[Patch, libfortran] PR 47571 Some janitorial cleanup

[Jerry DeLisle]

On 02/03/2011 04:45 AM, Janne Blomqvist wrote:
> On Wed, Feb 2, 2011 at 21:23, Janne Blomqvist<blomqvist.janne@gmail.com>  wrote:
>> Hi,
>>
>> I reviewed the Gfortran time intrinsics, both standard and extensions,
>> and AFAIK the only place where a monotonic clock fits the API, and
>> where we can expose high resolution, is the SYSTEM_CLOCK intrinsic.
>>
>> Now, due to the PR 47571 fix where we now call clock_gettime() via a
>> weakref, some of the original reason behind the gf_gettime() wrapper
>> has been lost, as now we still need to include fallback code in case
>> the weakref is not available. This needlessly bloats the code for
>> date_and_time() which is unable to use either the extra precision and
>> needs a realtime clock, not a monotonic clock. Additionally, in some
>> not quite bleeding edge Linux kernels, gettimeofday() is a vsyscall
>> and clock_gettime() isn't, leading to higher overhead for no benefit
>> (the difference is something like 1e6 vs 1e7 calls/s on current hw, so
>> it's exceedingly unlikely to actually matter in reality).  The only
>> fly in the ointment here is that POSIX 2008 has marked gettimeofday()
>> as obsolescent, however I don't see this mattering in reality for the
>> foreseeable future.
>>
>> The attached patch moves all the weakref trickery and clock_gettime()
>> usage from time_1.h to system_clock.c, where the only benefactor also
>> lives.
>
> Hi,
>
> updated patch attached. Compared to the previous one this might fix
> the build regression reported on HP-UX which does support weak symbols
> but apparently does barf on weak undefined references. This is done in
> a slightly kludgy way, in that in acinclude.m4 we previously have set
> GTHREAD_USE_WEAK to 0 for such targets, hence in the updated patch
> GTHREAD_USE_WEAK is defined and set to 1 if it's not previously
> present, and then we check for both SUPPORTS_WEAK and
> GTHREAD_USE_WEAK.
>
> 2011-02-03  Janne Blomqvist<jb@gcc.gnu.org>
>
> 	PR libfortran/47571
> 	* intrinsics/time_1.h (GF_CLOCK_MONOTONIC): Move to system_clock.c.
> 	(weak_gettime): Likewise.
> 	(gf_gettime): Change API, move weak_gettime() usage to
> 	system_clock.c
> 	* intrinsics/system_clock.c (GTHREAD_USE_WEAK): Define.
> 	(gf_gettime_mono): New function.
> 	(system_clock_4): Use gf_gettime_mono().
> 	(system_clock_8): Likewise.
> 	* intrinsics/date_and_time.c (date_and_time): Update gf_gettime()
> 	usage.
>
> Regtested on x86_64-unknown-linux-gnu, Ok for trunk?
>

OK and thanks for patch.

Jerry