Add ax_pthread.m4 for use in binutils-gdb

Message ID 20180323024534.21170-1-JPEWhacker@gmail.com
State New
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Series
  • Add ax_pthread.m4 for use in binutils-gdb
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Commit Message

Joshua Watt March 23, 2018, 2:45 a.m.
config/
	* ax_pthread.m4: Add file
---
 config/ax_pthread.m4 | 485 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 485 insertions(+)
 create mode 100644 config/ax_pthread.m4

-- 
2.14.3

Comments

Joshua Watt April 17, 2018, 5:24 p.m. | #1
On Thu, 2018-03-22 at 21:45 -0500, Joshua Watt wrote:
> config/

> 	* ax_pthread.m4: Add file

> ---

>  config/ax_pthread.m4 | 485

> +++++++++++++++++++++++++++++++++++++++++++++++++++

>  1 file changed, 485 insertions(+)

>  create mode 100644 config/ax_pthread.m4

> 

> diff --git a/config/ax_pthread.m4 b/config/ax_pthread.m4

> new file mode 100644

> index 00000000000..5fbf9fe0d68

> --- /dev/null

> +++ b/config/ax_pthread.m4

> @@ -0,0 +1,485 @@

> +#

> =====================================================================

> ======

> +#        https://www.gnu.org/software/autoconf-archive/ax_pthread.ht

> ml

> +#

> =====================================================================

> ======

> +#

> +# SYNOPSIS

> +#

> +#   AX_PTHREAD([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])

> +#

> +# DESCRIPTION

> +#

> +#   This macro figures out how to build C programs using POSIX

> threads. It

> +#   sets the PTHREAD_LIBS output variable to the threads library and

> linker

> +#   flags, and the PTHREAD_CFLAGS output variable to any special C

> compiler

> +#   flags that are needed. (The user can also force certain compiler

> +#   flags/libs to be tested by setting these environment variables.)

> +#

> +#   Also sets PTHREAD_CC to any special C compiler that is needed

> for

> +#   multi-threaded programs (defaults to the value of CC otherwise).

> (This

> +#   is necessary on AIX to use the special cc_r compiler alias.)

> +#

> +#   NOTE: You are assumed to not only compile your program with

> these flags,

> +#   but also to link with them as well. For example, you might link

> with

> +#   $PTHREAD_CC $CFLAGS $PTHREAD_CFLAGS $LDFLAGS ... $PTHREAD_LIBS

> $LIBS

> +#

> +#   If you are only building threaded programs, you may wish to use

> these

> +#   variables in your default LIBS, CFLAGS, and CC:

> +#

> +#     LIBS="$PTHREAD_LIBS $LIBS"

> +#     CFLAGS="$CFLAGS $PTHREAD_CFLAGS"

> +#     CC="$PTHREAD_CC"

> +#

> +#   In addition, if the PTHREAD_CREATE_JOINABLE thread-attribute

> constant

> +#   has a nonstandard name, this macro defines

> PTHREAD_CREATE_JOINABLE to

> +#   that name (e.g. PTHREAD_CREATE_UNDETACHED on AIX).

> +#

> +#   Also HAVE_PTHREAD_PRIO_INHERIT is defined if pthread is found

> and the

> +#   PTHREAD_PRIO_INHERIT symbol is defined when compiling with

> +#   PTHREAD_CFLAGS.

> +#

> +#   ACTION-IF-FOUND is a list of shell commands to run if a threads

> library

> +#   is found, and ACTION-IF-NOT-FOUND is a list of commands to run

> it if it

> +#   is not found. If ACTION-IF-FOUND is not specified, the default

> action

> +#   will define HAVE_PTHREAD.

> +#

> +#   Please let the authors know if this macro fails on any platform,

> or if

> +#   you have any other suggestions or comments. This macro was based

> on work

> +#   by SGJ on autoconf scripts for FFTW (http://www.fftw.org/) (with

> help

> +#   from M. Frigo), as well as ac_pthread and hb_pthread macros

> posted by

> +#   Alejandro Forero Cuervo to the autoconf macro repository. We are

> also

> +#   grateful for the helpful feedback of numerous users.

> +#

> +#   Updated for Autoconf 2.68 by Daniel Richard G.

> +#

> +# LICENSE

> +#

> +#   Copyright (c) 2008 Steven G. Johnson <stevenj@alum.mit.edu>

> +#   Copyright (c) 2011 Daniel Richard G. <skunk@iSKUNK.ORG>

> +#

> +#   This program is free software: you can redistribute it and/or

> modify it

> +#   under the terms of the GNU General Public License as published

> by the

> +#   Free Software Foundation, either version 3 of the License, or

> (at your

> +#   option) any later version.

> +#

> +#   This program is distributed in the hope that it will be useful,

> but

> +#   WITHOUT ANY WARRANTY; without even the implied warranty of

> +#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

> General

> +#   Public License for more details.

> +#

> +#   You should have received a copy of the GNU General Public

> License along

> +#   with this program. If not, see <https://www.gnu.org/licenses/>.

> +#

> +#   As a special exception, the respective Autoconf Macro's

> copyright owner

> +#   gives unlimited permission to copy, distribute and modify the

> configure

> +#   scripts that are the output of Autoconf when processing the

> Macro. You

> +#   need not follow the terms of the GNU General Public License when

> using

> +#   or distributing such scripts, even though portions of the text

> of the

> +#   Macro appear in them. The GNU General Public License (GPL) does

> govern

> +#   all other use of the material that constitutes the Autoconf

> Macro.

> +#

> +#   This special exception to the GPL applies to versions of the

> Autoconf

> +#   Macro released by the Autoconf Archive. When you make and

> distribute a

> +#   modified version of the Autoconf Macro, you may extend this

> special

> +#   exception to the GPL to apply to your modified version as well.

> +

> +#serial 24

> +

> +AU_ALIAS([ACX_PTHREAD], [AX_PTHREAD])

> +AC_DEFUN([AX_PTHREAD], [

> +AC_REQUIRE([AC_CANONICAL_HOST])

> +AC_REQUIRE([AC_PROG_CC])

> +AC_REQUIRE([AC_PROG_SED])

> +AC_LANG_PUSH([C])

> +ax_pthread_ok=no

> +

> +# We used to check for pthread.h first, but this fails if pthread.h

> +# requires special compiler flags (e.g. on Tru64 or Sequent).

> +# It gets checked for in the link test anyway.

> +

> +# First of all, check if the user has set any of the PTHREAD_LIBS,

> +# etcetera environment variables, and if threads linking works using

> +# them:

> +if test "x$PTHREAD_CFLAGS$PTHREAD_LIBS" != "x"; then

> +        ax_pthread_save_CC="$CC"

> +        ax_pthread_save_CFLAGS="$CFLAGS"

> +        ax_pthread_save_LIBS="$LIBS"

> +        AS_IF([test "x$PTHREAD_CC" != "x"], [CC="$PTHREAD_CC"])

> +        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"

> +        LIBS="$PTHREAD_LIBS $LIBS"

> +        AC_MSG_CHECKING([for pthread_join using $CC $PTHREAD_CFLAGS

> $PTHREAD_LIBS])

> +        AC_LINK_IFELSE([AC_LANG_CALL([], [pthread_join])],

> [ax_pthread_ok=yes])

> +        AC_MSG_RESULT([$ax_pthread_ok])

> +        if test "x$ax_pthread_ok" = "xno"; then

> +                PTHREAD_LIBS=""

> +                PTHREAD_CFLAGS=""

> +        fi

> +        CC="$ax_pthread_save_CC"

> +        CFLAGS="$ax_pthread_save_CFLAGS"

> +        LIBS="$ax_pthread_save_LIBS"

> +fi

> +

> +# We must check for the threads library under a number of different

> +# names; the ordering is very important because some systems

> +# (e.g. DEC) have both -lpthread and -lpthreads, where one of the

> +# libraries is broken (non-POSIX).

