On Mon, Mar 06, 2017 at 10:40:17PM +0800, Christopher Li wrote:
> On Sun, Mar 5, 2017 at 7:20 PM, Luc Van Oostenryck
> <luc.vanoostenryck@xxxxxxxxx> wrote:
> > A backend may need to know the size or the type of an
> > argument and there is no easy way to access to this info.
>
> Actually, there is a way to do it with two list iterative. Will comment
> it on the next patch that use the get_nth1_arg().
>
>
> > +static inline struct symbol *get_nth1_arg(struct symbol *fn, int idx)
> > +{
> > + struct symbol_list *args = fn->ctype.base_type->arguments;
> > + struct symbol *arg;
> > + int i = 0;
> > + FOR_EACH_PTR(args, arg) {
> > + if (++i == idx)
> > + return arg;
> > + } END_FOR_EACH_PTR(arg);
> > +
> > + return NULL;
>
> As I said, I am not sure this is necessary in the particular case.
> However, the nth list entry is some what useful. If we add that,
> we should add it to ptrlist.c. Then every time of ptr_list can have it.
>
> Also, there is no need to do "++i", it should use the list->nr to skip
> over the list node for the case where n is relative large. Then only do the
> counting inside the list node. If list is packed, it is every easier, we can
> just return from the index. Depend on we want to allow unpacked list
> or not.
Absolutely, this can be optimized.
But this serie is a work in progress to help Dibyendu and I won't
otherwise spend much time on sparse-llvm.
It should also be noted that, in general, counting the list entries
via the list->nr can be problematic as some part of the code store
NULL pointers to remove entries (but it's not the case here with
the arguments).
Luc Van Oostenryck
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