+/**
+ * Checks if node has a must_be_different constraint in output and adds a Keep
+ * then to assure the constraint.
+ */
+static void assure_different_constraints(ir_node *irn, constraint_env_t *env) {
+ const arch_register_req_t *req;
+ const arch_env_t *arch_env = be_get_birg_arch_env(env->birg);
+ ir_node *skipped_irn = belower_skip_proj(irn);
+
+ req = arch_get_register_req(arch_env, irn, -1);
+
+ if (arch_register_req_is(req, must_be_different)) {
+ const unsigned other = req->other_different;
+ int i;
+
+ if (arch_register_req_is(req, should_be_same)) {
+ const unsigned same = req->other_same;
+
+ if (is_po2(other) && is_po2(same)) {
+ int idx_other = ntz(other);
+ int idx_same = ntz(same);
+
+ /*
+ * We can safely ignore a should_be_same x must_be_different y
+ * IFF both inputs are equal!
+ */
+ if (get_irn_n(skipped_irn, idx_other) == get_irn_n(skipped_irn, idx_same)) {
+ return;
+ }
+ }
+ }
+ for (i = 0; 1U << i <= other; ++i) {
+ if (other & (1U << i)) {
+ ir_node *different_from = get_irn_n(skipped_irn, i);
+ gen_assure_different_pattern(irn, different_from, env);
+ }
+ }
+ }
+}
+
+/**
+ * Calls the functions to assure register constraints.
+ *
+ * @param irn The node to be checked for lowering
+ * @param walk_env The walker environment
+ */
+static void assure_constraints_walker(ir_node *irn, void *walk_env) {
+ if (is_Block(irn))
+ return;
+
+ if (sched_is_scheduled(irn) && mode_is_datab(get_irn_mode(irn)))
+ assure_different_constraints(irn, walk_env);
+}
+
+/**
+ * Melt all copykeeps pointing to the same node
+ * (or Projs of the same node), copying the same operand.
+ */
+static void melt_copykeeps(constraint_env_t *cenv) {
+ be_irg_t *birg = cenv->birg;
+ ir_graph *irg = be_get_birg_irg(birg);
+ op_copy_assoc_t *entry;
+
+ /* for all */
+ foreach_pset(cenv->op_set, entry) {
+ int idx, num_ck;
+ ir_node *cp;
+ struct obstack obst;
+ ir_nodeset_iterator_t iter;
+ ir_node **ck_arr, **melt_arr;
+
+ obstack_init(&obst);
+
+ /* collect all copykeeps */
+ num_ck = idx = 0;
+ foreach_ir_nodeset(&entry->copies, cp, iter) {
+ if (be_is_CopyKeep(cp)) {
+ obstack_grow(&obst, &cp, sizeof(cp));
+ ++num_ck;
+ }
+#ifdef KEEP_ALIVE_COPYKEEP_HACK
+ else {
+ set_irn_mode(cp, mode_ANY);
+ keep_alive(cp);
+ }
+#endif /* KEEP_ALIVE_COPYKEEP_HACK */
+ }