Hi, I have tried the following examples with the fanalyzer option in g++.
1 (a)
void myFunction()
{
char *p =new char;
}
int main()
{
func();
return 0;
}
1(b)
void myFunction()
{
try {
char *p = new char;
throw p;
}
catch(...) {
}
}
int main()
{
myFunction();
return 0;
}
In 1(a), there is no exception handling. When I ran `cc1plus`, a memory
leak was reported as shown in bug #94355.
In 1(b), there is a use of exception handling. When I ran cc1plus`, no
memory leaks were detected. I believe there should be one. Can you please
confirm from your side as well? As you said all the calls to try, catch and
throw got converted to _cxa prefixed functions. I am trying to find the
places where the corresponding checks can be placed for the analysis of
exception handling in gimple IR.
Please, let me know your thoughts on this.
On Fri, Mar 26, 2021 at 12:48 AM David Malcolm <dmalc...@redhat.com> wrote:
> On Thu, 2021-03-25 at 14:52 +0530, Saloni Garg via Gcc wrote:
> > Hi all,
> > I am an undergraduate student in AMU, Aligarh. I am interested in the
> > project* `Extend the static analysis pass`. *I have followed this(
> > https://gcc.gnu.org/pipermail/gcc/2021-March/234941.html) and been
> > able to
> > successfully build and successfully ran and pass the test suite for C
> > and
> > C++.
> >
> > I found this sub-project `C++ support (new/delete checking,
> > exceptions,
> > etc)` interesting and may be the conservative code for this can be
> > made
> > along the lines of malloc/free implementation in C. I found here(
> > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94355) that some part of
> > it
> > has already been implemented . I would like to expand it further and
> > learn
> > about it, maybe start with writing some test cases, please let me
> > know.
> >
> > Further, I am inclined on this(
> > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97111). Let me know if
> > it is
> > still available.
> >
> > Looking forward to hearing from you guys.
> > Thanks,
> > Saloni Garg
>
> Hi!
>
> I'm the author/maintainer of the static analysis pass, and would be the
> mentor for any GSoC project(s) involving it.
>
> I've already implemented most of the new/delete checking in GCC 11; the
> big missing component there is exception-handling.
>
> Implementing exception-handling in the analyzer could make a good GSoC
> project: it's non-trivial, but hopefully doable in one summer. I see
> you've already seen bug 97111, and there are some links in that bug to
> resources. Given that the analyzer runs on the gimple-ssa
> representation, by the time it sees the code, much of the exception-
> handling has already been translated into calls to various __cxa_-
> prefixed functions in the C++ runtime, so part of the work would
> involve "teaching" the analyzer about those functions. One way to make
> a start on this would be to create a collection of trivial C++ examples
> that use exceptions, and then look at analyzer dumps to see what IR is
> being "seen" by the analyzer for the various constructs. (I actually
> started this a long time ago and have a very crude barely-working
> prototype, but it was just the start, and I've forgotten almost all of
> it...)
>
> Hope this is helpful
> Dave
>
>
>
