Re: [GOOGLE] Unrestrict early inline restrictions for AutoFDO

[Dehao Chen <dehao at google dot com>]

The patch was committed to google-4_8, but it causes problem because
einline sets PARAM_EARLY_INLINING_INSNS = 11. This will cause
recursive inlining at einline stage (e.g. main->foo, foo->bar,
bar->foo) when autofdo is enabled.

The following patch can fix the problem by doing more targetted early inlining:

Index: gcc/predict.c
===================================================================
--- gcc/predict.c (revision 199593)
+++ gcc/predict.c (working copy)
@@ -175,6 +175,8 @@ cgraph_maybe_hot_edge_p (struct cgraph_edge *edge)
       && !maybe_hot_count_p (NULL,
                              edge->count))
     return false;
+  if (flag_auto_profile)
+    return false;
   if (edge->caller->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED
       || (edge->callee
   && edge->callee->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED))

Performance testing on-going...

Dehao

On Wed, May 29, 2013 at 3:44 PM, Dehao Chen <dehao@google.com> wrote:
> OK, I'll commit the early inline part.
>
> Dehao
>
> On Wed, May 29, 2013 at 10:00 AM, Xinliang David Li <davidxl@google.com> wrote:
>> The early inlining part is ok. The tracer optimization should be
>> revisited -- we should have more fine grain control on it (for
>> instance, based on FDO summary -- but that should be common to
>> FDO/LIPO).
>>
>> David
>>
>> On Wed, May 29, 2013 at 9:39 AM, Dehao Chen <dehao@google.com> wrote:
>>> In gcc4-8, the max einline iterations are restricted to 1. For
>>> AutoFDO, this is bad because early inline is not size restricted. This
>>> patch allows einline to do multiple iterations in AutoFDO. It also
>>> enables tracer optimization in AutoFDO.
>>>
>>> Bootstrapped and passed regression test.
>>>
>>> OK for googel-4_8?
>>>
>>> Thanks,
>>> Dehao
>>>
>>> Index: gcc/ipa-inline.c
>>> ===================================================================
>>> --- gcc/ipa-inline.c (revision 199416)
>>> +++ gcc/ipa-inline.c (working copy)
>>> @@ -2161,7 +2161,8 @@ early_inliner (void)
>>>      {
>>>        /* We iterate incremental inlining to get trivial cases of indirect
>>>   inlining.  */
>>> -      while (iterations < PARAM_VALUE (PARAM_EARLY_INLINER_MAX_ITERATIONS)
>>> +      while ((flag_auto_profile
>>> +      || iterations < PARAM_VALUE (PARAM_EARLY_INLINER_MAX_ITERATIONS))
>>>       && early_inline_small_functions (node))
>>>   {
>>>    timevar_push (TV_INTEGRATION);
>>> Index: gcc/opts.c
>>> ===================================================================
>>> --- gcc/opts.c (revision 199416)
>>> +++ gcc/opts.c (working copy)
>>> @@ -1644,6 +1644,8 @@ common_handle_option (struct gcc_options *opts,
>>>   opts->x_flag_peel_loops = value;
>>>        if (!opts_set->x_flag_value_profile_transformations)
>>>   opts->x_flag_value_profile_transformations = value;
>>> +      if (!opts_set->x_flag_tracer)
>>> + opts->x_flag_tracer = value;
>>>        if (!opts_set->x_flag_inline_functions)
>>>   opts->x_flag_inline_functions = value;
>>>        if (!opts_set->x_flag_ipa_cp)