-# from http://autoconf-archive.cryp.to/ax_tls.html
#
-# This was licensed under the GPL with the following exception:
+# AX_CHECK_TLS -- check whether the target supports TLS (thread-local storage)
#
-# 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.
+# Based on tls.m4 from gcc and extended by TLS link test for cross-compiling
+# support from http://old.nabble.com/Improve-TLS-link-test-for-cross-compiling-td24312975.html
#
-# This special exception to the GPL applies to versions of the
-# Autoconf Macro released by the Autoconf Macro 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.
+# Note that AX_TLS from http://autoconf-archive.cryp.to/ax_tls.html supports
+# more keywords for TLS. We are happy with the "__thread" only.
#
-AC_DEFUN([AX_TLS], [
- AC_MSG_CHECKING(for thread local storage (TLS) class)
- AC_CACHE_VAL(ac_cv_tls, [
- ax_tls_keywords="__thread __declspec(thread) none"
- for ax_tls_keyword in $ax_tls_keywords; do
- case $ax_tls_keyword in
- 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
- )
- esac
- done
-])
+# -- Karel Zak (04-Dec-2009)
+#
+dnl Check whether the target supports TLS.
+AC_DEFUN([AX_CHECK_TLS], [
+
+ AC_REQUIRE([AC_CANONICAL_HOST])
+
+ AC_ARG_ENABLE([tls],
+ AS_HELP_STRING([--disable-tls], [disable use of thread local support]),
+ [], enable_tls=yes)
+
+ AC_CACHE_CHECK([whether the target supports thread-local storage],
+ ax_cv_have_tls, [
+ AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }],
+ [dnl If the test case passed with dynamic linking, try again with
+ dnl static linking, but only if static linking is supported (not
+ dnl on Solaris 10). This fails with some older Red Hat releases.
+ chktls_save_LDFLAGS="$LDFLAGS"
+ LDFLAGS="-static $LDFLAGS"
+ AC_LINK_IFELSE([int main() { return 0; }],
+ AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }],
+ [ax_cv_have_tls=yes], [ax_cv_have_tls=no],[]),
+ [ax_cv_have_tls=yes])
+ LDFLAGS="$chktls_save_LDFLAGS"
+ if test $ax_cv_have_tls = yes; then
+ dnl So far, the binutils and the compiler support TLS.
+ dnl Also check whether the libc supports TLS, i.e. whether a variable
+ dnl with __thread linkage has a different address in different threads.
+ dnl First, find the thread_CFLAGS necessary for linking a program that
+ dnl calls pthread_create.
+ chktls_save_CFLAGS="$CFLAGS"
+ thread_CFLAGS=failed
+ for flag in '' '-pthread' '-lpthread'; do
+ CFLAGS="$flag $chktls_save_CFLAGS"
+ AC_LINK_IFELSE(
+ [AC_LANG_PROGRAM(
+ [#include <pthread.h>
+ void *g(void *d) { return NULL; }],
+ [pthread_t t; pthread_create(&t,NULL,g,NULL);])],
+ [thread_CFLAGS="$flag"])
+ if test "X$thread_CFLAGS" != Xfailed; then
+ break
+ fi
+ done
+ CFLAGS="$chktls_save_CFLAGS"
+ if test "X$thread_CFLAGS" != Xfailed; then
+ CFLAGS="$thread_CFLAGS $chktls_save_CFLAGS"
+ AC_RUN_IFELSE(
+ [AC_LANG_PROGRAM(
+ [#include <pthread.h>
+ __thread int a;
+ static int *a_in_other_thread;
+ static void *
+ thread_func (void *arg)
+ {
+ a_in_other_thread = &a;
+ return (void *)0;
+ }],
+ [pthread_t thread;
+ void *thread_retval;
+ int *a_in_main_thread;
+ if (pthread_create (&thread, (pthread_attr_t *)0,
+ thread_func, (void *)0))
+ return 0;
+ a_in_main_thread = &a;
+ if (pthread_join (thread, &thread_retval))
+ return 0;
+ return (a_in_other_thread == a_in_main_thread);])],
+ [ax_cv_have_tls=yes], [ax_cv_have_tls=no], [])
+ CFLAGS="$chktls_save_CFLAGS"
+ fi
+ fi],
+ [ax_cv_have_tls=no],
+ [dnl This is the cross-compiling case. Assume libc supports TLS if the
+ dnl binutils and the compiler do.
+ AC_LINK_IFELSE([__thread int a; int b; int main() { return a = b; }],
+ [chktls_save_LDFLAGS="$LDFLAGS"
+ dnl Shared library options may depend on the host; this check
+ dnl is only known to be needed for GNU/Linux.
+ case $host in
+ *-*-linux*)
+ LDFLAGS="-shared -Wl,--no-undefined $LDFLAGS"
+ ;;
+ esac
+ chktls_save_CFLAGS="$CFLAGS"
+ CFLAGS="-fPIC $CFLAGS"
+ dnl If -shared works, test if TLS works in a shared library.
+ AC_LINK_IFELSE([int f() { return 0; }],
+ [AC_LINK_IFELSE([__thread int a; int b; int f() { return a = b; }],
+ [ax_cv_have_tls=yes],
+ [ax_cv_have_tls=no])],
+ [ax_cv_have_tls=yes])
+ CFLAGS="$chktls_save_CFLAGS"
+ LDFLAGS="$chktls_save_LDFLAGS"], [ax_cv_have_tls=no])
+ ]
+ )])
- if test "$ac_cv_tls" != "none"; then
- dnl AC_DEFINE([TLS], [], [If the compiler supports a TLS storage class define it to that here])
- AC_DEFINE_UNQUOTED([TLS], $ac_cv_tls, [If the compiler supports a TLS storage class define it to that here])
+ if test "$enable_tls $ax_cv_have_tls" = "yes yes"; then
+ AC_DEFINE(HAVE_TLS, 1,
+ [Define to 1 if the target supports thread-local storage.])
fi
- AC_MSG_RESULT($ac_cv_tls)
])
projects / util-linux / commitdiff