https://gcc.gnu.org/g:a4dc4001999a8b504cde468618af12c9b870589b
commit r16-929-ga4dc4001999a8b504cde468618af12c9b870589b
Author: Jan Hubicka <hubi...@ucw.cz>
Date: Wed May 28 14:18:39 2025 +0200
Do not recompute profile when entry block has afdo count of 0
With normal profile feedback checking entry block count to be non-zero is
quite
reliable check for presence of non-0 profile in the body since the function
body can only be executed if the entry block was executed. With autofdo
this
is not true, since the entry block may just execute too few times to be
recorded. As a consequence we currently drop AFDO profile quite often.
This
patch fixes it.
gcc/ChangeLog:
* predict.cc (rebuild_frequencies): look harder for presence
of profile feedback.
Diff:
---
gcc/predict.cc | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/gcc/predict.cc b/gcc/predict.cc
index 16dd9b01112b..872f54d957a5 100644
--- a/gcc/predict.cc
+++ b/gcc/predict.cc
@@ -4444,11 +4444,14 @@ rebuild_frequencies (void)
bool inconsistency_found = false;
bool uninitialized_probablity_found = false;
bool uninitialized_count_found = false;
+ bool feedback_found = false;
cfun->cfg->count_max = profile_count::uninitialized ();
FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb)
{
cfun->cfg->count_max = cfun->cfg->count_max.max (bb->count);
+ if (bb->count.nonzero_p () && bb->count.quality () >= AFDO)
+ feedback_found = true;
/* Uninitialized count may be result of inlining or an omision in an
optimization pass. */
if (!bb->count.initialized_p ())
@@ -4516,8 +4519,7 @@ rebuild_frequencies (void)
Propagating from probabilities would make profile look consistent, but
because probablities after code duplication may not be representative
for a given run, we would only propagate the error further. */
- if (ENTRY_BLOCK_PTR_FOR_FN (cfun)->count.ipa ().nonzero_p ()
- && !uninitialized_count_found)
+ if (feedback_found && !uninitialized_count_found)
{
if (dump_file)
fprintf (dump_file,
