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re PR middle-end/38074 (missed inlining on Core2 Duo due to apparent wrong branch prediction/profile)

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PR tree-optimization/38074
	* cgraphbuild.c (compute_call_stmt_bb_frequency): Fix handling of 0
	entry frequency.
	* predict.c (combine_predictions_for_bb): Ignore predictor predicting
	in both dirrection for first match heuristics.
	(tree_bb_level_predictions): Disable noreturn heuristic when there
	is no returning path.

Co-Authored-By: Jakub Jelinek <jakub@redhat.com>

From-SVN: r142517
This commit is contained in:
Jan Hubicka 2008-12-06 09:34:20 +01:00 • committed by Jan Hubicka
parent abc79c3a6d
commit c0ee00211f
3 changed files with 52 additions and 6 deletions
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11
gcc/ChangeLog
View file

@ -1,3 +1,14 @@
2008-12-06 Jan Hubicka <jh@suse.cz>
Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/38074
* cgraphbuild.c (compute_call_stmt_bb_frequency): Fix handling of 0
entry frequency.
* predict.c (combine_predictions_for_bb): Ignore predictor predicting
in both dirrection for first match heuristics.
(tree_bb_level_predictions): Disable noreturn heuristic when there
is no returning path.
2008-12-05 Bernd Schmidt <bernd.schmidt@analog.com>
PR rtl-optimization/38272

7
gcc/cgraphbuild.c
View file

@ -109,13 +109,12 @@ int
compute_call_stmt_bb_frequency (basic_block bb)
{
int entry_freq = ENTRY_BLOCK_PTR->frequency;
int freq;
int freq = bb->frequency;
if (!entry_freq)
entry_freq = 1;
entry_freq = 1, freq++;
freq = (!bb->frequency && !entry_freq ? CGRAPH_FREQ_BASE
: bb->frequency * CGRAPH_FREQ_BASE / entry_freq);
freq = freq * CGRAPH_FREQ_BASE / entry_freq;
if (freq > CGRAPH_FREQ_MAX)
freq = CGRAPH_FREQ_MAX;

40
gcc/predict.c
View file

@ -820,8 +820,33 @@ combine_predictions_for_bb (basic_block bb)
probability = REG_BR_PROB_BASE - probability;
found = true;
/* First match heuristics would be widly confused if we predicted
both directions. */
if (best_predictor > predictor)
best_probability = probability, best_predictor = predictor;
{
struct edge_prediction *pred2;
int prob = probability;
for (pred2 = (struct edge_prediction *) *preds; pred2; pred2 = pred2->ep_next)
if (pred2 != pred && pred2->ep_predictor == pred->ep_predictor)
{
int probability2 = pred->ep_probability;
if (pred2->ep_edge != first)
probability2 = REG_BR_PROB_BASE - probability2;
if ((probability < REG_BR_PROB_BASE / 2) !=
(probability2 < REG_BR_PROB_BASE / 2))
break;
/* If the same predictor later gave better result, go for it! */
if ((probability >= REG_BR_PROB_BASE / 2 && (probability2 > probability))
|| (probability <= REG_BR_PROB_BASE / 2 && (probability2 < probability)))
prob = probability2;
}
if (!pred2)
best_probability = prob, best_predictor = predictor;
}
d = (combined_probability * probability
+ (REG_BR_PROB_BASE - combined_probability)
@ -1521,6 +1546,16 @@ static void
tree_bb_level_predictions (void)
{
basic_block bb;
bool has_return_edges = false;
edge e;
edge_iterator ei;
FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
if (!(e->flags & (EDGE_ABNORMAL | EDGE_FAKE | EDGE_EH)))
{
has_return_edges = true;
break;
}
apply_return_prediction ();
@ -1535,7 +1570,8 @@ tree_bb_level_predictions (void)
if (is_gimple_call (stmt))
{
if (gimple_call_flags (stmt) & ECF_NORETURN)
if ((gimple_call_flags (stmt) & ECF_NORETURN)
&& has_return_edges)
predict_paths_leading_to (bb, PRED_NORETURN,
NOT_TAKEN);
decl = gimple_call_fndecl (stmt);