> On Mon, Oct 6, 2014 at 11:22 AM, Jan Hubicka <hubi...@ucw.cz> wrote:
> > Rong,
> > Would be possible to use topn profiler to get resonale histograms for switch
> > expansion, too? In that case it may make sense to have value version of it
> > as well.
>
> The underlying topn_profiler can be used the same way as the current
> one_value profiler for different scenarios. However, I wonder if it is
> useful for switch value profiling -- the arc profiling can do the
> same.
Well, for switch expansion one really wants a histogram of values across the
switch
values for the decision tree balancing. But I guess this profiler does not fit
that very well.
Consider cases like
switch (a)
{
case 3:
case 5:
case 7:
prime();
case 2:
case 4:
case 6:
even();
default:
bogus ();
}
Arc profiling does tell you how often a is prime or even, but it does not help
you
to balance the tree, because the value ranges are iinterlacing
>
> David
>
> >
> > Otherwise the patch seems OK. I would implement it myself by introducing
> > separate
> > variables holding the topn profiler declaration, but can not think of
> > downsides of
> > doing it your way.
> >
> > The topn profiler should be better on determining the dominating target, so
> > perhaps
> > you could look into hooking it into ipa-profile.c. Extending speculative
> > edges for
> > multiple targets ought to be also quite easy - we need to update
> > speculative_call_info
> > to collect edges annotated to a given call stmt into a vector instead of
> > taking the
> > two references it does now.
> >
> > It would be also very nice to update it to handle case where all the edges
> > are direct
> > so we can use it tospeculatively inlinine functions that can be interposed
> > at runtime.
> >
> > Thanks,
> > Honza
> >
> > Index: gcc/tree-profile.c
> > ===================================================================
> > --- gcc/tree-profile.c (revision 215886)
> > +++ gcc/tree-profile.c (working copy)
> > @@ -56,6 +56,7 @@ along with GCC; see the file COPYING3. If not see
> > #include "target.h"
> > #include "tree-cfgcleanup.h"
> > #include "tree-nested.h"
> > +#include "params.h"
> >
> > static GTY(()) tree gcov_type_node;
> > static GTY(()) tree tree_interval_profiler_fn;
> > @@ -101,7 +102,10 @@ init_ic_make_global_vars (void)
> > {
> > ic_void_ptr_var
> > = build_decl (UNKNOWN_LOCATION, VAR_DECL,
> > - get_identifier ("__gcov_indirect_call_callee"),
> > + get_identifier (
> > + (PARAM_VALUE (PARAM_INDIR_CALL_TOPN_PROFILE) ?
> > + "__gcov_indirect_call_topn_callee" :
> > + "__gcov_indirect_call_callee")),
> > ptr_void);
> > TREE_PUBLIC (ic_void_ptr_var) = 1;
> > DECL_EXTERNAL (ic_void_ptr_var) = 1;
> > @@ -131,7 +135,10 @@ init_ic_make_global_vars (void)
> > {
> > ic_gcov_type_ptr_var
> > = build_decl (UNKNOWN_LOCATION, VAR_DECL,
> > - get_identifier ("__gcov_indirect_call_counters"),
> > + get_identifier (
> > + (PARAM_VALUE (PARAM_INDIR_CALL_TOPN_PROFILE) ?
> > + "__gcov_indirect_call_topn_counters" :
> > + "__gcov_indirect_call_counters")),
> > gcov_type_ptr);
> > TREE_PUBLIC (ic_gcov_type_ptr_var) = 1;
> > DECL_EXTERNAL (ic_gcov_type_ptr_var) = 1;
> > @@ -226,8 +233,10 @@ gimple_init_edge_profiler (void)
> > ptr_void,
> > NULL_TREE);
> > tree_indirect_call_profiler_fn
> > - = build_fn_decl ("__gcov_indirect_call_profiler_v2",
> > - ic_profiler_fn_type);
> > + = build_fn_decl ( (PARAM_VALUE
> > (PARAM_INDIR_CALL_TOPN_PROFILE) ?