> +

> +# Create a list of thread flags to try.  Items starting with a "-"

> are

> +# C compiler flags, and other items are library names, except for

> "none"

> +# which indicates that we try without any flags at all, and

> "pthread-config"

> +# which is a program returning the flags for the Pth emulation

> library.

> +

> +ax_pthread_flags="pthreads none -Kthread -pthread -pthreads

> -mthreads pthread --thread-safe -mt pthread-config"

> +

> +# The ordering *is* (sometimes) important.  Some notes on the

> +# individual items follow:

> +

> +# pthreads: AIX (must check this before -lpthread)

> +# none: in case threads are in libc; should be tried before -Kthread

> and

> +#       other compiler flags to prevent continual compiler warnings

> +# -Kthread: Sequent (threads in libc, but -Kthread needed for

> pthread.h)

> +# -pthread: Linux/gcc (kernel threads), BSD/gcc (userland threads),

> Tru64

> +#           (Note: HP C rejects this with "bad form for `-t'

> option")

> +# -pthreads: Solaris/gcc (Note: HP C also rejects)

> +# -mt: Sun Workshop C (may only link SunOS threads [-lthread], but

> it

> +#      doesn't hurt to check since this sometimes defines pthreads

> and

> +#      -D_REENTRANT too), HP C (must be checked before -lpthread,

> which

> +#      is present but should not be used directly; and before

> -mthreads,

> +#      because the compiler interprets this as "-mt" + "-hreads")

> +# -mthreads: Mingw32/gcc, Lynx/gcc

> +# pthread: Linux, etcetera

> +# --thread-safe: KAI C++

> +# pthread-config: use pthread-config program (for GNU Pth library)

> +

> +case $host_os in

> +

> +        freebsd*)

> +

> +        # -kthread: FreeBSD kernel threads (preferred to -pthread

> since SMP-able)

> +        # lthread: LinuxThreads port on FreeBSD (also preferred to

> -pthread)

> +

> +        ax_pthread_flags="-kthread lthread $ax_pthread_flags"

> +        ;;

> +

> +        hpux*)

> +

> +        # From the cc(1) man page: "[-mt] Sets various -D flags to

> enable

> +        # multi-threading and also sets -lpthread."

> +

> +        ax_pthread_flags="-mt -pthread pthread $ax_pthread_flags"

> +        ;;

> +

> +        openedition*)

> +

> +        # IBM z/OS requires a feature-test macro to be defined in

> order to

> +        # enable POSIX threads at all, so give the user a hint if

> this is

> +        # not set. (We don't define these ourselves, as they can

> affect

> +        # other portions of the system API in unpredictable ways.)

> +

> +        AC_EGREP_CPP([AX_PTHREAD_ZOS_MISSING],

> +            [

> +#            if !defined(_OPEN_THREADS) && !defined(_UNIX03_THREADS)

> +             AX_PTHREAD_ZOS_MISSING

> +#            endif

> +            ],

> +            [AC_MSG_WARN([IBM z/OS requires -D_OPEN_THREADS or

> -D_UNIX03_THREADS to enable pthreads support.])])

> +        ;;

> +

> +        solaris*)

> +

> +        # On Solaris (at least, for some versions), libc contains

> stubbed

> +        # (non-functional) versions of the pthreads routines, so

> link-based

> +        # tests will erroneously succeed. (N.B.: The stubs are

> missing

> +        # pthread_cleanup_push, or rather a function called by this

> macro,

> +        # so we could check for that, but who knows whether they'll

> stub

> +        # that too in a future libc.)  So we'll check first for the

> +        # standard Solaris way of linking pthreads (-mt -lpthread).

> +

> +        ax_pthread_flags="-mt,pthread pthread $ax_pthread_flags"

> +        ;;

> +esac

> +

> +# GCC generally uses -pthread, or -pthreads on some platforms (e.g.

> SPARC)

> +

> +AS_IF([test "x$GCC" = "xyes"],

> +      [ax_pthread_flags="-pthread -pthreads $ax_pthread_flags"])

> +

> +# The presence of a feature test macro requesting re-entrant

> function

> +# definitions is, on some systems, a strong hint that pthreads

> support is

> +# correctly enabled

> +

> +case $host_os in

> +        darwin* | hpux* | linux* | osf* | solaris*)

> +        ax_pthread_check_macro="_REENTRANT"

> +        ;;

> +

> +        aix*)

> +        ax_pthread_check_macro="_THREAD_SAFE"

> +        ;;

> +

> +        *)

> +        ax_pthread_check_macro="--"

> +        ;;

> +esac

> +AS_IF([test "x$ax_pthread_check_macro" = "x--"],

> +      [ax_pthread_check_cond=0],

> +      [ax_pthread_check_cond="!defined($ax_pthread_check_macro)"])

> +

> +# Are we compiling with Clang?

> +

> +AC_CACHE_CHECK([whether $CC is Clang],

> +    [ax_cv_PTHREAD_CLANG],

> +    [ax_cv_PTHREAD_CLANG=no

> +     # Note that Autoconf sets GCC=yes for Clang as well as GCC

> +     if test "x$GCC" = "xyes"; then

> +        AC_EGREP_CPP([AX_PTHREAD_CC_IS_CLANG],

> +            [/* Note: Clang 2.7 lacks __clang_[a-z]+__ */

> +#            if defined(__clang__) && defined(__llvm__)

> +             AX_PTHREAD_CC_IS_CLANG

> +#            endif

> +            ],

> +            [ax_cv_PTHREAD_CLANG=yes])

> +     fi

> +    ])

> +ax_pthread_clang="$ax_cv_PTHREAD_CLANG"

> +

> +ax_pthread_clang_warning=no

> +

> +# Clang needs special handling, because older versions handle the

> -pthread

> +# option in a rather... idiosyncratic way

> +

> +if test "x$ax_pthread_clang" = "xyes"; then

> +

> +        # Clang takes -pthread; it has never supported any other

> flag

> +

> +        # (Note 1: This will need to be revisited if a system that

> Clang

> +        # supports has POSIX threads in a separate library.  This

> tends not

> +        # to be the way of modern systems, but it's conceivable.)

> +

> +        # (Note 2: On some systems, notably Darwin, -pthread is not

> needed

> +        # to get POSIX threads support; the API is always present

> and

> +        # active.  We could reasonably leave PTHREAD_CFLAGS

> empty.  But

> +        # -pthread does define _REENTRANT, and while the Darwin

> headers

> +        # ignore this macro, third-party headers might not.)

