Remove overall growth from badness metrics

[Qing Zhao]

> On Jan 6, 2019, at 5:52 PM, Jan Hubicka <hubicka@ucw.cz> wrote:
> 
> Hi,
> this patch removes overall growth from badness metrics.  This code was
> added at a time inliner was purely function size based to give a hint
> that inlining more different functions into all callers is better than
> inlining one called very many times.
> 
> With profile we now have more fine grained information and in all
> tests I did this heuristics seems to be counter-productive now and
> harmful especially on large units where growth estimate gets out of
> date.
> 
> I plan to commit the patch tomorrow after re-testing everything after
> the bugfixes from today and yesterday.  In addition to this have found
> that current inline-unit-growth is too small for LTO of large programs
> (especially Firefox:) and there are important improvements when
> increased from 20 to 30 or 40.  I am re-running C++ benchmarks and other
> tests to decide about precise setting.  Finally I plan to increase
> the new parameters for bit more inlining at -O2 and -Os.

Usually increasing these parameters might increase the compilation time and the 
final code size, do you have any data for compilation time and code size impact from
these parameter change?

thanks.

Qing
> 
> Bootstrapped/regtested x86_64-linux, will commit it tomorrow.
> 
> 	* ipa-inline.c (edge_badness): Do not account overall_growth into
> 	badness metrics.
> Index: ipa-inline.c
> ===================================================================
> --- ipa-inline.c	(revision 267612)
> +++ ipa-inline.c	(working copy)
> @@ -1082,8 +1082,8 @@ edge_badness (struct cgraph_edge *edge,
>   /* When profile is available. Compute badness as:
> 
>                  time_saved * caller_count
> -     goodness =  -------------------------------------------------
> -	         growth_of_caller * overall_growth * combined_size
> +     goodness =  --------------------------------
> +	         growth_of_caller * combined_size
> 
>      badness = - goodness
> 
> @@ -1094,7 +1094,6 @@ edge_badness (struct cgraph_edge *edge,
> 	   || caller->count.ipa ().nonzero_p ())
>     {
>       sreal numerator, denominator;
> -      int overall_growth;
>       sreal inlined_time = compute_inlined_call_time (edge, edge_time);
> 
>       numerator = (compute_uninlined_call_time (edge, unspec_edge_time)
> @@ -1106,73 +1105,6 @@ edge_badness (struct cgraph_edge *edge,
>       else if (caller->count.ipa ().initialized_p ())
> 	numerator = numerator >> 11;
>       denominator = growth;
> -
> -      overall_growth = callee_info->growth;
> -
> -      /* Look for inliner wrappers of the form:
> -
> -	 inline_caller ()
> -	   {
> -	     do_fast_job...
> -	     if (need_more_work)
> -	       noninline_callee ();
> -	   }
> -	 Withhout panilizing this case, we usually inline noninline_callee
> -	 into the inline_caller because overall_growth is small preventing
> -	 further inlining of inline_caller.
> -
> -	 Penalize only callgraph edges to functions with small overall
> -	 growth ...
> -	*/
> -      if (growth > overall_growth
> -	  /* ... and having only one caller which is not inlined ... */
> -	  && callee_info->single_caller
> -	  && !edge->caller->global.inlined_to
> -	  /* ... and edges executed only conditionally ... */
> -	  && edge->sreal_frequency () < 1
> -	  /* ... consider case where callee is not inline but caller is ... */
> -	  && ((!DECL_DECLARED_INLINE_P (edge->callee->decl)
> -	       && DECL_DECLARED_INLINE_P (caller->decl))
> -	      /* ... or when early optimizers decided to split and edge
> -		 frequency still indicates splitting is a win ... */
> -	      || (callee->split_part && !caller->split_part
> -		  && edge->sreal_frequency () * 100
> -		     < PARAM_VALUE
> -			  (PARAM_PARTIAL_INLINING_ENTRY_PROBABILITY)
> -		  /* ... and do not overwrite user specified hints.   */
> -		  && (!DECL_DECLARED_INLINE_P (edge->callee->decl)
> -		      || DECL_DECLARED_INLINE_P (caller->decl)))))
> -	{
> -	  ipa_fn_summary *caller_info = ipa_fn_summaries->get (caller);
> -	  int caller_growth = caller_info->growth;
> -
> -	  /* Only apply the penalty when caller looks like inline candidate,
> -	     and it is not called once and.  */
> -	  if (!caller_info->single_caller && overall_growth < caller_growth
> -	      && caller_info->inlinable
> -	      && caller_info->size
> -		 < (DECL_DECLARED_INLINE_P (caller->decl)
> -		    ? MAX_INLINE_INSNS_SINGLE : MAX_INLINE_INSNS_AUTO))
> -	    {
> -	      if (dump)
> -		fprintf (dump_file,
> -			 "     Wrapper penalty. Increasing growth %i to %i\n",
> -			 overall_growth, caller_growth);
> -	      overall_growth = caller_growth;
> -	    }
> -	}
> -      if (overall_growth > 0)
> -        {
> -	  /* Strongly preffer functions with few callers that can be inlined
> -	     fully.  The square root here leads to smaller binaries at average.
> -	     Watch however for extreme cases and return to linear function
> -	     when growth is large.  */
> -	  if (overall_growth < 256)
> -	    overall_growth *= overall_growth;
> -	  else
> -	    overall_growth += 256 * 256 - 256;
> -	  denominator *= overall_growth;
> -        }
>       denominator *= ipa_fn_summaries->get (caller)->self_size + growth;
> 
>       badness = - numerator / denominator;
> @@ -1182,18 +1114,14 @@ edge_badness (struct cgraph_edge *edge,
> 	  fprintf (dump_file,
> 		   "      %f: guessed profile. frequency %f, count %" PRId64
> 		   " caller count %" PRId64
> -		   " time w/o inlining %f, time with inlining %f"
> -		   " overall growth %i (current) %i (original)"
> -		   " %i (compensated)\n",
> +		   " time w/o inlining %f, time with inlining %f\n",
> 		   badness.to_double (),
> 		   edge->sreal_frequency ().to_double (),
> 		   edge->count.ipa ().initialized_p () ? edge->count.ipa ().to_gcov_type () : -1,
> 		   caller->count.ipa ().initialized_p () ? caller->count.ipa ().to_gcov_type () : -1,
> 		   compute_uninlined_call_time (edge,
> 						unspec_edge_time).to_double (),
> -		   inlined_time.to_double (),
> -		   estimate_growth (callee),
> -		   callee_info->growth, overall_growth);
> +		   inlined_time.to_double ());
> 	}
>     }
>   /* When function local profile is not available or it does not give