Re: [PATCH] include/asm-ARCH/page.h:get_order() Reorganize and op timize

[Falk Hueffner]

"Perez-Gonzalez, Inaky" <[e-mail]> writes:

> > >     s = --s >> PAGE_SHIFT;
> > 
> > This code has undefined behaviour.
>  
> Do you mean that this:
> 
> s = (s-1) >> PAGE_SHIFT
> 
> is more deterministic? If so, I agree -- if you mean something else,
> I am kind of lost.

I mean that this code violates the rule that you may modify a value
only once between two sequence points. Newer gccs have a warning for
this (-Wsequence-point), the info page tells more.

Also, did I understand it right that you want to use fls even on
architectures that don't have it as a builtin? I would guess that will
actually be noticeably slower, since generic_fls is so complicated.

-- 
	Falk