Question

I am running into the following issue while profiling an application under VC6. When I profile the application, the profiler is indicating that a simple getter method similar to the following is being called many hundreds of thousands of times:

int SomeClass::getId() const
{
   return m_iId;
};

The problem is, this method is not called anywhere in the test app. When I change the code to the following:

int SomeClass::getId() const
{
   std::cout << "Is this method REALLY being called?" << std::endl;
   return m_iId;
};

The profiler never includes getId in the list of invoked functions. Comment out the cout and I’m right back to where I started, 130+ thousand calls! Just to be sure it wasn’t some cached profiler data or corrupted function lookup table, I’m doing a clean and rebuild between each test. Still the same results!

Any ideas?

Answer 1

I’d guess that what’s happening is that the compiler and/or the linker is ‘coalescing’ this very simple function to one or more other functions that are identical (the code generated for return m_iId is likely exactly the same as many other getters that happen to return a member that’s at the same offset).

essentially, a bunch of different functions that happen to have identical machine code implementations are all resolved to the same address, confusing the profiler.

You may be able to stop this from happening (if this is the problem) by turning off optimizations.