Re: [PATCH] Re: Bignum performance

[tomas]

On Tue, Aug 15, 2023 at 04:33:04PM +0200, Emanuel Berg wrote:
> Po Lu wrote:
> 
> >> Are we talking 1 word = 2 bytes = 16 bits here, s2c?
> >>
> >> If so, the range of fixnums are -32 768 to 32 767
> >> inclusive, so those are hardly huge numbers.
> >
> > Under Arm64, general purpose integer registers are 64 bits
> > wide. That is also the word size of said machine.
> 
> If they are, the range for fixnums is
> 
> (list (* -1 (expt 2 (1- 64)))
>       (1-   (expt 2 (1- 64))) )
> 
> (-9223372036854775808 9223372036854775807)
> 
> Only after that it gets slower :P

Unless SBCL uses tagged object representation. Unless the
compiler can prove that some "thing" is going to be an
int. Unless...

Cheers
-- 
t

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