> +

> +        PTHREAD_CFLAGS="-pthread"

> +        PTHREAD_LIBS=

> +

> +        ax_pthread_ok=yes

> +

> +        # However, older versions of Clang make a point of warning

> the user

> +        # that, in an invocation where only linking and no

> compilation is

> +        # taking place, the -pthread option has no effect ("argument

> unused

> +        # during compilation").  They expect -pthread to be passed

> in only

> +        # when source code is being compiled.

> +        #

> +        # Problem is, this is at odds with the way Automake and most

> other

> +        # C build frameworks function, which is that the same flags

> used in

> +        # compilation (CFLAGS) are also used in linking.  Many

> systems

> +        # supported by AX_PTHREAD require exactly this for POSIX

> threads

> +        # support, and in fact it is often not straightforward to

> specify a

> +        # flag that is used only in the compilation phase and not in

> +        # linking.  Such a scenario is extremely rare in practice.

> +        #

> +        # Even though use of the -pthread flag in linking would only

> print

> +        # a warning, this can be a nuisance for well-run software

> projects

> +        # that build with -Werror.  So if the active version of

> Clang has

> +        # this misfeature, we search for an option to squash it.

> +

> +        AC_CACHE_CHECK([whether Clang needs flag to prevent

> "argument unused" warning when linking with -pthread],

> +            [ax_cv_PTHREAD_CLANG_NO_WARN_FLAG],

> +            [ax_cv_PTHREAD_CLANG_NO_WARN_FLAG=unknown

> +             # Create an alternate version of $ac_link that compiles

> and

> +             # links in two steps (.c -> .o, .o -> exe) instead of

> one

> +             # (.c -> exe), because the warning occurs only in the

> second

> +             # step

> +             ax_pthread_save_ac_link="$ac_link"

> +             ax_pthread_sed='s/conftest\.\$ac_ext/conftest.$ac_objex

> t/g'

> +             ax_pthread_link_step=`$as_echo "$ac_link" | sed

> "$ax_pthread_sed"`

> +             ax_pthread_2step_ac_link="($ac_compile) && (echo ====

> >&5) && ($ax_pthread_link_step)"

> +             ax_pthread_save_CFLAGS="$CFLAGS"

> +             for ax_pthread_try in '' -Qunused-arguments -Wno-

> unused-command-line-argument unknown; do

> +                AS_IF([test "x$ax_pthread_try" = "xunknown"],

> [break])

> +                CFLAGS="-Werror -Wunknown-warning-option

> $ax_pthread_try -pthread $ax_pthread_save_CFLAGS"

> +                ac_link="$ax_pthread_save_ac_link"

> +                AC_LINK_IFELSE([AC_LANG_SOURCE([[int

> main(void){return 0;}]])],

> +                    [ac_link="$ax_pthread_2step_ac_link"

> +                     AC_LINK_IFELSE([AC_LANG_SOURCE([[int

> main(void){return 0;}]])],

> +                         [break])

> +                    ])

> +             done

> +             ac_link="$ax_pthread_save_ac_link"

> +             CFLAGS="$ax_pthread_save_CFLAGS"

> +             AS_IF([test "x$ax_pthread_try" = "x"],

> [ax_pthread_try=no])

> +             ax_cv_PTHREAD_CLANG_NO_WARN_FLAG="$ax_pthread_try"

> +            ])

> +

> +        case "$ax_cv_PTHREAD_CLANG_NO_WARN_FLAG" in

> +                no | unknown) ;;

> +                *) PTHREAD_CFLAGS="$ax_cv_PTHREAD_CLANG_NO_WARN_FLAG

> $PTHREAD_CFLAGS" ;;

> +        esac

> +

> +fi # $ax_pthread_clang = yes

> +

> +if test "x$ax_pthread_ok" = "xno"; then

> +for ax_pthread_try_flag in $ax_pthread_flags; do

> +

> +        case $ax_pthread_try_flag in

> +                none)

> +                AC_MSG_CHECKING([whether pthreads work without any

> flags])

> +                ;;

> +

> +                -mt,pthread)

> +                AC_MSG_CHECKING([whether pthreads work with -mt

> -lpthread])

> +                PTHREAD_CFLAGS="-mt"

> +                PTHREAD_LIBS="-lpthread"

> +                ;;

> +

> +                -*)

> +                AC_MSG_CHECKING([whether pthreads work with

> $ax_pthread_try_flag])

> +                PTHREAD_CFLAGS="$ax_pthread_try_flag"

> +                ;;

> +

> +                pthread-config)

> +                AC_CHECK_PROG([ax_pthread_config], [pthread-config], 

> [yes], [no])

> +                AS_IF([test "x$ax_pthread_config" = "xno"],

> [continue])

> +                PTHREAD_CFLAGS="`pthread-config --cflags`"

> +                PTHREAD_LIBS="`pthread-config --ldflags` `pthread-

> config --libs`"

> +                ;;

> +

> +                *)

> +                AC_MSG_CHECKING([for the pthreads library

> -l$ax_pthread_try_flag])

> +                PTHREAD_LIBS="-l$ax_pthread_try_flag"

> +                ;;

> +        esac

> +

> +        ax_pthread_save_CFLAGS="$CFLAGS"

> +        ax_pthread_save_LIBS="$LIBS"

> +        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"

> +        LIBS="$PTHREAD_LIBS $LIBS"

> +

> +        # Check for various functions.  We must include pthread.h,

> +        # since some functions may be macros.  (On the Sequent, we

> +        # need a special flag -Kthread to make this header compile.)

> +        # We check for pthread_join because it is in -lpthread on

> IRIX

> +        # while pthread_create is in libc.  We check for

> pthread_attr_init

> +        # due to DEC craziness with -lpthreads.  We check for

> +        # pthread_cleanup_push because it is one of the few pthread

> +        # functions on Solaris that doesn't have a non-functional

> libc stub.

> +        # We try pthread_create on general principles.

> +

> +        AC_LINK_IFELSE([AC_LANG_PROGRAM([#include <pthread.h>

> +#                       if $ax_pthread_check_cond

> +#                        error "$ax_pthread_check_macro must be

> defined"

> +#                       endif

> +                        static void routine(void *a) { a = 0; }

> +                        static void *start_routine(void *a) { return

> a; }],

> +                       [pthread_t th; pthread_attr_t attr;

> +                        pthread_create(&th, 0, start_routine, 0);

> +                        pthread_join(th, 0);

> +                        pthread_attr_init(&attr);

> +                        pthread_cleanup_push(routine, 0);

> +                        pthread_cleanup_pop(0) /* ; */])],

> +            [ax_pthread_ok=yes],

> +            [])

> +

> +        CFLAGS="$ax_pthread_save_CFLAGS"

> +        LIBS="$ax_pthread_save_LIBS"

> +

> +        AC_MSG_RESULT([$ax_pthread_ok])

> +        AS_IF([test "x$ax_pthread_ok" = "xyes"], [break])

> +

> +        PTHREAD_LIBS=""

> +        PTHREAD_CFLAGS=""

> +done

> +fi

> +

> +# Various other checks:

> +if test "x$ax_pthread_ok" = "xyes"; then

> +        ax_pthread_save_CFLAGS="$CFLAGS"

> +        ax_pthread_save_LIBS="$LIBS"

> +        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"

> +        LIBS="$PTHREAD_LIBS $LIBS"

> +

> +        # Detect AIX lossage: JOINABLE attribute is called

> UNDETACHED.

