This is currently not supported and will only be added later. Also update the
test cases to ensure no invariant code hoisting is applied.

llvm-svn: 275987

We use this opportunity to further classify the different user statements that
can arise and add TODOs for the ones not yet implemented.

llvm-svn: 275957

Initialize the list of references to a GPU array to ensure that the arrays that
need to be passed to kernel calls are computed correctly.  Furthermore, the very
same information is also necessary to compute synchronization correctly. As the
functionality to compute these references is already available, what is left for
us to do is only to connect the necessary functionality to compute array
reference information.

llvm-svn: 275798

Otherwise ppcg would try to call into pet functionality that this not available,
which obviously will cause trouble. As we can easily print these statements
ourselves, we just do so.

llvm-svn: 275579