chktls_save_LDFLAGS="$LDFLAGS"
LDFLAGS="-static $LDFLAGS"
AC_LINK_IFELSE([int main() { return 0; }],
- AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }],
- [gcc_cv_have_tls=yes], [gcc_cv_have_tls=no],[]),
+ [AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }],
+ [gcc_cv_have_tls=yes], [gcc_cv_have_tls=no],[])],
[gcc_cv_have_tls=yes])
LDFLAGS="$chktls_save_LDFLAGS"
if test $gcc_cv_have_tls = yes; then
CFLAGS="$chktls_save_CFLAGS"
if test "X$thread_CFLAGS" != Xfailed; then
CFLAGS="$thread_CFLAGS $chktls_save_CFLAGS"
+ dnl Test for an old glibc bug that violated the __thread property.
+ dnl Use volatile to ensure the compiler won't optimize away pointer
+ dnl accesses it might otherwise assume to be redundant, or reorder
+ dnl them and reuse storage, which might lead to them pointing to
+ dnl the same location.
AC_RUN_IFELSE(
[AC_LANG_PROGRAM(
[#include <pthread.h>
__thread int a;
- static int *a_in_other_thread;
+ static int *volatile a_in_other_thread;
static void *
thread_func (void *arg)
{
}],
[pthread_t thread;
void *thread_retval;
- int *a_in_main_thread;
+ int *volatile a_in_main_thread;
+ a_in_main_thread = &a;
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);])],