bool ItaniumABILanguageRuntime::GetDynamicTypeAndAddress( ValueObject &in_value, lldb::DynamicValueType use_dynamic, TypeAndOrName &class_type_or_name, Address &dynamic_address, Value::ValueType &value_type) { // For Itanium, if the type has a vtable pointer in the object, it will be at // offset 0 // in the object. That will point to the "address point" within the vtable // (not the beginning of the // vtable.) We can then look up the symbol containing this "address point" // and that symbol's name // demangled will contain the full class name. // The second pointer above the "address point" is the "offset_to_top". We'll // use that to get the // start of the value object which holds the dynamic type. // class_type_or_name.Clear(); value_type = Value::ValueType::eValueTypeScalar; // Only a pointer or reference type can have a different dynamic and static // type: if (CouldHaveDynamicValue(in_value)) { // First job, pull out the address at 0 offset from the object. AddressType address_type; lldb::addr_t original_ptr = in_value.GetPointerValue(&address_type); if (original_ptr == LLDB_INVALID_ADDRESS) return false; ExecutionContext exe_ctx(in_value.GetExecutionContextRef()); Process *process = exe_ctx.GetProcessPtr(); if (process == nullptr) return false; Error error; const lldb::addr_t vtable_address_point = process->ReadPointerFromMemory(original_ptr, error); if (!error.Success() || vtable_address_point == LLDB_INVALID_ADDRESS) { return false; } class_type_or_name = GetTypeInfoFromVTableAddress(in_value, original_ptr, vtable_address_point); if (class_type_or_name) { TypeSP type_sp = class_type_or_name.GetTypeSP(); // There can only be one type with a given name, // so we've just found duplicate definitions, and this // one will do as well as any other. // We don't consider something to have a dynamic type if // it is the same as the static type. So compare against // the value we were handed. if (type_sp) { if (ClangASTContext::AreTypesSame(in_value.GetCompilerType(), type_sp->GetForwardCompilerType())) { // The dynamic type we found was the same type, // so we don't have a dynamic type here... return false; } // The offset_to_top is two pointers above the vtable pointer. const uint32_t addr_byte_size = process->GetAddressByteSize(); const lldb::addr_t offset_to_top_location = vtable_address_point - 2 * addr_byte_size; // Watch for underflow, offset_to_top_location should be less than // vtable_address_point if (offset_to_top_location >= vtable_address_point) return false; const int64_t offset_to_top = process->ReadSignedIntegerFromMemory( offset_to_top_location, addr_byte_size, INT64_MIN, error); if (offset_to_top == INT64_MIN) return false; // So the dynamic type is a value that starts at offset_to_top // above the original address. lldb::addr_t dynamic_addr = original_ptr + offset_to_top; if (!process->GetTarget().GetSectionLoadList().ResolveLoadAddress( dynamic_addr, dynamic_address)) { dynamic_address.SetRawAddress(dynamic_addr); } return true; } } } return class_type_or_name.IsEmpty() == false; }