ffc team mailing list archive

[Johan Hake <johan.hake@xxxxxxxxx>]

On Wednesday 09 December 2009 08:39:17 Anders Logg wrote:
> On Wed, Dec 09, 2009 at 08:25:24AM -0800, Johan Hake wrote:
> > On Wednesday 09 December 2009 08:13:20 Anders Logg wrote:
> > > On Wed, Dec 09, 2009 at 08:04:48AM -0800, Johan Hake wrote:
> > > > On Wednesday 09 December 2009 01:59:58 Anders Logg wrote:
> > > > > On Tue, Dec 08, 2009 at 11:52:38PM -0800, Johan Hake wrote:
> > > > > > On Tuesday 08 December 2009 17:09:09 Anders Logg wrote:
> > > > > > > We're working on simplifying the FFC code (and parts of UFL).
> > > > > > > Both have grown out of hand and with limited resources (like
> > > > > > > Martin and Johan leaving for other ventures) we need to make
> > > > > > > the codebase easier to maintain.
> > > > > > >
> > > > > > > As part of this, we've made some changes to how UFL and FFC
> > > > > > > handle the preprocessing of forms. In particular, we've removed
> > > > > > > the caching of so called form data in a form. Ideally, this
> > > > > > > should not lead to any problems but there may be regressions
> > > > > > > such as slow JIT compilation as a result of not caching certain
> > > > > > > data so keep an eye out for this.
> > > > > >
> > > > > > Do you know why Martin did include these in the first place?
> > > > >
> > > > > Yes, we discussed it quite a bit but I believe he was never happy
> > > > > with the solution. We had things like form_data being cached in a
> > > > > form and form_data also storing a modified version of the form so
> > > > > there were things like
> > > > >
> > > > >   self.form.form_data().form
> > > > >
> > > > > being used in the form. I believe the new design is cleaner.
> > > >
> > > > Ok.
> > > >
> > > >   v = TestFunction
> > > >   u = TrialFunction
> > > >
> > > >   M0 = assemble(u*v*dx)
> > > >
> > > >   v = TestFunction
> > > >   u = TrialFunction
> > > >
> > > >   M1 = assemble(u*v*dx)
> > > >
> > > > I think that he wanted to prevent recompilation of M1, as it is
> > > > basically the same code that is generated as for M0. But due to some
> > > > internal and necessary they are treated differently. I think that the
> > > > form_data thing was a workaround for that. Is this correct?
> > >
> > > I don't think form_data has anything to do with this.
> > >
> > > The above code should not lead to any new code generation as both M0
> > > and M1 should have the same signatures. If not, there's a bug in
> > > jit.py in FFC. The code for M1 should be picked up from disk cache.
> >
> > Ok, I see that this is not the case for Arguments (BasisFunctions), but
> > it is for Coefficients (Functions):
> >
> >    f = Function(V)
> >    u = TestFunction(V)
> >
> >    m0 = assemble(v*f*dx)
> >
> >    f = Function(V)
> >
> >    m1 = assemble(v*f*dx)
> >
> > will now trigger a recompilation.
> >
> > Just take a repr on the two 'f' and see.
> 
> Should be fixed now. I've added a call to preprocess before computing
> the form signature.
> 
> Does it work now?

Did you push it?

  el = FiniteElement("CG",triangle,1)
  f = Coefficient(el)
  
  repr(f*dx)

  f = Coefficient(el)

  repr(f*dx)

repr does here return different results, and JitObject.signature() does only 
use repr on the passed form.

Johan

> --
> Anders
>