register_offset_hack() vs REGISTER_BYTE()

[Andrew Cagney]

> I'm seeing the following internal error:
> 
>     .../frame.c:591: internal-error: Failed to compute the register number
>     corresponding to 0x296
> 
> This is happening because the *addrp value in the following loop (which
> is in frame_register() in frame.c)...
> 
>           for (regnum = 0; regnum < NUM_REGS + NUM_PSEUDO_REGS; regnum++)
>             {
>               if (*addrp == register_offset_hack (current_gdbarch, regnum))
>                 {
>                   *realnump = regnum;
>                   return;
>                 }
>             }
> 
> ...is set using a value obtained from REGISTER_BYTE().  (See
> sentinel_frame_prev_register in sentinel-frame.c.)  But the
> value obtained from register_offset_hack() was computed by using the
> register's virtual type.

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;
     }

Andrew