+static ir_node *prepare_constr_insn(be_chordal_env_t *env, ir_node *irn)
+{
+ be_insn_t *insn = chordal_scan_insn(env, irn);
+ bitset_t *def_constr = bitset_alloca(env->cls->n_regs);
+ bitset_t *tmp = bitset_alloca(env->cls->n_regs);
+ ir_node *bl = get_nodes_block(insn->irn);
+ int i, j;
+
+ if(!insn->has_constraints)
+ goto end;
+
+ /* insert copies for nodes that occur constrained more than once. */
+ for(i = insn->use_start; i < insn->n_ops; ++i) {
+ be_operand_t *op = &insn->ops[i];
+
+ if(op->has_constraints) {
+ for(j = i + 1; j < insn->n_ops; ++j) {
+ be_operand_t *a_op = &insn->ops[j];
+
+ if(a_op->carrier == op->carrier && a_op->has_constraints) {
+ ir_node *copy = be_new_Copy(env->cls, env->irg, bl, op->carrier);
+
+ sched_add_before(insn->irn, copy);
+ set_irn_n(insn->irn, a_op->pos, copy);
+ DBG((env->dbg, LEVEL_3, "inserting multiple constr copy %+F for %+F pos %d\n", copy, insn->irn, a_op->pos));
+ }
+ }
+ }
+ }
+
+ /* collect all registers occuring in out constraints. */
+ for(i = 0; i < insn->use_start; ++i) {
+ be_operand_t *op = &insn->ops[i];
+ if(op->has_constraints)
+ bitset_or(def_constr, op->regs);
+ }
+
+ /*
+ insert copies for all constrained arguments living through the node
+ and being constrained to a register which also occurs in out constraints.
+ */
+ for(i = insn->use_start; i < insn->n_ops; ++i) {
+ be_operand_t *op = &insn->ops[i];
+
+ bitset_copy(tmp, op->regs);
+ bitset_and(tmp, def_constr);
+
+ /*
+ Check, if
+ 1) the operand is constrained.
+ 2) lives through the node.
+ 3) is constrained to a register occuring in out constraints.
+ */
+ if(op->has_constraints && values_interfere(env->lv, insn->irn, op->carrier) && bitset_popcnt(tmp) > 0) {
+ /*
+ only create the copy if the operand is no copy.
+ this is necessary since the assure constraints phase inserts
+ Copies and Keeps for operands which must be different from the results.
+ Additional copies here would destroy this.
+ */
+ if(!be_is_Copy(op->carrier)) {
+ ir_node *copy = be_new_Copy(env->cls, env->irg, bl, op->carrier);
+
+ sched_add_before(insn->irn, copy);
+ set_irn_n(insn->irn, op->pos, copy);
+ DBG((env->dbg, LEVEL_3, "inserting constr copy %+F for %+F pos %d\n", copy, insn->irn, op->pos));
+ be_liveness_update(env->lv, op->carrier);
+ }
+ }
+ }
+
+end:
+ obstack_free(&env->obst, insn);
+ return insn->next_insn;
+}
+
+static void pre_spill_prepare_constr_walker(ir_node *bl, void *data)
+{
+ be_chordal_env_t *env = data;
+ ir_node *irn;
+ for(irn = sched_first(bl); !sched_is_end(irn);) {
+ irn = prepare_constr_insn(env, irn);
+ }
+}
+
+void be_pre_spill_prepare_constr(be_chordal_env_t *cenv) {
+ irg_block_walk_graph(cenv->irg, pre_spill_prepare_constr_walker, NULL, (void *) cenv);
+}
+