+#define has_limited_constr(req, irn) \
+ (arch_get_register_req(arch_env, (req), irn, -1) && (req)->type == arch_register_req_type_limited)
+
+typedef struct _operand_t operand_t;
+
+struct _operand_t {
+ ir_node *irn;
+ ir_node *carrier;
+ operand_t *partner;
+ int pos;
+ arch_register_req_t req;
+};
+
+typedef struct {
+ operand_t *ops;
+ int n_ops;
+ int use_start;
+ ir_node *next_insn;
+ unsigned has_constraints : 1;
+} insn_t;
+
+static insn_t *scan_insn(be_chordal_env_t *env, ir_node *irn, struct obstack *obst)
+{
+ const arch_env_t *arch_env = env->main_env->arch_env;
+ operand_t o;
+ insn_t *insn;
+ int i, n;
+
+ insn = obstack_alloc(obst, sizeof(insn[0]));
+ memset(insn, 0, sizeof(insn[0]));
+
+ insn->next_insn = sched_next(irn);
+ if(get_irn_mode(irn) == mode_T) {
+ ir_node *p;
+
+ for(p = sched_next(irn); is_Proj(p); p = sched_next(p)) {
+ if(arch_irn_consider_in_reg_alloc(arch_env, env->cls, p)) {
+ o.carrier = p;
+ o.irn = irn;
+ o.pos = -(get_Proj_proj(p) + 1);
+ o.partner = NULL;
+ arch_get_register_req(arch_env, &o.req, p, -1);
+ obstack_grow(obst, &o, sizeof(o));
+ insn->n_ops++;
+ insn->has_constraints |= arch_register_req_is(&o.req, limited);
+ }
+ }
+
+ insn->next_insn = p;
+ }
+
+ else if(arch_irn_consider_in_reg_alloc(arch_env, env->cls, irn)) {
+ o.carrier = irn;
+ o.irn = irn;
+ o.pos = -1;
+ o.partner = NULL;
+ arch_get_register_req(arch_env, &o.req, irn, -1);
+ obstack_grow(obst, &o, sizeof(o));
+ insn->n_ops++;
+ insn->has_constraints |= arch_register_req_is(&o.req, limited);
+ }
+
+ insn->use_start = insn->n_ops;
+
+ for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
+ ir_node *op = get_irn_n(irn, i);
+
+ if(arch_irn_consider_in_reg_alloc(arch_env, env->cls, op)) {
+ o.carrier = op;
+ o.irn = irn;
+ o.pos = i;
+ o.partner = NULL;
+ arch_get_register_req(arch_env, &o.req, irn, i);
+ obstack_grow(obst, &o, sizeof(o));
+ insn->n_ops++;
+ insn->has_constraints |= arch_register_req_is(&o.req, limited);
+ }
+ }
+
+ insn->ops = obstack_finish(obst);
+ return insn;
+}
+
+static operand_t *find_unpaired_use(insn_t *insn, const operand_t *op, int can_be_constrained)
+{
+ int i;
+ operand_t *res = NULL;
+
+ for(i = insn->use_start; i < insn->n_ops; ++i) {
+ operand_t *op = &insn->ops[i];
+ int has_constraint = arch_register_req_is(&op->req, limited);
+
+ if(!values_interfere(op->carrier, op->irn) && !op->partner && (!has_constraint || can_be_constrained)) {
+ if(arch_register_req_is(&op->req, should_be_same) && op->req.other == op->carrier)
+ return op;
+ else
+ res = op;
+ }
+ }
+
+ return res;
+}
+
+static void pair_up_operands(insn_t *insn)
+{
+ firm_dbg_module_t *dbg = firm_dbg_register("firm.be.chordal.constr");
+ int i;
+
+ for(i = 0; i < insn->use_start; ++i) {
+ operand_t *op = &insn->ops[i];
+ int has_constraint = arch_register_req_is(&op->req, limited);
+ operand_t *partner = find_unpaired_use(insn, op, !has_constraint);
+
+ if(partner) {
+ op->partner = partner;
+ partner->partner = op;
+ }
+ }
+}
+
+static ir_node *handle_constraints(be_chordal_alloc_env_t *alloc_env, ir_node *irn)
+{
+ be_chordal_env_t *env = alloc_env->chordal_env;
+ void *base = obstack_base(&env->obst);
+ insn_t *insn = scan_insn(env, irn, &env->obst);
+ ir_node *res = insn->next_insn;
+
+ if(insn->has_constraints) {
+ firm_dbg_module_t *dbg = firm_dbg_register("firm.be.chordal.constr");
+ const arch_env_t *aenv = env->main_env->arch_env;
+ int n_regs = env->cls->n_regs;
+ bitset_t *bs = bitset_alloca(n_regs);
+ ir_node **alloc_nodes = alloca(n_regs * sizeof(alloc_nodes[0]));
+ bipartite_t *bp = bipartite_new(n_regs, n_regs);
+ int *assignment = alloca(n_regs * sizeof(assignment[0]));
+ pmap *partners = pmap_create();
+
+ int i, n_alloc;
+ long col;
+ const ir_edge_t *edge;
+ ir_node *perm = insert_Perm_after(aenv, env->cls, env->dom_front, sched_prev(irn));
+
+ /* Registers are propagated by insert_Perm_after(). Clean them here! */
+ if(perm) {
+ foreach_out_edge(perm, edge) {
+ ir_node *proj = get_edge_src_irn(edge);
+ arch_set_irn_register(aenv, proj, NULL);
+ }
+ }
+
+
+ be_liveness(env->irg);
+ insn = scan_insn(env, irn, &env->obst);
+
+ DBG((dbg, LEVEL_1, "handling constraints for %+F\n", irn));
+
+ /*
+ * If there was no Perm made, nothing was alive in this register class.