> +        AC_CACHE_CHECK([for joinable pthread attribute],

> +            [ax_cv_PTHREAD_JOINABLE_ATTR],

> +            [ax_cv_PTHREAD_JOINABLE_ATTR=unknown

> +             for ax_pthread_attr in PTHREAD_CREATE_JOINABLE

> PTHREAD_CREATE_UNDETACHED; do

> +                 AC_LINK_IFELSE([AC_LANG_PROGRAM([#include

> <pthread.h>],

> +                                                 [int attr =

> $ax_pthread_attr; return attr /* ; */])],

> +                                [ax_cv_PTHREAD_JOINABLE_ATTR=$ax_pth

> read_attr; break],

> +                                [])

> +             done

> +            ])

> +        AS_IF([test "x$ax_cv_PTHREAD_JOINABLE_ATTR" != "xunknown" &&

> \

> +               test "x$ax_cv_PTHREAD_JOINABLE_ATTR" !=

> "xPTHREAD_CREATE_JOINABLE" && \

> +               test "x$ax_pthread_joinable_attr_defined" != "xyes"],

> +              [AC_DEFINE_UNQUOTED([PTHREAD_CREATE_JOINABLE],

> +                                  [$ax_cv_PTHREAD_JOINABLE_ATTR],

> +                                  [Define to necessary symbol if

> this constant

> +                                   uses a non-standard name on your

> system.])

> +               ax_pthread_joinable_attr_defined=yes

> +              ])

> +

> +        AC_CACHE_CHECK([whether more special flags are required for

> pthreads],

> +            [ax_cv_PTHREAD_SPECIAL_FLAGS],

> +            [ax_cv_PTHREAD_SPECIAL_FLAGS=no

> +             case $host_os in

> +             solaris*)

> +             ax_cv_PTHREAD_SPECIAL_FLAGS="-

> D_POSIX_PTHREAD_SEMANTICS"

> +             ;;

> +             esac

> +            ])

> +        AS_IF([test "x$ax_cv_PTHREAD_SPECIAL_FLAGS" != "xno" && \

> +               test "x$ax_pthread_special_flags_added" != "xyes"],

> +              [PTHREAD_CFLAGS="$ax_cv_PTHREAD_SPECIAL_FLAGS

> $PTHREAD_CFLAGS"

> +               ax_pthread_special_flags_added=yes])

> +

> +        AC_CACHE_CHECK([for PTHREAD_PRIO_INHERIT],

> +            [ax_cv_PTHREAD_PRIO_INHERIT],

> +            [AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include

> <pthread.h>]],

> +                                             [[int i =

> PTHREAD_PRIO_INHERIT;]])],

> +                            [ax_cv_PTHREAD_PRIO_INHERIT=yes],

> +                            [ax_cv_PTHREAD_PRIO_INHERIT=no])

> +            ])

> +        AS_IF([test "x$ax_cv_PTHREAD_PRIO_INHERIT" = "xyes" && \

> +               test "x$ax_pthread_prio_inherit_defined" != "xyes"],

> +              [AC_DEFINE([HAVE_PTHREAD_PRIO_INHERIT], [1], [Have

> PTHREAD_PRIO_INHERIT.])

> +               ax_pthread_prio_inherit_defined=yes

> +              ])

> +

> +        CFLAGS="$ax_pthread_save_CFLAGS"

> +        LIBS="$ax_pthread_save_LIBS"

> +

> +        # More AIX lossage: compile with *_r variant

> +        if test "x$GCC" != "xyes"; then

> +            case $host_os in

> +                aix*)

> +                AS_CASE(["x/$CC"],

> +                    [x*/c89|x*/c89_128|x*/c99|x*/c99_128|x*/cc|x*/cc

> 128|x*/xlc|x*/xlc_v6|x*/xlc128|x*/xlc128_v6],

> +                    [#handle absolute path differently from PATH

> based program lookup

> +                     AS_CASE(["x$CC"],

> +                         [x/*],

> +                         [AS_IF([AS_EXECUTABLE_P([${CC}_r])],[PTHREA

> D_CC="${CC}_r"])],

> +                         [AC_CHECK_PROGS([PTHREAD_CC],[${CC}_r],[$CC

> ])])])

> +                ;;

> +            esac

> +        fi

> +fi

> +

> +test -n "$PTHREAD_CC" || PTHREAD_CC="$CC"

> +

> +AC_SUBST([PTHREAD_LIBS])

> +AC_SUBST([PTHREAD_CFLAGS])

> +AC_SUBST([PTHREAD_CC])

> +

> +# Finally, execute ACTION-IF-FOUND/ACTION-IF-NOT-FOUND:

> +if test "x$ax_pthread_ok" = "xyes"; then

> +        ifelse([$1],,[AC_DEFINE([HAVE_PTHREAD],[1],[Define if you

> have POSIX threads libraries and header files.])],[$1])

> +        :

> +else

> +        ax_pthread_ok=no

> +        $2

> +fi

> +AC_LANG_POP

> +])dnl AX_PTHREAD


Ping? I'd really like to get this in binutils, which apparently
requires getting it here first.

Thanks,
Joshua Watt
Pedro Alves April 17, 2018, 9:50 p.m. | #2
On 04/17/2018 06:24 PM, Joshua Watt wrote:
> Ping? I'd really like to get this in binutils, which apparently

> requires getting it here first.


I think it would help if you mentioned what this is and
what is the intended use case.

Was this discussed on the binutils or gdb lists?

Thanks,
Pedro Alves
Joshua Watt April 17, 2018, 10:10 p.m. | #3
On Tue, 2018-04-17 at 22:50 +0100, Pedro Alves wrote:
> On 04/17/2018 06:24 PM, Joshua Watt wrote:

> > Ping? I'd really like to get this in binutils, which apparently

> > requires getting it here first.

> 

> I think it would help if you mentioned what this is and

> what is the intended use case.


Ah, that would probably be helpful! Yes, this was discussed on the
binutils mailing list, see:
https://sourceware.org/ml/binutils/2018-02/msg00260.html

In short summary: the gold linker doesn't currently build for mingw,
but only because it is attempting to link against libpthread
incorrectly on that platform. Instead of bringing in more specialized
logic to account for that, I opted to include the autotools
ax_pthread.m4 macro (this patch) that automatically handles discovering
pthreads on a wide variety of platforms and compilers, including mingw.

binutils slaves its config/ directory to GCC, so the patch is required
to be committed here first, and then it will be ported over there.

Thanks,
Joshua Watt

> 

> Was this discussed on the binutils or gdb lists?

> 

> Thanks,

> Pedro Alves
Pedro Alves April 18, 2018, 10:20 a.m. | #4
On 04/17/2018 11:10 PM, Joshua Watt wrote:
> On Tue, 2018-04-17 at 22:50 +0100, Pedro Alves wrote:

>> On 04/17/2018 06:24 PM, Joshua Watt wrote:

>>> Ping? I'd really like to get this in binutils, which apparently

>>> requires getting it here first.

