[gambit-list] Speed of u8vector-ref
feeley at iro.umontreal.ca
Tue Oct 27 10:04:53 EDT 2009
On 2009-10-27, at 9:54 AM, Alex Queiroz wrote:
> According to statprof, I am spending nearly 40% of my running
> time in lines which call 'board-ref', which is simply defined as:
> (define board-ref u8vector-ref)
> 'u8vector-ref' seems a pretty low-level call, so I can't see how this
> can be improved further. It is just a macro around '##u8vector-ref'.
That's hard to believe... If u8vector-ref is really a *macro* you
can't use "define" to set board-ref to that macro.
(define-macro (board-ref v i) `(u8vector-ref ,v ,i))
Alternatively, don't use a macro for u8vector-ref and give the
declarations (declare (extended-bindings) (block)) so that the
compiler can inline u8vector-ref (my guess is that your code is
actually doing a procedure call to u8vector-ref, which will be slow).
When in doubt, use the -expansion option to gsc to see what is
inlined. If you are in serious doubt, use the -gvm option to view the
GVM code produced (.gvm file). If you can't believe what is
happening, use the -keep-c option to get the .c file and see if it is
calling the ___U8VECTORREF C macro. If the execution of the program
contradicts the laws of physics, send email to Brad Lucier.
More information about the Gambit-list