On 9/29/20 11:22 AM, John Paul Adrian Glaubitz wrote:
Hello!
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?
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.
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?).
I can never remember more than that, and usually go build a compiler and
inspect its output to figure more.
nathan
--
Nathan Sidwell
