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[Bug libstdc++/53504] New: configure script of platform TLS support.
- From: "lyricconch at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Mon, 28 May 2012 05:11:41 +0000
- Subject: [Bug libstdc++/53504] New: configure script of platform TLS support.
- Auto-submitted: auto-generated
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53504
Bug #: 53504
Summary: configure script of platform TLS support.
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: lyricconch@gmail.com
file: gcc-4.70/stdc++v3/configure
line: 51506
#include <pthread.h>
__thread int a;
static int *volatile a_in_other_thread;
static void *
thread_func (void *arg)
{
a_in_other_thread = &a;
return (void *)0;
}
int
main ()
{
pthread_t thread;
void *thread_retval;
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;
if (pthread_join (thread, &thread_retval))
return 0;
return (a_in_other_thread == a_in_main_thread);
;
return 0;
}
_ACEOF
if ac_fn_c_try_run "$LINENO"; then :
gcc_cv_have_tls=yes
else
gcc_cv_have_tls=no
fi
1. if we have TLS support, &a will be difference value in main() and
hread_func(), which means (a_in_other_thread == a_in_main_thread) eval to
false.
so, with TLS support => program exit with 0.
2. if "pthread_create" or "pthread_join" fails, program also exit with 0. "no
threads, no TLS".
so, without TLS support => program exit with 0.
whatever ac_fn_c_try_run get, this can not be right.