It hardly seems worth the trouble, especially since the compiler won't handle !HEAP_IN_LOW_MEMORY. It's already the case that the limiting factor on some systems is the inability to find a sufficiently large chunk of memory in the low address space. A similar change will be needed to reclaim those low bits, so it might be worth putting in that effort first.
Or you could wait until you get a 64-bit machine, surely not too far in the future. On Tue, Aug 10, 2010 at 3:01 PM, Taylor R Campbell <[email protected]> wrote: > Currently, I believe the only objects whose addresses are not aligned > on word boundaries are compiled entries. If we forced them to be > aligned, then the log_2 (bits per word) low-order bits of every object > address would be zero, and we could shift the address by that many > bits when storing it as an object's datum. > > This would let us quadruple the usable virtual address space on 32-bit > systems, or octuple it if we got rid of the scode type tags and some > unused type tags too (using records instead or something) and reduced > the tags to five bits. > > Probably more trouble than it's worth, but it's a cute thought > nevertheless which wouldn't require rewriting half of MIT Scheme. > > (I still occasionally think about this because while some of you lucky > folks may be on super-snappy 64-bit machines, I'm still using a six- > year-old 32-bit laptop.) > > _______________________________________________ > MIT-Scheme-devel mailing list > [email protected] > http://lists.gnu.org/mailman/listinfo/mit-scheme-devel > _______________________________________________ MIT-Scheme-devel mailing list [email protected] http://lists.gnu.org/mailman/listinfo/mit-scheme-devel
