+ obstack_free(&obst, NULL);
+ }
+}
+
+/**
+ * Walks over all nodes to assure register constraints.
+ *
+ * @param birg The birg structure containing the irg
+ */
+void assure_constraints(be_irg_t *birg) {
+ ir_graph *irg = be_get_birg_irg(birg);
+ const arch_env_t *arch_env = be_get_birg_arch_env(birg);
+ constraint_env_t cenv;
+ op_copy_assoc_t *entry;
+ ir_node **nodes;
+ FIRM_DBG_REGISTER(firm_dbg_module_t *mod, "firm.be.lower.constr");
+
+ be_assure_dom_front(birg);
+
+ DEBUG_ONLY(cenv.dbg = mod;)
+ cenv.birg = birg;
+ cenv.op_set = new_pset(cmp_op_copy_assoc, 16);
+ obstack_init(&cenv.obst);
+
+ irg_walk_blkwise_graph(irg, NULL, assure_constraints_walker, &cenv);
+
+ /* melt copykeeps, pointing to projs of */
+ /* the same mode_T node and keeping the */
+ /* same operand */
+ melt_copykeeps(&cenv);
+
+ /* for all */
+ foreach_pset(cenv.op_set, entry) {
+ int n;
+ ir_node *cp;
+ ir_nodeset_iterator_t iter;
+ be_ssa_construction_env_t senv;
+
+ n = ir_nodeset_size(&entry->copies);
+ nodes = alloca(n * sizeof(nodes[0]));
+
+ /* put the node in an array */
+ DBG((mod, LEVEL_1, "introduce copies for %+F ", entry->op));
+
+ /* collect all copies */
+ n = 0;
+ foreach_ir_nodeset(&entry->copies, cp, iter) {
+ nodes[n++] = cp;
+ DB((mod, LEVEL_1, ", %+F ", cp));
+ }
+
+ DB((mod, LEVEL_1, "\n"));
+
+ /* introduce the copies for the operand and it's copies */
+ be_ssa_construction_init(&senv, birg);
+ be_ssa_construction_add_copy(&senv, entry->op);
+ be_ssa_construction_add_copies(&senv, nodes, n);
+ be_ssa_construction_fix_users(&senv, entry->op);
+ be_ssa_construction_destroy(&senv);
+
+ /* Could be that not all CopyKeeps are really needed, */
+ /* so we transform unnecessary ones into Keeps. */
+ foreach_ir_nodeset(&entry->copies, cp, iter) {
+ if (be_is_CopyKeep(cp) && get_irn_n_edges(cp) < 1) {
+ ir_node *keep;
+ int n = get_irn_arity(cp);
+
+ keep = be_new_Keep(arch_get_irn_reg_class(arch_env, cp, -1),
+ irg, get_nodes_block(cp), n, (ir_node **)&get_irn_in(cp)[1]);
+ sched_add_before(cp, keep);
+
+ /* Set all ins (including the block) of the CopyKeep BAD to keep the verifier happy. */
+ sched_remove(cp);
+ be_kill_node(cp);
+ }