Re: Different multiply operator for pointers and integers

[Laura Tosoratto <Laura dot Tosoratto at roma1 dot infn dot it>]

Dave Korn wrote:

> > -----Original Message-----
> > From: gcc-owner On Behalf Of Richard Earnshaw
> > Sent: 16 December 2004 16:40
> >    
>
>  
>
> > On Thu, 2004-12-16 at 16:32, Laura Tosoratto wrote:
> >    
>
>  
>
> > > In the same time, it needs all addresses to be hold in a 
> > >      
> > specific part 
> >    
> >
> > > of register file (we defined a reg_class to represent this 
> > >      
> > set of regs) .
> >    
>
>
>  
>
> > You just need to provide multiple alternatives to the 
> > standard multiply operator.
> >
> > If your two register classes are matched by the constraint letters 'x'
> > and 'y' respectively, then you just need a pattern something like
> >
> > (define_insn "muldi"
> >   [(set (match_operand:DI 0 "register_operand" "=x,y")
> >         (mult:DI (match_operand:DI 1 "register_operand" "%x,y")
> > 		 (match_operand:DI 2 "register_operand" "x,y")))]
> >  ""
> >  "@
> >  mult_fmt1 %0, %1, %2
> >  mult_fmt2 %0, %1, %2")
> >
> >    
>
>  Doesn't that assume that the registers that hold pointers can _only_ be used
> for pointers and not for integers?  It doesn't necessarily follow from Laura's
> original description that those registers _can't_ hold integers, only that
> pointers _must_ be in one of them.
>
>    cheers, 
>      DaveK
>  
Yes, those registers _can_ hold integers but they _must_ hold pointers.
The mult_i instruction must be used when operands are integers, and the 
mult_a instruction must be used when one of the operands is a pointer.

Can I do all the work with constraint letters?

Thanks,
Laura