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Re: Paradoxical subreg questions
- To: law at cygnus dot com
- Subject: Re: Paradoxical subreg questions
- From: John Wehle <john at feith dot com>
- Date: Wed, 12 Jan 2000 20:28:07 -0500 (EST)
- cc: amylaar at cygnus dot co dot uk, gcc at gcc dot gnu dot org
> > Are the other bits of the DImode hard register assumed clobbered by the
> > set? In other words:
> >
> > (set (subreg:DI (reg:SI 76) 0) (reg:DI 77))
> >
> >
> > implies:
> >
> > (clobber (reg:DI 76))
>
> I'm not sure that's even valid RTL. We are allowed to create paradoxical
> SUBREGs for a rvalue, but I'm not sure they're valid for an lvalue.
I'm seeing this type of RTL generated on the alpha when compiling:
int
func (int a)
{
int b;
int i;
b = 0;
for (i = a; i < 10; i++)
b += i;
return b;
}
> In the SUBREG section of the manual it discusses stores to normal SUBREGs
> but does not cover stores to paradoxical SUBREGs at all.
I noticed. :-( Hence the desire to be enlightened as to the exact meaning.
-- John
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