On Wed, 2019-10-30 at 10:27 +0100, Richard Biener wrote:
>
> Hmm, not sure - I'd like to write
>
> for (gimple *use_stmt : imm_stmt_uses (SSAVAR))
> for (use_operand_p use_p : <need to refer to the iterator object
> from
> above>)
> ...
>
> I don't see how that's possible. It would need to be "awkward" like
>
> for (auto it : imm_stmt_uses (SSAVAR))
> {
> gimple *use_stmt = *it;
> for (use_operand_p use_p : it)
> ...
> }
>
> so the first loops iteration object are the actual iterator and you'd
> have to do extra indirection to get at the actual stmt you iterated
> to.
>
> So I'd extend C++ (hah) to allow
>
> for (gimple *use_stmt : imm_stmt_uses (SSAVAR))
> for (use_operand_p use_p : auto)
> ...
>
> where 'auto' magically selects the next iterator object in scope
> [that matches].
>
> ;)
Have you applied for a patent yet? :D
How about this one?
for (gimple* use_stmt : imm_stmt_uses (SSAVAR))
for (use_operand_p use_p : imm_uses_on_stmt (*use_stmt))
... where helper function "imm_uses_on_stmt" returns a range object
that offers a begin and end function and its own iterator type.
Another concept that could be interesting are filter iterators.
We used a simplistic re-implementation (c++03) to avoid dragging in
boost when working on AMS
https://github.com/erikvarga/gcc/blob/master/gcc/filter_iterator.h
Example uses are
https://github.com/erikvarga/gcc/blob/master/gcc/ams.h#L845
https://github.com/erikvarga/gcc/blob/master/gcc/ams.cc#L3715
I think there are also some places in RTL where filter iterators could
be used, e.g. "iterate over all MEMs in an RTL" could be made to look
something like that:
for (auto&& i : filter_rtl (my_rtl_obj, MEM_P))
...
Anyway, maybe it can plant some ideas.
Cheers,
Oleg
