[Bug gcov-profile/55674] [4.8 Regression] >20% size increase of lto/pgo binaries since r193747

[tejohnson at google dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55674

--- Comment #20 from Teresa Johnson <tejohnson at google dot com> 2012-12-21 16:26:17 UTC ---
On Fri, Dec 21, 2012 at 8:15 AM, hubicka at ucw dot cz
<gcc-bugzilla@gcc.gnu.org> wrote:
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55674
>
> --- Comment #19 from Jan Hubicka <hubicka at ucw dot cz> 2012-12-21 16:15:34 UTC ---
>> As another data point, in our internal benchmarks I had tried a few
>> values and 99.9% gave the best performance. Just going down to 99.0%
>> reduced the inlining too much, even compared to the old static cutoff
>> count, missing some key inlines and reducing performance.
> this really should not happen too much.  I still think something along the
> following lines
> is desirable.  Does it helps setting more resonable threshold?

I'll give this patch a try and let you know how it affects the
performance I see. But unrolling shouldn't affect inlining, since all
unrolling is after inlining, right?

Thanks,
Teresa

>
> Honza
>
> Index: predict.c
> ===================================================================
> *** predict.c    (revision 194655)
> --- predict.c    (working copy)
> *************** maybe_hot_count_p (struct function *fun,
> *** 145,151 ****
>       {
>         ws = find_working_set (PARAM_VALUE (HOT_BB_COUNT_WS_PERMILLE));
>         gcc_assert (ws);
> !       min_count = ws->min_counter;
>       }
>     return (count >= min_count);
>   }
> --- 145,156 ----
>       {
>         ws = find_working_set (PARAM_VALUE (HOT_BB_COUNT_WS_PERMILLE));
>         gcc_assert (ws);
> !
> !       /* We want all counters above ws->min_counter * profile_info->runs
> !      to be safely identified as hot regions.  This may be spoiled
> !      by optimizations such as unrolling that reduce counts of the
> !      body, thus divide by 32.  */
> !       min_count = ws->min_counter / 32;
>       }
>     return (count >= min_count);
>   }
>
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