On Sunday 20 March 2005 01:58, Giovanni Bajo wrote:
> Paul Schlie <[EMAIL PROTECTED]> wrote:
> > - Sorry, I'm confused; can you give me an example of legal C
> > expression specifying an indirect jump to an arbitrary location
> > within a function?
>
> It is possible in GNU C at least:
>
> int foo(int dest)
> {
> __label__ l1, l2, l3;
> void *lb[] = { &&l1, &&l2, &&l3 };
> int x = 0;
>
> goto *lb[dest];
>
> l1:
> x += 1;
> l2:
> x += 1;
> l3:
> x += 1;
> return x;
> }
>
> I would not design a backend so that such a feature is deemed to be
> impossible to support.
Don't we know which labels are targets of indirect jumps?
So the proposed restriction now becomes: functions *and targets of indirect
jumps* must be aligned to an N word boundary. I'd guess that the latter are
sufficiently rare that this is still an acceptable restriction.
Paul
