Q150572: FIX: Error C1001: _asm Instruction Accessing Stack Using [ebp]

Article: Q150572
Product(s): Microsoft C Compiler
Version(s): 2.0,2.1,2.2,4.0,4.2,5.0,6.0
Operating System(s): 
Keyword(s): kbCompiler kbVC200bug kbVC210bug kbVC220bug kbVC400bug kbVC410bug kbVC420bug kbVC500bug
Last Modified: 13-FEB-2002

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The information in this article applies to:

- Microsoft Visual C++, versions 2.0, 2.1, 2.2, 4.0 
- Microsoft Visual C++, 32-bit Enterprise Edition, versions 4.2, 5.0, 6.0 
- Microsoft Visual C++, 32-bit Professional Edition, versions 4.2, 5.0, 6.0 
- Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
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SYMPTOMS
========

Inline assembly code that uses [ebp] to gain access to arguments or local
variables on the stack results in this error:

  fatal error C1001: INTERNAL COMPILER ERROR
  (compiler file '\school.tp3\test\c10\src\P2\386\codegen.c', line 4040)

CAUSE
=====

When an argument is passed to a function, or a local variable is declared in a
function, the argument or variable is placed on the stack, and is already
referenced in terms of [ebp]. When [ebp] is used explicitly to reference that
argument or variable as in ccb[ebp], for example, the compiler adds [ebp] again,
resulting in an illegal address. The compiler fails to catch this as a
meaningful error, and instead generates error C1001.

RESOLUTION
==========

Do not attempt to gain access to stack arguments or variables in terms of
[ebp].

NOTE: In the sample code in this article, lcb[ebp] and ccb[ebp] are invalid
references; lcb and ccb need to be referenced directly. Otherwise, the compiler
does not catch the illegal reference.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article.

This problem was corrected in Microsoft Visual C++ 6.0 Service Pack 5.

MORE INFORMATION
================

Sample Code
-----------

  /* Compile options needed:none
  */ 

  #include <windows.h>

  void masmfunc(DWORD ccb){

     _asm mov eax ,dword ptr ccb[ebp];   //C1001

  //Or,
  //  DWORD lcb = 20;

  // _asm mov eax ,dword ptr lcb[ebp];   //C1001

  }

Additional query words: kbVC400bug

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Keywords          : kbCompiler kbVC200bug kbVC210bug kbVC220bug kbVC400bug kbVC410bug kbVC420bug kbVC500bug kbVC600bug kbNoUpdate 
Technology        : kbVCsearch kbVC400 kbAudDeveloper kbVC220 kbVC420 kbVC500 kbVC600 kbVC200 kbVC210 kbVC32bitSearch kbVC500Search
Version           : :2.0,2.1,2.2,4.0,4.2,5.0,6.0
Issue type        : kbbug
Solution Type     : kbfix

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