+ /* When there is no successor or only one choice, prediction is easy.
+
+ We are lazy for now and predict only basic blocks with two outgoing
+ edges. It is possible to predict generic case too, but we have to
+ ignore first match heuristics and do more involved combining. Implement
+ this later. */
+ if (nedges != 2)
+ {
+ if (!bb->count)
+ set_even_probabilities (bb);
+ clear_bb_predictions (bb);
+ if (dump_file)
+ fprintf (dump_file, "%i edges in bb %i predicted to even probabilities\n",
+ nedges, bb->index);
+ return;
+ }
+
+ if (dump_file)
+ fprintf (dump_file, "Predictions for bb %i\n", bb->index);
+
+ preds = pointer_map_contains (bb_predictions, bb);
+ if (preds)
+ {
+ /* We implement "first match" heuristics and use probability guessed
+ by predictor with smallest index. */
+ for (pred = *preds; pred; pred = pred->ep_next)
+ {
+ int predictor = pred->ep_predictor;
+ int probability = pred->ep_probability;
+
+ if (pred->ep_edge != first)
+ probability = REG_BR_PROB_BASE - probability;
+
+ found = true;
+ if (best_predictor > predictor)
+ best_probability = probability, best_predictor = predictor;
+
+ d = (combined_probability * probability
+ + (REG_BR_PROB_BASE - combined_probability)
+ * (REG_BR_PROB_BASE - probability));
+
+ /* Use FP math to avoid overflows of 32bit integers. */
+ if (d == 0)
+ /* If one probability is 0% and one 100%, avoid division by zero. */
+ combined_probability = REG_BR_PROB_BASE / 2;
+ else
+ combined_probability = (((double) combined_probability)
+ * probability
+ * REG_BR_PROB_BASE / d + 0.5);
+ }
+ }
+
+ /* Decide which heuristic to use. In case we didn't match anything,
+ use no_prediction heuristic, in case we did match, use either
+ first match or Dempster-Shaffer theory depending on the flags. */
+
+ if (predictor_info [best_predictor].flags & PRED_FLAG_FIRST_MATCH)
+ first_match = true;
+
+ if (!found)
+ dump_prediction (dump_file, PRED_NO_PREDICTION, combined_probability, bb, true);
+ else
+ {
+ dump_prediction (dump_file, PRED_DS_THEORY, combined_probability, bb,
+ !first_match);
+ dump_prediction (dump_file, PRED_FIRST_MATCH, best_probability, bb,
+ first_match);
+ }
+
+ if (first_match)
+ combined_probability = best_probability;
+ dump_prediction (dump_file, PRED_COMBINED, combined_probability, bb, true);
+
+ if (preds)
+ {
+ for (pred = *preds; pred; pred = pred->ep_next)
+ {
+ int predictor = pred->ep_predictor;
+ int probability = pred->ep_probability;
+
+ if (pred->ep_edge != EDGE_SUCC (bb, 0))
+ probability = REG_BR_PROB_BASE - probability;
+ dump_prediction (dump_file, predictor, probability, bb,
+ !first_match || best_predictor == predictor);
+ }
+ }
+ clear_bb_predictions (bb);
+
+ if (!bb->count)
+ {
+ first->probability = combined_probability;
+ second->probability = REG_BR_PROB_BASE - combined_probability;
+ }
+}
+
+/* Predict edge probabilities by exploiting loop structure. */
+
+static void
+predict_loops (void)
+{
+ loop_iterator li;
+ struct loop *loop;
+
+ scev_initialize ();
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