Re: [Classpath] style question

[Tom Tromey]

>>>>> ">" == C Scott Ananian <address@hidden> writes:

>> What I was saying, in effect, was that duplicate array bounds
>> checks should be optimized away, *if the compiler can determine
>> that they are, in fact, duplicate*.

Yes.  In this case I don't think it is too far-fetched that a compiler
could discover this.  Strings are used often enough that teaching a
Java compiler about String.length wouldn't be unreasonable.  (gcj
can't do these optimizations now, but we plan to do them in the
future.)

>>  Using the try-catch construct obscures this fact, so it makes it
>> harder for the compiler to Do The Right Thing.

I agree with this too.  Also, since exceptions are presumably
exceptional, compiler writers probably won't spend as much time
optimizing them as they will on unexceptional code paths.

I think we have to ask, though, what the goal is.  If it is
performance, then there is no single answer, since different
implementations have different tradeoffs.  For instance with gcj I
think exceptions are a bit more expensive than they are with, say,
Sun's JDK.  OTOH other things are cheaper (and ultimately a redundant
bounds check will be free).

If the goal is clarity, then it is a little harder to judge.

Tom