[OpenMP] Changes error handling for omp_target_is_accessible

Addresses rewiev comments.
Changes LIT test to XFAIL on nvptx.
Changes implementation to provide better debug information to the user about failures.

Author: nicebert

offload/plugins-nextgen/amdgpu/src/rtl.cpp

@@ -3027,7 +3027,7 @@ struct AMDGPUDeviceTy : public GenericDeviceTy, AMDGenericDeviceTy {
     return ((IsAPU || OMPX_ApuMaps) && IsXnackEnabled);
   }
 
-  bool isAccessiblePtrImpl(const void *Ptr, size_t Size) override {
+  Expected<bool> isAccessiblePtrImpl(const void *Ptr, size_t Size) override {
     hsa_amd_pointer_info_t Info;
     Info.size = sizeof(hsa_amd_pointer_info_t);
 
@@ -3036,8 +3036,8 @@ struct AMDGPUDeviceTy : public GenericDeviceTy, AMDGenericDeviceTy {
     hsa_status_t Status =
         hsa_amd_pointer_info(Ptr, &Info, malloc, &Count, &Agents);
 
-    if (Status != HSA_STATUS_SUCCESS)
-      return false;
+    if (auto Err = Plugin::check(Status, "error in hsa_amd_pointer_info: %s"))
+      return std::move(Err);
 
     // Checks if the pointer is known by HSA and accessible by the device
     for (uint32_t i = 0; i < Count; i++)

offload/plugins-nextgen/common/include/PluginInterface.h

@@ -1071,10 +1071,7 @@ struct GenericDeviceTy : public DeviceAllocatorTy {
 
   /// Returns true if the plugin can guarantee that the associated
   /// storage is accessible
-  bool isAccessiblePtr(const void *Ptr, size_t Size);
-  virtual bool isAccessiblePtrImpl(const void *Ptr, size_t Size) {
-    return false;
-  }
+  Expected<bool> isAccessiblePtr(const void *Ptr, size_t Size);
 
   virtual Expected<omp_interop_val_t *>
   createInterop(int32_t InteropType, interop_spec_t &InteropSpec) {
@@ -1176,6 +1173,10 @@ struct GenericDeviceTy : public DeviceAllocatorTy {
   /// Per device setting of MemoryManager's Threshold
   virtual size_t getMemoryManagerSizeThreshold() { return 0; }
 
+  virtual Expected<bool> isAccessiblePtrImpl(const void *Ptr, size_t Size) {
+    return false;
+  }
+
   /// Environment variables defined by the OpenMP standard.
   Int32Envar OMP_TeamLimit;
   Int32Envar OMP_NumTeams;

offload/plugins-nextgen/common/src/PluginInterface.cpp

@@ -1593,7 +1593,7 @@ Error GenericDeviceTy::syncEvent(void *EventPtr) {
 
 bool GenericDeviceTy::useAutoZeroCopy() { return useAutoZeroCopyImpl(); }
 
-bool GenericDeviceTy::isAccessiblePtr(const void *Ptr, size_t Size) {
+Expected<bool> GenericDeviceTy::isAccessiblePtr(const void *Ptr, size_t Size) {
   return isAccessiblePtrImpl(Ptr, Size);
 }
 
@@ -2153,7 +2153,17 @@ int32_t GenericPluginTy::use_auto_zero_copy(int32_t DeviceId) {
 
 int32_t GenericPluginTy::is_accessible_ptr(int32_t DeviceId, const void *Ptr,
                                            size_t Size) {
-  return getDevice(DeviceId).isAccessiblePtr(Ptr, Size);
+  auto HandleError = [&](Error Err) -> bool {
+    [[maybe_unused]] std::string ErrStr = toString(std::move(Err));
+    DP("Failure while checking accessibility of pointer %p for device %d: %s", Ptr, DeviceId, ErrStr.c_str());
+    return false;
+  };
+
+  auto AccessibleOrErr = getDevice(DeviceId).isAccessiblePtr(Ptr, Size);
+  if (Error Err = AccessibleOrErr.takeError())
+    return HandleError(std::move(Err));
+  
+  return *AccessibleOrErr;
 }
 
 int32_t GenericPluginTy::get_global(__tgt_device_binary Binary, uint64_t Size,

offload/test/mapping/is_accessible.cpp

@@ -7,7 +7,7 @@
 // RUN: | %fcheck-generic -check-prefix=NO_USM
 
 // REQUIRES: unified_shared_memory
-// REQUIRES: amdgpu
+// XFAIL: nvptx
 
 // CHECK: SUCCESS
 // NO_USM: Not accessible