DOCUMENT:Q104776  02-NOV-1999  [fortran]
TITLE   :BUG: Endless Loop in Code Containing Graphics & Compiled -Ox
PRODUCT :Microsoft Fortran Compiler
PROD/VER::1.0,1.0a
OPER/SYS:
KEYWORDS:

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

 - Microsoft FORTRAN PowerStation for MS-DOS, versions 1.0, 1.0a 
-------------------------------------------------------------------------------

SYMPTOMS
========

A program may execute in an infinite loop if it was compiled with full
optimization (-Ox) and contains a do loop calling some of the graphics routines
[such as POLYGON_W()].

CAUSE
=====

Some of the graphics functions (such as POLYGON_W) prevent optimized code from
recognizing the end condition for the loop.

STATUS
======

Microsoft has confirmed this to be a problem in FORTRAN PowerStation for MS-DOS,
version 1.0 and 1.0a.

This problems does not apply to FORTRAN PowerStation 32.

RESOLUTION
==========

Compile the program with no optimization (this is the default).

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

   c Compile options needed:    -Ox
   c The following program will output in an infinite loop:

         include 'fgraph.fi'
         include 'fgraph.fd'
         INTEGER*2  status, npts

         RECORD     / wxycoord /  wxyarr(3)

         status = setvideomode(18)
         do it=1,2
            write (*,'(i4\)') it
            wxyarr(1).wx = 43.d0
            wxyarr(1).wy = 85.d0
            wxyarr(2).wx = 50.d0
            wxyarr(2).wy = 71.d0
            wxyarr(3).wx = 45.d0
            wxyarr(3).wy = 85.d0
            npts = 3
            status = POLYGON_W($GBORDER, wxyarr, npts)
         enddo
         END

Additional query words: nofpsnt 1.00

======================================================================
Keywords          :  
Technology        : kbAudDeveloper kbFortranSearch kbZNotKeyword3 kbFORTRANPower100DOS kbFORTRANPower100aDOS
Version           : :1.0,1.0a

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

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