if !defined(_OPEN_THREADS) && !defined(_UNIX03_THREADS)
181             AX_PTHREAD_ZOS_MISSING
182#            endif
183            ],
184            [AC_MSG_WARN([IBM z/OS requires -D_OPEN_THREADS or -D_UNIX03_THREADS to enable pthreads support.])])
185        ;;
186
187        solaris*)
188
189        # On Solaris (at least, for some versions), libc contains stubbed
190        # (non-functional) versions of the pthreads routines, so link-based
191        # tests will erroneously succeed. (N.B.: The stubs are missing
192        # pthread_cleanup_push, or rather a function called by this macro,
193        # so we could check for that, but who knows whether they'll stub
194        # that too in a future libc.)  So we'll check first for the
195        # standard Solaris way of linking pthreads (-mt -lpthread).
196
197        ax_pthread_flags="-mt,pthread pthread $ax_pthread_flags"
198        ;;
199esac
200
201# GCC generally uses -pthread, or -pthreads on some platforms (e.g. SPARC)
202
203AS_IF([test "x$GCC" = "xyes"],
204      [ax_pthread_flags="-pthread -pthreads $ax_pthread_flags"])
205
206# The presence of a feature test macro requesting re-entrant function
207# definitions is, on some systems, a strong hint that pthreads support is
208# correctly enabled
209
210case $host_os in
211        darwin* | hpux* | linux* | osf* | solaris*)
212        ax_pthread_check_macro="_REENTRANT"
213        ;;
214
215        aix*)
216        ax_pthread_check_macro="_THREAD_SAFE"
217        ;;
218
219        *)
220        ax_pthread_check_macro="--"
221        ;;
222esac
223AS_IF([test "x$ax_pthread_check_macro" = "x--"],
224      [ax_pthread_check_cond=0],
225      [ax_pthread_check_cond="!defined($ax_pthread_check_macro)"])
226
227# Are we compiling with Clang?
228
229AC_CACHE_CHECK([whether $CC is Clang],
230    [ax_cv_PTHREAD_CLANG],
231    [ax_cv_PTHREAD_CLANG=no
232     # Note that Autoconf sets GCC=yes for Clang as well as GCC
233     if test "x$GCC" = "xyes"; then
234        AC_EGREP_CPP([AX_PTHREAD_CC_IS_CLANG],
235            [/* Note: Clang 2.7 lacks __clang_[a-z]+__ */
236#            if defined(__clang__) && defined(__llvm__)
237             AX_PTHREAD_CC_IS_CLANG
238#            endif
239            ],
240            [ax_cv_PTHREAD_CLANG=yes])
241     fi
242    ])
243ax_pthread_clang="$ax_cv_PTHREAD_CLANG"
244
245ax_pthread_clang_warning=no
246
247# Clang needs special handling, because older versions handle the -pthread
248# option in a rather... idiosyncratic way
249
250if test "x$ax_pthread_clang" = "xyes"; then
251
252        # Clang takes -pthread; it has never supported any other flag
253
254        # (Note 1: This will need to be revisited if a system that Clang
255        # supports has POSIX threads in a separate library.  This tends not
256        # to be the way of modern systems, but it's conceivable.)
257
258        # (Note 2: On some systems, notably Darwin, -pthread is not needed
259        # to get POSIX threads support; the API is always present and
260        # active.  We could reasonably leave PTHREAD_CFLAGS empty.  But
261        # -pthread does define _REENTRANT, and while the Darwin headers
262        # ignore this macro, third-party headers might not.)
263
264        PTHREAD_CFLAGS="-pthread"
265        PTHREAD_LIBS=
266
267        ax_pthread_ok=yes
268
269        # However, older versions of Clang make a point of warning the user
270        # that, in an invocation where only linking and no compilation is
271        # taking place, the -pthread option has no effect ("argument unused
272        # during compilation").  They expect -pthread to be passed in only
273        # when source code is being compiled.
274        #
275        # Problem is, this is at odds with the way Automake and most other
276        # C build frameworks function, which is that the same flags used in
277        # compilation (CFLAGS) are also used in linking.  Many systems
278        # supported by AX_PTHREAD require exactly this for POSIX threads
279        # support, and in fact it is often not straightforward to specify a
280        # flag that is used only in the compilation phase and not in
281        # linking.  Such a scenario is extremely rare in practice.
282        #
283        # Even though use of the -pthread flag in linking would only print
284        # a warning, this can be a nuisance for well-run software projects
285        # that build with -Werror.  So if the active version of Clang has
286        # this misfeature, we search for an option to squash it.
