+/* From a controlling predicate in DOM determine the arguments from
+ the PHI node PHI that are chosen if the predicate evaluates to
+ true and false and store them to *TRUE_ARG_P and *FALSE_ARG_P if
+ they are non-NULL. Returns true if the arguments can be determined,
+ else return false. */
+
+static bool
+extract_true_false_args_from_phi (basic_block dom, gimple phi,
+ tree *true_arg_p, tree *false_arg_p)
+{
+ basic_block bb = gimple_bb (phi);
+ edge true_edge, false_edge, tem;
+ tree arg0 = NULL_TREE, arg1 = NULL_TREE;
+
+ /* We have to verify that one edge into the PHI node is dominated
+ by the true edge of the predicate block and the other edge
+ dominated by the false edge. This ensures that the PHI argument
+ we are going to take is completely determined by the path we
+ take from the predicate block.
+ We can only use BB dominance checks below if the destination of
+ the true/false edges are dominated by their edge, thus only
+ have a single predecessor. */
+ extract_true_false_edges_from_block (dom, &true_edge, &false_edge);
+ tem = EDGE_PRED (bb, 0);
+ if (tem == true_edge
+ || (single_pred_p (true_edge->dest)
+ && (tem->src == true_edge->dest
+ || dominated_by_p (CDI_DOMINATORS,
+ tem->src, true_edge->dest))))
+ arg0 = PHI_ARG_DEF (phi, tem->dest_idx);
+ else if (tem == false_edge
+ || (single_pred_p (false_edge->dest)
+ && (tem->src == false_edge->dest
+ || dominated_by_p (CDI_DOMINATORS,
+ tem->src, false_edge->dest))))
+ arg1 = PHI_ARG_DEF (phi, tem->dest_idx);
+ else
+ return false;
+ tem = EDGE_PRED (bb, 1);
+ if (tem == true_edge
+ || (single_pred_p (true_edge->dest)
+ && (tem->src == true_edge->dest
+ || dominated_by_p (CDI_DOMINATORS,
+ tem->src, true_edge->dest))))
+ arg0 = PHI_ARG_DEF (phi, tem->dest_idx);
+ else if (tem == false_edge
+ || (single_pred_p (false_edge->dest)
+ && (tem->src == false_edge->dest
+ || dominated_by_p (CDI_DOMINATORS,
+ tem->src, false_edge->dest))))
+ arg1 = PHI_ARG_DEF (phi, tem->dest_idx);
+ else
+ return false;
+ if (!arg0 || !arg1)
+ return false;
+
+ if (true_arg_p)
+ *true_arg_p = arg0;
+ if (false_arg_p)
+ *false_arg_p = arg1;
+
+ return true;
+}
+