CPaintDC dc(this);
CFont font;
dc.SelectObject(font); // why does this build?
The function CDC::SelectObject takes a pointer of type CFont but why does this build with providing an object? I came across this issue that the above code is unpredictable and can crash sometimes but not always.
The code in question is valid, sort of. It compiles due to a combination of two things:
The CFont::operator HFONT().
An undocumented CDC::SelectObject overload taking an HGDIOBJ handle.
When the compiler tries to match an overload for dc.SelectObject(font), none of them match. So next it tries the user-defined conversion operator (operator HFONT()) that returns an HFONT. That matches the undocumented overload taking an HGDIOBJ (both HGDIOBJ and HFONT are typedef'd as void*).
The code posted in the question is almost correct, too, with 2 exceptions:
The font object is destroyed while still being selected into a device context. While this causes a double-delete bug (the font object is owned by the CFont instance and the device context), the call to DeleteFont gracefully fails when passed an invalid handle.
The font object previously selected into the device context is lost, and thereby leaked.
Neither issue causes unpredictable behavior or intermittent crashes. As explained in your answer, the real code, however, looks like this:
CFont* pOldFont = (CFont*) dc.SelectObject(font);
That is a bug that exhibits undefined behavior. dc.SelectObject(font) returns an HGDIOBJ (typedef'd as void*), which is subsequently cast to an unrelated type (CFont*). While storing the font previously selected into the device context to later restore it is correct, the code is not. An implementation that honors ownership could be:
CPaintDC dc(this);
CFont font;
CFont oldFont;
// Transfer ownership of font to the DC, and the previously selected font into oldFont
oldFont.Attach(dc.SelectObject(font.Detach()));
// Use dc
// Transfer ownership back
font.Attach(dc.SelectObject(oldFont.Detach()));
// oldFont goes out of scope; this a no-op since it no longer owns any resources
// font goes out of scope, releasing all resources owned by it
// dc goes out of scope, releasing all resources owned by objects selected into it
If you are willing to temporarily sacrifice strict ownership semantics, you can make your life easier by using the more standard implementation:
CPaintDC dc(this);
CFont font;
CFont* pOldFont = dc.SelectObject(&font);
// Use dc
dc.SelectObject(pOldFont);
This is safe, even if you exit early, without restoring the device context. It would still lead to a double-delete on the font object owned by both the CFont instance and the device context (which is handled gracefully by the API). It doesn't exhibit a font leak, though, because things are more complicated than it seems: There is another invisible owner involved here, a map controlled by MFC that stores temporary objects (like those returned from CGdiObject::FromHandle, which SelectObject(CFont*) calls). The temporary objects are cleaned up as part of MFC's idle time processing.
I agree with answer by IInspectable and here is my own proof of concept how this works:
#include "stdafx.h"
#include <iostream>
class A {
int a_int = 6;
char* a_carp = "A derived";
public:
operator int() { return a_int; }
operator char*() { return a_carp; }
};
class B : public A {
float b_float = 5.7;
char* b_carp = "B Derived";
public:
operator float() { return b_float; }
operator char*() { return b_carp; }
};
void Print(char * text)
{
std::cout << text << std::endl;
}
int main() {
B b_obj;
// long a = b_obj;
char* c_p = b_obj;
Print(b_obj);
return 0;
}
The above code builds and the output is "B Derived".
How does it works?
When we use an object in place of a different type, the object looks for appropriate conversion operator. If it finds it, it applies it and converts that for you.
In this case, that operator was HFONT(). It is important to note the actual name of the operator doesn't matter, its the return type/signature that matters. So when it finds a match (correct signature), it calls it.
Why unpredictable behavior?
Let me clear that as well since I mention that in OP. The code I posted was related to build issue but the actual code was this:
CFont* pOldFont = (CFont*) dc.SelectObject(font);
And the forced typecasting (CFont*) was the problem. If we pass HGDIOBJ to SelectObject(), it returns HGDIOBJ but it was forced typecasted to CFont * and that was the problem so there is nothing else wrong with using conversion operators.
I am upgrading an application from VC6 to VS2010 (Legacy Code). The application runs as it should in VC6 but after converting the project to VS2010 I encountered some problems.
On exiting the application, the program breaks while attempting to lock on entering a critical section.
