9. An optimization apparatus comprising: a processor; a memory in operable communication with the processor; a multi-file optimized code generation (MFOCG) subsystem which includes a compiler back end and a linker, the MFOCG subsystem executable by the processor using the memory; and an incremental inter-procedural dataflow analysis (IIPDA) code which includes: a call graph input interface that receives a program call graph which identifies procedures of a program, an intermediate language representation input interface, a basis procedure set input interface, and a prior dataflow values input interface, the IIPDA also including an updated dataflow values output interface, and an impacted procedures set output interface which outputs a set IS of the procedures which are impacted directly or indirectly by a set of one or more source code edits, where the set IS is smaller than the set of all procedures identified in the call graph, wherein at least one procedure is represented in IS using at least one of the following: a compiler's internal ID of the procedure, a pointer to a function structure, a pointer to another procedure structure, a key to an entry in a group of symbols used in the program, and wherein the IIPDA is executable by the processor using the memory to transform inputs provided through the input interfaces into outputs provided through the output interfaces as part of a results-equivalent substitute for an exhaustive inter-procedural dataflow analysis by the MFOCG subsystem of all procedures identified in the program call graph.
9. An optimization apparatus comprising: a processor; a memory in operable communication with the processor; a multi-file optimized code generation (MFOCG) subsystem which includes a compiler back end and a linker, the MFOCG subsystem executable by the processor using the memory; and an incremental inter-procedural dataflow analysis (IIPDA) code which includes: a call graph input interface that receives a program call graph which identifies procedures of a program, an intermediate language representation input interface, a basis procedure set input interface, and a prior dataflow values input interface, the IIPDA also including an updated dataflow values output interface, and an impacted procedures set output interface which outputs a set IS of the procedures which are impacted directly or indirectly by a set of one or more source code edits, where the set IS is smaller than the set of all procedures identified in the call graph, wherein at least one procedure is represented in IS using at least one of the following: a compiler's internal ID of the procedure, a pointer to a function structure, a pointer to another procedure structure, a key to an entry in a group of symbols used in the program, and wherein the IIPDA is executable by the processor using the memory to transform inputs provided through the input interfaces into outputs provided through the output interfaces as part of a results-equivalent substitute for an exhaustive inter-procedural dataflow analysis by the MFOCG subsystem of all procedures identified in the program call graph. 11. The optimization apparatus of claim 9 , further comprising a basis procedure set that includes at least one procedure whose source code has been edited subsequent to a most recent compilation of the procedure.