Hi, On Wed, Jun 30 2021, Richard Biener wrote: > On Wed, Jun 30, 2021 at 3:46 AM Martin Sebor <mse...@gmail.com> wrote: >> On 6/29/21 4:58 AM, Richard Biener wrote:
[...] >> > >> > But I wonder if since you now identified them they could be massaged >> > prior to doing the change. >> > >> > I do hope we end up not needing .to_vec () after all, if no users remain ;) >> >> I'd be happy to if none remained. I see how to eliminate those in >> calls to functions like c_parser_declaration_or_fndef() (done in >> the attached revision of the patch), but no easy way to get rid >> of those that replace other implicit conversions, like all those >> assignments to the vec members of the ipa_call_arg_values ctor. >> If it's appropriate to std::move those then that would get rid >> of the .to_vec () call. I'm not familiar with the code but I >> have the impression it might be meant more as a reference to >> some "remote" object (an instance of ipa_auto_call_arg_values?) >> If that's right then making the vec members auto_vec references >> (or pointers) would be one way to "fix" this. > > I think ipa_call_arg_values is just a temporary container used to > pass a collection of vec<>s along API boundaries. I'm not sure > whether it's default CTOR is ever used but it's definitely an > optimization avoiding extra indirection (when changing the vec<> > members to vec<> * or references, in case the default CTOR is > not used). It _might_ be that the vecs are all just read and never > written to in the APIs using this abstract type No, IPA-CP does add and then remove extra context-specific values in the auto version of the container, ipa_auto_call_arg_values, but I do not think that consumers of ipa_call_arg_values do. The caching mechanism can make a (partial) copy. > but then it's > likely the vector are always appropriately pre-allocated. They are, they should never be reallocated. > Maybe using array_slice instead of vec<> members would work, > but they'd pack less efficient (but I guess not an issue for this > aggregate which should be only used temporarily for argument > passing). I need to educate myself more about array_slice to to comment on that. But note that apart from reducing the number of parameters, there is also an ipa_call_arg_values field in ipa_call_context and especially ipa_cached_call_context. Martin
