[PATCH, 4.9/4.10] Profile based option tuning

Pengfei Yuan 0xcoolypf@gmail.com
Wed Jul 23 11:29:00 GMT 2014


I guess some optimizations are controlled only by "optimize_size", not
by the profile.
Other optimizations are controlled by the profile.
So this patch does not have very much effectiveness (only 0.9% size reduction).

2014-07-23 17:26 GMT+08:00 Richard Biener <richard.guenther@gmail.com>:
> On Wed, Jul 23, 2014 at 2:39 AM, Pengfei Yuan <0xcoolypf@gmail.com> wrote:
>> In the experiment, about 60% (1019/1699) profile data files are empty
>> (all counters are zero).
>
> Well, but you are globally overriding options even for the parts with
> profile.  The whole point of profile-feedback is to get at the interesting
> parts (those with non-zero counters).
>
> What you say is that not enough parts of the compiler care for
> the actual profiles and thus portions with all-zero counters are
> treated as if they were hot?  Then better fix that.
>
> Richard.
>
>> 2014-07-22 21:39 GMT+08:00 Richard Biener <richard.guenther@gmail.com>:
>>> On Mon, Jul 21, 2014 at 7:13 AM, Pengfei Yuan <0xcoolypf@gmail.com> wrote:
>>>> Hi,
>>>>
>>>> This patch tunes optimization options based on profile data:
>>>> * Disable PGO options if profile is not available or empty.
>>>> * Optimize for size if profile is available but empty.
>>>
>>> Err ... these don't seem interesting cases to "optimize" for?
>>>
>>> Richard.



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