RFA: give the return column a size (Was: Re: RFA: Use _Unwind_Ptr)

[Jim Wilson]

On Tue, 2003-07-15 at 11:48, Richard Sandiford wrote:
> Might be wrong here, but it sounds like this might break big-endian mips
> n32 (for the same reason that rth mentioned wrt the unwind-dw2.c change).
> The return address register is 64 bits wide but Pmode == ptr_mode == SImode.

The MIPS port maps DWARF_FRAME_RETURN_COLUMN to the HI register, so it
should not be affected.  Joern is adding code for the case where
DWARF_FRAME_RETURN_COLUMN maps to a register which is not known to gcc,
e.g. the PC register, and thus we need to supply a default size.  This
should be rare.

There is the possibility of a different problem here, where the
DWARF_FRAME_RETURN_COLUMN maps to a known register which is a different
size than than return address.  In that case, we would have to ignore
DWARF_FRAME_RETURN_COLUMN in the main loop, and always provide a value
after the loop.  In that case, we probably do have to use
RETURN_ADDR_RTX like Joern suggested, and then use Pmode if
RETURN_ADDR_RTX is not defined.
-- 
Jim Wilson, GNU Tools Support, http://www.specifix.com