diff options
| author | Paolo Bonzini <bonzini@gnu.org> | 2010-06-10 16:01:32 +0000 |
|---|---|---|
| committer | Paolo Bonzini <bonzini@gnu.org> | 2010-06-10 16:01:32 +0000 |
| commit | 8b4e6b9f21bb2bb2dca5f190f2934702c3ede888 (patch) | |
| tree | fd108602b58d1ba472ec2692f62098157aec0f86 /config/tls.m4 | |
| parent | 3baae9d67ef47142e1d2681aa11a4640414a9748 (diff) | |
| download | gdb-8b4e6b9f21bb2bb2dca5f190f2934702c3ede888.zip gdb-8b4e6b9f21bb2bb2dca5f190f2934702c3ede888.tar.gz gdb-8b4e6b9f21bb2bb2dca5f190f2934702c3ede888.tar.bz2 | |
sync changelog with gcc, plus commit the following patch:
2010-06-09 Iain Sandoe <iains@gcc.gnu.org>
PR bootstrap/43170
* tls.m4 (GCC_CHECK_TLS): Add volatile qualifier to the test
references. Move the main () test reference ahead of
pthread_create(). Add a comment to explain the requirements
of the test.
Diffstat (limited to 'config/tls.m4')
| -rw-r--r-- | config/tls.m4 | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/config/tls.m4 b/config/tls.m4 index ef7e6d0..4e170c8 100644 --- a/config/tls.m4 +++ b/config/tls.m4 @@ -38,11 +38,16 @@ AC_DEFUN([GCC_CHECK_TLS], [ 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) { @@ -51,11 +56,11 @@ AC_DEFUN([GCC_CHECK_TLS], [ }], [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);])], |