bool lower_instructions(exec_list *instructions, unsigned what_to_lower);
bool lower_noise(exec_list *instructions);
bool lower_variable_index_to_cond_assign(exec_list *instructions,
bool lower_instructions(exec_list *instructions, unsigned what_to_lower);
bool lower_noise(exec_list *instructions);
bool lower_variable_index_to_cond_assign(exec_list *instructions,