[offload][sycl] Introduce `DRIVER_ID` device property (#217562)
Prior to the introduction of liboffload contexts, Level Zero devices
under different driver instances used to each receive their own
`L0ContextTy`s.
https://github.com/llvm/llvm-project/pull/209144 introduced contexts,
which are designed to map to a single `ze_context` on L0.
`olCreateContext` accepts a user-defined device list and is restricted
to accept devices within a single platform. This restriction is
insufficient for L0 - passing devices from different driver instances is
allowed under this contract, but does not make sense on L0 as
`zeContextCreate` needs a concrete driver instance as a parameter.
Introduce a `DRIVER_ID` device property. On CUDA and AMD, it is always
equal to 0. On L0, it is a distinct integer for each driver instance. A
set of devices can be used to create a context if and only if they all
belong to the same platform and have the same DRIVER_ID.
Change libsycl to create separate logical SYCL platforms (which share
their ol_platform_handle_t) for each possible liboffload (platform,
driverId) pair.
Assisted-by: Codex (5.6 Sol)
llvm-project
0434d8f1 - [offload][sycl] Introduce `DRIVER_ID` device property (#217562)
