dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

Then we might as well use size_t. :-)

If I remember correctly, we discussed at some point (5 years back or
so) whether to use size_t or dolfin:uint = unsigned int. A related
discussion was which type to use for UFC. We landed on unsigned
int. So a change will be needed also in UFC.

Is PetscInt = size_t?

PS: I'm Cc:ing the list for further discussion. Quite a lot of traffic
has moved off the list to questions/bug reports which means it will
not be visible to everyone.

--
Anders


On Thu, May 24, 2012 at 06:37:25PM -0000, Jason Bacon wrote:
> Any reason not to call it dolfin::size_t?  The name size_t is meant to
> indicate the size of a pointer, which is not the same size as a standard
> uint on 64-bit systems.
>
> Cheers,
>
>      -J
>
> On 05/24/12 13:12, Anders Logg wrote:
> > On Thu, May 24, 2012 at 06:02:58PM -0000, Johan Hake wrote:
> >> On 05/24/2012 07:28 PM, Jason Bacon wrote:
> >>> Well, I think the code will have to be carefully examined and altered to
> >>> avoid truncation errors when mixing PetscInt and smaller types.  I
> >>> attached the patches necessary to make it compile, but there may still
> >>> be truncation issues where int arithmetic is used on subscripts elsewhere.
> >>>
> >>> I think this is an important issue, given that "int" subscripts limit
> >>> arrays to 2^31 elements, and Dolfin will be used on many systems with
> >>> far more address space than that.
> >>>
> >>> I personally make a point of using size_t for all array subscripts.
> >>> It's standard, unsigned, and matches the address size on the underlying
> >>> architecture.  That would eliminate the issue on 64-bit systems, which
> >>> is the only place it will matter anyway.
> >> Sounds like a good solution, but it will take some thorough search and
> >> replace...
> > We can make dolfin::uint a typedef for size_t.
> >
> > And I expect some SWIG fixes will be necessary...
> >
> >
> >
> >> Johan
> >>
> >>> Cheers,
> >>>
> >>>        -J
> >>>
> >>> On 05/24/12 11:53, Anders Logg wrote:
> >>>> On Wed, May 23, 2012 at 02:02:57PM -0000, Jason Bacon wrote:
> >>>>> Public bug reported:
> >>>>>
> >>>>>
> >>>>> Have you guys tested with a 64-bit PETSc yet? ( PETSc built with --with-64-bit-indices and/or --with-64-bit-pointers).
> >>>>>
> >>>>> The Dolfin code interfacing with PETSc uses int in a lot of places where
> >>>>> it should use PetscInt.  I can send a minimal set of patches required to
> >>>>> make it compile, but there are still runtime problems, so the code is
> >>>>> going to need more thorough examination and testing.
> >>>> We also use a lot of reinterpret_cast<>    from 'unsigned int'. How will
> >>>> that work with 64 bit PETSc?
> >>>>
> >>>>
> >>>
>
>