The lock count usually alternates from -1(Unlocked) to -2(Locked) but just before the program crashes, the lock count is 0.
g_RenderTargetCriticalSection.Lock();// Breaks here
if (g_RenderTargets.Lookup(this, pRenderTarget))
{
ASSERT_VALID(pRenderTarget);
g_RenderTargets.RemoveKey(this);
delete pRenderTarget;
}
g_RenderTargetCriticalSection.Unlock();
Here is the CCriticalSection::Lock() function where ::EnterCriticalSection(&m_sect); fails. I found it strange that on failing, the lock count changes from 0 to -4??
_AFXMT_INLINE BOOL (::CCriticalSection::Lock())
{
::EnterCriticalSection(&m_sect);
return TRUE;
}
If anyone has encountered anything similar to this, some insight would be greatly appreciated. Thanks in advance.
The comments indicate this is a file-scope object destructor order issue. There are various ways you could address this. Since I haven't seen the rest of the code it's difficult to offer specific advice, but one idea is to change the CS to live in a shared_ptr and have your CWnd hold onto a copy so it won't be destroyed prematurely. e.g.:
std::shared_ptr<CCriticalSection> g_renderTargetCriticalSection(new CCriticalSection());
Then in your window class:
class CMyWindow : public CWnd
{
private:
std::shared_ptr<CCriticalSection> m_renderTargetCriticalSection;
public:
CMyWindow()
: m_renderTargetCriticalSection(g_renderTargetCriticalSection)
{
// ...
}
~CMyWindow()
{
// guaranteed to still be valid since our shared_ptr is keeping it alive
CSingleLock lock(m_renderTargetCriticalSection.get(), TRUE);
// ...
}
// ...
};
The issue was that the application's Main Window was being destroyed after the application's global object was destroyed. This meant that the g_renderTargetCriticalSection was already Null when the main window was trying to be destroyed.
The solution was to destroy the Application's main window before it's global object (CDBApp theApp) calls ExitInstance() and is destroyed.
int CDBApp::ExitInstance()
{
LOGO_RELEASE
//Destroy the Main Window before the CDBApp Object (theApp) is destroyed.
if(m_Instance.m_hWnd)
m_Instance.DestroyWindow();
return CWinApp::ExitInstance();
}
This code doesn't make sense:
int CDBApp::ExitInstance()
{
LOGO_RELEASE
//Destroy the Main Window before the CDBApp Object (theApp) is destroyed.
if(m_Instance.m_hWnd)
m_Instance.DestroyWindow();
return CWinApp::ExitInstance();
}
m_Instance is a handle, not a class, so it can't be used to call functions!
This is excerpt from my WinMain method. It is not complete but I think it is sufficient to illustrate core of problem. Please don't ask why I am deleting data module explicitly when it should be done automatically. This is entirely another issue (has to do with incorrect finalization order when application initialization ends prematurely with exception in one of constructors).
extern PACKAGE TDataModule_Local *DataModule_Local;
class TDataModule_Local :
public TDataModule
{
...
public:
__fastcall TDataModule_Local(TComponent *Owner);
__fastcall ~TDataModule_Local();
}
WINAPI wWinMain(HINSTANCE, HINSTANCE, LPTSTR, int)
{
Application->Initialize();
Application->CreateForm(__classid(TMainForm), &MainForm);
Application->CreateForm(__classid(TDataModule_Local), &DataModule_Local);
Application->Run();
if (DataModule_Local != NULL)
{
delete DataModule_Local; // destructor not called! why?
DataModule_Local = NULL;
}
return 0;
}
Whats weird destructor of data module is not called when I use delete operator. Is is called after program reaches enclosing brace of WinMain method:
You said
deleting data module explicitly when it should be done automatically
Obviously whatever code is designed to free it automatically is still trying to do so, blissfully ignorant of your problems with finalization order.
Just because you've set your pointer to NULL doesn't mean that there isn't a copy of the pointer sitting in a list of objects to be cleaned up on exit.
I'm creating a DirectX 11 helper class that looks kind of like this:
#import "DXClass.h" // I have declared the constructor and the other methods here
// All of the DirectX libraries are imported in the header as well
DXClass::DXClass()
{
// Pointers created, etc.
}
DXClass:~DXClass()
{
// Other DirectX objects released
// With an if (bbSRView) {}, the exception still occurs, so bbSRView is not NULL
// bbSRView is a ID3D11ShaderResourceView*
// When the other violation does not occur, one does here:
bbSRView->Release();
bbSRView = NULL;
// More releases
void DXClass::Initialize()
{
SetupDisplay();
// Other initialization that works fine
}
void DXClass::SetupDisplay()
{
// This is where the debugger shows the access violation.