>>

>> I think it would help if you mentioned what this is and

>> what is the intended use case.

> 

> Ah, that would probably be helpful! Yes, this was discussed on the

> binutils mailing list, see:

> https://sourceware.org/ml/binutils/2018-02/msg00260.html

> 

> In short summary: the gold linker doesn't currently build for mingw,

> but only because it is attempting to link against libpthread

> incorrectly on that platform. Instead of bringing in more specialized

> logic to account for that, I opted to include the autotools

> ax_pthread.m4 macro (this patch) that automatically handles discovering

> pthreads on a wide variety of platforms and compilers, including mingw.

> 

> binutils slaves its config/ directory to GCC, so the patch is required

> to be committed here first, and then it will be ported over there.


Thanks, that helps indeed.

I agree that the ax_pthread.m4 approach makes sense.  Better to use
a field-tested macro than reinvent the wheel.  We're using other
files from the autoconf-archive archive already, for similar reasons
(e.g., config/ax_check_define.m4, and gdb/ax_cxx_compile_stdcxx.m4).

Since GCC won't be using it (yet at least, but it's conceivable it
could make use of it in future), there should be no harm in
installing it even if GCC is in stage 4, IMO.

I don't have the authority to approve it, though.

Thanks,
Pedro Alves
Joshua Watt May 8, 2018, 11:47 p.m. | #5
On Wed, Apr 18, 2018, 05:20 Pedro Alves <palves@redhat.com> wrote:

> On 04/17/2018 11:10 PM, Joshua Watt wrote:

> > On Tue, 2018-04-17 at 22:50 +0100, Pedro Alves wrote:

> >> On 04/17/2018 06:24 PM, Joshua Watt wrote:

> >>> Ping? I'd really like to get this in binutils, which apparently

> >>> requires getting it here first.

> >>

> >> I think it would help if you mentioned what this is and

> >> what is the intended use case.

> >

> > Ah, that would probably be helpful! Yes, this was discussed on the

> > binutils mailing list, see:

> > https://sourceware.org/ml/binutils/2018-02/msg00260.html

> >

> > In short summary: the gold linker doesn't currently build for mingw,

> > but only because it is attempting to link against libpthread

> > incorrectly on that platform. Instead of bringing in more specialized

> > logic to account for that, I opted to include the autotools

> > ax_pthread.m4 macro (this patch) that automatically handles discovering

> > pthreads on a wide variety of platforms and compilers, including mingw.

> >

> > binutils slaves its config/ directory to GCC, so the patch is required

> > to be committed here first, and then it will be ported over there.

>

> Thanks, that helps indeed.

>

> I agree that the ax_pthread.m4 approach makes sense.  Better to use

> a field-tested macro than reinvent the wheel.  We're using other

> files from the autoconf-archive archive already, for similar reasons

> (e.g., config/ax_check_define.m4, and gdb/ax_cxx_compile_stdcxx.m4).

>

> Since GCC won't be using it (yet at least, but it's conceivable it

> could make use of it in future), there should be no harm in

> installing it even if GCC is in stage 4, IMO.

>

> I don't have the authority to approve it, though.

>

> Thanks,

> Pedro Alves

>


Ping (again)

>
Jason Merrill May 9, 2018, 3:25 p.m. | #6
Applied.

On Tue, May 8, 2018 at 7:47 PM, Joshua Watt <jpewhacker@gmail.com> wrote:
> On Wed, Apr 18, 2018, 05:20 Pedro Alves <palves@redhat.com> wrote:

>

>> On 04/17/2018 11:10 PM, Joshua Watt wrote:

>> > On Tue, 2018-04-17 at 22:50 +0100, Pedro Alves wrote:

>> >> On 04/17/2018 06:24 PM, Joshua Watt wrote:

>> >>> Ping? I'd really like to get this in binutils, which apparently

>> >>> requires getting it here first.

>> >>

>> >> I think it would help if you mentioned what this is and

>> >> what is the intended use case.

>> >

>> > Ah, that would probably be helpful! Yes, this was discussed on the

>> > binutils mailing list, see:

>> > https://sourceware.org/ml/binutils/2018-02/msg00260.html

>> >

>> > In short summary: the gold linker doesn't currently build for mingw,

>> > but only because it is attempting to link against libpthread

>> > incorrectly on that platform. Instead of bringing in more specialized

>> > logic to account for that, I opted to include the autotools

>> > ax_pthread.m4 macro (this patch) that automatically handles discovering

>> > pthreads on a wide variety of platforms and compilers, including mingw.

>> >

>> > binutils slaves its config/ directory to GCC, so the patch is required

>> > to be committed here first, and then it will be ported over there.

>>

>> Thanks, that helps indeed.

>>

>> I agree that the ax_pthread.m4 approach makes sense.  Better to use

>> a field-tested macro than reinvent the wheel.  We're using other

>> files from the autoconf-archive archive already, for similar reasons

>> (e.g., config/ax_check_define.m4, and gdb/ax_cxx_compile_stdcxx.m4).

>>

>> Since GCC won't be using it (yet at least, but it's conceivable it

>> could make use of it in future), there should be no harm in

>> installing it even if GCC is in stage 4, IMO.

>>

>> I don't have the authority to approve it, though.

>>

>> Thanks,

>> Pedro Alves

>>

>

> Ping (again)

