Re: Compiler writers will love this language

mwotton@cse.unsw.edu.au (Mark Alexander Wotton) wrote:


>On 20 Jun 2003 00:02:55 -0400, Eric posted:
>> mwotton@cse.unsw.edu.au (Mark Alexander Wotton) wrote


[snip]


>> I admit, reference-counting has its problems and I have been toying
>> around with an idea for what I call "compile-time
>> reference-counting". Basically, I am looking for a set of rules,
>> that will allow the compiler to figure out when to release memory
>> for an object, *without* having to allocate memory space for a
>> reference counter value. Instead, using these rules, the compiler
>> can analyse code at compile time and statically work out the
>> life-time of an object. Its a bit wishy washy at the moment but if
>> its at all possible, I will write a paper on it :)
>
>It smells a bit undecidable to me. At least for the complete case, I think
>this reduces to the halting problem.
>
> Object foo(Object x, Object y) {
> if (halts(x)) {
> return y;
> } else {
> return x;
> }
> }
>
>When do you release x's memory?


          if branch: yes, else branch: no.


          Your code would make sense to me if the return values were
switched. Is that what you meant, or am I missing something?


>You may be able to find some decent heuristics, but I suspect it's a lot
>harder than it looks.


          It does have that feel to me, too.


Sincerely,


Gene Wirchenko

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