1. A method for executing a unit of code, the method comprising: receiving the unit of code, wherein the unit of code includes: a fallback code that is based on a source code, and a compiled code derived from the source code, wherein the compiled code: is based on at least one assumption associated with a runtime environment during execution of the compiled code, and when executed, implements one or more checkpoints for determining whether the at least one assumption holds true; executing, via a processor, the compiled code; encountering a particular one of the one or more checkpoints; at the particular one checkpoint, determining whether the at least one assumption holds true; and upon determining that the at least one assumption does not hold true: rolling over to and executing the fallback code, by performing steps that include: updating the runtime environment to a specific state that represents one that would have otherwise been present had the fallback code been executed in place of the compiled code, wherein updating the runtime environment includes: restoring at least one local variable based on the specific state, and maintaining global variables.