>

>>

Patch

diff --git a/config/ax_pthread.m4 b/config/ax_pthread.m4
new file mode 100644
index 00000000000..5fbf9fe0d68
--- /dev/null
+++ b/config/ax_pthread.m4
@@ -0,0 +1,485 @@ 
+# ===========================================================================
+#        https://www.gnu.org/software/autoconf-archive/ax_pthread.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_PTHREAD([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])
+#
+# DESCRIPTION
+#
+#   This macro figures out how to build C programs using POSIX threads. It
+#   sets the PTHREAD_LIBS output variable to the threads library and linker
+#   flags, and the PTHREAD_CFLAGS output variable to any special C compiler
+#   flags that are needed. (The user can also force certain compiler
+#   flags/libs to be tested by setting these environment variables.)
+#
+#   Also sets PTHREAD_CC to any special C compiler that is needed for
+#   multi-threaded programs (defaults to the value of CC otherwise). (This
+#   is necessary on AIX to use the special cc_r compiler alias.)
+#
+#   NOTE: You are assumed to not only compile your program with these flags,
+#   but also to link with them as well. For example, you might link with
+#   $PTHREAD_CC $CFLAGS $PTHREAD_CFLAGS $LDFLAGS ... $PTHREAD_LIBS $LIBS
+#
+#   If you are only building threaded programs, you may wish to use these
+#   variables in your default LIBS, CFLAGS, and CC:
+#
+#     LIBS="$PTHREAD_LIBS $LIBS"
+#     CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
+#     CC="$PTHREAD_CC"
+#
+#   In addition, if the PTHREAD_CREATE_JOINABLE thread-attribute constant
+#   has a nonstandard name, this macro defines PTHREAD_CREATE_JOINABLE to
+#   that name (e.g. PTHREAD_CREATE_UNDETACHED on AIX).
+#
+#   Also HAVE_PTHREAD_PRIO_INHERIT is defined if pthread is found and the
+#   PTHREAD_PRIO_INHERIT symbol is defined when compiling with
+#   PTHREAD_CFLAGS.
+#
+#   ACTION-IF-FOUND is a list of shell commands to run if a threads library
+#   is found, and ACTION-IF-NOT-FOUND is a list of commands to run it if it
+#   is not found. If ACTION-IF-FOUND is not specified, the default action
+#   will define HAVE_PTHREAD.
+#
+#   Please let the authors know if this macro fails on any platform, or if
+#   you have any other suggestions or comments. This macro was based on work
+#   by SGJ on autoconf scripts for FFTW (http://www.fftw.org/) (with help
+#   from M. Frigo), as well as ac_pthread and hb_pthread macros posted by
+#   Alejandro Forero Cuervo to the autoconf macro repository. We are also
+#   grateful for the helpful feedback of numerous users.
+#
+#   Updated for Autoconf 2.68 by Daniel Richard G.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Steven G. Johnson <stevenj@alum.mit.edu>
+#   Copyright (c) 2011 Daniel Richard G. <skunk@iSKUNK.ORG>
+#
+#   This program is free software: you can redistribute it and/or modify it
+#   under the terms of the GNU General Public License as published by the
+#   Free Software Foundation, either version 3 of the License, or (at your
+#   option) any later version.
+#
+#   This program is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+#   Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License along
+#   with this program. If not, see <https://www.gnu.org/licenses/>.
+#
+#   As a special exception, the respective Autoconf Macro's copyright owner
+#   gives unlimited permission to copy, distribute and modify the configure
+#   scripts that are the output of Autoconf when processing the Macro. You
+#   need not follow the terms of the GNU General Public License when using
+#   or distributing such scripts, even though portions of the text of the
+#   Macro appear in them. The GNU General Public License (GPL) does govern
+#   all other use of the material that constitutes the Autoconf Macro.
+#
+#   This special exception to the GPL applies to versions of the Autoconf
+#   Macro released by the Autoconf Archive. When you make and distribute a
+#   modified version of the Autoconf Macro, you may extend this special
+#   exception to the GPL to apply to your modified version as well.
+
+#serial 24
+
+AU_ALIAS([ACX_PTHREAD], [AX_PTHREAD])
+AC_DEFUN([AX_PTHREAD], [
+AC_REQUIRE([AC_CANONICAL_HOST])
+AC_REQUIRE([AC_PROG_CC])
+AC_REQUIRE([AC_PROG_SED])
+AC_LANG_PUSH([C])
+ax_pthread_ok=no
+
+# We used to check for pthread.h first, but this fails if pthread.h
+# requires special compiler flags (e.g. on Tru64 or Sequent).
+# It gets checked for in the link test anyway.
+
+# First of all, check if the user has set any of the PTHREAD_LIBS,
+# etcetera environment variables, and if threads linking works using
+# them:
+if test "x$PTHREAD_CFLAGS$PTHREAD_LIBS" != "x"; then
+        ax_pthread_save_CC="$CC"
+        ax_pthread_save_CFLAGS="$CFLAGS"
+        ax_pthread_save_LIBS="$LIBS"
+        AS_IF([test "x$PTHREAD_CC" != "x"], [CC="$PTHREAD_CC"])
+        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
+        LIBS="$PTHREAD_LIBS $LIBS"
+        AC_MSG_CHECKING([for pthread_join using $CC $PTHREAD_CFLAGS $PTHREAD_LIBS])
+        AC_LINK_IFELSE([AC_LANG_CALL([], [pthread_join])], [ax_pthread_ok=yes])
+        AC_MSG_RESULT([$ax_pthread_ok])
+        if test "x$ax_pthread_ok" = "xno"; then
+                PTHREAD_LIBS=""
+                PTHREAD_CFLAGS=""
+        fi
+        CC="$ax_pthread_save_CC"
+        CFLAGS="$ax_pthread_save_CFLAGS"
+        LIBS="$ax_pthread_save_LIBS"
+fi
+
+# We must check for the threads library under a number of different
+# names; the ordering is very important because some systems
+# (e.g. DEC) have both -lpthread and -lpthreads, where one of the
+# libraries is broken (non-POSIX).
+
+# Create a list of thread flags to try.  Items starting with a "-" are
+# C compiler flags, and other items are library names, except for "none"
+# which indicates that we try without any flags at all, and "pthread-config"
+# which is a program returning the flags for the Pth emulation library.
+
+ax_pthread_flags="pthreads none -Kthread -pthread -pthreads -mthreads pthread --thread-safe -mt pthread-config"
+
+# The ordering *is* (sometimes) important.  Some notes on the
+# individual items follow:
+
+# pthreads: AIX (must check this before -lpthread)
+# none: in case threads are in libc; should be tried before -Kthread and
+#       other compiler flags to prevent continual compiler warnings
+# -Kthread: Sequent (threads in libc, but -Kthread needed for pthread.h)
+# -pthread: Linux/gcc (kernel threads), BSD/gcc (userland threads), Tru64
+#           (Note: HP C rejects this with "bad form for `-t' option")
+# -pthreads: Solaris/gcc (Note: HP C also rejects)
+# -mt: Sun Workshop C (may only link SunOS threads [-lthread], but it
+#      doesn't hurt to check since this sometimes defines pthreads and
+#      -D_REENTRANT too), HP C (must be checked before -lpthread, which
+#      is present but should not be used directly; and before -mthreads,
+#      because the compiler interprets this as "-mt" + "-hreads")
+# -mthreads: Mingw32/gcc, Lynx/gcc
+# pthread: Linux, etcetera
+# --thread-safe: KAI C++
