RE: [PATCH, FT32] initial support

[James Bowman <james dot bowman at ftdichip dot com>]

> On 05/08/2015 06:04 PM, James Bowman wrote:
> >
> >> Are you using LRA or reload?  The former is definitely preferred and for
> >> a simple target like this, I'd expect the transition to be very easy.
> >
> > I'm using reload. Attempting to naively switch on LRA resulted in
> >    internal compiler error: Max. number of generated reload insns per insn is achieved (90)
> > so I would be very interested in a pointer an LRA clues.D Thanks.
> Vladimir Makarov would be the best contact point.  I'm a bit surprised
> you ran into this issue given the simplicity of the port.
>
> I'd minimize the testcase, then enable debugging dumps, then look at the
> insn that's causing LRA to loop.  If Vlad helps, he's probably going to
> want that minimized testcase as well, so it's time well spent.
>

It seems that with whenever a function's frame is bigger than 512 bytes,
LRA loops.  Likely this causes a problem because there is no actual
instruction for subtracting constants more than 512.  However, there is a
"link" pattern that allows this. It is puzzling.

Do you think it would be easier to make the submission as is, then debug
the LRA issues from that point? If so, I have attached the current patch set.

Thanks.

--
James Bowman
FTDI Open Source Liaison

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