Very long instruction word
All above ILP techniques are implemented at a higher cost with increased hardware complexity. Before executing any operations in-parallel, the processor must verify that the instructions do not have interdependencies. There are many types of interdependencies, but a simple example would be a program in which the first instruction's result is used as an input for the second instruction. They clearly cannot execute at the same time, and the second instruction cannot be executed before the first. Modern out-of-order processors use major resources in order to take advantage of these techniques, since the scheduling of instructions must be determined dynamically as a program executes based on dependencies.