DOCUMENT:Q106520  24-MAR-2000  [fortran]
TITLE   :FIX: /Ge Fails to Detect Stack Overflow
PRODUCT :Microsoft Fortran Compiler
PROD/VER::1.0,1.0a
OPER/SYS:
KEYWORDS:kberrmsg kbFortranPS kbLangFortran

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

 - Microsoft FORTRAN PowerStation for MS-DOS, versions 1.0, 1.0a 
 - Microsoft Fortran Powerstation 32 for Windows NT, version 1.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

Programs compiled with the /Ge option produce the following run-time error

   DOSXMSF : fatal error DX1020: unhandled exception: General protection fault;

when a stack overflow occurs, instead of the expected R6000 stack overflow
message.

STATUS
======

Microsoft has confirmed this to be a problem in FORTRAN PowerStation version 1.0
for MS-DOS. This problem was corrected in Microsoft FORTRAN PowerStation 32,
version 4.0.

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

The stack-checking routine enabled by the /Ge option does not detect stack
overflow. Because the default stack size for the FORTRAN PowerStation is 32K, a
general protection (GP) fault is unlikely to be caused by a stack overflow. The
exception to this is when one of the following types of programs is written:

 - Programs deliberately designed to use up the stack. This would involve
   extensive use of automatic variables, indirect recursion, or deeply nested
   subroutine and function calls totaling thousands of passed arguments.

 - Programs that circumvent the link time check for stack use based on name
   decorations. These programs may cause stack overflow if they contain problems
   related to passing arguments. This check is circumvented by declaring the
   routine to use the C or VARYING calling conventions or by using the ALIAS
   attribute.

 - Programs that call Assembly language routines that incorrectly use the stack.

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

The following code can be used to illustrate the problem:

   C Compile options needed: /Ge
         subroutine recur(y)
         integer y
         y = y + 1
         call indrec(y)
         end
         subroutine indrec(i)
         integer i
         i = i + 1
         call recur(i)
         end
         integer x
         x = 0
         call recur(x)
         end

NOTE: The /Ge compiler option is no longer used for stack-probe checks under
FORTRAN PowerStation 32, version 4.0. Attempting to use this option will
generate the message:

   Command line warning D2004: obsolete option /Ge ignored.

Additional query words: 1.00 gpf gp-fault

======================================================================
Keywords          : kberrmsg kbFortranPS kbLangFortran 
Technology        : kbAudDeveloper kbFortranSearch kbZNotKeyword2 kbZNotKeyword3 kbFORTRANPower32100NT kbFORTRANPower100DOS kbFORTRANPower100aDOS
Version           : :1.0,1.0a
Issue type        : kbbug
Solution Type     : kbfix

=============================================================================

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