Re: [abc] abc static analysis bug (fwd)

Hi Ondrej,

Thanks for tracking this down.

What should we send to the guys who reported this bug so that they
can get a running abc?

Cheers, Laurie

+-----------------------------------------------------------------
| Laurie Hendren --- laurie.hendren@mcgill.ca
| Associate Dean (Academic), Faculty of Science,
| Dawson Hall, McGill University, 853 Sherbrooke St W,
| Montreal QC H3A 2T6 Canada, 514-398-7179, fax 514-398-1774
+----------------------------------------------------------------
| For contact and home page info as Professor, Computer Science:
| http://www.sable.mcgill.ca/~hendren --- hendren@cs.mcgill.ca
| Research: http://www.sable.mcgill.ca http://aspectbench.org
+----------------------------------------------------------------

On Tue, 31 Jan 2006, Ondrej Lhotak wrote:

> I've fixed this in Paddle revision 2277.
>
> Here's the log message:
>
> Fix cflow analysis bug reported by Sebastian Kanthak.
> Call graph edges corresponding to thread starts (Kind.THREAD) need to
> be handled specially in two ways. First, for mayCflow computation, they
> must be excluded from the call graph. Second, for mustCflow computation,
> all their targets must be treated as entry points. We were doing the
> first but forgot to do the second. This change fixes this.
>
> Ondrej
>
> On Mon, Jan 30, 2006 at 11:31:00AM -0500, Laurie Hendren wrote:
> > Ondrej,
> >
> > Can you take a look at this?
> >
> > Thanks, Laurie
> >
> >
> > +-----------------------------------------------------------------
> > | Laurie Hendren --- laurie.hendren@mcgill.ca
> > | Associate Dean (Academic), Faculty of Science,
> > | Dawson Hall, McGill University, 853 Sherbrooke St W,
> > | Montreal QC H3A 2T6 Canada, 514-398-7179, fax 514-398-1774
> > +----------------------------------------------------------------
> > | For contact and home page info as Professor, Computer Science:
> > | http://www.sable.mcgill.ca/~hendren --- hendren@cs.mcgill.ca
> > | Research: http://www.sable.mcgill.ca http://aspectbench.org
> > +----------------------------------------------------------------
> >
> > ---------- Forwarded message ----------
> > Date: Mon, 30 Jan 2006 16:47:53 +0100
> > From: Sebastian Kanthak <skanthak@gmail.com>
> > Reply-To: sebastian.kanthak@muehlheim.de
> > To: hendren@sable.mcgill.ca
> > Cc: Mira Mezini <mezini@informatik.tu-darmstadt.de>,
> > Michael Haupt <haupt@informatik.tu-darmstadt.de>
> > Subject: abc static analysis bug
> >
> > Dear Mrs. Hendren,
> >
> > we recently submitted a paper on cflow implementations to PLDI, which
> > was rejected. We have, however, received a very helpful review
> > detailing the cflow optimisations as applied by abc.
> >
> > We are currently trying to incorporate some of the suggestions and are
> > performing a more detailed analysis of our benchmarks. It seems I have
> > hit a bug in abc's interprocedural cflow optimizations with our
> > benchmark (attached to this e-mail).
> >
> > When compiling the benchmark with "-O3 -main-class TestAbc",
> > unconditional advice execution is woven into Foo.foo() (although it
> > can be reached outside the control flow) and Foo.m() does not contain
> > any logic for updating the state of the control flow (although it must
> > not be omitted, here). You can verify that something is wrong by
> > running the benchmark twice; the first time compiled with -O1, the
> > second time compiled with -O3. To run the benchmark, please use the
> > following parameters and notice the "count=<n>" parameter in the
> > output.
> >
> > java TestAbc 1 10 5 10 1
> >
> > When compiled with -O1, you'll get the correct value of "count=40",
> > but with -O3 a value of "count=120" will be printed.
> >
> > I think the bug is caused by the way we spawn several threads in
> > CFlow.run. Apparently, your call graph analysis does not correctly
> > analyze which method gets executed due to Thread.start() (which is a
> > very hard problem, in general), but I'm sure you can debug this issue
> > better than I could.
> >
> > I hope this information is helpful to you.
> >
> > Sebastian Kanthak
> >
> > --
> > Research Assistant
> > Software Technology Group
> > Darmstadt University of Technology, Germany
>
>
>
>
>
>
>
Received on Tue Jan 31 22:42:59 2006