1# =========================================================================== 2# http://www.nongnu.org/autoconf-archive/ax_tls.html 3# =========================================================================== 4# 5# SYNOPSIS 6# 7# AX_TLS 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 only knows about GCC 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# 20# This program is free software: you can redistribute it and/or modify it 21# under the terms of the GNU General Public License as published by the 22# Free Software Foundation, either version 3 of the License, or (at your 23# option) any later version. 24# 25# This program is distributed in the hope that it will be useful, but 26# WITHOUT ANY WARRANTY; without even the implied warranty of 27# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General 28# Public License for more details. 29# 30# You should have received a copy of the GNU General Public License along 31# with this program. If not, see <http://www.gnu.org/licenses/>. 32# 33# As a special exception, the respective Autoconf Macro's copyright owner 34# gives unlimited permission to copy, distribute and modify the configure 35# scripts that are the output of Autoconf when processing the Macro. You 36# need not follow the terms of the GNU General Public License when using 37# or distributing such scripts, even though portions of the text of the 38# Macro appear in them. The GNU General Public License (GPL) does govern 39# all other use of the material that constitutes the Autoconf Macro. 40# 41# This special exception to the GPL applies to versions of the Autoconf 42# Macro released by the Autoconf Archive. When you make and distribute a 43# modified version of the Autoconf Macro, you may extend this special 44# exception to the GPL to apply to your modified version as well. 45 46AC_DEFUN([AX_TLS], [ 47 AC_MSG_CHECKING(for thread local storage specifier) 48 AC_CACHE_VAL(ac_cv_tls, [ 49 ax_tls_keywords="__thread __declspec(thread) none" 50 for ax_tls_keyword in $ax_tls_keywords; do 51 case $ax_tls_keyword in 52 none) ac_cv_tls=none ; break ;; 53 *) 54 # MPICH2 modification: This was an AC_TRY_COMPILE before, but 55 # Darwin with non-standard compilers will accept __thread at 56 # compile time but fail to link due to an undefined 57 # "__emutls_get_address" symbol unless -lgcc_eh is added to the 58 # link line. 59 AC_LINK_IFELSE( 60 [AC_LANG_PROGRAM([$ax_tls_keyword int bar = 5;],[++bar;])], 61 [ac_cv_tls=$ax_tls_keyword ; break], 62 [ac_cv_tls=none]) 63 esac 64 done 65]) 66 67 if test "$ac_cv_tls" != "none"; then 68 # MPICH2 modification: this was "TLS" before instead of 69 # "MPIU_TLS_SPECIFIER", but TLS had a reasonably high chance of conflicting 70 # with a system library. 71 AC_DEFINE_UNQUOTED([MPIU_TLS_SPECIFIER], $ac_cv_tls, [If the compiler supports a TLS storage class define it to that here]) 72 fi 73 AC_MSG_RESULT($ac_cv_tls) 74]) 75