[Mono-devel-list] RAPGO Proposal
Willibald.Krenn at gmx.at
Tue Nov 30 08:45:07 EST 2004
Jonathan Pryor schrieb:
> In theory, you're possibly correct. In practice, you're not. :-)
Ok, seems it was a bad idea after all :-)
> The only platforms where C++ and Mono exceptions could possibly work
> portably is on platforms where the C++ ABI is standardized. The only
> such platform I'm aware of is IA64 (Itanic, er, Itanium), and Mono
> doesn't have a JIT for that platform AFAIK.
AMD64 also has a standardized interface for stack-unwinding (=exception
handling; I guess it was inspired by IA64.)
> Furthermore, if the platform *does* have a C++ ABI standard, then Mono
> could just re-use the C++ exception structures, allowing C++ exceptions
> to be properly handled by the Mono runtime. A C++ compiler wouldn't be
I can only speak for AMD64: Yes, you can throw exceptions in C-only code:
_Unwind_Exception *newException =
newException->exception_class = 0xaabbcc00aabbcc00;
newException->exception_cleanup = &FreeNewException;
But you can not catch exceptions with C-only code. This is because the
C++ compiler generates special unwind-information (AFAIK in dwarf2
format) and exception handling is dependand on this information.
BTW: On Linux-AMD64 it's possible (as probably in IA64) that different
compilers can catch exceptions thrown in modules compiled with 'foreign'
Note that a try/catch block does not incur runtime overhead on AMD64 -
just throwing an exception is very costly..
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