The difference in instrumentation runtime is huge -- as topn profiler
is pretty expensive to run.
With FDO, it is probably better to make early inlining more aggressive
in order to get more context sensitive profiling.
David
On Sat, Oct 18, 2014 at 10:05 AM, Jan Hubicka <hubi...@ucw.cz> wrote:
>> Increasing the number of early inliner iterations from 1 to 2 enables more
>> indirect calls to be promoted/inlined before instrumentation. This in turn
>> reduces the instrumentation overhead, particularly for more expensive
>> indirect
>> call topn profiling.
>
> How much difference you get here? One posibility would be also to run
> specialized
> ipa-cp before profile instrumentation.
>
> Honza
>>
>> Passes internal testing and regression tests. Ok for google/4_9?
>>
>> 2014-10-18 Teresa Johnson <tejohn...@google.com>
>>
>> Google ref b/17934523
>> * opts.c (finish_options): Increase max-early-inliner-iterations to 2
>> for profile-gen and profile-use builds.
>>
>> Index: opts.c
>> ===================================================================
>> --- opts.c (revision 216286)
>> +++ opts.c (working copy)
>> @@ -870,6 +869,14 @@ finish_options (struct gcc_options *opts, struct g
>> opts->x_param_values, opts_set->x_param_values);
>> }
>>
>> + if (opts->x_profile_arc_flag
>> + || opts->x_flag_branch_probabilities)
>> + {
>> + maybe_set_param_value
>> + (PARAM_EARLY_INLINER_MAX_ITERATIONS, 2,
>> + opts->x_param_values, opts_set->x_param_values);
>> + }
>> +
>> if (!(opts->x_flag_auto_profile
>> || (opts->x_profile_arc_flag || opts->x_flag_branch_probabilities)))
>> {
>>
>>
>> --
>> Teresa Johnson | Software Engineer | tejohn...@google.com | 408-460-2413
