Hi,
This patch fixes problems I noticed by exploring profiles of some hot
functions in GCC. In particular the propagation sometimes changed
precise 0 to afdo 0 for paths calling abort and sometimes we could
propagate more when we accept that some paths has 0 count.
Finally there was important bug in computing all_known which
resulted in BB probabilities to be quite broken after afdo.
Bootstrapped/regtested x86_64-linux, comitted.
gcc/ChangeLog:
* auto-profile.cc (update_count_by_afdo_count): Make static;
add variant accepting profile_count.
(afdo_find_equiv_class): Use update_count_by_afdo_count.
(afdo_propagate_edge): Likewise.
(afdo_propagate): Likewise.
(afdo_calculate_branch_prob): Fix handling of all_known.
(afdo_annotate_cfg): Annotate by 0 where both afdo and static
profile agrees.
diff --git a/gcc/auto-profile.cc b/gcc/auto-profile.cc
index a3832016ba8..9b5be665f58 100644
--- a/gcc/auto-profile.cc
+++ b/gcc/auto-profile.cc
@@ -1265,8 +1265,8 @@ set_bb_annotated (basic_block bb, bb_set *annotated)
annotated->insert (bb);
}
-/* Update profile_count by known autofdo count. */
-void
+/* Update COUNT by known autofdo count C. */
+static void
update_count_by_afdo_count (profile_count *count, gcov_type c)
{
if (c)
@@ -1279,6 +1279,19 @@ update_count_by_afdo_count (profile_count *count,
gcov_type c)
*count = profile_count::zero ().afdo ();
}
+/* Update COUNT by known autofdo count C. */
+static void
+update_count_by_afdo_count (profile_count *count, profile_count c)
+{
+ if (c.nonzero_p ())
+ *count = c;
+ /* In case we have guessed profile which is already zero, preserve
+ quality info. */
+ else if (count->nonzero_p ()
+ || count->quality () < c.quality ())
+ *count = c;
+}
+
/* For a given BB, set its execution count. Attach value profile if a stmt
is not in PROMOTED, because we only want to promote an indirect call once.
Return TRUE if BB is annotated. */
@@ -1419,7 +1432,7 @@ afdo_find_equiv_class (bb_set *annotated_bb)
bb1->count.dump (dump_file);
fprintf (dump_file, "\n");
}
- bb->count = bb1->count;
+ update_count_by_afdo_count (&bb->count, bb1->count);
set_bb_annotated (bb, annotated_bb);
}
}
@@ -1442,7 +1455,7 @@ afdo_find_equiv_class (bb_set *annotated_bb)
bb1->count.dump (dump_file);
fprintf (dump_file, "\n");
}
- bb->count = bb1->count;
+ update_count_by_afdo_count (&bb->count, bb1->count);
set_bb_annotated (bb, annotated_bb);
}
}
@@ -1505,7 +1518,7 @@ afdo_propagate_edge (bool is_succ, bb_set *annotated_bb)
total_known_count.dump (dump_file);
fprintf (dump_file, "\n");
}
- bb->count = total_known_count;
+ update_count_by_afdo_count (&bb->count, total_known_count);
set_bb_annotated (bb, annotated_bb);
changed = true;
}
@@ -1531,7 +1544,7 @@ afdo_propagate_edge (bool is_succ, bb_set *annotated_bb)
}
else if (num_unknown_edges > 1
&& is_bb_annotated (bb, *annotated_bb)
- && total_known_count >= bb->count)
+ && (total_known_count >= bb->count || !bb->count.nonzero_p ()))
{
FOR_EACH_EDGE (e, ei, is_succ ? bb->succs : bb->preds)
{
@@ -1671,7 +1684,7 @@ afdo_propagate (bb_set *annotated_bb)
if (!is_bb_annotated (bb, *annotated_bb)
&& is_bb_annotated ((basic_block)bb->aux, *annotated_bb))
{
- bb->count = ((basic_block)bb->aux)->count;
+ update_count_by_afdo_count (&bb->count, ((basic_block)bb->aux)->count);
set_bb_annotated (bb, annotated_bb);
if (dump_file)
{
@@ -1994,7 +2007,7 @@ afdo_calculate_branch_prob (bb_set *annotated_bb)
FOR_EACH_BB_FN (bb, cfun)
if (is_bb_annotated (bb, *annotated_bb))
{
- bool all_known = false;
+ bool all_known = true;
profile_count total_count = profile_count::zero ().afdo ();
FOR_EACH_EDGE (e, ei, bb->succs)
@@ -2006,7 +2019,7 @@ afdo_calculate_branch_prob (bb_set *annotated_bb)
still propagate the rest. */
if (e->probability.nonzero_p ())
{
- all_known = true;
+ all_known = false;
break;
}
}
@@ -2091,6 +2104,22 @@ afdo_annotate_cfg (void)
set_bb_annotated (bb, &annotated_bb);
}
}
+ /* We try to preserve static profile for BBs with 0
+ afdo samples, but if even static profile agrees with 0,
+ consider it final so propagation works better. */
+ for (basic_block bb : zero_bbs)
+ if (bb->count.nonzero_p ())
+ {
+ update_count_by_afdo_count (&bb->count, 0);
+ set_bb_annotated (bb, &annotated_bb);
+ if (dump_file)
+ {
+ fprintf (dump_file, " Annotating bb %i with count ", bb->index);
+ bb->count.dump (dump_file);
+ fprintf (dump_file,
+ " (has 0 count in both static and afdo profile)\n");
+ }
+ }
/* Exit without clobbering static profile if there was no
non-zero count. */
if (!profile_found)
