On Thu, 2012-03-29 at 12:11 -0700, Per Bothner wrote:
> I would expect the opposite: On modern systems arithmetic (including
> bitwise operations) is effectively free, but cache misses are
> expensive,
> so compact data structures are what counts.
>
> You wouldn't use a read-modify-write instruction except for "volatile"
> accesses.

I can report at least one system (not Scheme) that I know promotes
bitvectors to bytevectors for speed purposes precisely because masking
out the bits is too expensive.  In my own tests this has been born out
as well.

--
Aaron W. Hsu | arcfide@sacrideo.us | http://www.sacrideo.us
Programming is just another word for the lost art of thinking.

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