implementing exception handlers in a front end

[Gaius Mulley]

Hi,

I'm currently trying to implement the exception handling in GNU
Modula-2 and was wondering which of the following two routes to use.
I was initially enthusiastic about using __builtin_setjmp/
__builtin_longjmp as Modula-2 exceptions can be implemented with these
mechanisms - and it would also be tantalisingly easy to code..

  However, upon searching this list I see that there are a number of
problems with __builtin_setjmp and __builtin_longjmp and have begun
to examine TRY_CATCH_EXPR nodes instead.  It seems that if this later
route is taken then the front end also needs to add:

DEFTREECODE (THROW_EXPR, "throw", tcc_unary, 1)

to its language tree.def and gimplify this.  Before I embark on this
I'd like to ask whether using __builtin_longjmp/__builtin_setjmp is
definitely the wrong way to go?

regards,
Gaius