287
288        AC_CACHE_CHECK([whether Clang needs flag to prevent "argument unused" warning when linking with -pthread],
289            [ax_cv_PTHREAD_CLANG_NO_WARN_FLAG],
290            [ax_cv_PTHREAD_CLANG_NO_WARN_FLAG=unknown
291             # Create an alternate version of $ac_link that compiles and
292             # links in two steps (.c -> .o, .o -> exe) instead of one
293             # (.c -> exe), because the warning occurs only in the second
294             # step
295             ax_pthread_save_ac_link="$ac_link"
296             ax_pthread_sed='s/conftest\.\$ac_ext/conftest.$ac_objext/g'
297             ax_pthread_link_step=`$as_echo "$ac_link" | sed "$ax_pthread_sed"`
298             ax_pthread_2step_ac_link="($ac_compile) && (echo ==== >&5) && ($ax_pthread_link_step)"
299             ax_pthread_save_CFLAGS="$CFLAGS"
300             for ax_pthread_try in '' -Qunused-arguments -Wno-unused-command-line-argument unknown; do
301                AS_IF([test "x$ax_pthread_try" = "xunknown"], [break])
302                CFLAGS="-Werror -Wunknown-warning-option $ax_pthread_try -pthread $ax_pthread_save_CFLAGS"
303                ac_link="$ax_pthread_save_ac_link"
304                AC_LINK_IFELSE([AC_LANG_SOURCE([[int main(void){return 0;}]])],
305                    [ac_link="$ax_pthread_2step_ac_link"
306                     AC_LINK_IFELSE([AC_LANG_SOURCE([[int main(void){return 0;}]])],
307                         [break])
308                    ])
309             done
310             ac_link="$ax_pthread_save_ac_link"
311             CFLAGS="$ax_pthread_save_CFLAGS"
312             AS_IF([test "x$ax_pthread_try" = "x"], [ax_pthread_try=no])
313             ax_cv_PTHREAD_CLANG_NO_WARN_FLAG="$ax_pthread_try"
314            ])
315
316        case "$ax_cv_PTHREAD_CLANG_NO_WARN_FLAG" in
317                no | unknown) ;;
318                *) PTHREAD_CFLAGS="$ax_cv_PTHREAD_CLANG_NO_WARN_FLAG $PTHREAD_CFLAGS" ;;
319        esac
320
321fi # $ax_pthread_clang = yes
322
323if test "x$ax_pthread_ok" = "xno"; then
324for ax_pthread_try_flag in $ax_pthread_flags; do
325
326        case $ax_pthread_try_flag in
327                none)
328                AC_MSG_CHECKING([whether pthreads work without any flags])
329                ;;
330
331                -mt,pthread)
332                AC_MSG_CHECKING([whether pthreads work with -mt -lpthread])
333                PTHREAD_CFLAGS="-mt"
334                PTHREAD_LIBS="-lpthread"
335                ;;
336
337                -*)
338                AC_MSG_CHECKING([whether pthreads work with $ax_pthread_try_flag])
339                PTHREAD_CFLAGS="$ax_pthread_try_flag"
340                ;;
341
342                pthread-config)
343                AC_CHECK_PROG([ax_pthread_config], [pthread-config], [yes], [no])
344                AS_IF([test "x$ax_pthread_config" = "xno"], [continue])
345                PTHREAD_CFLAGS="`pthread-config --cflags`"
346                PTHREAD_LIBS="`pthread-config --ldflags` `pthread-config --libs`"
347                ;;
348
349                *)
350                AC_MSG_CHECKING([for the pthreads library -l$ax_pthread_try_flag])
351                PTHREAD_LIBS="-l$ax_pthread_try_flag"
352                ;;
353        esac
354
355        ax_pthread_save_CFLAGS="$CFLAGS"
356        ax_pthread_save_LIBS="$LIBS"
357        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
358        LIBS="$PTHREAD_LIBS $LIBS"
359
360        # Check for various functions.  We must include pthread.h,
361        # since some functions may be macros.  (On the Sequent, we
362        # need a special flag -Kthread to make this header compile.)
363        # We check for pthread_join because it is in -lpthread on IRIX
364        # while pthread_create is in libc.  We check for pthread_attr_init
365        # due to DEC craziness with -lpthreads.  We check for
366        # pthread_cleanup_push because it is one of the few pthread
367        # functions on Solaris that doesn't have a non-functional libc stub.
368        # We try pthread_create on general principles.
369
370        AC_LINK_IFELSE([AC_LANG_PROGRAM([#include <pthread.h>
371#                       if $ax_pthread_check_cond
372#                        error "$ax_pthread_check_macro must be defined"
373#                       endif
374                        static void routine(void *a) { a = 0; }
375                        static void *start_routine(void *a) { return a; }],
376                       [pthread_t th; pthread_attr_t attr;
377                        pthread_create(&th, 0, start_routine, 0);
378                        pthread_join(th, 0);
379                        pthread_attr_init(&attr);
380                        pthread_cleanup_push(routine, 0);
381                        pthread_cleanup_pop(0) /* ; */])],
382            [ax_pthread_ok=yes],
383            [])
384
385        CFLAGS="$ax_pthread_save_CFLAGS"
386        LIBS="$ax_pthread_save_LIBS"
387
388        AC_MSG_RESULT([$ax_pthread_ok])
389        AS_IF([test "x$ax_pthread_ok" = "xyes"], [break])
390
391        PTHREAD_LIBS=""
392        PTHREAD_CFLAGS=""
393done
394fi
395
396# Various other checks:
397if test "x$ax_pthread_ok" = "xyes"; then
398        ax_pthread_save_CFLAGS="$CFLAGS"
399        ax_pthread_save_LIBS="$LIBS"
400        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
401        LIBS="$PTHREAD_LIBS $LIBS"
402
403        # Detect AIX lossage: JOINABLE attribute is called UNDETACHED.
