From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 14428 invoked by alias); 28 May 2012 05:11:58 -0000 Received: (qmail 14417 invoked by uid 22791); 28 May 2012 05:11:56 -0000 X-SWARE-Spam-Status: No, hits=-3.5 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00 X-Spam-Check-By: sourceware.org Received: from localhost (HELO gcc.gnu.org) (127.0.0.1) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Mon, 28 May 2012 05:11:42 +0000 From: "lyricconch at gmail dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug libstdc++/53504] New: configure script of platform TLS support. Date: Mon, 28 May 2012 06:42:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: libstdc++ X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: lyricconch at gmail dot com X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Changed-Fields: Message-ID: X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org X-SW-Source: 2012-05/txt/msg02619.txt.bz2 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 __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.