1. A tangible computer-readable storage medium having computer executable instructions stored thereon, the computer executable instructions, comprising: identifying during an application loading a processor extension instruction for processing a basic block in the application; extending a processor with said processor extension instruction; replacing a portion of the application that calls for executing the processor extension instruction, said portion being replaced with a non-trapping null instruction nullifying the portion of the application that calls for executing a processor extension instruction by changing a value of one or more processor extension control registers; and sharing the processor extension instruction among two or more applications by determining which of the two or more application makes the most use of said processor extension instruction and exclusively assigning the processor extension instruction to one of the two or more applications that is observed to make the most use of said processor extension instruction.