[EMAIL PROTECTED] (Carl R. Witty) writes:
> Sigbjorn Finne <[EMAIL PROTECTED]> writes:
> > Clearly there's a range of optimisations possible here; using an
> > efficiently implemented bignum library being one (not irrelevant) way
> > to improve matters. Changing the representation of Integer is another,
> > distinguishing at the Haskell level between ones that fit in a machine
> > word and those that don't. We plan to use such a representation for
> > GHC/Hugs.
>
> I'm glad to hear it; do you have anything written on exactly how you
> this will work?
The plan is to use something like
data Integer = Small Int# | Big { ... }
where '...' is the GMP representation. You then need a full set of
overflow-detecting primitive operations on Int. I've done a few
experiments with using gcc's 'long long' type to implement these
portably (well, portably across 32-bit architectures...), and it seems
possible.
The common case of applying a dyadic operation to small Integers would
then be pretty close in performance to that of Int (a couple of
indirect jumps, and a test/branch for the overflow detection, to be
precise).
Cheers,
Simon
--
Simon Marlow [EMAIL PROTECTED]
University of Glasgow http://www.dcs.gla.ac.uk/~simonm/
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