404        AC_CACHE_CHECK([for joinable pthread attribute],
405            [ax_cv_PTHREAD_JOINABLE_ATTR],
406            [ax_cv_PTHREAD_JOINABLE_ATTR=unknown
407             for ax_pthread_attr in PTHREAD_CREATE_JOINABLE PTHREAD_CREATE_UNDETACHED; do
408                 AC_LINK_IFELSE([AC_LANG_PROGRAM([#include <pthread.h>],
409                                                 [int attr = $ax_pthread_attr; return attr /* ; */])],
410                                [ax_cv_PTHREAD_JOINABLE_ATTR=$ax_pthread_attr; break],
411                                [])
412             done
413            ])
414        AS_IF([test "x$ax_cv_PTHREAD_JOINABLE_ATTR" != "xunknown" && \
415               test "x$ax_cv_PTHREAD_JOINABLE_ATTR" != "xPTHREAD_CREATE_JOINABLE" && \
416               test "x$ax_pthread_joinable_attr_defined" != "xyes"],
417              [AC_DEFINE_UNQUOTED([PTHREAD_CREATE_JOINABLE],
418                                  [$ax_cv_PTHREAD_JOINABLE_ATTR],
419                                  [Define to necessary symbol if this constant
420                                   uses a non-standard name on your system.])
421               ax_pthread_joinable_attr_defined=yes
422              ])
423
424        AC_CACHE_CHECK([whether more special flags are required for pthreads],
425            [ax_cv_PTHREAD_SPECIAL_FLAGS],
426            [ax_cv_PTHREAD_SPECIAL_FLAGS=no
427             case $host_os in
428             solaris*)
429             ax_cv_PTHREAD_SPECIAL_FLAGS="-D_POSIX_PTHREAD_SEMANTICS"
430             ;;
431             esac
432            ])
433        AS_IF([test "x$ax_cv_PTHREAD_SPECIAL_FLAGS" != "xno" && \
434               test "x$ax_pthread_special_flags_added" != "xyes"],
435              [PTHREAD_CFLAGS="$ax_cv_PTHREAD_SPECIAL_FLAGS $PTHREAD_CFLAGS"
436               ax_pthread_special_flags_added=yes])
437
438        AC_CACHE_CHECK([for PTHREAD_PRIO_INHERIT],
439            [ax_cv_PTHREAD_PRIO_INHERIT],
440            [AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include <pthread.h>]],
441                                             [[int i = PTHREAD_PRIO_INHERIT;]])],
442                            [ax_cv_PTHREAD_PRIO_INHERIT=yes],
443                            [ax_cv_PTHREAD_PRIO_INHERIT=no])
444            ])
445        AS_IF([test "x$ax_cv_PTHREAD_PRIO_INHERIT" = "xyes" && \
446               test "x$ax_pthread_prio_inherit_defined" != "xyes"],
447              [AC_DEFINE([HAVE_PTHREAD_PRIO_INHERIT], [1], [Have PTHREAD_PRIO_INHERIT.])
448               ax_pthread_prio_inherit_defined=yes
449              ])
450
451        CFLAGS="$ax_pthread_save_CFLAGS"
452        LIBS="$ax_pthread_save_LIBS"
453
454        # More AIX lossage: compile with *_r variant
455        if test "x$GCC" != "xyes"; then
456            case $host_os in
457                aix*)
458                AS_CASE(["x/$CC"],
459                    [x*/c89|x*/c89_128|x*/c99|x*/c99_128|x*/cc|x*/cc128|x*/xlc|x*/xlc_v6|x*/xlc128|x*/xlc128_v6],
460                    [#handle absolute path differently from PATH based program lookup
461                     AS_CASE(["x$CC"],
462                         [x/*],
463                         [AS_IF([AS_EXECUTABLE_P([${CC}_r])],[PTHREAD_CC="${CC}_r"])],
464                         [AC_CHECK_PROGS([PTHREAD_CC],[${CC}_r],[$CC])])])
465                ;;
466            esac
467        fi
468fi
469
470test -n "$PTHREAD_CC" || PTHREAD_CC="$CC"
471
472AC_SUBST([PTHREAD_LIBS])
473AC_SUBST([PTHREAD_CFLAGS])
474AC_SUBST([PTHREAD_CC])
475
476# Finally, execute ACTION-IF-FOUND/ACTION-IF-NOT-FOUND:
477if test "x$ax_pthread_ok" = "xyes"; then
478        ifelse([$1],,[AC_DEFINE([HAVE_PTHREAD],[1],[Define if you have POSIX threads libraries and header files.])],[$1])
479        :
480else
481        ax_pthread_ok=no
482        $2
483fi
484AC_LANG_POP
485])dnl AX_PTHREAD
486