[llvm] [Offload] Ensure to load images when the device is used (PR #103002)

[Johannes Doerfert via llvm-commits]

================
@@ -32,6 +35,43 @@
 using namespace llvm::omp::target::ompt;
 #endif
 
+// If offload is enabled, ensure that device DeviceID has been initialized.
+//
+// The return bool indicates if the offload is to the host device
+// There are three possible results:
+// - Return false if the taregt device is ready for offload
+// - Return true without reporting a runtime error if offload is
+//   disabled, perhaps because the initial device was specified.
+// - Report a runtime error and return true.
+//
+// If DeviceID == OFFLOAD_DEVICE_DEFAULT, set DeviceID to the default device.
+// This step might be skipped if offload is disabled.
+bool checkDevice(int64_t &DeviceID, ident_t *Loc) {
+  if (OffloadPolicy::get(*PM).Kind == OffloadPolicy::DISABLED) {
+    DP("Offload is disabled\n");
+    return true;
+  }
+
+  if (DeviceID == OFFLOAD_DEVICE_DEFAULT) {
+    DeviceID = omp_get_default_device();
+    DP("Use default device id %" PRId64 "\n", DeviceID);
+  }
+
+  // Proposed behavior for OpenMP 5.2 in OpenMP spec github issue 2669.
+  if (omp_get_num_devices() == 0) {
+    DP("omp_get_num_devices() == 0 but offload is manadatory\n");
+    handleTargetOutcome(false, Loc);
+    return true;
+  }
+
+  if (DeviceID == omp_get_initial_device()) {
+    DP("Device is host (%" PRId64 "), returning as if offload is disabled\n",
+       DeviceID);
+    return true;
+  }
+  return false;
+}
+
----------------
jdoerfert wrote:

This code is just moved and the last part was split off into PluginManager.cpp.

https://github.com/llvm/llvm-project/pull/103002