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1# ===========================================================================
2#          http://www.gnu.org/software/autoconf-archive/ax_tls.html
3# ===========================================================================
4#
5# SYNOPSIS
6#
7#   AX_TLS([action-if-found], [action-if-not-found])
8#
9# DESCRIPTION
10#
11#   Provides a test for the compiler support of thread local storage (TLS)
12#   extensions. Defines TLS if it is found. Currently knows about GCC/ICC
13#   and MSVC. I think SunPro uses the same as GCC, and Borland apparently
14#   supports either.
15#
16# LICENSE
17#
18#   Copyright (c) 2008 Alan Woodland <ajw05@aber.ac.uk>
19#   Copyright (c) 2010 Diego Elio Petteno` <flameeyes@gmail.com>
20#
21#   This program is free software: you can redistribute it and/or modify it
22#   under the terms of the GNU General Public License as published by the
23#   Free Software Foundation, either version 3 of the License, or (at your
24#   option) any later version.
25#
26#   This program is distributed in the hope that it will be useful, but
27#   WITHOUT ANY WARRANTY; without even the implied warranty of
28#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
29#   Public License for more details.
30#
31#   You should have received a copy of the GNU General Public License along
32#   with this program. If not, see <http://www.gnu.org/licenses/>.
33#
34#   As a special exception, the respective Autoconf Macro's copyright owner
35#   gives unlimited permission to copy, distribute and modify the configure
36#   scripts that are the output of Autoconf when processing the Macro. You
37#   need not follow the terms of the GNU General Public License when using
38#   or distributing such scripts, even though portions of the text of the
39#   Macro appear in them. The GNU General Public License (GPL) does govern
40#   all other use of the material that constitutes the Autoconf Macro.
41#
42#   This special exception to the GPL applies to versions of the Autoconf
43#   Macro released by the Autoconf Archive. When you make and distribute a
44#   modified version of the Autoconf Macro, you may extend this special
45#   exception to the GPL to apply to your modified version as well.
46
47#serial 10
48
49AC_DEFUN([AX_TLS], [
50  AC_MSG_CHECKING(for thread local storage (TLS) class)
51  AC_CACHE_VAL(ac_cv_tls, [
52    ax_tls_keywords="__thread __declspec(thread) none"
53    for ax_tls_keyword in $ax_tls_keywords; do
54       AS_CASE([$ax_tls_keyword],
55          [none], [ac_cv_tls=none ; break],
56          [AC_TRY_COMPILE(
57              [#include <stdlib.h>
58               static void
59               foo(void) {
60               static ] $ax_tls_keyword [ int bar;
61               exit(1);
62               }],
63               [],
64               [ac_cv_tls=$ax_tls_keyword ; break],
65               ac_cv_tls=none
66           )])
67    done
68  ])
69  AC_MSG_RESULT($ac_cv_tls)
70
71  AS_IF([test "$ac_cv_tls" != "none"],
72    AC_DEFINE_UNQUOTED([TLS], $ac_cv_tls, [If the compiler supports a TLS storage class define it to that here])
73      m4_ifnblank([$1], [$1]),
74    m4_ifnblank([$2], [$2])
75  )
76])
77