FIX: Calling a Function Returning double May Not Pop FPU Stack (167995)

The information in this article applies to:

Microsoft Visual C++, 32-bit Enterprise Edition 5.0
Microsoft Visual C++, 32-bit Professional Edition 5.0

This article was previously published under Q167995

SYMPTOMS

When you call a function that returns a double, from within a conditional, and build with /Od, the compiler does not pop the Coprocessor stack. This may cause a floating point stack overflow (0xc0000092), or later calculations involving the FPU to evaluate to -1.#IND00. The sample below demonstrates a form of this bug.

RESOLUTION

Enable global optimizations (/Og).

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug has been corrected in Visual Studio 97 Service Pack 1.

For additional information about the Visual Studio 97 Service Pack 1, please see the following article in the Microsoft Knowledge Base:

170365 INFO: Visual Studio 97 Service Packs - What, Where, and Why

MORE INFORMATION

Sample Code

   // Compile options needed: /Od
   #include <float.h>
   #include <stdio.h>
   double func()
   {
     return 1.0;
   }
   void main()
   {
      int i;
      double d=2.0;
      // uncomment the next line to unmask exception
      //_controlfp(_EM_OVERFLOW, _MCW_EM );
      for( i = 0; i < 10; i++ )
      {
         if( func() );
      }
      // outputs -1.#IND00
      printf("%f",d+d);
   }

Modification Type:	Minor	Last Reviewed:	7/5/2005
Keywords:	kbBug kbcode kbCompiler kbfix kbVS97sp1fix KB167995