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# ===========================================================================
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# http://www.gnu.org/software/autoconf-archive/ax_pthread.html
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# ===========================================================================
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# AX_PTHREAD([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])
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# This macro figures out how to build C programs using POSIX threads. It
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# sets the PTHREAD_LIBS output variable to the threads library and linker
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# flags, and the PTHREAD_CFLAGS output variable to any special C compiler
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# flags that are needed. (The user can also force certain compiler
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# flags/libs to be tested by setting these environment variables.)
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# Also sets PTHREAD_CC to any special C compiler that is needed for
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# multi-threaded programs (defaults to the value of CC otherwise). (This
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# is necessary on AIX to use the special cc_r compiler alias.)
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# NOTE: You are assumed to not only compile your program with these flags,
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# but also link it with them as well. e.g. you should link with
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# $PTHREAD_CC $CFLAGS $PTHREAD_CFLAGS $LDFLAGS ... $PTHREAD_LIBS $LIBS
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# If you are only building threads programs, you may wish to use these
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# variables in your default LIBS, CFLAGS, and CC:
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# LIBS="$PTHREAD_LIBS $LIBS"
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# CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
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# In addition, if the PTHREAD_CREATE_JOINABLE thread-attribute constant
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# has a nonstandard name, defines PTHREAD_CREATE_JOINABLE to that name
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# (e.g. PTHREAD_CREATE_UNDETACHED on AIX).
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# ACTION-IF-FOUND is a list of shell commands to run if a threads library
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# is found, and ACTION-IF-NOT-FOUND is a list of commands to run it if it
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# is not found. If ACTION-IF-FOUND is not specified, the default action
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# will define HAVE_PTHREAD.
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# Please let the authors know if this macro fails on any platform, or if
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# you have any other suggestions or comments. This macro was based on work
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# by SGJ on autoconf scripts for FFTW (http://www.fftw.org/) (with help
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# from M. Frigo), as well as ac_pthread and hb_pthread macros posted by
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# Alejandro Forero Cuervo to the autoconf macro repository. We are also
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# grateful for the helpful feedback of numerous users.
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# Copyright (c) 2008 Steven G. Johnson <stevenj@alum.mit.edu>
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# This program is free software: you can redistribute it and/or modify it
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# under the terms of the GNU General Public License as published by the
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# Free Software Foundation, either version 3 of the License, or (at your
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# option) any later version.
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
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# Public License for more details.
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# You should have received a copy of the GNU General Public License along
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# with this program. If not, see <http://www.gnu.org/licenses/>.
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# As a special exception, the respective Autoconf Macro's copyright owner
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# gives unlimited permission to copy, distribute and modify the configure
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# scripts that are the output of Autoconf when processing the Macro. You
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# need not follow the terms of the GNU General Public License when using
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# or distributing such scripts, even though portions of the text of the
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# Macro appear in them. The GNU General Public License (GPL) does govern
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# all other use of the material that constitutes the Autoconf Macro.
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# This special exception to the GPL applies to versions of the Autoconf
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# Macro released by the Autoconf Archive. When you make and distribute a
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# modified version of the Autoconf Macro, you may extend this special
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# exception to the GPL to apply to your modified version as well.
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AU_ALIAS([ACX_PTHREAD], [AX_PTHREAD])
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AC_DEFUN([AX_PTHREAD], [
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AC_REQUIRE([AC_CANONICAL_HOST])
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# We used to check for pthread.h first, but this fails if pthread.h
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# requires special compiler flags (e.g. on True64 or Sequent).
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# It gets checked for in the link test anyway.
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# First of all, check if the user has set any of the PTHREAD_LIBS,
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# etcetera environment variables, and if threads linking works using
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if test x"$PTHREAD_LIBS$PTHREAD_CFLAGS" != x; then
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CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
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LIBS="$PTHREAD_LIBS $LIBS"
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AC_MSG_CHECKING([for pthread_join in LIBS=$PTHREAD_LIBS with CFLAGS=$PTHREAD_CFLAGS])
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AC_TRY_LINK_FUNC(pthread_join, ax_pthread_ok=yes)
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AC_MSG_RESULT($ax_pthread_ok)
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if test x"$ax_pthread_ok" = xno; then
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CFLAGS="$save_CFLAGS"
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# We must check for the threads library under a number of different
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# names; the ordering is very important because some systems
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# (e.g. DEC) have both -lpthread and -lpthreads, where one of the
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# libraries is broken (non-POSIX).
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# Create a list of thread flags to try. Items starting with a "-" are
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# C compiler flags, and other items are library names, except for "none"
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# which indicates that we try without any flags at all, and "pthread-config"
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# which is a program returning the flags for the Pth emulation library.