// factory is declared as DXGIFactory*
HRESULT hr = CreateDXGIFactory(__uuidof(IDXGIFactory), (void **)&factory);
// Loop through adapters and outputs, etc.
}
This class is initialized like this: dxClass = new DXClass();
The Initialize() function is called in another method of the class that created dxClass.
When the application is run, I get an access violation at the beginning of the setupDisplay() function. However, if I take the code in setupDisplay() and put it in Initialize(), removing the call to setupDisplay(), no access violation occurs. Also, if I remove the code from setupDisplay() so that it is an empty function, and then call it in Initialize(), no access violation occurs.
It appears that no pointers are NULL, and the application will start fine if it is changed as described above. However, on another note, the application receives another access violation when quitting. The debugger points to a Release() call on an ID3D11ShaderResourceView*, which I have pointed out in my code snippet. This pointer also appears to be valid.
I have also checked the similar questions, but the this pointer of the class appears to be valid, and I am not creating any buffers that could be overflowing. There also isn't anything that could be deleting/freeing the object early.
I have no idea what could be causing the errors. :/
Thanks :D
EDIT:
Here's an isolated test, with the same errors:
I have in my main function:
INT APIENTRY wWinMain(HINSTANCE, HINSTANCE, LPWSTR, INT)
{
App *app = new App();
app->Run();
app->Release();
}
In my App class, I have removed all window functionality and any other variables so that it looks like this:
App::App()
{
dxClass = new DXClass();
}
App::~App()
{
delete dxClass;
}
void App::Run()
{
dxClass->Initialize();
while (true) {} // Never reaches here
}
The access violation still occurs at the same place. Also, same results if I replace the factory instance variable with:
IDXGIFactory *f;
HRESULT hr = CreateDXGIFactory(__uuidof(IDXGIFactory), (void **)&f);
Which has worked for me in other applications.
An access violation when calling Release() usually means the object has already received it's final Release() from somewhere else (and it has destroyed itself). One possible solution would be to AddRef() when passing the pointer into your DXClass
Is there any sense to step-execute release code? I noticed that some lines of code are omitted, i.e. some method calls. Also variable preview doesn't show some variables and shows invalid (not real) values for some others, so it's all quite misleading.
I'm asking this question, because loading WinDbg crashdump file into Visual Studio brings the same stack and variables partial view as step-execution. Are there any way to improve crashdump analyze experience, except recompiling application without optimalizations?
Windows, Visual Studio 2005, unmanaged C++
Yes - if you have the .pdb for the build, and the .dmp file from the crash, then you can open the debugger on the exact point of failure, and examine the state of your app at that point.
As several have noted - some variables will be optimized away, but if you're mildly creative / inquisitive, you'll find ways to obtain those values.
You can build in a root crash handler for your code to generate a .dmp file automatically which works on all Windows flavors (assuming you are creating a Windows app) using something like the following:
// capture the unhandled exception hook - we will create a mini dump for ourselves
// NOTE: according to docs, if a debugger is present, this API won't succeed (ie. debug builds ignore this)
MiniDumper::Install(
true,
filename,
"Please send a copy of this file, along with a brief description of the problem, to [insert your email address here] so that we might fix this issue."
);
The above would require the MiniDumper class I wrote, below:
#pragma once
#include <dbghelp.h>
#include "DynamicLinkLibrary.h"
#include "FileName.h"
//////////////////////////////////////////////////////////////////////////
// MiniDumper
//
// Provides a mechanism whereby an application will generate its own mini dump file anytime
// it throws an unhandled exception (or at the client's request - see GenerateMiniDump, below).
//
// Warning: the C-runtime will NOT invoke our unhandled handler if you are running a debugger
// due to the way that the SetUnhandledExceptionFilter() API works (q.v.)
//
// To use this facility, simply call MiniDumper::Install - for example, during CWinApp initialization.
//
// Once this has been installed, all current and future threads in this process will be covered.
// This is unlike the StructuredException and CRTInvalidParameter classes, which must be installed for
// for each thread for which you wish to use their services.
