Re: register_offset_hack() vs REGISTER_BYTE()

[Andrew Cagney <ac131313@redhat.com>]

>> Er, for a legacy architecture, register_offset_hack(i) (aka 
>> current_regcache->descr->register_offset) should be REGISTER_BYTE(i). 
>> See init_legacy_regcache_descr.
>> 
>> Sounds like the MIPS is sneeking past:
>> 
>>    /* If an old style architecture, fill in the remainder of the
>>       register cache descriptor using the register macros.  */
>>    if (!gdbarch_pseudo_register_read_p (gdbarch)
>>        && !gdbarch_pseudo_register_write_p (gdbarch)
>>        && !gdbarch_register_type_p (gdbarch))
>>      {
>>        descr->legacy_p = 1;
>>        init_legacy_regcache_descr (gdbarch, descr);
>>        return descr;
>>      }
> 
> 
> Hmm, yes.  I just added some pseudo registers...

Can probably change REGISTER_BYTE to a pre-initialized method with 
predicate (see DEPRECATED_PC_IN_CALL_DUMMY for an example), and then add 
a predicate test for it to the above mix.

Sentinel frame should probably also be switched to using 
register_offset_hack(), instead of REGISTER_BYTE(), so that it is more 
consistent with the frame code.

Sounds like it's time to s/ REGISTER_BYTE / DEPRECATED_REGISTER_BYTE /. 
  It isn't yet possible to eliminate that macro from the MIPS since it 
is that hardwired mystery that defines the MIPS remote protocol :-(

Andrew