+ * This means, that the node has no operands, thus no input constraints.
+ * so it had output constraints. The other results then can be assigned freeliy.
+ */
+
+ pair_up_operands(insn);
+
+ for(i = 0, n_alloc = 0; i < insn->n_ops; ++i) {
+ operand_t *op = &insn->ops[i];
+ if(arch_register_req_is(&op->req, limited)) {
+ pmap_insert(partners, op->carrier, op->partner ? op->partner->carrier : NULL);
+ alloc_nodes[n_alloc] = op->carrier;
+
+ DBG((dbg, LEVEL_2, "\tassociating %+F and %+F\n", op->carrier, pmap_get(partners, op->carrier)));
+
+ bitset_clear_all(bs);
+ op->req.limited(op->req.limited_env, bs);
+ bitset_andnot(bs, alloc_env->ignore_colors);
+
+ bitset_foreach(bs, col)
+ bipartite_add(bp, n_alloc, col);
+
+ n_alloc++;
+ }
+ }
+
+ if(perm) {
+ foreach_out_edge(perm, edge) {
+ ir_node *proj = get_edge_src_irn(edge);
+
+ assert(is_Proj(proj));
+
+ if(values_interfere(proj, irn)) {
+ assert(n_alloc < n_regs);
+ alloc_nodes[n_alloc] = proj;
+ pmap_insert(partners, proj, NULL);
+
+ bitset_clear_all(bs);
+ arch_get_allocatable_regs(aenv, proj, -1, bs);
+ bitset_andnot(bs, alloc_env->ignore_colors);
+ bitset_foreach(bs, col)
+ bipartite_add(bp, n_alloc, col);
+
+ n_alloc++;
+ }
+ }
+ }
+
+ bipartite_matching(bp, assignment);
+
+ for(i = 0; i < n_alloc; ++i) {
+ int j;
+ ir_node *nodes[2];
+ const arch_register_t *reg = arch_register_for_index(env->cls, assignment[i]);
+
+ nodes[0] = alloc_nodes[i];
+ nodes[1] = pmap_get(partners, alloc_nodes[i]);
+
+ for(j = 0; j < 2; ++j) {
+ if(!nodes[j])
+ continue;
+
+ arch_set_irn_register(aenv, nodes[j], reg);
+ pset_hinsert_ptr(alloc_env->pre_colored, nodes[j]);
+ DBG((dbg, LEVEL_2, "\tsetting %+F to register %s\n", nodes[j], reg->name));
+ }
+ }
+
+
+ if(perm) {
+ bitset_clear_all(bs);
+ foreach_out_edge(perm, edge) {
+ ir_node *proj = get_edge_src_irn(edge);
+ const arch_register_t *reg = arch_get_irn_register(aenv, proj);
+
+ if(reg != NULL)
+ bitset_set(bs, reg->index);
+ }
+
+ // bitset_or(bs, alloc_env->ignore_colors);
+ foreach_out_edge(perm, edge) {
+ ir_node *proj = get_edge_src_irn(edge);
+ const arch_register_t *reg = arch_get_irn_register(aenv, proj);
+
+ DBG((dbg, LEVEL_2, "\tchecking reg of %+F: %s\n", proj, reg ? reg->name : "<none>"));
+
+ if(reg == NULL) {
+ col = bitset_next_clear(bs, 0);
+ reg = arch_register_for_index(env->cls, col);
+ bitset_set(bs, reg->index);
+ arch_set_irn_register(aenv, proj, reg);
+ pset_insert_ptr(alloc_env->pre_colored, proj);
+ DBG((dbg, LEVEL_2, "\tsetting %+F to register %s\n", proj, reg->name));
+ }
+ }
+ }
+
+ pmap_destroy(partners);
+ }
+
+ obstack_free(&env->obst, base);
+ return res;
+}
+
+/**
+ * Handle constraint nodes in each basic block.
+ * be_insert_constr_perms() inserts Perm nodes which perm
+ * over all values live at the constrained node right in front
+ * of the constrained node. These Perms signal a constrained node.
+ * For further comments, refer to handle_constraints_at_perm().
+ */
+static void constraints(ir_node *bl, void *data)
+{
+ firm_dbg_module_t *dbg = firm_dbg_register("firm.be.chordal.constr");
+ be_chordal_alloc_env_t *env = data;
+ arch_env_t *arch_env = env->chordal_env->main_env->arch_env;
+ ir_node *irn;
+
+ for(irn = sched_first(bl); !sched_is_end(irn);) {
+ irn = handle_constraints(env, irn);
+ }
+}
+