I don't think anyone would argue that the compiler in question is far from optimal for compiling this particular program.

However, if you are writing a general purpose compiler, you need to accommodate any program. Each of the properties (e.g. no use of getters, only one variable) that you point out about this program would take a compiler pass to establish.

I haven't thought too much about it, but some of the properties are very likely to be undecidable by static analysis for many programs.

It seems likely that using time to determine whether the program being compiled has these properties would not be efficient for most real world programs, even if it did provide enough information to choose a more optimal compilation strategy in some cases.