core changes for mep port

[Steven Bosscher]

On 3/28/07, Julian Brown <julian@codesourcery.com> wrote:
> Steven Bosscher wrote:
> > All of this feels (to me anyway) like adding a lot of code to the
> > middle end to support MEP specific arch features.  I understand it is
> > in the mission statement that more ports is a goal for GCC, but I
> > wonder if this set of changes is worth the maintenance burden...
>
> FWIW, it sounds to me like this feature may also be useful for current
> iterations of the ARM NEON extension (which we're planning to submit
> support for quite soon). NEON supports various operations on DImode
> quantities, but we don't use them for normal code at present because
> moving values from NEON back to ARM core registers is relatively slow,
> so we want to avoid doing that as far as possible.
>
> So, if there was a way of specifying that a particular value should be
> kept in a NEON register, that'd be a good thing, I think.

And if you use this coprocessor hackery, it will be exactly what Ian
opposed in his first reply: "As far as I can see you're using new
modes to drive register class preferences."

Gr.
Steven