DOCUMENT:Q150572  13-FEB-2002  [visualc]
TITLE   :FIX: Error C1001: _asm Instruction Accessing Stack Using [ebp]
PRODUCT :Microsoft C Compiler
PROD/VER::2.0,2.1,2.2,4.0,4.2,5.0,6.0
OPER/SYS:
KEYWORDS:kbCompiler kbVC200bug kbVC210bug kbVC220bug kbVC400bug kbVC410bug kbVC420bug kbVC500bug

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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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