Re: Fwd: Re: Registers used for exception handling on Linux/m68k?
Hi Nathan!
On 9/29/20 7:58 PM, Nathan Sidwell wrote:
> On 9/29/20 11:22 AM, John Paul Adrian Glaubitz wrote:
>>
>> I'm looking for an information regarding exception handling on Linux/m68k, in particular
>> I need to know what registers are used by the ABI in order to implement the functions
>> "getExceptionPointerRegister" and "getExceptionSelectorRegister" in the M680x0 backend
>> in LLVM [1], [2].
>
> I don;t know what those functions are, but from their names they seem to be related to figuring out the exception object and type?
I think so. I'm not a compiler expert hence my questions :-).
> Do you understand the itanium ABI's unwinding mechanism --
> 1) follow stack to get to landing pad.
> 2) invoke landing pad to see if it wants to catch
> 3) if not, continue following stack
> 4) once we've found one to catch it, we need to unwind properly, which involves invoking cleanups. and eventually getting to the catcher
>
> invoking the landing pad means passing (a) an integer telling it what's happening, and (b) a pointer to data.
This seems to be the data that I need. I just need to understand how that works.
>> I looked into the GCC source code to find the corresponding parts but I could only find
>> the macros prefixed with "EH_" [4] which I didn't fully understand.
>
> Those are the bits you want. one of those is the selector (0?) and the other is the data pointer (1?).
OK. But aren't they passed through particular registers on m68k? Or is this something specific
to LLVM?
Thanks for the help!
Adrian
--
.''`. John Paul Adrian Glaubitz
: :' : Debian Developer - glaubitz@debian.org
`. `' Freie Universitaet Berlin - glaubitz@physik.fu-berlin.de
`- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913
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