[llvm] [Offload] Add device UID (PR #164391)

[Robert Imschweiler via llvm-commits]

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@@ -1196,6 +1202,14 @@ struct GenericDeviceTy : public DeviceAllocatorTy {
   /// global device id and is not the device id visible to the OpenMP user.
   const int32_t DeviceId;
 
+  /// The unique identifier of the device.
+  /// Per default, the unique identifier of the device is set to the device id,
+  /// combined with the plugin name, since the offload device id may overlap
+  /// between different plugins.
+  std::string DeviceUid;
+  /// Construct the device UID from the vendor (U)UID.
+  void setDeviceUidFromVendorUid(StringRef VendorUid);
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ro-i wrote:

> Ok, I can also return std::string and thus remove the attribute

But then, I have to do the hsa/cuda call every time. That doesn't seem appropriate?

https://github.com/llvm/llvm-project/pull/164391