Fix: update ax_pthread macro to handle newer clang
[urcu.git] / m4 / ax_pthread.m4
1 # ===========================================================================
2 # http://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 <http://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 23
86
87 AU_ALIAS([ACX_PTHREAD], [AX_PTHREAD])
88 AC_DEFUN([AX_PTHREAD], [
89 AC_REQUIRE([AC_CANONICAL_HOST])
90 AC_REQUIRE([AC_PROG_CC])
91 AC_REQUIRE([AC_PROG_SED])
92 AC_LANG_PUSH([C])
93 ax_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:
102 if 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"
119 fi
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
131 ax_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
153 case $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 $ax_pthread_flags"
198 ;;
199 esac
200
201 # GCC generally uses -pthread, or -pthreads on some platforms (e.g. SPARC)
202
203 AS_IF([test "x$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
210 case $host_os in
211 darwin* | hpux* | linux* | osf* | solaris*)
212 ax_pthread_check_macro="_REENTRANT"
213 ;;
214
215 aix*)
216 ax_pthread_check_macro="_THREAD_SAFE"
217 ;;
218
219 *)
220 ax_pthread_check_macro="--"
221 ;;
222 esac
223 AS_IF([test "x$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
229 AC_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 ])
243 ax_pthread_clang="$ax_cv_PTHREAD_CLANG"
244
245 ax_pthread_clang_warning=no
246
247 # Clang needs special handling, because older versions handle the -pthread
248 # option in a rather... idiosyncratic way
249
250 if test "x$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
321 fi # $ax_pthread_clang = yes
322
323 if test "x$ax_pthread_ok" = "xno"; then
324 for 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=""
393 done
394 fi
395
396 # Various other checks:
397 if 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],[$CC])])])
465 ;;
466 esac
467 fi
468 fi
469
470 test -n "$PTHREAD_CC" || PTHREAD_CC="$CC"
471
472 AC_SUBST([PTHREAD_LIBS])
473 AC_SUBST([PTHREAD_CFLAGS])
474 AC_SUBST([PTHREAD_CC])
475
476 # Finally, execute ACTION-IF-FOUND/ACTION-IF-NOT-FOUND:
477 if test "x$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 :
480 else
481 ax_pthread_ok=no
482 $2
483 fi
484 AC_LANG_POP
485 ])dnl AX_PTHREAD
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