diff options
Diffstat (limited to 'gcc/predict.c')
| -rw-r--r-- | gcc/predict.c | 40 |
1 files changed, 38 insertions, 2 deletions
diff --git a/gcc/predict.c b/gcc/predict.c index c6e933f..73dbcbd 100644 --- a/gcc/predict.c +++ b/gcc/predict.c @@ -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); |