[clang] [llvm] [OpenMP] Adds omp_target_is_accessible routine (PR #138294)

[Shilei Tian via llvm-commits]

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@@ -3027,6 +3027,29 @@ struct AMDGPUDeviceTy : public GenericDeviceTy, AMDGenericDeviceTy {
     return ((IsAPU || OMPX_ApuMaps) && IsXnackEnabled);
   }
 
+  bool isAccessiblePtrImpl(const void *Ptr, size_t Size) override {
+    hsa_amd_pointer_info_t Info;
+    Info.size = sizeof(hsa_amd_pointer_info_t);
+
+    hsa_agent_t *Agents = nullptr;
+    uint32_t Count = 0;
+    hsa_status_t Status =
+        hsa_amd_pointer_info(Ptr, &Info, malloc, &Count, &Agents);
+
+    if (Status != HSA_STATUS_SUCCESS)
+      return false;
+
+    // Checks if the pointer is known by HSA and accessible by the device
+    for (uint32_t i = 0; i < Count; i++)
+      if (Agents[i].handle == getAgent().handle)
+        return Info.sizeInBytes >= Size;
+
+    // If the pointer is unknown to HSA it's assumed a host pointer
+    // in that case the device can access it on unified memory support is
+    // enabled
+    return IsXnackEnabled;
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shiltian wrote:

Then it should be documented.

https://github.com/llvm/llvm-project/pull/138294