Re: rtlopt loop unroller question

[Toon Moene <toon at moene dot indiv dot nluug dot nl>]

Daniel Jacobowitz wrote:

> On Thu, Oct 23, 2003 at 10:12:59PM +0200, Toon Moene wrote:

> > Auto-increment doesn't work here, because
> >
> > 	LD	Rx,4(Ry)+
> >
> > is not allowed, only
> >
> > 	LD	Rx,(Ry)+
>
>
> What I'm saying is that
> 	ldr Rx, [Ry, #4]!
> is the "4(Ry)+" that you describe above.
>
> But there's no 2^N restriction so that still leaves me in the dark what
> this was developed for.

Ah, I see - I didn't understand the notation; so it's a funny way to 
write a pre-increment (add 4 to Ry temporarily to use in the address 
expression, load from that, then add 4 to Ry permanently).

I wonder if any other architecture could benefit from this and it's a 
sure loss for most that support {PRE|POST}_INCREMENT.

--
Toon Moene - mailto:toon@moene.indiv.nluug.nl - phoneto: +31 346 214290
Saturnushof 14, 3738 XG  Maartensdijk, The Netherlands
Maintainer, GNU Fortran 77: http://gcc.gnu.org/onlinedocs/g77_news.html
GNU Fortran 95: http://gcc.gnu.org/fortran/ (under construction)