draft: [lldb] Upgrade ValueObject::GetData to return llvm::Expected

lldb/include/lldb/ValueObject/ValueObject.h

@@ -757,7 +757,7 @@ class ValueObject {
   virtual size_t GetPointeeData(DataExtractor &data, uint32_t item_idx = 0,
                                 uint32_t item_count = 1);
 
-  virtual uint64_t GetData(DataExtractor &data, Status &error);
+  virtual llvm::Expected<DataExtractor> GetData();
 
   virtual bool SetData(DataExtractor &data, Status &error);
 

lldb/source/Plugins/Language/CPlusPlus/CxxStringTypes.cpp

@@ -68,11 +68,9 @@ static bool CharStringSummaryProvider(ValueObject &valobj, Stream &stream) {
 
 template <StringElementType ElemType>
 static bool CharSummaryProvider(ValueObject &valobj, Stream &stream) {
-  DataExtractor data;
-  Status error;
-  valobj.GetData(data, error);
+  auto data_or_err = valobj.GetData();
 
-  if (error.Fail())
+  if (!data_or_err)
     return false;
 
   std::string value;
@@ -84,7 +82,7 @@ static bool CharSummaryProvider(ValueObject &valobj, Stream &stream) {
   if (!value.empty())
     stream.Printf("%s ", value.c_str());
 
-  options.SetData(std::move(data));
+  options.SetData(std::move(*data_or_err));
   options.SetStream(&stream);
   options.SetPrefixToken(ElemTraits.first);
   options.SetQuote('\'');
@@ -169,11 +167,9 @@ bool lldb_private::formatters::Char32SummaryProvider(
 
 bool lldb_private::formatters::WCharSummaryProvider(
     ValueObject &valobj, Stream &stream, const TypeSummaryOptions &) {
-  DataExtractor data;
-  Status error;
-  valobj.GetData(data, error);
+  auto data_or_err = valobj.GetData();
 
-  if (error.Fail())
+  if (!data_or_err)
     return false;
 
   // Get a wchar_t basic type from the current type system
@@ -191,7 +187,7 @@ bool lldb_private::formatters::WCharSummaryProvider(
   const uint32_t wchar_size = *size;
 
   StringPrinter::ReadBufferAndDumpToStreamOptions options(valobj);
-  options.SetData(std::move(data));
+  options.SetData(std::move(*data_or_err));
   options.SetStream(&stream);
   options.SetPrefixToken("L");
   options.SetQuote('\'');

lldb/source/Plugins/Language/CPlusPlus/LibCxxList.cpp

@@ -273,15 +273,13 @@ ValueObjectSP ForwardListFrontEnd::GetChildAtIndex(uint32_t idx) {
 
   // we need to copy current_sp into a new object otherwise we will end up with
   // all items named __value_
-  DataExtractor data;
-  Status error;
-  current_sp->GetData(data, error);
-  if (error.Fail())
+  auto data_or_err = current_sp->GetData();
+  if (!data_or_err)
     return nullptr;
 
-  return CreateValueObjectFromData(llvm::formatv("[{0}]", idx).str(), data,
-                                   m_backend.GetExecutionContextRef(),
-                                   m_element_type);
+  return CreateValueObjectFromData(
+      llvm::formatv("[{0}]", idx).str(), *data_or_err,
+      m_backend.GetExecutionContextRef(), m_element_type);
 }
 
 lldb::ChildCacheState ForwardListFrontEnd::Update() {
@@ -394,15 +392,13 @@ lldb::ValueObjectSP ListFrontEnd::GetChildAtIndex(uint32_t idx) {
 
   // we need to copy current_sp into a new object otherwise we will end up with
   // all items named __value_
-  DataExtractor data;
-  Status error;
-  current_sp->GetData(data, error);
-  if (error.Fail())
+  auto data_or_err = current_sp->GetData();
+  if (!data_or_err)
     return lldb::ValueObjectSP();
 
   StreamString name;
   name.Printf("[%" PRIu64 "]", (uint64_t)idx);
-  return CreateValueObjectFromData(name.GetString(), data,
+  return CreateValueObjectFromData(name.GetString(), *data_or_err,
                                    m_backend.GetExecutionContextRef(),
                                    m_element_type);
 }

lldb/source/Plugins/Language/ObjC/Cocoa.cpp

@@ -1205,13 +1205,11 @@ bool lldb_private::formatters::ObjCSELSummaryProvider(
     valobj_sp = ValueObject::CreateValueObjectFromAddress("text", data_address,
                                                           exe_ctx, charstar);
   } else {
-    DataExtractor data;
-    Status error;
-    valobj.GetData(data, error);
-    if (error.Fail())
+    auto data_or_err = valobj.GetData();
+    if (!data_or_err)
       return false;
-    valobj_sp =
-        ValueObject::CreateValueObjectFromData("text", data, exe_ctx, charstar);
+    valobj_sp = ValueObject::CreateValueObjectFromData("text", *data_or_err,
+                                                       exe_ctx, charstar);
   }
 
   if (!valobj_sp)