//
class MiniDumper
{
public:
// install the mini dumper (and optionally, hook the unhandled exception filter chain)
// #param filename is the mini dump filename to use (please include a path)
// #return success or failure
// NOTE: we can be called more than once to change our options (unhook unhandled, change the filename)
static bool Install(bool bHookUnhandledExceptionFilter, const CFilename & filenameMiniDump, const CString & strCustomizedMessage, DWORD dwMiniDumpType = MiniDumpNormal)
{
return GetSingleton().Initialize(bHookUnhandledExceptionFilter, filenameMiniDump, strCustomizedMessage, dwMiniDumpType);
}
// returns true if we've been initialized (but doesn't indicate if we have hooked the unhandled exception filter or not)
static bool IsInitialized() { return g_bInstalled; }
// returns true if we've been setup to intercept unhandled exceptions
static bool IsUnhandledExceptionHooked() { return g_bInstalled && GetSingleton().m_bHookedUnhandledExceptionFilter; }
// returns the filename we've been configured to write to if we're requested to generate a mini dump
static CFilename GetMiniDumpFilename() { return g_bInstalled ? GetSingleton().m_filenameMiniDump : ""; }
// you may use this wherever you have a valid EXCEPTION_POINTERS in order to generate a mini dump of whatever exception just occurred
// use the GetExceptionInformation() intrinsic to obtain the EXCEPTION_POINTERS in an __except(filter) context
// returns success or failure
// DO NOT hand the result of GenerateMiniDump to your __except(filter) - instead use a proper disposition value (q.v. __except)
// NOTE: you *must* have already installed MiniDumper or this will only error
static bool GenerateMiniDump(EXCEPTION_POINTERS * pExceptionPointers);
private:
// based on dbghelp.h
typedef BOOL (WINAPI * MINIDUMPWRITEDUMP_FUNC_PTR)(
HANDLE hProcess,
DWORD dwPid,
HANDLE hFile,
MINIDUMP_TYPE DumpType,
CONST PMINIDUMP_EXCEPTION_INFORMATION ExceptionParam,
CONST PMINIDUMP_USER_STREAM_INFORMATION UserStreamParam,
CONST PMINIDUMP_CALLBACK_INFORMATION CallbackParam
);
// data we need to pass to our mini dump thread
struct ExceptionThreadData
{
ExceptionThreadData(EXCEPTION_POINTERS * exceptionPointers, bool bUnhandled, DWORD threadID = ::GetCurrentThreadId())
: pExceptionPointers(exceptionPointers)
, dwThreadID(threadID)
, bUnhandledException(bUnhandled)
{
}
EXCEPTION_POINTERS * pExceptionPointers;
DWORD dwThreadID;
bool bUnhandledException;
};
// our unhandled exception filter (called automatically by the run time if we've been installed to do so)
static LONG CALLBACK UnhandledExceptionFilter(EXCEPTION_POINTERS * pExceptionPointers);
// creates a new thread in which to generate our mini dump (so we don't run out of stack)
static bool ExecuteMiniDumpThread(EXCEPTION_POINTERS * pExceptionPointers, bool bUnhandledException);
// thread entry point for generating a mini dump file
static DWORD WINAPI MiniDumpThreadProc(LPVOID lpParam);
// obtains the one and only instance
static MiniDumper & GetSingleton();
// flag to indicate if we're installed or not
static bool g_bInstalled;
// create us
MiniDumper()
: m_pPreviousFilter(NULL)
, m_pWriteMiniDumpFunction(NULL)
, m_bHookedUnhandledExceptionFilter(false)
{
}
// install our unhandled exception filter
bool Initialize(bool bHookUnhandledExceptionFilter, const CFilename & filenameMiniDump, const CString & strCustomizedMessage, DWORD dwMiniDumpType);
// generates a mini dump file
bool GenerateMiniDumpFile(ExceptionThreadData * pData);
// handle an unhandled exception
bool HandleUnhandledException(ExceptionThreadData * pData);
bool m_bHookedUnhandledExceptionFilter;
CFilename m_filenameMiniDump;
CString m_strCustomizedMessage;
DWORD m_dwMiniDumpType;
MINIDUMPWRITEDUMP_FUNC_PTR m_pWriteMiniDumpFunction;
LPTOP_LEVEL_EXCEPTION_FILTER m_pPreviousFilter;
};
And its implementation:
#include "StdAfx.h"
#include "MiniDumper.h"
using namespace Toolbox;
//////////////////////////////////////////////////////////////////////////
// Static Members
bool MiniDumper::g_bInstalled = false;
// returns true if we were able to create a mini dump for this exception
bool MiniDumper::GenerateMiniDump(EXCEPTION_POINTERS * pExceptionPointers)
