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libsodium/m4/ax_tls.m4
2017-11-25 22:29:20 +01:00

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# ===========================================================================
# https://www.gnu.org/software/autoconf-archive/ax_tls.html
# ===========================================================================
#
# SYNOPSIS
#
# AX_TLS([action-if-found], [action-if-not-found])
#
# DESCRIPTION
#
# Provides a test for the compiler support of thread local storage (TLS)
# extensions. Defines TLS if it is found. Currently knows about C++11,
# GCC/ICC, and MSVC. I think SunPro uses the same as GCC, and Borland
# apparently supports either.
#
# LICENSE
#
# Copyright (c) 2008 Alan Woodland <ajw05@aber.ac.uk>
# Copyright (c) 2010 Diego Elio Petteno` <flameeyes@gmail.com>
#
# 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 14
AC_DEFUN([AX_TLS], [
AC_MSG_CHECKING([for thread local storage (TLS) class])
AC_CACHE_VAL([ac_cv_tls],
[for ax_tls_keyword in thread_local _Thread_local __thread '__declspec(thread)' none; do
AS_CASE([$ax_tls_keyword],
[none], [ac_cv_tls=none ; break],
[AC_TRY_COMPILE(
[#include <stdlib.h>
static void
foo(void) {
static ] $ax_tls_keyword [ int bar;
exit(1);
}],
[],
[ac_cv_tls=$ax_tls_keyword ; break],
ac_cv_tls=none
)])
done
])
AC_MSG_RESULT([$ac_cv_tls])
AS_IF([test "$ac_cv_tls" != "none"],
[AC_DEFINE_UNQUOTED([TLS],[$ac_cv_tls],[If the compiler supports a TLS storage class define it to that here])
m4_ifnblank([$1],[$1])],
[m4_ifnblank([$2],[$2])])
])