SDL memory leaks and Visual Leak Detector
Alright, so I think my program might have a memory leak. It's an SDL application, and it seems to have grown too large for me to manually pinpoint the leak. I searched around for a windows equivalent of Valgrind (I'm running Windows 7 x64 and using Visual Studio 2010), and eventually came across Visual Leak Detector. Unfortunately, it doesn't seem to want to generate ay output.
I set up another project, an empty console application, and set up VLD the same way as in my SDL app. Upon running the program, VLD worked perfectly and caught every memory leak that I threw at it. But in the SDL app, it just outputs "Visual Leak Detector Version 2.2 installed." at the beginning of the debug session and nothing else, even when I intentionally created a memory leak right in the main function.
The closest I can tell, it might have to do with SDL screwing with the program entry point. But that's just a guess. Is there any way to get VLD to work with SDL?
You could try to deleaker . It is a powerful tool for debugging memory leaks.
I had a similar problem using SDL library as well. In my case though, I was trying to use the default Memory Leak detection of Visual Studio 2010 because I didn't wanted to use a third party library/application.
Fixing the issue
If after all the required includes, define and function call you still don't see any memory leaks printed out, it might be that your Runtime Library is not set properly.
Double check if you have the debug version of the Runtime Library instead of the non-debug one (/MT and /MD).
Multi-threaded Debug (/MTd)
Multi-threaded Debug DLL (/MDd)
The compiler defines _DEBUG when you specify the /MTd or /Mdd option. These options specify debug versions of the C run-time library. See _DEBUG reference MSDN
Thus, the _DEBUG symbol must be defined in order to enable CRT code.
[...] When _DEBUG is not defined, calls to _CrtSetDbgFlag are removed during preprocessing [...]. See MSDN reference
So building a debug build is not enough to ensure _DEBUG will be defined.
This is something that you usually don't change in a normal project, but following a tutorial for SDL could lead you were I was.
Hopefully, it is going to help someone else, or even you.
More Details below
I was following the MSDN page to enable Memory leak detection out of the box with VS 2010.
After declaring those
#define _CRTDBG_MAP_ALLOC
#include <stdlib.h>
#include <crtdbg.h>
I enabled them into my code and I inserted a deliberate memory leak
int main( int argc, char* args[] )
{
_CrtSetDbgFlag( _CRTDBG_ALLOC_MEM_DF | _CRTDBG_LEAK_CHECK_DF );
_CrtSetReportMode( _CRT_ERROR, _CRTDBG_MODE_DEBUG );
int *pArray = (int*)malloc(sizeof(int) * 24); // Memory not freed
return 0;
}
Nothing was printed out.
So, I looked at the assembly and it was definitively not generating the CRT code at all as you can see:
int main( int argc, char* args[] )
{
012932F0 push ebp
012932F1 mov ebp,esp
012932F3 sub esp,0CCh
012932F9 push ebx
012932FA push esi
012932FB push edi
012932FC lea edi,[ebp-0CCh]
01293302 mov ecx,33h
01293307 mov eax,0CCCCCCCCh
0129330C rep stos dword ptr es:[edi]
_CrtSetDbgFlag( _CRTDBG_ALLOC_MEM_DF | _CRTDBG_LEAK_CHECK_DF );
_CrtSetReportMode( _CRT_ERROR, _CRTDBG_MODE_DEBUG ); // Nothing in both case!
int *pArray = (int*)malloc(sizeof(int) * 24);
0129330E mov esi,esp
01293310 push 60h
01293312 call dword ptr [__imp__malloc (129E4CCh)]
01293318 add esp,4
0129331B cmp esi,esp
0129331D call @ILT+580(__RTC_CheckEsp) (1291249h)
01293322 mov dword ptr [pArray],eax
Then, I realized that the _DEBUG symbol was probably not getting defined.
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