+# pthread-config: use pthread-config program (for GNU Pth library)
+
+case $host_os in
+
+        freebsd*)
+
+        # -kthread: FreeBSD kernel threads (preferred to -pthread since SMP-able)
+        # lthread: LinuxThreads port on FreeBSD (also preferred to -pthread)
+
+        ax_pthread_flags="-kthread lthread $ax_pthread_flags"
+        ;;
+
+        hpux*)
+
+        # From the cc(1) man page: "[-mt] Sets various -D flags to enable
+        # multi-threading and also sets -lpthread."
+
+        ax_pthread_flags="-mt -pthread pthread $ax_pthread_flags"
+        ;;
+
+        openedition*)
+
+        # IBM z/OS requires a feature-test macro to be defined in order to
+        # enable POSIX threads at all, so give the user a hint if this is
+        # not set. (We don't define these ourselves, as they can affect
+        # other portions of the system API in unpredictable ways.)
+
+        AC_EGREP_CPP([AX_PTHREAD_ZOS_MISSING],
+            [
+#            if !defined(_OPEN_THREADS) && !defined(_UNIX03_THREADS)
+             AX_PTHREAD_ZOS_MISSING
+#            endif
+            ],
+            [AC_MSG_WARN([IBM z/OS requires -D_OPEN_THREADS or -D_UNIX03_THREADS to enable pthreads support.])])
+        ;;
+
+        solaris*)
+
+        # On Solaris (at least, for some versions), libc contains stubbed
+        # (non-functional) versions of the pthreads routines, so link-based
+        # tests will erroneously succeed. (N.B.: The stubs are missing
+        # pthread_cleanup_push, or rather a function called by this macro,
+        # so we could check for that, but who knows whether they'll stub
+        # that too in a future libc.)  So we'll check first for the
+        # standard Solaris way of linking pthreads (-mt -lpthread).
+
+        ax_pthread_flags="-mt,pthread pthread $ax_pthread_flags"
+        ;;
+esac
+
+# GCC generally uses -pthread, or -pthreads on some platforms (e.g. SPARC)
+
+AS_IF([test "x$GCC" = "xyes"],
+      [ax_pthread_flags="-pthread -pthreads $ax_pthread_flags"])
+
+# The presence of a feature test macro requesting re-entrant function
+# definitions is, on some systems, a strong hint that pthreads support is
+# correctly enabled
+
+case $host_os in
+        darwin* | hpux* | linux* | osf* | solaris*)
+        ax_pthread_check_macro="_REENTRANT"
+        ;;
+
+        aix*)
+        ax_pthread_check_macro="_THREAD_SAFE"
+        ;;
+
+        *)
+        ax_pthread_check_macro="--"
+        ;;
+esac
+AS_IF([test "x$ax_pthread_check_macro" = "x--"],
+      [ax_pthread_check_cond=0],
+      [ax_pthread_check_cond="!defined($ax_pthread_check_macro)"])
+
+# Are we compiling with Clang?
+
+AC_CACHE_CHECK([whether $CC is Clang],
+    [ax_cv_PTHREAD_CLANG],
+    [ax_cv_PTHREAD_CLANG=no
+     # Note that Autoconf sets GCC=yes for Clang as well as GCC
+     if test "x$GCC" = "xyes"; then
+        AC_EGREP_CPP([AX_PTHREAD_CC_IS_CLANG],
+            [/* Note: Clang 2.7 lacks __clang_[a-z]+__ */
+#            if defined(__clang__) && defined(__llvm__)
+             AX_PTHREAD_CC_IS_CLANG
+#            endif
+            ],
+            [ax_cv_PTHREAD_CLANG=yes])
+     fi
+    ])
+ax_pthread_clang="$ax_cv_PTHREAD_CLANG"
+
+ax_pthread_clang_warning=no
+
+# Clang needs special handling, because older versions handle the -pthread
+# option in a rather... idiosyncratic way
+
+if test "x$ax_pthread_clang" = "xyes"; then
+
+        # Clang takes -pthread; it has never supported any other flag
+
+        # (Note 1: This will need to be revisited if a system that Clang
+        # supports has POSIX threads in a separate library.  This tends not
+        # to be the way of modern systems, but it's conceivable.)
+
+        # (Note 2: On some systems, notably Darwin, -pthread is not needed
+        # to get POSIX threads support; the API is always present and
+        # active.  We could reasonably leave PTHREAD_CFLAGS empty.  But
+        # -pthread does define _REENTRANT, and while the Darwin headers
+        # ignore this macro, third-party headers might not.)
+
+        PTHREAD_CFLAGS="-pthread"
+        PTHREAD_LIBS=
+
+        ax_pthread_ok=yes
+
+        # However, older versions of Clang make a point of warning the user
+        # that, in an invocation where only linking and no compilation is
+        # taking place, the -pthread option has no effect ("argument unused
+        # during compilation").  They expect -pthread to be passed in only
+        # when source code is being compiled.
+        #
+        # Problem is, this is at odds with the way Automake and most other
+        # C build frameworks function, which is that the same flags used in
+        # compilation (CFLAGS) are also used in linking.  Many systems
+        # supported by AX_PTHREAD require exactly this for POSIX threads
+        # support, and in fact it is often not straightforward to specify a
+        # flag that is used only in the compilation phase and not in
+        # linking.  Such a scenario is extremely rare in practice.
+        #
+        # Even though use of the -pthread flag in linking would only print
+        # a warning, this can be a nuisance for well-run software projects
+        # that build with -Werror.  So if the active version of Clang has
+        # this misfeature, we search for an option to squash it.
+
+        AC_CACHE_CHECK([whether Clang needs flag to prevent "argument unused" warning when linking with -pthread],
+            [ax_cv_PTHREAD_CLANG_NO_WARN_FLAG],
+            [ax_cv_PTHREAD_CLANG_NO_WARN_FLAG=unknown
+             # Create an alternate version of $ac_link that compiles and
+             # links in two steps (.c -> .o, .o -> exe) instead of one
+             # (.c -> exe), because the warning occurs only in the second
+             # step
+             ax_pthread_save_ac_link="$ac_link"
+             ax_pthread_sed='s/conftest\.\$ac_ext/conftest.$ac_objext/g'
+             ax_pthread_link_step=`$as_echo "$ac_link" | sed "$ax_pthread_sed"`
+             ax_pthread_2step_ac_link="($ac_compile) && (echo ==== >&5) && ($ax_pthread_link_step)"
+             ax_pthread_save_CFLAGS="$CFLAGS"
+             for ax_pthread_try in '' -Qunused-arguments -Wno-unused-command-line-argument unknown; do
+                AS_IF([test "x$ax_pthread_try" = "xunknown"], [break])
+                CFLAGS="-Werror -Wunknown-warning-option $ax_pthread_try -pthread $ax_pthread_save_CFLAGS"
+                ac_link="$ax_pthread_save_ac_link"
+                AC_LINK_IFELSE([AC_LANG_SOURCE([[int main(void){return 0;}]])],
+                    [ac_link="$ax_pthread_2step_ac_link"
+                     AC_LINK_IFELSE([AC_LANG_SOURCE([[int main(void){return 0;}]])],
+                         [break])
+                    ])
+             done
+             ac_link="$ax_pthread_save_ac_link"
+             CFLAGS="$ax_pthread_save_CFLAGS"
+             AS_IF([test "x$ax_pthread_try" = "x"], [ax_pthread_try=no])
+             ax_cv_PTHREAD_CLANG_NO_WARN_FLAG="$ax_pthread_try"
+            ])
+
+        case "$ax_cv_PTHREAD_CLANG_NO_WARN_FLAG" in
+                no | unknown) ;;
