After inline summary is recomputed, the large code growth problem will
also be better controlled, right?
David
On Thu, Nov 13, 2014 at 2:48 PM, Xinliang David Li <davi...@google.com> wrote:
> Is there a need to have 10 iterations of early inline for autofdo?
>
> David
>
> On Thu, Nov 13, 2014 at 2:25 PM, Dehao Chen <de...@google.com> wrote:
>> In AutoFDO, we increase einline iterations. This could lead to
>> extensive code bloat if we have recursive calls like:
>>
>> dtor() {
>> destroy(node);
>> }
>>
>> destroy(node) {
>> destroy(left)
>> destroy(right)
>> }
>>
>> In this case, the size growth will be around 8 which is smaller than
>> threshold (11). However, if we allow this to happen for 2 iterations,
>> it will expand the size by 1024X. To fix this problem, we want to set
>> a much smaller threshold in the AutoFDO case. This is because AutoFDO
>> do not not rely on aggressive einline to gain more profile context.
>>
>> And also, in AutoFDO pass, after we processed a function, we need to
>> recompute inline parameters because rebuild_cgraph_edges will zero out
>> all inline parameters.
>>
>> The patch is attached below, bootstrapped and perf test on-going. OK
>> for google-4_9?
>>
>> Thanks,
>> Dehao
>>
>> Index: gcc/auto-profile.c
>> ===================================================================
>> --- gcc/auto-profile.c (revision 217523)
>> +++ gcc/auto-profile.c (working copy)
>> @@ -1771,6 +1771,7 @@ auto_profile (void)
>> free_dominance_info (CDI_DOMINATORS);
>> free_dominance_info (CDI_POST_DOMINATORS);
>> rebuild_cgraph_edges ();
>> + compute_inline_parameters (cgraph_get_node
>> (current_function_decl), true);
>> pop_cfun ();
>> }
>>
>> Index: gcc/opts.c
>> ===================================================================
>> --- gcc/opts.c (revision 217523)
>> +++ gcc/opts.c (working copy)
>> @@ -1853,6 +1853,12 @@ common_handle_option (struct gcc_options *opts,
>> maybe_set_param_value (
>> PARAM_EARLY_INLINER_MAX_ITERATIONS, 10,
>> opts->x_param_values, opts_set->x_param_values);
>> + maybe_set_param_value (
>> + PARAM_EARLY_INLINING_INSNS, 4,
>> + opts->x_param_values, opts_set->x_param_values);
>> + maybe_set_param_value (
>> + PARAM_EARLY_INLINING_INSNS_COMDAT, 4,
>> + opts->x_param_values, opts_set->x_param_values);
>> value = true;
>> /* No break here - do -fauto-profile processing. */
>> case OPT_fauto_profile:
