+ set_irn_in(block, k, in_X);
+ env->modified = 1;
+} /* apply_cf */
+
+/**
+ * Exchange a node by its leader.
+ * Beware: in rare cases the mode might be wrong here, for instance
+ * AddP(x, NULL) is a follower of x, but with different mode.
+ * Fix it here.
+ */
+static void exchange_leader(ir_node *irn, ir_node *leader)
+{
+ ir_mode *mode = get_irn_mode(irn);
+ if (mode != get_irn_mode(leader)) {
+ /* The conv is a no-op, so we are free to place it
+ * either in the block of the leader OR in irn's block.
+ * Probably placing it into leaders block might reduce
+ * the number of Conv due to CSE. */
+ ir_node *block = get_nodes_block(leader);
+ dbg_info *dbg = get_irn_dbg_info(irn);
+
+ leader = new_rd_Conv(dbg, block, leader, mode);
+ }
+ exchange(irn, leader);
+} /* exchange_leader */
+
+/**
+ * Check, if all users of a mode_M node are dead. Use
+ * the Def-Use edges for this purpose, as they still
+ * reflect the situation.
+ */
+static int all_users_are_dead(const ir_node *irn)
+{
+ int i, n = get_irn_n_outs(irn);
+
+ for (i = 1; i <= n; ++i) {
+ const ir_node *succ = irn->out[i].use;
+ const node_t *block = get_irn_node(get_nodes_block(succ));
+ const node_t *node;
+
+ if (block->type.tv == tarval_unreachable) {
+ /* block is unreachable */
+ continue;
+ }
+ node = get_irn_node(succ);
+ if (node->type.tv != tarval_top) {
+ /* found a reachable user */
+ return 0;
+ }
+ }
+ /* all users are unreachable */
+ return 1;
+} /* all_user_are_dead */
+
+/**
+ * Walker: Find reachable mode_M nodes that have only
+ * unreachable users. These nodes must be kept later.
+ */
+static void find_kept_memory(ir_node *irn, void *ctx)
+{
+ environment_t *env = (environment_t*)ctx;
+ node_t *node, *block;
+
+ if (get_irn_mode(irn) != mode_M)
+ return;
+
+ block = get_irn_node(get_nodes_block(irn));
+ if (block->type.tv == tarval_unreachable)
+ return;
+
+ node = get_irn_node(irn);
+ if (node->type.tv == tarval_top)
+ return;
+
+ /* ok, we found a live memory node. */
+ if (all_users_are_dead(irn)) {
+ DB((dbg, LEVEL_1, "%+F must be kept\n", irn));
+ ARR_APP1(ir_node *, env->kept_memory, irn);
+ }
+} /* find_kept_memory */