1. A method for operating a processing system, comprising: executing a first program instruction that associates a hardware register of a processor with a data stream; populating a cache of the processor with a first portion of data of the data stream; populating the hardware register with first data of the first portion of data; receiving a second program instruction that accesses the hardware register; executing the second program instruction; after said executing the second program instruction, automatically populating the hardware register with second data of the first portion of data; receiving a third program instruction that accesses the hardware register; and executing the third program instruction.