[Sbcl-devel] Re: [Sbcl-commits] numbers.lisp,1.26,1.27

[Alexey D. <ade...@co...>]

Christophe Rhodes <cs...@ca...> writes:

> Alexey Dejneka <ade...@co...> writes:
> 
> > The last case cuts an argument to BIGNUM-ELEMENT-TYPE. Of course, it
> > can be replaced with (logior (%bignum-ref x 0) (ash (%bignum-ref x 1)
> > 32)), but does Alpha backend support 64-bit arguments?
> 
> Maybe I'm missing something...
> 
> Would it not be easier to do e.g.
>   (defun +-mod32 (x y)
>     (logand (+ x y) #.(1- (ash 1 width))))
> and similar for the other modular functions?

It will not work; it will be transformed to

  (defun +-mod32 (x y)
    (+-mod32 (+ x y)))

which results in a full recursive call of +-MOD32 (because there
is no VOP without restrictions on argument types).

If you add (DECLARE (NOTINLINE +)), it will probably work, but it
will be less efficient than the current version. But you can
replace ASSERT with IF, and if the condition fails use your
version.

-- 
Regards,
Alexey Dejneka

"Alas, the spheres of truth are less transparent than those of
illusion." -- L.E.J. Brouwer