[SYCL] tests to validate sub-devices have parent (or not) (#1346)

These are the tests for intel/llvm#7167

All devices available when using ONEAPI_DEVICE_SELECTOR are root devices, even those which are gotten via the sub-device selection choices ( e.g. ONEAPI_DEVICE_SELECTOR=level_zero:*.* ). In this PR we are ensuring that all devices gotten with that environment variable are root devices that have no parent. And, conversely, that when not using it, any sub-devices do report the correct parent.

Author: cperkinsintel

SYCL/OneapiDeviceSelector/sub-devices.cpp

@@ -0,0 +1,79 @@
+// works on PVC or ATS, however, the gpu-intel-gen12 identifier seems to
+// not be working with  REQUIRES ,
+// TODO : fix gpu-intel-XXXX identifiers for REQUIRE and UNSUPPORTED
+
+// REQUIRES: gpu
+
+// open question on whether this will work with CUDA or Hip.
+
+// RUN: %clangxx -fsycl %s -o %t.out
+
+// select sub-devices
+//   ONEAPI_DEVICE_SELECTOR=(any backend):(any
+//   device).(all-the-sub-devices).(all-sub-sub-devices)
+// RUN: env ONEAPI_DEVICE_SELECTOR="*:*.*"  %t.out
+// RUN: env ONEAPI_DEVICE_SELECTOR="*:*.*.*"  %t.out
+
+// select root devices and pass arg to test so it knows.
+// RUN: env ONEAPI_DEVICE_SELECTOR="*:gpu" %t.out 1
+// RUN: %t.out 1
+
+#include <sycl/sycl.hpp>
+using namespace sycl;
+
+int main(int Argc, const char *Argv[]) {
+  std::vector<device> devices = device::get_devices();
+  std::cout << devices.size() << " devices found." << std::endl;
+  // root devices, no matter the selector should not have parents.
+  for (const device &dev : devices) {
+    std::cout << "name: " << dev.get_info<info::device::name>() << std::endl;
+    try {
+      // unlike sub-devices gotten from device.get_info<device::parent_device>
+      // sub-devices gotten via ONEAPI_DEVICE_SELECTOR pretend to be root
+      // devices and do NOT have parents.
+      device parentDev = dev.get_info<info::device::parent_device>();
+      std::cout << "unexpected parent name: "
+                << parentDev.get_info<info::device::name>() << std::endl;
+      assert(false && "we should not be here. asking for a parent should throw "
+                      "an exception");
+
+    } catch (sycl::exception &e) {
+      std::cout << "Yay. No parent device gotten" << std::endl;
+    }
+  }
+  // any argument indicates "normal" usage, no sub-devices promoted by
+  // ONEAPI_DEVICE_SELECTOR
+  if (Argc > 1) {
+    constexpr info::partition_property partitionProperty =
+        info::partition_property::partition_by_affinity_domain;
+    constexpr info::partition_affinity_domain affinityDomain =
+        info::partition_affinity_domain::next_partitionable;
+    device d = device(gpu_selector_v);
+    try {
+      std::vector<device> sub_devices =
+          d.create_sub_devices<partitionProperty>(affinityDomain);
+      for (const device &sub_dev : sub_devices) {
+        std::cout << "child name: " << sub_dev.get_info<info::device::name>()
+                  << std::endl;
+        try {
+          // sub-devices gotten from device.get_info<device::parent_device>
+          // should have parents.
+          device parentDev = sub_dev.get_info<info::device::parent_device>();
+          std::cout << "cool parent name: "
+                    << parentDev.get_info<info::device::name>() << std::endl;
+        } catch (sycl::exception &e) {
+          std::cout << "exception: " << e.what() << std::endl;
+          assert(false && "we should not be here. asking for a parent of a "
+                          "sub-device should NOT throw an exception ");
+        }
+      }
+    } catch (sycl::exception &e) {
+      // whatever GPU device we are on does not support sub-devices at all.
+      // Nothing to do.
+      std::cout << "this device " << d.get_info<info::device::name>()
+                << " does not support sub-devices. Nothing tested."
+                << std::endl;
+    }
+  }
+  return 0;
+}