Re: PATCH: libffi: add MIPS O32 DWARF-2 unwind info

[David Daney <ddaney at avtrex dot com>]

Casey Marshall wrote:

> The attached patch adds DWARF-2 unwinding info for MIPS ffi_call_O32.
> I'm kind of new to both DWARF-2 and MIPS assembly, so this may not be
> completely correct. I have tried this on a modified 3.3.3 -- the
> changes since then appear to have been only to the SIZEOF_ARG macro --
> but have not tried it on a newer version. It seems to work, since
> things like `invokethrow.java' work properly for me now.
>
> Note that this is only for the O32 ABI. I think that N32 would be
> similar (identical?) to this, but I can't test it.
>
> Also: GCJ emits references to __gcj_personality_v0 in the assembler it
> generates, as a "personality" in the CIE. I didn't know if this was
> appropriate for the ffi code, so I merely omitted it. Is this ok?
>  

I am not a DWARF-2 expert either, but it is my understanding that the 
personality is only involved in catching exceptions.  If they are only 
"passing through" there is no need for a personality.

BTW, How did you generate the .eh_frame data?  You can see what you have 
to emulate by compiling simple 'C' functions with -fexcptions.

David Daney.