Re: [RFA] better alpha_register_virtual_type

[Andrew Cagney <ac131313@redhat.com>]

> On Mon, Jun 02, 2003 at 12:30:36PM -0400, Daniel Jacobowitz wrote:
> 
>> Yes.  I was a little surprised by the void_data_ptr/void_func_ptr bit,
>> but I see that d10v does the same thing, so it must be right :)

For the d10v it is 100% right.  The d10v's PC needs to be a code pointer 
so that it it is automatically converted into a CORE_ADDR when used in 
equations vis:

(gdb) ptype $pc
type = void (*)()
(gdb) x/i $pc
0x10140b8 <main+20>:    ld      r0, @r11        ||      nop
(gdb) print/x $pc
$1 = 0x10140b8
(gdb) print/x (int)$pc
$2 = 0x502e

>> Hmm, I'm not sure.  Any particular reason for this patch?
> 
> 
> Well, the void_func_ptr bit is nice because "info r" yields
> 
> 	pc             0x12000053c      0x12000053c <main+16>
> 
> The void_data_ptr bits I think just document which registers
> are ABI mandated to contain pointer values all of the time.
> 
> Actually, I have a related question here.  Something that I
> didn't notice earlier is that d10v is using register_type,
> not register_virtual_type.  Looking at the guts of regcache.c,
> it would appear that the later is deprecated, since not 
> having a register_type hook (among other things) results in
> legacy_p being set.
> 
> I thought it obvious to rename my existing hook, but that changes
> the behaviour of "info r" -- I no longer get the pc decoded, and
> indeed "ptype $pc" once again yields int64_t.

Something weird is happening.  The only thing notable about the d10v is 
that it doesn't set PC_REGNUM (per above, the d10v works).  Perhaphs the 
alpha definition is confusing std-regs.c / builtin-regs.c (but that 
doesn't make much sense).

> Is this a bug elsewhere in gdb, or what?

Perhaps.

Andrew