Re: [rfa:i386] Add mmx registers

[Andrew Cagney <ac131313@ges.redhat.com>]

>   Date: Tue, 13 Aug 2002 10:35:37 -0400
>    From: Andrew Cagney <ac131313@ges.redhat.com>
> 
>    > Hello,
>    >    > This adds mmx registers to the i386.
>    >
>    Done, this is what I committed.
> 
> Ouch!  This patch uncovers a problem in the new regcache code and
> segfaults on my FreeBSD 4.6-STABLE system.  The problem is that:
> 
> My Red Hat GNU/Linux tests didn't bat an eyelid :-(
> 
>    +  set_gdbarch_pseudo_register_read (gdbarch, i386_pseudo_register_read);
>    +  set_gdbarch_pseudo_register_write (gdbarch, i386_pseudo_register_write);
> 
> changes the i386 target's register cache from "legacy" to "new".  This
> means that there isn't room for the pseudo registers in
> register_valid_p, yet registers_changed() tries to frob the entries
> for the pseudo registers.
> 
> I don't see an obvious way to fix this.  Any bright ideas Andrew?
> 
> Hmm, yes.  It should be clearing:
>     [0 .. current_regcache->descr->nr_raw_registers)

PS: The code should also still allocate nr_cooked_registers worth of 
register_valid_p.  That way, erant code won't crash things.

I'll fix both in a tick.

Andrew