Backported r187026 from branches/google/gcc-4_6

PTAL at this patch.


2012-03-12  Richard Guenther  <rguenther@suse.de>

	* gthr.h (__GTHREAD_MUTEX_INIT_FUNCTION): Adjust specification.
	* gthr-posix.h (__GTHREAD_MUTEX_INIT_FUNCTION): Define.
	(__gthread_mutex_init_function): New function.
	* gthr-single.h (__GTHREAD_MUTEX_INIT_FUNCTION): Define.

	PR gcov/49484
	* libgcov.c: Include gthr.h.
	(__gcov_flush_mx): New global variable.
	(init_mx, init_mx_once): New functions.
	(__gcov_flush): Protect self with a mutex.
	(__gcov_fork): Re-initialize mutex after forking.
	* unwind-dw2-fde.c: Change condition under which to use
	__GTHREAD_MUTEX_INIT_FUNCTION.

Testing: Built all of ChromeOS with this compiler successfully.
Built bootstrap crosstool with and without the patch and found no regressions.

[asharif, 2012-05-01 21:51:04]

This patch fixes a profile collection issue we see when profiling Chrome.

[asharif, 2012-05-01 22:40:12]

+carrot@

[jingyu, 2012-05-01 22:51:22]

1) Please add an description entry to libgcc/ChangeLog.google-4_6

2) Your gcc/ChangeLog.google-4_6 change reverts someone else's change. Please
update it and also update the time of your entry.

3) Please list in the Description field what tests you have done.

Thanks,
Jing

On 2012/05/01 22:40:12, asharif wrote:
> +carrot@

[asharif, 2012-05-02 18:24:24]

On 2012/05/01 22:51:22, jingyu wrote:
> 1) Please add an description entry to libgcc/ChangeLog.google-4_6

Done.

> 
> 2) Your gcc/ChangeLog.google-4_6 change reverts someone else's change. Please
> update it and also update the time of your entry.

Done.

> 
> 3) Please list in the Description field what tests you have done.

Done.

> 
> Thanks,
> Jing
> 
> On 2012/05/01 22:40:12, asharif wrote:
> > +carrot@

[jingyu, 2012-05-02 20:30:57]

LGTM

On Wed, May 2, 2012 at 11:24 AM,  <asharif@chromium.org> wrote:
> On 2012/05/01 22:51:22, jingyu wrote:
>>
>> 1) Please add an description entry to libgcc/ChangeLog.google-4_6
>
>
> Done.
>
>
>
>> 2) Your gcc/ChangeLog.google-4_6 change reverts someone else's change.
>
> Please
>>
>> update it and also update the time of your entry.
>
>
> Done.
>
>
>
>> 3) Please list in the Description field what tests you have done.
>
>
> Done.
>
>
>> Thanks,
>> Jing
>
>
>> On 2012/05/01 22:40:12, asharif wrote:
>> > +carrot@
>
>
>
>
> http://codereview.appspot.com/6148044/