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ax_pthread_flags="pthreads none -Kthread -kthread lthread -pthread -pthreads -mthreads pthread --thread-safe -mt pthread-config"
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# The ordering *is* (sometimes) important. Some notes on the
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# individual items follow:
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# pthreads: AIX (must check this before -lpthread)
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# none: in case threads are in libc; should be tried before -Kthread and
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# other compiler flags to prevent continual compiler warnings
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# -Kthread: Sequent (threads in libc, but -Kthread needed for pthread.h)
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# -kthread: FreeBSD kernel threads (preferred to -pthread since SMP-able)
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# lthread: LinuxThreads port on FreeBSD (also preferred to -pthread)
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# -pthread: Linux/gcc (kernel threads), BSD/gcc (userland threads)
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# -pthreads: Solaris/gcc
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# -mthreads: Mingw32/gcc, Lynx/gcc
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# -mt: Sun Workshop C (may only link SunOS threads [-lthread], but it
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# doesn't hurt to check since this sometimes defines pthreads too;
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# also defines -D_REENTRANT)
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# ... -mt is also the pthreads flag for HP/aCC
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# pthread: Linux, etcetera
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# --thread-safe: KAI C++
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# pthread-config: use pthread-config program (for GNU Pth library)
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case "${host_cpu}-${host_os}" in
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# On Solaris (at least, for some versions), libc contains stubbed
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# (non-functional) versions of the pthreads routines, so link-based
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# tests will erroneously succeed. (We need to link with -pthreads/-mt/
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# -lpthread.) (The stubs are missing pthread_cleanup_push, or rather
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# a function called by this macro, so we could check for that, but
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# who knows whether they'll stub that too in a future libc.) So,
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# we'll just look for -pthreads and -lpthread first:
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ax_pthread_flags="-pthreads pthread -mt -pthread $ax_pthread_flags"
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acx_pthread_flags="-pthread $acx_pthread_flags"
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if test x"$ax_pthread_ok" = xno; then
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for flag in $ax_pthread_flags; do
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AC_MSG_CHECKING([whether pthreads work without any flags])
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AC_MSG_CHECKING([whether pthreads work with $flag])
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PTHREAD_CFLAGS="$flag"
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AC_CHECK_PROG(ax_pthread_config, pthread-config, yes, no)
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if test x"$ax_pthread_config" = xno; then continue; fi
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PTHREAD_CFLAGS="`pthread-config --cflags`"
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PTHREAD_LIBS="`pthread-config --ldflags` `pthread-config --libs`"
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AC_MSG_CHECKING([for the pthreads library -l$flag])
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PTHREAD_LIBS="-l$flag"
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save_CFLAGS="$CFLAGS"
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LIBS="$PTHREAD_LIBS $LIBS"
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CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
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# Check for various functions. We must include pthread.h,
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# since some functions may be macros. (On the Sequent, we
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# need a special flag -Kthread to make this header compile.)
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# We check for pthread_join because it is in -lpthread on IRIX
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# while pthread_create is in libc. We check for pthread_attr_init
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# due to DEC craziness with -lpthreads. We check for
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# pthread_cleanup_push because it is one of the few pthread
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# functions on Solaris that doesn't have a non-functional libc stub.
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# We try pthread_create on general principles.
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AC_TRY_LINK([#include <pthread.h>
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static void routine(void* a) {a=0;}
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static void* start_routine(void* a) {return a;}],
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[pthread_t th; pthread_attr_t attr;
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pthread_attr_init(&attr);
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pthread_cleanup_push(routine, 0);
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pthread_create(&th,0,start_routine,0);
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pthread_cleanup_pop(0); ],
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CFLAGS="$save_CFLAGS"
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AC_MSG_RESULT($ax_pthread_ok)
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if test "x$ax_pthread_ok" = xyes; then
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# Various other checks:
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if test "x$ax_pthread_ok" = xyes; then
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LIBS="$PTHREAD_LIBS $LIBS"
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save_CFLAGS="$CFLAGS"
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CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
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# Detect AIX lossage: JOINABLE attribute is called UNDETACHED.
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AC_MSG_CHECKING([for joinable pthread attribute])
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for attr in PTHREAD_CREATE_JOINABLE PTHREAD_CREATE_UNDETACHED; do
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AC_TRY_LINK([#include <pthread.h>], [int attr=$attr; return attr;],
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[attr_name=$attr; break])
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AC_MSG_RESULT($attr_name)
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if test "$attr_name" != PTHREAD_CREATE_JOINABLE; then
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AC_DEFINE_UNQUOTED(PTHREAD_CREATE_JOINABLE, $attr_name,
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[Define to necessary symbol if this constant
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uses a non-standard name on your system.])
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AC_MSG_CHECKING([if more special flags are required for pthreads])
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case "${host_cpu}-${host_os}" in
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*-aix* | *-freebsd* | *-darwin*) flag="-D_THREAD_SAFE";;
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*solaris* | *-osf* | *-hpux*) flag="-D_REENTRANT";;
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AC_MSG_RESULT(${flag})
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if test "x$flag" != xno; then
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PTHREAD_CFLAGS="$flag $PTHREAD_CFLAGS"
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CFLAGS="$save_CFLAGS"
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# More AIX lossage: must compile with xlc_r or cc_r
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if test x"$GCC" != xyes; then
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AC_CHECK_PROGS(PTHREAD_CC, xlc_r cc_r, ${CC})
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AC_SUBST(PTHREAD_LIBS)
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AC_SUBST(PTHREAD_CFLAGS)
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# Finally, execute ACTION-IF-FOUND/ACTION-IF-NOT-FOUND:
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if test x"$ax_pthread_ok" = xyes; then
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ifelse([$1],,AC_DEFINE(HAVE_PTHREAD,1,[Define if you have POSIX threads libraries and header files.]),[$1])
added
removed
m4/ax_pthread.m4
