Wrong optimization when calling virtual function implemented both in a plugin and in the calling module.

[emmanuel_attia]

Hi

Intel 12 Compiler seems to inline virtual functions where he should'nt (when optimization and IPO enabled).

The given solution should output (tested with Intel Compiler 11 and Visual C++ 2005/2008)

Caller implementation

Plugin implementation

But if i compile the Caller (EXE) with Intel 12 (Compiler XE 12.0.2.154 [IA-32]), with /O2 and /Qipoit outputs

Caller implementation

Callerimplementation

This is very surprising from a professionnal compiler to have such a subjective interpretation of the keyword "virtual"...

Regards,

Emmanuel

[Om_S_Intel]

This seems a bug in Intel compiler. I am investigating the issue. I will update when done.

[Om_S_Intel]

I reproduced the issue using VS2010 IDE.

I could not reproduce the issue when using command lines give below:

c:\>icl /c /Qvc10 /Zi /W3 /O2 /Oi /Qipo /Qftz- -D WIN32 -D NDEBUG -D _WINDOWS -D _USRDLL -D INTEL12BUGPLUGIN_EXPORTS -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:Intel12BugPlugin.dll /Qoption,link,/DLL "kernel32.lib" "user32.lib" "gdi32.lib" "winspool.lib" "comdlg32.lib" "advapi32.lib" "shell32.lib" "ole32.lib" "oleaut32.lib" "uuid.lib" "odbc32.lib" "odbccp32.lib" Plugin.obj

c:\>icl /c /Qvc10 /Zi /W3 /Od /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 Caller.cpp

c:>icl Intel12BugPlugin.lib Caller.obj

Is there something missing?

[emmanuel_attia]

I don't understand, did you manage to reproduce the bug within the IDE or do you need me to send you a solution with Visual 2010 ?

I'm not use to command line, although running the lines you gave me the compiler outputs:

ipo: remark #11001: performing single-file optimizations

And I don't know how to force multi-file optimization (because I already tested like I said in the initial post that the bug happen only in multi-file optimization (/Qipo) and not single fine optimization (/Qip).

Obviously in single-file optimization, the compiler has no hint to issue make static call from virtual call.

[emmanuel_attia]

After some trial, I have reproduced the bug with the following command lines:

[bash]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/Plugin.cpp
icl /Qoption,link,/OUT:Plugin.dll /Qoption,link,/DLL "kernel32.lib" "user32.lib" Plugin.obj
icl /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 Caller/Caller.cpp Plugin.lib
[/bash]

[Om_S_Intel]

I have submitted a bug report to Intel compiler development team on this. I will update the thread when I have more info on this.

[Om_S_Intel]

If you use compiler option -Qopt-class-analysis- then the problem is resolved.

[Om_S_Intel]

Knowlege base article based on this thread is available at http://software.intel.com/en-us/articles/wrong-optimization-in-class-analysis-when-calling-virtual-function/.

[emmanuel_attia]

Hi, thanks for your fix, it will be very usefull.

It this still considered as a bug to be solved by the Compiler Team ?

Best regards and thanks again.

[Om_S_Intel]

The fix is implemeted by compiler team but it is not targeted for Intel compiler 12.0.

In case you can not manage with work-around, please let us know.

[Om_S_Intel]

The issue is fixed in latest Intel C++ Composer XE 12.1. The composer is available for download from Intel download center.