env->live = bitset_obstack_alloc(&env->obst, node_count);
env->colors = bitset_obstack_alloc(&env->obst, colors_n);
env->in_colors = bitset_obstack_alloc(&env->obst, colors_n);
env->colors_n = colors_n;
env->cls = cls;
env->live = bitset_obstack_alloc(&env->obst, node_count);
env->colors = bitset_obstack_alloc(&env->obst, colors_n);
env->in_colors = bitset_obstack_alloc(&env->obst, colors_n);
env->colors_n = colors_n;
env->cls = cls;