[petsc-dev] What is this even supposed to do?

[Barry Smith]

On Sep 8, 2010, at 4:14 AM, Jed Brown wrote:

> "to" is uninitialized here, it can't possibly work.
> 
> PetscErrorCode PETSCMAP1(VecScatterBegin)(VecScatter ctx,Vec xin,Vec yin,InsertMode addv,ScatterMode mode)
> {
>  VecScatter_MPI_General *to,*from;
>  PetscScalar            *xv,*yv,*svalues;
>  MPI_Request            *rwaits,*swaits;
>  PetscErrorCode         ierr;
>  PetscInt               i,*indices,*sstarts,nrecvs,nsends,bs;
> 
>  PetscFunctionBegin;
> #if defined(PETSC_HAVE_CUDA)
>  if (xin->valid_GPU_array == PETSC_CUDA_GPU) {
>    if (!ctx->spptr) {
>      PetscInt *indices,n = to->n; 
>      ierr = PetscMalloc(n*sizeof(PetscInt),&indices);CHKERRQ(ierr);
>      ierr = PetscMemcpy(indices,to->indices,n*sizeof(PetscInt));CHKERRQ(ierr);
>      ierr = PetscSortRemoveDupsInt(&n,indices);CHKERRQ(ierr);
> 
>      ierr = PetscIntView(n,indices,0);CHKERRQ(ierr);
> 
>      ierr = PetscFree(indices);CHKERRQ(ierr);
>    }
>  } else {
>    ierr = VecGetArrayRead(xin,(const PetscScalar**)&xv);CHKERRQ(ierr);
>  }
> #else
>  ierr = VecGetArrayRead(xin,(const PetscScalar**)&xv);CHKERRQ(ierr);
> #endif
> 
> 
> 
> The PETSC_HAVE_CUDA block was added by
> 
>  changeset:   16792:571800d0bf67
>  parent:      16784:e7052ddd3def
>  user:        Barry Smith bsmith at mcs.anl.gov
>  date:        Mon Aug 23 18:37:40 2010 -0500
>  summary:     better message in check of positive definite shift for ILU
> 
> With commit messages like these...

   Sorry, my fault. It is because I don't have a decent hg commit tool that tells me what I changed so I can comment on it.

   Yes that code is currently broken, I started in and then got distracted and didn't finish it. You can just stick it inside a #if defined(foo) for now.

   Barry

> 
> 
> This can probably just get relocated to later in the function (after
> "to" is resolved), but I hear that CUDA works (I'm fighting with a
> broken CUDA environment at the moment), in which case this branch must
> never be taken, so it should just be deleted.
> 
> Jed