Wrong optimization in class analysis when calling virtual function

Reference Number : 
DPD200167436

Version : 
Intel C++ compiler 12.0

Operating System : 
Windows

Problem Description : 

Intel C++ compiler is doing wrong "class analysis" optimization when calling virtual function, implemented both in a plug-in and in the calling module.

When we compile the following test case with Intel compiler 12.0, we get wrong output. If we remove /Qipo option, the issue is does not show up.

// plugin.h    #pragma once    struct Interface  {      virtual void __stdcall Member() = 0;  };  

// plugin.cpp    #include "Plugin.h"  #include <stdio.h>    struct Implementation : public Interface  {      virtual void __stdcall Member()      {          printf("Plugin implementation\n");      }  };    extern "C" __declspec(dllexport)  Interface * _cdecl PluginCreator()  {      return new Implementation();  }  

// caller.cpp    #include "Plugin.h"  #include <stdio.h>    extern "C" Interface * _cdecl PluginCreator();    struct CallerImplementation : public Interface  {      virtual void __stdcall Member()      {          printf("Caller implementation\n");      }  };    int main(int argc, char ** argv)  {      Interface * caller = new CallerImplementation();      Interface * plugin = PluginCreator();        //__debugbreak();      caller->Member();      plugin->Member();     printf("Done\n");      return 0;  }  

C:\>icl -c /Qvc10 /Zi /W3 /O2 /Oi /Qipo /Qftz- -D WIN32 -D NDEBUG -D _WINDOWS -D _USRDLL -D _WINDLL -D _UNICODE -DUNICODE /EHsc /MD /GS /Gy /fp:precise /Zc:wchar_t /Zc:forScope /Gd /TP Plugin.cpp


C:\> icl /Qoption,link,/OUT:Plugin.dll /Qoption,link,/DLL "kernel32.lib" "user32.lib" Plugin.obj

C:> icl -c /Qvc10 /Zi /W3 /O2 /Oi /Qipo /Qftz- -D WIN32 -D NDEBUG -D _CONSOLE -D _UNICODE -D UNICODE /EHsc /MD /GS /Gy /fp:precise /Zc:wchar_t /Zc:forScope /Gd /TP -Qopt-class-analysis- Caller.cpp

C:>\ icl caller.obj Plugin.lib

The sample code for demonstrating the issue is taken from the Intel C++ compiler user forum, link http://software.intel.com/en-us/forums/showthread.php?t=81587&p=1#151043


Resolution Status : 

A bug in "class analysis" optimization is the cause for this runtime issue. We do have external option (-Qopt-class-analysis-) to disable this optimization. For now, this option can be used as workaround to avoid this issue.

Ex:
icl -Qopt-class-analysis- caller.obj Plugin.lib



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25 May, 2011


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Source: http://software.intel.com/en-us/articles/wrong-optimization-in-class-analysis-when-calling-virtual-function/
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