1. A method, in a data processing system, for compiling a portion of source code into an executable portion of code, comprising: determining, by a compiler executing on a processor in the data processing system, an optimization to apply to a portion of source code; determining, by the compiler, if the optimization as applied to the portion of source code will result in unsafe optimized code and is thus an unsafe optimization, wherein unsafe optimized code is code that introduces a new source of exceptions being generated by the optimized code that was not previously present in the original source code or generates results which are different from the results that would have been obtained by the original source code; in response to a determination that the optimization is an unsafe optimization, generating, by the compiler, an aggressively compiled code version of the portion of source code, in which the unsafe optimization is applied, and a conservatively compiled code version in which the unsafe optimization is not applied; and storing, by the compiler, both the aggressively compiled code version and conservatively compiled code version in a storage device associated with the data processing system.