https://gcc.gnu.org/g:ed02d762d51d9544aeca52a8b306c2da2f36bd7f
commit r16-1609-ged02d762d51d9544aeca52a8b306c2da2f36bd7f
Author: Jan Hubicka <hubi...@ucw.cz>
Date: Sun Jun 22 06:55:41 2025 +0200
Handle functions with 0 profile in auto-profile
This is the last part of the infrastructure to allow functions with
local profiles and 0 global autofdo counts.
Bootstrapped/regtested x86_64-linux, comitted.
gcc/ChangeLog:
* auto-profile.cc (afdo_set_bb_count): Dump inline stacks
and reasons when lookup failed.
(afdo_set_bb_count): Record info about BBs with zero AFDO count.
(afdo_annotate_cfg): Set profile to global0_afdo if there are
no samples in profile.
Diff:
---
gcc/auto-profile.cc | 69 +++++++++++++++++++++++++++++++++++++++++++----------
1 file changed, 57 insertions(+), 12 deletions(-)
diff --git a/gcc/auto-profile.cc b/gcc/auto-profile.cc
index 202f1083633d..a3832016ba80 100644
--- a/gcc/auto-profile.cc
+++ b/gcc/auto-profile.cc
@@ -914,12 +914,33 @@ autofdo_source_profile::get_callsite_total_count (
get_inline_stack_in_node (gimple_location (edge->call_stmt), &stack,
edge->caller);
+ if (dump_file)
+ {
+ if (!edge->caller->inlined_to)
+ fprintf (dump_file, "Looking up afdo profile for call %s -> %s stack:",
+ edge->caller->dump_name (), edge->callee->dump_name ());
+ else
+ fprintf (dump_file, "Looking up afdo profile for call %s -> %s
transitively %s stack:",
+ edge->caller->dump_name (), edge->callee->dump_name (),
+ edge->caller->inlined_to->dump_name ());
+ dump_inline_stack (dump_file, &stack);
+ }
function_instance *s = get_function_instance_by_inline_stack (stack);
- if (s == NULL
- ||(afdo_string_table->get_index_by_decl (edge->callee->decl)
- != s->name()))
- return 0;
+ if (s == NULL)
+ {
+ if (dump_file)
+ fprintf (dump_file, "No function instance found\n");
+ return 0;
+ }
+ if (afdo_string_table->get_index_by_decl (edge->callee->decl) != s->name ())
+ {
+ if (dump_file)
+ fprintf (dump_file, "Mismatched name of callee %s and profile %s\n",
+ IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (edge->callee->decl)),
+ afdo_string_table->get_name (s->name ()));
+ return 0;
+ }
return s->total_count () * afdo_count_scale;
}
@@ -1263,7 +1284,7 @@ update_count_by_afdo_count (profile_count *count,
gcov_type c)
Return TRUE if BB is annotated. */
static bool
-afdo_set_bb_count (basic_block bb)
+afdo_set_bb_count (basic_block bb, hash_set <basic_block> &zero_bbs)
{
gimple_stmt_iterator gsi;
gcov_type max_count = 0;
@@ -1348,6 +1369,13 @@ afdo_set_bb_count (basic_block bb)
(int64_t)(max_count * afdo_count_scale));
return true;
}
+ else
+ {
+ if (dump_file)
+ fprintf (dump_file,
+ " bb %i has statements with 0 count\n", bb->index);
+ zero_bbs.add (bb);
+ }
return false;
}
@@ -2050,9 +2078,10 @@ afdo_annotate_cfg (void)
/* In the first pass only store non-zero counts. */
gcov_type head_count = s->head_count () * autofdo::afdo_count_scale;
bool profile_found = head_count > 0;
+ hash_set <basic_block> zero_bbs;
FOR_EACH_BB_FN (bb, cfun)
{
- if (afdo_set_bb_count (bb))
+ if (afdo_set_bb_count (bb, zero_bbs))
{
if (bb->count.quality () == AFDO)
{
@@ -2063,14 +2092,30 @@ afdo_annotate_cfg (void)
}
}
/* Exit without clobbering static profile if there was no
- non-zero count.
- ??? Instead of keeping guessed profile we can introduce
- GUESSED_GLOBAL0_AFDO. */
+ non-zero count. */
if (!profile_found)
{
- if (dump_file)
- fprintf (dump_file, "No afdo samples found"
- "; keeping original profile\n");
+ /* create_gcov only dumps symbols with some samples in them.
+ This means that we get nonempty zero_bbs only if some
+ nonzero counts in profile were not matched with statements.
+ ??? We can adjust create_gcov to also recordinfo
+ about function with no samples. Then we can distinguish
+ between lost profiles which should be kept local and
+ real functions with 0 samples during train run. */
+ if (zero_bbs.is_empty ())
+ {
+ if (dump_file)
+ fprintf (dump_file, "No afdo samples found"
+ "; Setting global count to afdo0\n");
+ }
+ else
+ {
+ if (dump_file)
+ fprintf (dump_file, "Setting global count to afdo0\n");
+ }
+ FOR_ALL_BB_FN (bb, cfun)
+ if (bb->count.quality () == GUESSED_LOCAL)
+ bb->count = bb->count.global0afdo ();
loop_optimizer_finalize ();
free_dominance_info (CDI_DOMINATORS);
