Re: PATCH: 0/6 [2nd try]: Add AVX support

Nathan Froyd
2010-03-07T21:07:49Z

On Sun, Mar 07, 2010 at 08:46:34PM +0100, Mark Kettenis wrote:
> > From: Nathan Froyd <froydnj@codesourcery.com>
> > The third alternative--again, what's adopted for the PPC SPE 64-bit
> > registers--is to give %ymmNh their own DWARF register numbers. I
> > suppose it's also ABI-incompatible, but it seems like it fits with your
> > approach much better than either of the above alternatives.
>
> I don't think that would be a good idea. It means you can't refer to
> something stored in a %ymmN register with a single register number.

Sure you can. GDB knows to merge %ymmNh with %xmmN if it needs to to
make %ymmN, which will have only one register number.

> The compiler will have to use a more complicated expression (which may
> not be possible for older debug info formats) for these. As a result,
> things like "info address" become rather useless.

I suppose the importance of that depends on how important supporting
older debug info formats is. I haven't looked into whether the SPE bits
are well supported under non-DWARF formats.

-Nathan