[PATCH] adjust dwarf ra column to libexc expectations on mips-irix

[Richard Sandiford]

Olivier Hainque <hainque@adacore.com> writes:
> + /* The system unwinder in libexc requires a specific dwarf return address
> +    column to work.  */
> + #undef  DWARF_FRAME_RETURN_COLUMN
> + #define DWARF_FRAME_RETURN_COLUMN (FP_REG_LAST + 1)
> + 

My main concern is that:

  DWARF_FRAME_REG (FP_REG_LAST + 1) == FP_REG_LAST + 1

which is a lie given the definition above.  Wouldn't it be safer/
more correct to override DWARF_FRAME_REG with something like:

  #define DWARF_FRAME_REG(REGNO) \
    ((REGNO) <= FP_REG_LAST ? (REGNO) : INVALID_REGNUM)

at the same time?  I don't know of anything in particular that
would break without this though.

Richard