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From: dwl@mercury.udev.cdc.com (Daren W Latham)
Newsgroups: comp.sys.mips
Subject: compiler bug
Message-ID: <18302@shamash.cdc.com>
Date: 5 Mar 90 19:45:47 GMT
Sender: news@shamash.cdc.com
Reply-To: dwl@mercury.udev.cdc.com (Daren W Latham)
Organization: Control Data Corp., Arden Hills, MN
Lines: 56

I have just run across what I believe is a bug in the C compiler.  It doesn't
matter if optimization is turned on or not.  This program works correctly with
other C compilers.  Does anybody (mips perhaps) know if this bug is documented,
or just what the status of this is.  I am running on:

  RC2030: MIPS R2000A Processor Chip, Revision 2.0
          MIPS R2010A VLSI Floating Point Chip Revision: 2.0
          RISC/os Release 4.10 mips Version UMIPS

and on a

  M2000: MIPS R3000 Processor Chip, Revision 2.0
         MIPS R3010 VLSI Floating Point Chip Revision: 2.0
         RISC/os Release 4_0 mips Version UMIPS

--
Daren W. Latham                        | <dwl@udev.cdc.com>
Control Data Corporation               | (612)482-3457
Arden Hills, MN                        |

/*  sample program to show compiler bug
 *
 *  Note that the first printf displays a value of 10 and the second
 *  printf correctly displays a value of 13 for 5+8.
 *
 *  It doesn't make a difference if optimization is turned on or off.
 *
 */

#include <stdio.h>

#define  PushArg(n)              argStack[argStackP++] = n
#define  PopArg()                argStack[--argStackP]

main()
{
  int  argStack[10];
  int  argStackP = 0;
  int  temp;

  PushArg(5);
  PushArg(8);

  temp = PopArg() + PopArg();

  printf ("temp = %d \n", temp);

  PushArg(5);
  PushArg(8);

  temp = PopArg();

  temp += PopArg();

  printf ("temp = %d \n", temp);
}