lldb/source/Plugins/Language/ObjC/NSString.cpp

@@ -291,13 +291,11 @@ bool lldb_private::formatters::NSAttributedStringSummaryProvider(
       "string_ptr", pointer_value, exe_ctx, type));
   if (!child_ptr_sp)
     return false;
-  DataExtractor data;
-  Status error;
-  child_ptr_sp->GetData(data, error);
-  if (error.Fail())
+  auto data_or_err = child_ptr_sp->GetData();
+  if (!data_or_err)
     return false;
   ValueObjectSP child_sp(child_ptr_sp->CreateValueObjectFromData(
-      "string_data", data, exe_ctx, type));
+      "string_data", *data_or_err, exe_ctx, type));
   child_sp->GetValueAsUnsigned(0);
   if (child_sp)
     return NSStringSummaryProvider(*child_sp, stream, options);

lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntime.cpp

@@ -549,15 +549,15 @@ ThreadSP AppleObjCRuntime::GetBacktraceThreadFromException(
        idx++) {
     ValueObjectSP dict_entry = reserved_dict->GetChildAtIndex(idx);
 
-    DataExtractor data;
-    data.SetAddressByteSize(dict_entry->GetProcessSP()->GetAddressByteSize());
-    Status error;
-    dict_entry->GetData(data, error);
-    if (error.Fail()) return ThreadSP();
+    auto data_or_err = dict_entry->GetData();
+    if (!data_or_err)
+      return ThreadSP();
+    data_or_err->SetAddressByteSize(
+        dict_entry->GetProcessSP()->GetAddressByteSize());
 
     lldb::offset_t data_offset = 0;
-    auto dict_entry_key = data.GetAddress(&data_offset);
-    auto dict_entry_value = data.GetAddress(&data_offset);
+    auto dict_entry_key = data_or_err->GetAddress(&data_offset);
+    auto dict_entry_value = data_or_err->GetAddress(&data_offset);
 
     auto key_nsstring = objc_object_from_address(dict_entry_key, "key");
     StreamString key_summary;

lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp

@@ -247,13 +247,15 @@ static lldb::addr_t GetVTableAddress(Process &process,
   // We have an object already read from process memory,
   // so just extract VTable pointer from it
 
-  DataExtractor data;
-  Status err;
-  auto size = valobj.GetData(data, err);
-  if (err.Fail() || vbtable_ptr_offset + data.GetAddressByteSize() > size)
+  auto data_or_err = valobj.GetData();
+  if (!data_or_err)
+    return LLDB_INVALID_ADDRESS;
+
+  auto size = data_or_err->GetByteSize();
+  if (vbtable_ptr_offset + data_or_err->GetAddressByteSize() > size)
     return LLDB_INVALID_ADDRESS;
 
-  return data.GetAddress(&vbtable_ptr_offset);
+  return data_or_err->GetAddress(&vbtable_ptr_offset);
 }
 
 static int64_t ReadVBaseOffsetFromVTable(Process &process,

lldb/source/ValueObject/ValueObject.cpp

@@ -691,13 +691,20 @@ size_t ValueObject::GetPointeeData(DataExtractor &data, uint32_t item_idx,
       ValueObjectSP pointee_sp = Dereference(error);
       if (error.Fail() || pointee_sp.get() == nullptr)
         return 0;
-      return pointee_sp->GetData(data, error);
+      auto data_or_err = pointee_sp->GetData();
+      if (!data_or_err)
+        return 0;
+      data = *data_or_err;
+      return data.GetByteSize();
     } else {
       ValueObjectSP child_sp = GetChildAtIndex(0);
       if (child_sp.get() == nullptr)
         return 0;
-      Status error;
-      return child_sp->GetData(data, error);
+      auto data_or_err = child_sp->GetData();
+      if (!data_or_err)
+        return 0;
+      data = *data_or_err;
+      return data.GetByteSize();
     }
     return true;
   } else /* (items > 1) */
@@ -764,22 +771,25 @@ size_t ValueObject::GetPointeeData(DataExtractor &data, uint32_t item_idx,
   return 0;
 }
 
-uint64_t ValueObject::GetData(DataExtractor &data, Status &error) {
+llvm::Expected<DataExtractor> ValueObject::GetData() {
   UpdateValueIfNeeded(false);
   ExecutionContext exe_ctx(GetExecutionContextRef());
-  error = m_value.GetValueAsData(&exe_ctx, data, GetModule().get());
+  DataExtractor data;
+  Status error = m_value.GetValueAsData(&exe_ctx, data, GetModule().get());
   if (error.Fail()) {
     if (m_data.GetByteSize()) {
       data = m_data;
       error.Clear();
-      return data.GetByteSize();
+      data.SetAddressByteSize(m_data.GetAddressByteSize());
+      data.SetByteOrder(m_data.GetByteOrder());
+      return data;
     } else {
-      return 0;
+      return llvm::createStringError("GetData failed: %s", error.AsCString());
     }
   }
   data.SetAddressByteSize(m_data.GetAddressByteSize());
   data.SetByteOrder(m_data.GetByteOrder());
-  return data.GetByteSize();
+  return data;
 }
 
 bool ValueObject::SetData(DataExtractor &data, Status &error) {