Re: [RFA] mips-tdep.c: Add dwarf/dwarf2 regnum mapping functions

[Andrew Cagney <ac131313 at redhat dot com>]

> When using dwarf2 debug info, floating point registers are mapped
> incorrectly for certain mips targets.  It turns out that Irix is the
> only one that's getting it right due to the fact that FP0_REGNUM is
> defined to be 32.
>
> Thanks to Chris Demetriou for diagnosing this problem and suggesting
> the solution.
>
> [Note: Irix cross some other mips target is currently broken due to
> the fact that FP0_REGNUM is not multiarched yet.]

I don't think FP0_REGNUM should be multi-arched.  The only reference to 
FP0_REGNUM in generic code that I could find was this gem:

  if (FP0_REGNUM >= 0)  /* need floating point? */
    {
      if ((regno >= 0 && regno < FP0_REGNUM) ||
          regno == PC_REGNUM  ||
          (NPC_REGNUM >= 0 && regno == NPC_REGNUM) ||
          regno == FP_REGNUM  ||
          regno == SP_REGNUM)
        return;                 /* not a floating point register */

      if ((fpregs = proc_get_fpregs (pi)) == NULL)
        proc_error (pi, "fetch_registers, get_fpregs", __LINE__);

      supply_fpregset (fpregs);
    }

mips_tdep could certainly gain a local tdep->fp0_regnum though.

> Okay?

Yes, just make it a little bit more robust.  The i386 does this:

  /* This will hopefully provoke a warning.  */
  return NUM_REGS + NUM_PSEUDO_REGS;

when it doesn't know what to do with a register.

Andrew

> +static int
> +mips_dwarf_reg_to_regnum (int num)
> +{
> +  if (num < 32)
> +    return num;
> +  else
> +    return num + FP0_REGNUM - 32;
> +}
> +
> +/* Convert a dwarf2 register number to a gdb REGNUM */
> +
> +static int
> +mips_dwarf2_reg_to_regnum (int num)
> +{
> +  if (num < 32)
> +    return num;
> +  else
> +    return num + FP0_REGNUM - 32;
> +}
> +
> +
>  /* Convert an integer into an address.  By first converting the value
>     into a pointer and then extracting it signed, the address is
>     guarenteed to be correctly sign extended.  */
> @@ -5980,6 +6003,8 @@ mips_gdbarch_init (struct gdbarch_info i
>    /* Map debug register numbers onto internal register numbers.  */
>    set_gdbarch_stab_reg_to_regnum (gdbarch, mips_stab_reg_to_regnum);
>    set_gdbarch_ecoff_reg_to_regnum (gdbarch, mips_ecoff_reg_to_regnum);
> +  set_gdbarch_dwarf_reg_to_regnum (gdbarch, mips_dwarf_reg_to_regnum);
> +  set_gdbarch_dwarf2_reg_to_regnum (gdbarch, mips_dwarf2_reg_to_regnum);
>  
>    /* Initialize a frame */
>    set_gdbarch_deprecated_frame_init_saved_regs (gdbarch, mips_frame_init_saved_regs);