+/**
+ * Update the nodes after a match in the value table. If both nodes have
+ * the same MacroBlock but different Blocks, we must ensure that the node
+ * with the dominating Block (the node that is near to the MacroBlock header
+ * is stored in the table.
+ * Because a MacroBlock has only one "non-exception" flow, we don't need
+ * dominance info here: We known, that one block must dominate the other and
+ * following the only block input will allow to find it.
+ */
+static void update_known_irn(ir_node *known_irn, const ir_node *new_ir_node) {
+ ir_node *known_blk, *new_block, *block, *mbh;
+
+ if (get_opt_global_cse()) {
+ /* Block inputs are meaning less */
+ return;
+ }
+ known_blk = get_irn_n(known_irn, -1);
+ new_block = get_irn_n(new_ir_node, -1);
+ if (known_blk == new_block) {
+ /* already in the same block */
+ return;
+ }
+ /*
+ * We expect the typical case when we built the graph. In that case, the
+ * known_irn is already the upper one, so checking this should be faster.
+ */
+ block = new_block;
+ mbh = get_Block_MacroBlock(new_block);
+ for (;;) {
+ if (block == known_blk) {
+ /* ok, we have found it: known_block dominates new_block as expected */
+ return;
+ }
+ if (block == mbh) {
+ /*
+ * We have reached the MacroBlock header NOT founding
+ * the known_block. new_block must dominate known_block.
+ * Update known_irn.
+ */
+ set_irn_n(known_irn, -1, new_block);
+ return;
+ }
+ assert(get_Block_n_cfgpreds(block) == 1);
+ block = get_Block_cfgpred_block(block, 0);
+ }
+} /* update_value_table */
+