Abstract: A processor contains a configurable functional unit that is capable of executing reconfigurable instructions, whose effect can be redefined at run-time by loading a configuration program. Reconfigurable instructions are selected in combinations of more than one different reconfigurable instruction. A respective configuration program is generated for each combination of instructions. Each time when an instruction from one of the combinations is needed during execution and the configurable functional unit is not configured with the configuration program for that combination, the configuration program for all of the instructions of that combination into the configurable functional unit. The reconfigurable instruction selects which instruction of the combination is executed.