{
// obtain the mini dump in a new thread context (which will have its own stack)
return ExecuteMiniDumpThread(pExceptionPointers, false);
}
// this is called from the run time if we were installed to hook the unhandled exception filter
LONG CALLBACK MiniDumper::UnhandledExceptionFilter(EXCEPTION_POINTERS * pExceptionPointers)
{
// attempt to generate the mini dump (use a separate thread to ensure this one is frozen & we have a fresh stack to work with)
ExecuteMiniDumpThread(pExceptionPointers, true);
// terminate this process, now
::TerminateProcess(GetCurrentProcess(), 0xFFFFFFFF);
// carry on as normal (we should never get here due to TerminateProcess, above)
return EXCEPTION_CONTINUE_SEARCH;
}
bool MiniDumper::ExecuteMiniDumpThread(EXCEPTION_POINTERS * pExceptionPointers, bool bUnhandledException)
{
// because this may have been created by a stack overflow
// we may be very very low on stack space
// so we'll create a new, temporary stack to work with until we fix this situation
ExceptionThreadData data(pExceptionPointers, bUnhandledException);
DWORD dwScratch;
HANDLE hMiniDumpThread = ::CreateThread(NULL, 0, MiniDumpThreadProc, &data, 0, &dwScratch);
if (hMiniDumpThread)
{
VERIFY(::WaitForSingleObject(hMiniDumpThread, INFINITE) == WAIT_OBJECT_0);
VERIFY(::GetExitCodeThread(hMiniDumpThread, &dwScratch));
VERIFY(::CloseHandle(hMiniDumpThread));
return AsBool(dwScratch);
}
return false;
}
DWORD WINAPI MiniDumper::MiniDumpThreadProc(LPVOID lpParam)
{
// retrieve our exception context from our creator
ExceptionThreadData * pData = (ExceptionThreadData *)lpParam;
// generate the actual mini dump file in this thread context - with our own stack
if (pData->bUnhandledException)
return GetSingleton().HandleUnhandledException(pData);
else
return GetSingleton().GenerateMiniDumpFile(pData);
}
bool MiniDumper::HandleUnhandledException(ExceptionThreadData * pData)
{
// generate the actual mini dump file first - hopefully we get this even if the following errors
const bool bMiniDumpSucceeded = GenerateMiniDumpFile(pData);
// try to inform the user of what's happened
CString strMessage = FString("An Unhandled Exception occurred in %s\n\nUnfortunately, this requires that the application be terminated.", CFilename::GetModuleFilename());
// create the mini dump file
if (bMiniDumpSucceeded)
{
// let user know about the mini dump
strMessage.AppendFormat("\n\nOn a higher note, we have saved some diagnostic information in %s", m_filenameMiniDump.c_str());
}
// append any custom message(s)
if (!IsEmpty(m_strCustomizedMessage))
strMessage.AppendFormat("\n\n%s", m_strCustomizedMessage);
// cap it off with an apology
strMessage.Append("\n\nThis application must be terminated now. All unsaved data will be lost. We are deeply sorry for the inconvenience.");
// let the user know that things have gone terribly wrong
::MessageBox(GetAppWindow(), strMessage, "Internal Error - Unhandled Exception", MB_ICONERROR);
// indicate success or not
return bMiniDumpSucceeded;
}
//////////////////////////////////////////////////////////////////////////
// Instance Members
MiniDumper & MiniDumper::GetSingleton()
{
static std::auto_ptr<MiniDumper> g_pSingleton(new MiniDumper);
return *g_pSingleton.get();
}
bool MiniDumper::Initialize(bool bHookUnhandledExceptionFilter, const CFilename & filenameMiniDump, const CString & strCustomizedMessage, DWORD dwMiniDumpType)
{
// check if we need to link to the the mini dump function
if (!m_pWriteMiniDumpFunction)
{
try
{
// attempt to load the debug helper DLL
DynamicLinkLibrary dll("DBGHelp.dll", true);
// get the function address we need
m_pWriteMiniDumpFunction = (MINIDUMPWRITEDUMP_FUNC_PTR)dll.GetProcAddress("MiniDumpWriteDump", false);
}
catch (CCustomException &)
{
// we failed to load the dll, or the function didn't exist
// either way, m_pWriteMiniDumpFunction will be NULL
ASSERT(m_pWriteMiniDumpFunction == NULL);
// there is nothing functional about the mini dumper if we have no mini dump function pointer
return false;
}
}
// record the filename to write our mini dumps to (NOTE: we don't do error checking on the filename provided!)
