[m68k 1/2] define DWARF_FRAME_RETURN_COLUMN

[Andreas Schwab]

Richard Sandiford <richard@codesourcery.com> writes:

> Andreas Schwab <schwab@suse.de> writes:
>> Richard Sandiford <richard@codesourcery.com> writes:
>>> If I've understood correctly, the real problem here is that binutils has
>>> used an undefined dwarf register (24) in its CIEs, and element 24 of the
>>> dwarf register size table isn't set to sizeof (Pmode).  Is that right?
>>
>> When DWARF support for m68k was added to binutils ARG_POINTER_REGNUM
>> didn't exist yet, and gcc used 24 for the return column.
>
> Ah.  That's indeed unfortunate.  So the idea of "fixing" binutils
> is obviously out then.
>
> Any thoughts on whether the gcc fix I suggested is the right one?

IIUC the right fix would be to define DWARF_FRAME_REGISTERS to 25 and
modify DWARF_FRAME_REGNUM so that ARG_POINTER_REGNUM is mapped outside of
the DWARF_FRAME_REGISTERS range, since it is not a hard register.  That
should restore the behaviour of gcc before the addition of argptr.

Andreas.

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Andreas Schwab, SuSE Labs, schwab@suse.de
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