FIX: Global Optimizations (/Og) May Cause the Compiler to Hang (168029)

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 Q168029

SYMPTOMS

The compiler hangs when you are building a function that contains many expressions involving floating-point operations and the /Og optimization is enabled.

RESOLUTION

Disable global optimizations for the file that is causing the compiler to hang. You can do this with either #pragma optimize("g",off) or by using the /Og- switch.

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

The following sample reproduces the problem. Other examples of this problem are too large to demonstrate in a small sample.

Sample Code

    // Compile options: /c /Og
    float f(int i)
    {
      switch(i)
      {
      case  1: return ( 1.1f * i );
      case  2: return ( 2.2f * i );
      case  3: return ( 3.3f * i );
      case  4: return ( 4.4f * i );
      case  5: return ( 5.5f * i );
      case  6: return ( 6.6f * i );
      case  7: return ( 7.7f * i );
      case  8: return ( 8.8f * i );
      }

    return(2.0f*i);
    }

Modification Type:	Minor	Last Reviewed:	7/5/2005
Keywords:	kbBug kbcode kbCompiler kbfix kbVS97sp1fix KB168029