[petsc-dev] using typedef for each different memory space the variable lives in

[Barry Smith]

   Currently we use PetscScalar and PetscScalar * to refer to variables that 
could be in any memory space. On the CPU, on the GPU, in Kokkos, etc.

   Would it make sense to use typedef to indicate at each location the true 
type of the memory location when possible? 

   typedef PetscReal PetscKokkosReal   means the variable is in the Kokkos 
memory space
   typedef PetscReal PetscCUDAReal
   typedef PetscReal PetscNVSHEMReal

   etc. 

  Then one could write things like 

  struct {
     ...
     PetscNVSHEMReal *values;
  }

  Similarly inside kernels one would use the type type associated with the 
kernel, cuda with cuda etc. 

  I think the resulting code will be much clearer and easier to dive into, then 
having to first figure out where each variable lives.

  I find the current code confusing because one cannot immediately see a 
variable declaration and know where it lives, even though it does live 
somewhere in particular..

  Barry