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From: mrm@puffin.eng.sun.com (Marianne Mueller)
Newsgroups: comp.sys.sun
Subject: Sun3 optimizer bug fixed in "next release"
Keywords: Software
Message-ID: <8305@brazos.Rice.edu>
Date: 30 May 90 21:55:58 GMT
Sender: root@rice.edu
Organization: Sun-Spots
Lines: 33
Approved: Sun-Spots@rice.edu
X-Sun-Spots-Digest: Volume 9, Issue 187, message 14

Yup, bug in the 4.1 sun3 cc for the program

#include "stdio.h"

        cgf2(x)
        {
                int     dir, step, steps;

                (void) printf("%d\n", x);
                steps = (x == 50) ? 2 : 0;
                dir = -1;
                for (step = steps; step > 0; --step)
                        cgf2(x + dir * step);
        }

        main()
        {
                cgf2(50);
        }


This bug, alas, seems to be present in C 1.0, but gladly, is fixed in the
"next release", for which alpha is just begun.

total proof:

mrm% /usr/lang/SC1.0/cc -O4 optbug.c
mrm% a.out
50
48
49

As you say, the workaround is to compile at -O1.