+void be_peephole_new_node(ir_node * nw)
+{
+ be_liveness_introduce(lv, nw);
+}
+
+/**
+ * must be called from peephole optimisations before a node will be killed
+ * and its users will be redirected to new_node.
+ * so bepeephole can update its internal state.
+ *
+ * Note: killing a node and rewiring is only allowed if new_node produces
+ * the same registers as old_node.
+ */
+static void be_peephole_before_exchange(const ir_node *old_node,
+ ir_node *new_node)
+{
+ const arch_register_t *reg;
+ unsigned reg_idx;
+ bool old_is_current = false;
+
+ DB((dbg, LEVEL_1, "About to exchange and kill %+F with %+F\n", old_node, new_node));
+
+ assert(sched_is_scheduled(skip_Proj_const(old_node)));
+ assert(sched_is_scheduled(skip_Proj(new_node)));
+
+ if (current_node == old_node) {
+ old_is_current = true;
+
+ /* next node to be processed will be killed. Its scheduling predecessor
+ * must be processed next. */
+ current_node = sched_next(current_node);
+ assert (!is_Bad(current_node));
+
+ /* we can't handle liveness updates correctly when exchange current node
+ * with something behind it */
+ assert(value_dominates(skip_Proj(new_node), skip_Proj_const(old_node)));
+ }
+
+ if (!mode_is_data(get_irn_mode(old_node)))
+ return;
+
+ reg = arch_get_irn_register(old_node);
+ if (reg == NULL) {
+ panic("No register assigned at %+F", old_node);
+ }
+ assert(reg == arch_get_irn_register(new_node) &&
+ "KILLING a node and replacing by different register is not allowed");
+
+ reg_idx = reg->global_index;
+ if (register_values[reg_idx] == old_node || old_is_current) {
+ register_values[reg_idx] = new_node;
+ }
+
+ be_liveness_remove(lv, old_node);
+}
+
+void be_peephole_exchange(ir_node *old, ir_node *nw)
+{
+ be_peephole_before_exchange(old, nw);
+ sched_remove(old);
+ exchange(old, nw);
+ be_peephole_new_node(nw);
+}
+
+/**
+ * block-walker: run peephole optimization on the given block.
+ */