[Haskell] GHC 64bit?

Ben Rudiak-Gould benrg at dark.darkweb.com
Fri Feb 13 01:50:11 EST 2004

On 13 Feb 2004, Ketil Malde wrote:

> Axel Simon <A.Simon at kent.ac.uk> writes:
> > I wonder if such an effort is worthwhile. If all pointers are suddenly
> > twice the size then the footprint of a program roughly doubles. 
> > [...]
> > It would be interesting if Haskell programs could run in the lower 4 GB 
> > while running in 64 bit mode. Then you could have large data structures 
> > (or memory mapped files) in C land.
> That's an interesting possibility -- at least part of my program is a
> large UArray of Word8, which could probably be FFI'ed relatively
> easily. 

... but which doesn't need to be, because UArrays of Word8 will not grow
in size, no matter how large the pointers. :-)

Seriously, this seems like a good approach to supporting 64 bits cheaply:
put everything in the lower 4GB except for arrays. (They'd have an
indirection box with a 64-bit pointer in the lower 4GB.) Does anyone need
more than 4GB of non-array data?

> Hmm..how about 32 bit pointers, but with 8 byte boundary alignment?
> This should give an effective pointer size of 35 bits, adressing
> up to 32Gb.

This is also a good idea.

-- Ben

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