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llvm-project/lldb/source/Plugins/LanguageRuntime/CPlusPlus/ItaniumABI/ItaniumABILanguageRuntime.cpp
Greg Clayton cc4d0146b4 This checking is part one of trying to add some threading safety to our 
internals. The first part of this is to use a new class:

lldb_private::ExecutionContextRef

This class holds onto weak pointers to the target, process, thread and frame
and it also contains the thread ID and frame Stack ID in case the thread and
frame objects go away and come back as new objects that represent the same
logical thread/frame. 

ExecutionContextRef objcets have accessors to access shared pointers for
the target, process, thread and frame which might return NULL if the backing
object is no longer available. This allows for references to persistent program
state without needing to hold a shared pointer to each object and potentially
keeping that object around for longer than it needs to be. 

You can also "Lock" and ExecutionContextRef (which contains weak pointers)
object into an ExecutionContext (which contains strong, or shared pointers)
with code like

ExecutionContext exe_ctx (my_obj->GetExectionContextRef().Lock());

llvm-svn: 150801
2012-02-17 07:49:44 +00:00

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//===-- ItaniumABILanguageRuntime.cpp --------------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "ItaniumABILanguageRuntime.h"
#include "lldb/Breakpoint/BreakpointLocation.h"
#include "lldb/Core/ConstString.h"
#include "lldb/Core/Error.h"
#include "lldb/Core/Module.h"
#include "lldb/Core/PluginManager.h"
#include "lldb/Core/Scalar.h"
#include "lldb/Core/ValueObject.h"
#include "lldb/Core/ValueObjectMemory.h"
#include "lldb/Symbol/ClangASTContext.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/RegisterContext.h"
#include "lldb/Target/StopInfo.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/Thread.h"
#include <vector>
using namespace lldb;
using namespace lldb_private;
static const char *pluginName = "ItaniumABILanguageRuntime";
static const char *pluginDesc = "Itanium ABI for the C++ language";
static const char *pluginShort = "language.itanium";
static const char *vtable_demangled_prefix = "vtable for ";
bool
ItaniumABILanguageRuntime::CouldHaveDynamicValue (ValueObject &in_value)
{
return in_value.IsPossibleCPlusPlusDynamicType();
}
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;
ExecutionContext exe_ctx (in_value.GetExecutionContextRef());
Target *target = exe_ctx.GetTargetPtr();
Process *process = exe_ctx.GetProcessPtr();
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;
}
bool
ItaniumABILanguageRuntime::IsVTableName (const char *name)
{
if (name == NULL)
return false;
// Can we maybe ask Clang about this?
if (strstr (name, "_vptr$") == name)
return true;
else
return false;
}
//------------------------------------------------------------------
// Static Functions
//------------------------------------------------------------------
lldb_private::LanguageRuntime *
ItaniumABILanguageRuntime::CreateInstance (Process *process, lldb::LanguageType language)
{
// FIXME: We have to check the process and make sure we actually know that this process supports
// the Itanium ABI.
if (language == eLanguageTypeC_plus_plus)
return new ItaniumABILanguageRuntime (process);
else
return NULL;
}
void
ItaniumABILanguageRuntime::Initialize()
{
PluginManager::RegisterPlugin (pluginName,
pluginDesc,
CreateInstance);
}
void
ItaniumABILanguageRuntime::Terminate()
{
PluginManager::UnregisterPlugin (CreateInstance);
}
//------------------------------------------------------------------
// PluginInterface protocol
//------------------------------------------------------------------
const char *
ItaniumABILanguageRuntime::GetPluginName()
{
return pluginName;
}
const char *
ItaniumABILanguageRuntime::GetShortPluginName()
{
return pluginShort;
}
uint32_t
ItaniumABILanguageRuntime::GetPluginVersion()
{
return 1;
}
void
ItaniumABILanguageRuntime::SetExceptionBreakpoints ()
{
if (!m_process)
return;
if (!m_cxx_exception_bp_sp)
m_cxx_exception_bp_sp = m_process->GetTarget().CreateBreakpoint (NULL,
NULL,
"__cxa_throw",
eFunctionNameTypeBase,
true);
else
m_cxx_exception_bp_sp->SetEnabled (true);
if (!m_cxx_exception_alloc_bp_sp)
m_cxx_exception_alloc_bp_sp = m_process->GetTarget().CreateBreakpoint (NULL,
NULL,
"__cxa_allocate",
eFunctionNameTypeBase,
true);
else
m_cxx_exception_alloc_bp_sp->SetEnabled (true);
}
void
ItaniumABILanguageRuntime::ClearExceptionBreakpoints ()
{
if (!m_process)
return;
if (m_cxx_exception_bp_sp.get())
{
m_cxx_exception_bp_sp->SetEnabled (false);
}
if (m_cxx_exception_alloc_bp_sp.get())
{
m_cxx_exception_bp_sp->SetEnabled (false);
}
}
bool
ItaniumABILanguageRuntime::ExceptionBreakpointsExplainStop (lldb::StopInfoSP stop_reason)
{
if (!m_process)
return false;
if (!stop_reason ||
stop_reason->GetStopReason() != eStopReasonBreakpoint)
return false;
uint64_t break_site_id = stop_reason->GetValue();
lldb::BreakpointSiteSP bp_site_sp = m_process->GetBreakpointSiteList().FindByID(break_site_id);
if (!bp_site_sp)
return false;
uint32_t num_owners = bp_site_sp->GetNumberOfOwners();
bool check_cxx_exception = false;
break_id_t cxx_exception_bid;
bool check_cxx_exception_alloc = false;
break_id_t cxx_exception_alloc_bid;
if (m_cxx_exception_bp_sp)
{
check_cxx_exception = true;
cxx_exception_bid = m_cxx_exception_bp_sp->GetID();
}
if (m_cxx_exception_alloc_bp_sp)
{
check_cxx_exception_alloc = true;
cxx_exception_alloc_bid = m_cxx_exception_alloc_bp_sp->GetID();
}
for (uint32_t i = 0; i < num_owners; i++)
{
break_id_t bid = bp_site_sp->GetOwnerAtIndex(i)->GetBreakpoint().GetID();
if ((check_cxx_exception && (bid == cxx_exception_bid)) ||
(check_cxx_exception_alloc && (bid == cxx_exception_alloc_bid)))
return true;
}
return false;
}
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