FIX: C1001 Error Compiling Naked Function with /Og and /G5

The information in this article applies to:

• The Microsoft C/C++ Compiler (CL.EXE), included with Microsoft Visual C++, 32-bit Edition, version 2.0 on the following platform: x86

SYMPTOMS

Compiling a function with the __declspec(naked) modifier, but without an __asm block for the epilog code, and using the /Og and /G5 switches, results in the following error:

   fatal error C1001: INTERNAL COMPILER ERROR
                 (compiler file 'l:\b_bld\c2\P2\main.c', line 374)
     Please choose the Technical Support command on the Visual C++
     Help menu, or open the Technical Support help file for more
     information

RESOLUTION

Implement a epilog code block in your function.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This problem was fixed in Microsoft Visual C++, 32-bit Edition, version 4.0.

MORE INFORMATION

If a function is declared with the __declspec(naked) modifier, the compiler will not generate any prolog or epilog code. Users should implement their own prolog and epilog code, using blocks of inline assembler code.

NOTE: without proper prolog and epilog code, the code will not execute correctly.

Sample Code

/* Compile options needed: /Og /G5
   Note that /O1, /O2, and /Ox all imply /Og
*/

void __declspec(naked) NakedFunction()

    __asm
    {
    // prolog code
    }

    printf( "Inside naked function\n" );

    // note: epilog __asm block missing