bool
ItaniumABILanguageRuntime::GetDynamicTypeAndAddress (ValueObject &in_value,
lldb::DynamicValueType use_dynamic,
TypeAndOrName &class_type_or_name,
Address &dynamic_address)
{
// 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.
//
// Only a pointer or reference type can have a different dynamic and static type:
if (CouldHaveDynamicValue (in_value))
{
// FIXME: Can we get the Clang Type and ask it if the thing is really virtual? That would avoid false positives,
// at the cost of not looking for the dynamic type of objects if DWARF->Clang gets it wrong.
// 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;
Target *target = in_value.GetUpdatePoint().GetTargetSP().get();
Process *process = in_value.GetUpdatePoint().GetProcessSP().get();
char memory_buffer[16];
DataExtractor data(memory_buffer, sizeof(memory_buffer),
process->GetByteOrder(),
process->GetAddressByteSize());
size_t address_byte_size = process->GetAddressByteSize();
Error error;
size_t bytes_read = process->ReadMemory (original_ptr,
memory_buffer,
address_byte_size,
error);
if (!error.Success() || (bytes_read != address_byte_size))
{
return false;
}
uint32_t offset_ptr = 0;
lldb::addr_t vtable_address_point = data.GetAddress (&offset_ptr);
if (offset_ptr == 0)
return false;
// Now find the symbol that contains this address:
SymbolContext sc;
Address address_point_address;
if (target && !target->GetSectionLoadList().IsEmpty())
{
if (target->GetSectionLoadList().ResolveLoadAddress (vtable_address_point, address_point_address))
{
target->GetImages().ResolveSymbolContextForAddress (address_point_address, eSymbolContextSymbol, sc);
Symbol *symbol = sc.symbol;
if (symbol != NULL)
{
const char *name = symbol->GetMangled().GetDemangledName().AsCString();
if (strstr(name, vtable_demangled_prefix) == name)
{
// We are a C++ class, that's good. Get the class name and look it up:
const char *class_name = name + strlen(vtable_demangled_prefix);
class_type_or_name.SetName (class_name);
TypeList class_types;
uint32_t num_matches = target->GetImages().FindTypes (sc,
ConstString(class_name),
true,
UINT32_MAX,
class_types);
if (num_matches == 1)
{
class_type_or_name.SetTypeSP(class_types.GetTypeAtIndex(0));
}
else if (num_matches > 1)
{
for (size_t i = 0; i < num_matches; i++)
{
lldb::TypeSP this_type(class_types.GetTypeAtIndex(i));
if (this_type)
{
if (ClangASTContext::IsCXXClassType(this_type->GetClangFullType()))
{
// 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:
clang::ASTContext *in_ast_ctx = in_value.GetClangAST ();
clang::ASTContext *this_ast_ctx = this_type->GetClangAST ();
if (in_ast_ctx != this_ast_ctx
|| !ClangASTContext::AreTypesSame (in_ast_ctx,
in_value.GetClangType(),
this_type->GetClangFullType()))
{
class_type_or_name.SetTypeSP (this_type);
return true;
}
return false;
}
}
}
}
else
return false;
// The offset_to_top is two pointers above the address.
Address offset_to_top_address = address_point_address;
int64_t slide = -2 * ((int64_t) target->GetArchitecture().GetAddressByteSize());
offset_to_top_address.Slide (slide);
Error error;
lldb::addr_t offset_to_top_location = offset_to_top_address.GetLoadAddress(target);
size_t bytes_read = process->ReadMemory (offset_to_top_location,
memory_buffer,
address_byte_size,
error);
if (!error.Success() || (bytes_read != address_byte_size))
{
return false;
}
offset_ptr = 0;
int64_t offset_to_top = data.GetMaxS64(&offset_ptr, process->GetAddressByteSize());
// 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 (!target->GetSectionLoadList().ResolveLoadAddress (dynamic_addr, dynamic_address))
{
dynamic_address.SetOffset(dynamic_addr);
dynamic_address.SetSection(NULL);
}
return true;
}
}
}
}
}
return false;
}