if (!IsEmpty(filenameMiniDump))
m_filenameMiniDump = filenameMiniDump;
// record the custom message to tell the user on an unhandled exception
m_strCustomizedMessage = strCustomizedMessage;
// check if they're updating the unhandled filter chain
if (bHookUnhandledExceptionFilter && !m_bHookedUnhandledExceptionFilter)
{
// we need to hook the unhandled exception filter chain
m_pPreviousFilter = ::SetUnhandledExceptionFilter(&MiniDumper::UnhandledExceptionFilter);
}
else if (!bHookUnhandledExceptionFilter && m_bHookedUnhandledExceptionFilter)
{
// we need to un-hook the unhandled exception filter chain
VERIFY(&MiniDumper::UnhandledExceptionFilter == ::SetUnhandledExceptionFilter(m_pPreviousFilter));
}
// set type of mini dump to generate
m_dwMiniDumpType = dwMiniDumpType;
// record that we've been installed
g_bInstalled = true;
// if we got here, we must have been successful
return true;
}
bool MiniDumper::GenerateMiniDumpFile(ExceptionThreadData * pData)
{
// NOTE: we don't check this before now because this allows us to generate an exception in a different thread context (rather than an exception while processing an exception in the main thread)
ASSERT(g_bInstalled);
if (!g_bInstalled)
return false;
HANDLE hFile = ::CreateFile(m_filenameMiniDump.c_str(), GENERIC_WRITE, FILE_SHARE_READ, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
if (hFile == INVALID_HANDLE_VALUE)
{
// indicate failure
return false;
}
else
{
// NOTE: don't use exception_info - its a #define!!!
Initialized<_MINIDUMP_EXCEPTION_INFORMATION> ex_info;
ex_info.ThreadId = pData->dwThreadID;
ex_info.ExceptionPointers = pData->pExceptionPointers;
// generate our mini dump
bool bStatus = FALSE != ((*m_pWriteMiniDumpFunction)(GetCurrentProcess(), GetCurrentProcessId(), hFile, (MINIDUMP_TYPE)m_dwMiniDumpType, &ex_info, NULL, NULL));
// close the mini dump file
::CloseHandle(hFile);
return bStatus;
}
}
I apologize for the fact that this is not a drop-in solution. There are dependencies on other parts of my Toolbox library. But I think it would go a long way towards giving you the right idea as to how to build-in "capture a crash mini-dump" automatically from your code, which you can then combine with your .dsp files that you can make a normal part of your development cycle - so that when a .dmp comes in - you can fire up the debugger on it with your saved .pdb from your release build (which you don't distribute!) and you can debug the crash conditions quite easily.
The above code is an amalgam of many different sources - code snippets from debugging books, from MSDN documentation, etc., etc. If I have left out attribution I mean no harm. However, I do no believe that any of the above code is significantly created by anyone but myself.
Recompile just the file of interest without optimisations :)
In general:
Switch to interleaved disassembly mode. Single-stepping through the disassembly will enable you to step into function calls that would otherwise be skipped over, and make inlined code more evident.
Look for alternative ways of getting at values in variables the debugger is not able to directly show you. If they were passed in as arguments, look up the callstack - you will often find they are visible in the caller. If they were retrieved via getters from some object, examine that object; glance over the assembly generated by the code that calculates them to work out where they were stored; etc. If all else fails and disabling optimisations / adding a printf() distorts timings sufficiently to affect debugging, add a dummy global variable and set it to the value of interest on entry to the section of interest.
At least is not a IA64 dump...
There really isn't much you can do beyond having full dump and private symbols. Modern compilers have a field day with your code and is barely recognisable, specially if you add something like LTCG.
There are two things I found usefull:
Walk up the stack until you get a good anchor on what 'this' really points to. Most times when you are in an object method frame 'this' is unreliable because of registry optmizations. Usually several calls up the stack you get an object that has the correct address and you can navigate, member reference by member reference, until your crash point and have a correct value for 'this'
uf (Windbg's unassembly function command). This little helper can list a function dissasembly in a more manageable form than the normal dissasembly view. Because it follows jumps and code re-arranges, is easier to follow the logic of uf output.
The most important thing is to have the symbol files (*.pdb). You can generate them for release builds, by default they are not active.
Then you have to know that because of optimizations, code might get re-ordered, so debugging could look a bit jerky. Also some intermediate variables might have got optimized away. Generally speaking the behaviour and visibility of data might have some restrictions.
With Visual Studio C++ 2008 you can automatically debug the *.dmp files. I believe it also works for VS 2005. For older compilers I am afraid you´ll have to use WinDbg... (Also specify of course the *.pdb files for WinDbg, otherwise the info will be quite limited)