Microsoft KB Archive/168029

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

Article ID: 168029

Article Last Modified on 7/5/2005

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APPLIES TO


 * Microsoft Visual C++ 5.0 Enterprise Edition
 * Microsoft Visual C++ 5.0 Professional Edition

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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); }

Additional query words: /O2 Release Maximum Speed

Keywords: kbbug kbfix kbvs97sp1fix kbcode kbcompiler KB168029

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