Re: memory layouts of C++ classes

tomtzigt@frc602.intel.com (Theodore Omtzigt - MAP-Folsom) writes:


      After walking the heap to reverse engineer the memory layout
      of a class in MFC, I figured this forum might provide a better
      answer. How does a C++ compiler build the memory layout of a class
      and a derived class? Also, what is the difference in memory layout
      of a regular C++ compiler and the memory layouts used by SOM compilers
      to provide binary consistency? Thanks in advance,


Naturally, different compilers do it differently.


If I remember right, g++ places the base structure first
(using the normal C structure rules), then a virtual
function pointer if required, then any inherited classes
one after another.


Borland C places the virtual function pointer BEFORE the
first structure, at a negative offset. Inherited classes
as before.


Don't know how they handle multiple inheritance, virtual
base classes, or having the first virtual function in an
inherited class.




Cliff
--
cliffc@cs.rice.edu -- Massively Scalar Compiler Group, Rice University
--

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