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@x | http://www.sacrideo.us Programming is just another word for the lost art of thinking.
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