Q43175: Bad Code Produced for specific source when optimizations used

Article: Q43175
Product(s): See article
Version(s): 1.00 1.01 2.00
Operating System(s): MS-DOS
Keyword(s): ENDUSER | buglist1.00 buglist1.01 buglist2.00 | mspl13_c
Last Modified: 18-MAY-1989

When compiling the source code below, the QuickC and QCL compilers
will produce incorrect code if any optimizations other than loop
optimization are enabled. If optimizations are disabled or only loop
optimization is used, the compilers will generate correct code.

Microsoft is researching this problem and will post new information as
it becomes available.

This program will demonstrate the problem when compiled with
optimizations enabled (/O):

#include <stdio.h>

void main( void )
{
    int a, b, c;

    a = 0;
    b = 2 - ( 63 * a );
    c = ( b % 31 );       /* c should be 2
                             (the remainder of 2/31) */

    if( b != c )
    {
         printf( "FAILED\n" );
         exit( 1 );
    }
    else
    {
         printf( "PASSED\n" );
         exit( 0 );
    }
}

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