GDB broken on MIPS targets with unmarked binaries

[Andrew Cagney]

> There's an interesting crash on startup in a mips-elf GDB nowadays... the
> code reads:
> 
>     default:
>       tdep->mips_abi_string = "default";
>       tdep->mips_default_saved_regsize = MIPS_REGSIZE;
>       tdep->mips_default_stack_argsize = MIPS_REGSIZE;
>       tdep->mips_fp_register_double = (REGISTER_VIRTUAL_SIZE (FP0_REGNUM) == 8);
>       tdep->mips_last_arg_regnum = A0_REGNUM + 8 - 1;
>       tdep->mips_last_fp_arg_regnum = FPA0_REGNUM + 8 - 1;
>       tdep->mips_regs_have_home_p = 1;
>       tdep->gdb_target_is_mips64 = 0;
>       tdep->default_mask_address_p = 0;
>       set_gdbarch_long_bit (gdbarch, 32);
>       set_gdbarch_ptr_bit (gdbarch, 32);
>       set_gdbarch_long_long_bit (gdbarch, 64);
>       break;
> 
> Something brought in recently, probably by the OS ABI changes if I had to
> guess, is causing the check of REGISTER_VIRTUAL_SIZE to fail.  I've no idea
> why.  Compiling a mips-elf (not mips-linux, which sets MIPS_DEFAULT_ABI) and
> running gdb on an unmarked ELF binary reproduces this.

I'd suspect this:

2002-05-08  Andrew Cagney  <ac131313@redhat.com>

         * gdbarch.sh (init_gdbarch_swap): Do not clear the swap section.
         (clear_gdbarch_swap): New function.
         (initialize_non_multiarch): Call.
         (gdbarch_update_p): Before calling init(), swap out and clear the
         existing architecture.
         * gdbarch.c: Regenerate.

The comment from arm-tdep.c should help explain why the above code is 
broken:

   /* We can't use NUM_REGS nor NUM_PSEUDO_REGS here, since that still
      references the old architecture vector, not the one we are
      building here.  */
   prologue_cache.saved_regs = (CORE_ADDR *)
     xcalloc (1, (sizeof (CORE_ADDR)
                  * (gdbarch_num_regs (gdbarch)
                     + gdbarch_num_pseudo_regs (gdbarch))));

As far as I can tell though, REGISTER_VIRTUAL_SIZE expands to 
REGISTER_VIRTUAL_TYPE which is still a macro?

Andrew