> > + "__gcov_indirect_call_topn_profiler":
> > + "__gcov_indirect_call_profiler_v2"),
> > + ic_profiler_fn_type);
> > }
> > TREE_NOTHROW (tree_indirect_call_profiler_fn) = 1;
> > DECL_ATTRIBUTES (tree_indirect_call_profiler_fn)
> > @@ -398,6 +407,12 @@ gimple_gen_ic_profiler (histogram_value value, uns
> > gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
> > tree ref_ptr = tree_coverage_counter_addr (tag, base);
> >
> > + if ( (PARAM_VALUE (PARAM_INDIR_CALL_TOPN_PROFILE) &&
> > + tag == GCOV_COUNTER_V_INDIR) ||
> > + (!PARAM_VALUE (PARAM_INDIR_CALL_TOPN_PROFILE) &&
> > + tag == GCOV_COUNTER_ICALL_TOPNV))
> > + return;
> > +
> > ref_ptr = force_gimple_operand_gsi (&gsi, ref_ptr,
> > true, NULL_TREE, true, GSI_SAME_STMT);
> >
> > @@ -442,8 +457,7 @@ gimple_gen_ic_func_profiler (void)
> > stmt1: __gcov_indirect_call_profiler_v2 (profile_id,
> > ¤t_function_decl)
> > */
> > - gsi =
> > - gsi_after_labels (split_edge
> > (single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun))));
> > + gsi = gsi_after_labels (split_edge (single_succ_edge
> > (ENTRY_BLOCK_PTR_FOR_FN (cfun))));
> >
> > cur_func = force_gimple_operand_gsi (&gsi,
> > build_addr (current_function_decl,
> > Index: gcc/value-prof.c
> > ===================================================================
> > --- gcc/value-prof.c (revision 215886)
> > +++ gcc/value-prof.c (working copy)
> > @@ -60,6 +60,7 @@ along with GCC; see the file COPYING3. If not see
> > #include "builtins.h"
> > #include "tree-nested.h"
> > #include "hash-set.h"
> > +#include "params.h"
> >
> > /* In this file value profile based optimizations are placed. Currently
> > the
> > following optimizations are implemented (for more detailed descriptions
> > @@ -359,6 +360,22 @@ dump_histogram_value (FILE *dump_file, histogram_v
> > }
> > fprintf (dump_file, ".\n");
> > break;
> > + case HIST_TYPE_INDIR_CALL_TOPN:
> > + fprintf (dump_file, "Indirect call topn ");
> > + if (hist->hvalue.counters)
> > + {
> > + int i;
> > +
> > + fprintf (dump_file, "accu:%"PRId64, hist->hvalue.counters[0]);
> > + for (i = 1; i < (GCOV_ICALL_TOPN_VAL << 2); i += 2)
> > + {
> > + fprintf (dump_file, " target:%"PRId64 " value:%"PRId64,
> > + (int64_t) hist->hvalue.counters[i],
> > + (int64_t) hist->hvalue.counters[i+1]);
> > + }
> > + }
> > + fprintf (dump_file, ".\n");
> > + break;
> > case HIST_TYPE_MAX:
> > gcc_unreachable ();
> > }
> > @@ -432,9 +449,14 @@ stream_in_histogram_value (struct lto_input_block
> > break;
> >
> > case HIST_TYPE_IOR:
> > - case HIST_TYPE_TIME_PROFILE:
> > + case HIST_TYPE_TIME_PROFILE:
> > ncounters = 1;
> > break;
> > +
> > + case HIST_TYPE_INDIR_CALL_TOPN:
> > + ncounters = (GCOV_ICALL_TOPN_VAL << 2) + 1;
> > + break;
> > +
> > case HIST_TYPE_MAX:
> > gcc_unreachable ();
> > }
> > @@ -1920,8 +1942,12 @@ gimple_indirect_call_to_profile (gimple stmt, hist
> >
> > values->reserve (3);
> >
> > - values->quick_push (gimple_alloc_histogram_value (cfun,
> > HIST_TYPE_INDIR_CALL,
> > - stmt, callee));
> > + values->quick_push (gimple_alloc_histogram_value (
> > + cfun,
> > + PARAM_VALUE (PARAM_INDIR_CALL_TOPN_PROFILE) ?
> > + HIST_TYPE_INDIR_CALL_TOPN :
> > + HIST_TYPE_INDIR_CALL,
> > + stmt, callee));
> >
> > return;
> > }
> > @@ -2011,9 +2037,9 @@ gimple_find_values_to_profile (histogram_values *v
> > hist->n_counters = 3;
> > break;
> >
> > - case HIST_TYPE_TIME_PROFILE:
> > - hist->n_counters = 1;
> > - break;
> > + case HIST_TYPE_TIME_PROFILE:
> > + hist->n_counters = 1;
> > + break;
> >
> > case HIST_TYPE_AVERAGE:
> > hist->n_counters = 2;
> > @@ -2023,6 +2049,10 @@ gimple_find_values_to_profile (histogram_values *v
> > hist->n_counters = 1;
> > break;
> >
> > + case HIST_TYPE_INDIR_CALL_TOPN:
> > + hist->n_counters = GCOV_ICALL_TOPN_NCOUNTS;
> > + break;
> > +
> > default:
> > gcc_unreachable ();
> > }
> > Index: gcc/value-prof.h
> > ===================================================================
> > --- gcc/value-prof.h (revision 215886)
> > +++ gcc/value-prof.h (working copy)
> > @@ -35,6 +35,8 @@ enum hist_type
> > HIST_TYPE_AVERAGE, /* Compute average value (sum of all values). */
> > HIST_TYPE_IOR, /* Used to compute expected alignment. */
> > HIST_TYPE_TIME_PROFILE, /* Used for time profile */
> > + HIST_TYPE_INDIR_CALL_TOPN, /* Tries to identify the top N most frequently
> > + called functions in indirect call. */
> > HIST_TYPE_MAX
> > };
> >
> > Index: gcc/profile.c
> > ===================================================================
> > --- gcc/profile.c (revision 215886)
> > +++ gcc/profile.c (working copy)
> > @@ -183,6 +183,7 @@ instrument_values (histogram_values values)
> > break;
> >
> > case HIST_TYPE_INDIR_CALL:
> > + case HIST_TYPE_INDIR_CALL_TOPN:
> > gimple_gen_ic_profiler (hist, t, 0);
> > break;
> >
