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Message-ID: <3EB1C2C8.5080502@redhat.com>
Date: Fri, 02 May 2003 00:58:00 -0000
From: Andrew Cagney <ac131313@redhat.com>
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To: Kevin Buettner <kevinb@redhat.com>
Cc: gdb@sources.redhat.com
Subject: Re: register_offset_hack() vs REGISTER_BYTE()
References: <1030502003824.ZM26690@localhost.localdomain>
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> 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