Making Covoar More C++
joel at rtems.org
Thu Mar 25 00:54:33 UTC 2021
On Wed, Mar 24, 2021, 7:28 PM Chris Johns <chrisj at rtems.org> wrote:
> On 25/3/21 6:54 am, Joel Sherrill wrote:
> > On Wed, Mar 24, 2021 at 2:42 PM Gedare Bloom <gedare at rtems.org
> > <mailto:gedare at rtems.org>> wrote:
> > On Wed, Mar 24, 2021 at 1:35 PM Joel Sherrill <joel at rtems.org
> > <mailto:joel at rtems.org>> wrote:
> > >
> > > Hi
> > >
> > > There has been a lot of talk about making covoar use more C++
> > > features. It seems to be an issue on every patch. I almost
> > > replied to Gedare's comment at the bottom of a patch
> > > but decided it needed another thread:
> > >
> > > "I still struggle reviewing this codebase, in part because it is
> > > (TM) and in part because I'm not so proficient in C++ to make
> > > recommendations how to write this better. I think, if the goal is
> > > eventually to make this more C++ like code, then new code coming in
> > > should aim to move the needle in that direction rather than
> > > to propagate the old ways of doing."
> > >
> > Thanks for taking this on.
Alex's willing to make some of the changes. It's just a matter of having a
baseline so when we make changes they can be tested thoroughly. We now have
about a half dozen architectures producing reports so it is a good baseline.
I was actually thinking that once all of these are merged, it might be a
good place to tag because any git bisect might want to come back to here.
> > > I personally do NOT want to see changes to C++ in one leaf class
> > > the other architectures not get the same changes. I would prefer
> to see
> > > all these corrections and base changes in the same style with
> > > changes to C-isms. I'm not opposed to the changes but let's take
> > > Target class one. There are multiple target classes. Changing one
> > > independent of the others isn't a good idea.
> > >
> > This is reasonable to me.
> > > I'd like to see us get a working baseline in and then do something
> > > sweep std::string through Target* as a single patch. This is
> easier to
> > > test and review since it would only be C string to std::string.
> > > switch to C++ output a file at a time. Redo the report output. Etc.
> > > Discrete chunks instead of piecemeal.
> > >
> > > Covoar has spent years broken and some is from changing working
> > > things to do things "a better way" with no baseline to check
> > > We need to get a baseline.
> > >
> > > Please. Let's get a working baseline and then approach this more
> > > methodically. No one is going to suffer from seeing a C string a
> > > while longer. :)
> > >
> > I'm fine, as long as there is a plan in place and some clear
> > directions. It would help to have tickets to organize the path
> > forward.
One issue is the order of the changes. I at first thought about making the
string changes and then realized that we would end up having C printf and
have to temporarily add c_str a lot. It likely makes more sense to sweep
all the output first and then switch to C++ strings.
I have also asked Alex to put together some diagrams so we can discuss this
better. I think there is some data flow and delivered inheritance in this
program that is not being understood by everyone.
Plus Alex and I talked earlier this evening and think we have a reasonable
path to greatly speed it up without massive overhauls.
> > I'm willing to oblige continued use of C'ism for now, but I want to
> > know the plan and maybe a deadline of sorts by which I can start to
> > picky again :) I don't like to be in limbo.
> > I'd love to have a deadline but I can't guarantee how long Alex can
> > work on it. But unless he gets pulled, he can pick on this for a while.
> Joel, I pushed a number of changes to move covoar towards C++ back when I
> in the ELF and DWARF support. The C++ nature of the interfaces I brought
> in from
> the tool kit required some refactoring. I have not seen much action since
> so Gedare's question seems reasonable.
Yes you did and because we did not review the reports, there was a backlog
of issues that had to be fixed. Some from this change some from other
changes. No blame. I just want a better baseline this time.
> The need for this code to be C++ and not a mix comes down to what you want
> see happen. There is no real need to move the code closer to C++ other than
> improving the technical quality and that is about the life of the code in
> project. If you are willing to look after the code as is then I am fine
> that. If you would like to see the code move to C++ and away from C then
> also happen. It would be an interesting way to learn more about C++.
> I find the code hard to work on because I do not know if I am looking at C
> needing to use C solutions or C++ and I should be pulling on C++ threads
> where they go. I also see this is an issue for those working on the code.
> some recent patches I pointed out new code being call from C++ code with
> objects that was written in C. I pointed this out and the next patch was
There really isn't any straight C code in here. Just C-strings and C style
> > My guess is that C string to std::string is probably a good pass by
> > itself since method signatures may change.
> I think anything you feel can be changed and is in reach is welcome.
> > There isn't much file input but that could be a pass by itself
> > along the way,
> > Then sweep output one file at a time leaving reporting for last as
> > a batch.
> > Do you see an order?
> Maybe we organise a group session online where we all look over the code
> together and discuss various aspects of the architecture and what it means
> a strictly C vs C++ point of view. Any change like this cannot happen in a
> vacuum and I believe C++ is more of a taught language than C. C styles are
> easier to pick up by reading code. My introduction to C++ was in the
> with a Rational training course and documentation. It takes time to
> relearn C
> solutions you know and have at hand in C++.
This sounds good.
> I have no idea what we would need to hold such a session and who would be
> interested but I am happy to be there and be part of it.
Probably just a Google meeting is fine
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the devel