Bryan Cantrill wrote On 11/01/07 13:33,:
>>>>Every aggregating function has to have a defined, fixed type, that
>>>>determines
>>>>how its implementation in kernel and userland, a portion of which is quoted
>>>>above, performs the underlying arithmetic. Since our original release, the
>>>>type signatures of the aggregating functions to which you are referring
>>>>have their signature as: sum(uint64_t arg), and so on.
>>>
>>>As Bryan mentioned earlier, quantize()/lquantize() also treat their
>>>arguments
>>>as uint64_t but in the kernel implementation convert it to int64_t. Can the
>>>same thing be done for max()/min()/avg()?
>>>
>>>- akolb
>>
>>Not without breaking program compatibility, because the type signatures
>>we assigned to the aggregating functions also determine the default
>>base that is used when printf()'ing an aggregation, and therefore would
>>break the output of programs that rely or desire the unsigned behavior.
>
>
> Mike and I just talked about this -- he didn't realize that we already
> have precedent for doing this in the fix (and patch) for 6320439.
> And because we print aggregation results out as signed 64-bit values (that
> is "dtrace -n BEGIN'{ @ = max(-10); exit(0); }'" does what you think it
> should), the only D program that this could break would be one relying
> on aggregating values above 2^63 -- and as Chad pointed out, these
> can silently overflow and break anyway.
>
> So I think we can go ahead and fix that bug as filed. And yes, passing
> the type information down to the kernel would be a cleaner way of doing
> it -- but that's also a hell of a lot more work, and it only benefits
> those that are aggregating values greater than 2^63...
+1
<SOAPBOX>
not having unsigned is one of the things they did right in Java.
</SOAPBOX>
-Pete.
>
> - Bryan
>
> --------------------------------------------------------------------------
> Bryan Cantrill, Sun Microsystems FishWorks. http://blogs.sun.com/bmc
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