[SYCL] Add new metadata kernel_arg_exclusive_ptr

[elizabethandrews]

kernel_arg_exclusive_ptr metadata guarantees that the kernel
pointer argument, or pointers that derive from it, will not be
dereferenced outside current invocation of the kernel.

At the moment, this guarantee is met by the base pointer of an
accessor.

Signed-off-by: Elizabeth Andrews elizabeth.andrews@intel.com

[premanandrao]

I am okay with the general SYCL changes. I would like @kbobrovs review the ESIMD changes.

[elizabethandrews]

I am okay with the general SYCL changes. I would like @kbobrovs review the ESIMD changes.

Thanks for taking a look. Just an FYI there are no ESIMD changes in this patch at the moment. We still generate the same metadata.

[elizabethandrews]

@intel/llvm-gatekeepers I think this patch is ready for review and merge. There is a pending question of whether we can replace ESIMD metadata kernel_arg_accessor_ptr to use the new metadata kernel_arg_exclusive_ptr since both metadata seem to be maintaining list of boolean values for kernel arguments (to mark base pointer of accessor). I think that discussion is orthogonal to this patch. If ESIMD metadata can be replaced, I will do it in a follow-up patch. Else I will remove the FIXME in a follow-up patch once the discussion is complete