+                *) PTHREAD_CFLAGS="$ax_cv_PTHREAD_CLANG_NO_WARN_FLAG $PTHREAD_CFLAGS" ;;
+        esac
+
+fi # $ax_pthread_clang = yes
+
+if test "x$ax_pthread_ok" = "xno"; then
+for ax_pthread_try_flag in $ax_pthread_flags; do
+
+        case $ax_pthread_try_flag in
+                none)
+                AC_MSG_CHECKING([whether pthreads work without any flags])
+                ;;
+
+                -mt,pthread)
+                AC_MSG_CHECKING([whether pthreads work with -mt -lpthread])
+                PTHREAD_CFLAGS="-mt"
+                PTHREAD_LIBS="-lpthread"
+                ;;
+
+                -*)
+                AC_MSG_CHECKING([whether pthreads work with $ax_pthread_try_flag])
+                PTHREAD_CFLAGS="$ax_pthread_try_flag"
+                ;;
+
+                pthread-config)
+                AC_CHECK_PROG([ax_pthread_config], [pthread-config], [yes], [no])
+                AS_IF([test "x$ax_pthread_config" = "xno"], [continue])
+                PTHREAD_CFLAGS="`pthread-config --cflags`"
+                PTHREAD_LIBS="`pthread-config --ldflags` `pthread-config --libs`"
+                ;;
+
+                *)
+                AC_MSG_CHECKING([for the pthreads library -l$ax_pthread_try_flag])
+                PTHREAD_LIBS="-l$ax_pthread_try_flag"
+                ;;
+        esac
+
+        ax_pthread_save_CFLAGS="$CFLAGS"
+        ax_pthread_save_LIBS="$LIBS"
+        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
+        LIBS="$PTHREAD_LIBS $LIBS"
+
+        # Check for various functions.  We must include pthread.h,
+        # since some functions may be macros.  (On the Sequent, we
+        # need a special flag -Kthread to make this header compile.)
+        # We check for pthread_join because it is in -lpthread on IRIX
+        # while pthread_create is in libc.  We check for pthread_attr_init
+        # due to DEC craziness with -lpthreads.  We check for
+        # pthread_cleanup_push because it is one of the few pthread
+        # functions on Solaris that doesn't have a non-functional libc stub.
+        # We try pthread_create on general principles.
+
+        AC_LINK_IFELSE([AC_LANG_PROGRAM([#include <pthread.h>
+#                       if $ax_pthread_check_cond
+#                        error "$ax_pthread_check_macro must be defined"
+#                       endif
+                        static void routine(void *a) { a = 0; }
+                        static void *start_routine(void *a) { return a; }],
+                       [pthread_t th; pthread_attr_t attr;
+                        pthread_create(&th, 0, start_routine, 0);
+                        pthread_join(th, 0);
+                        pthread_attr_init(&attr);
+                        pthread_cleanup_push(routine, 0);
+                        pthread_cleanup_pop(0) /* ; */])],
+            [ax_pthread_ok=yes],
+            [])
+
+        CFLAGS="$ax_pthread_save_CFLAGS"
+        LIBS="$ax_pthread_save_LIBS"
+
+        AC_MSG_RESULT([$ax_pthread_ok])
+        AS_IF([test "x$ax_pthread_ok" = "xyes"], [break])
+
+        PTHREAD_LIBS=""
+        PTHREAD_CFLAGS=""
+done
+fi
+
+# Various other checks:
+if test "x$ax_pthread_ok" = "xyes"; then
+        ax_pthread_save_CFLAGS="$CFLAGS"
+        ax_pthread_save_LIBS="$LIBS"
+        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
+        LIBS="$PTHREAD_LIBS $LIBS"
+
+        # Detect AIX lossage: JOINABLE attribute is called UNDETACHED.
+        AC_CACHE_CHECK([for joinable pthread attribute],
+            [ax_cv_PTHREAD_JOINABLE_ATTR],
+            [ax_cv_PTHREAD_JOINABLE_ATTR=unknown
+             for ax_pthread_attr in PTHREAD_CREATE_JOINABLE PTHREAD_CREATE_UNDETACHED; do
+                 AC_LINK_IFELSE([AC_LANG_PROGRAM([#include <pthread.h>],
+                                                 [int attr = $ax_pthread_attr; return attr /* ; */])],
+                                [ax_cv_PTHREAD_JOINABLE_ATTR=$ax_pthread_attr; break],
+                                [])
+             done
+            ])
+        AS_IF([test "x$ax_cv_PTHREAD_JOINABLE_ATTR" != "xunknown" && \
+               test "x$ax_cv_PTHREAD_JOINABLE_ATTR" != "xPTHREAD_CREATE_JOINABLE" && \
+               test "x$ax_pthread_joinable_attr_defined" != "xyes"],
+              [AC_DEFINE_UNQUOTED([PTHREAD_CREATE_JOINABLE],
+                                  [$ax_cv_PTHREAD_JOINABLE_ATTR],
+                                  [Define to necessary symbol if this constant
+                                   uses a non-standard name on your system.])
+               ax_pthread_joinable_attr_defined=yes
+              ])
+
+        AC_CACHE_CHECK([whether more special flags are required for pthreads],
+            [ax_cv_PTHREAD_SPECIAL_FLAGS],
+            [ax_cv_PTHREAD_SPECIAL_FLAGS=no
+             case $host_os in
+             solaris*)
+             ax_cv_PTHREAD_SPECIAL_FLAGS="-D_POSIX_PTHREAD_SEMANTICS"
+             ;;
+             esac
+            ])
+        AS_IF([test "x$ax_cv_PTHREAD_SPECIAL_FLAGS" != "xno" && \
+               test "x$ax_pthread_special_flags_added" != "xyes"],
+              [PTHREAD_CFLAGS="$ax_cv_PTHREAD_SPECIAL_FLAGS $PTHREAD_CFLAGS"
+               ax_pthread_special_flags_added=yes])
+
+        AC_CACHE_CHECK([for PTHREAD_PRIO_INHERIT],
+            [ax_cv_PTHREAD_PRIO_INHERIT],
+            [AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include <pthread.h>]],
+                                             [[int i = PTHREAD_PRIO_INHERIT;]])],
+                            [ax_cv_PTHREAD_PRIO_INHERIT=yes],
+                            [ax_cv_PTHREAD_PRIO_INHERIT=no])
+            ])
+        AS_IF([test "x$ax_cv_PTHREAD_PRIO_INHERIT" = "xyes" && \
+               test "x$ax_pthread_prio_inherit_defined" != "xyes"],
+              [AC_DEFINE([HAVE_PTHREAD_PRIO_INHERIT], [1], [Have PTHREAD_PRIO_INHERIT.])
+               ax_pthread_prio_inherit_defined=yes
+              ])
+
+        CFLAGS="$ax_pthread_save_CFLAGS"
+        LIBS="$ax_pthread_save_LIBS"
+
+        # More AIX lossage: compile with *_r variant
+        if test "x$GCC" != "xyes"; then
+            case $host_os in
+                aix*)
+                AS_CASE(["x/$CC"],
+                    [x*/c89|x*/c89_128|x*/c99|x*/c99_128|x*/cc|x*/cc128|x*/xlc|x*/xlc_v6|x*/xlc128|x*/xlc128_v6],
+                    [#handle absolute path differently from PATH based program lookup
+                     AS_CASE(["x$CC"],
+                         [x/*],
+                         [AS_IF([AS_EXECUTABLE_P([${CC}_r])],[PTHREAD_CC="${CC}_r"])],
+                         [AC_CHECK_PROGS([PTHREAD_CC],[${CC}_r],[$CC])])])
+                ;;
+            esac
+        fi
+fi
+
+test -n "$PTHREAD_CC" || PTHREAD_CC="$CC"
+
+AC_SUBST([PTHREAD_LIBS])
+AC_SUBST([PTHREAD_CFLAGS])
+AC_SUBST([PTHREAD_CC])
+
+# Finally, execute ACTION-IF-FOUND/ACTION-IF-NOT-FOUND:
+if test "x$ax_pthread_ok" = "xyes"; then
+        ifelse([$1],,[AC_DEFINE([HAVE_PTHREAD],[1],[Define if you have POSIX threads libraries and header files.])],[$1])
+        :
+else
+        ax_pthread_ok=no
+        $2
+fi
+AC_LANG_POP
+])dnl AX_PTHREAD