Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!gatech!mcnc!rti!trt
From: trt@rti.UUCP (Thomas Truscott)
Newsgroups: comp.sys.hp
Subject: +O2 common-subexpression bug
Message-ID: <3091@rti.UUCP>
Date: 28 Jul 89 20:19:46 GMT
Distribution: comp
Organization: Research Triangle Institute, RTP, NC
Lines: 24

Under HP-UX 6.5, the following program gives different
answers when compiled with and without "-O" (a.k.a. "+O2").
[Apologies if this has been mentioned before,
I do not follow this group closely.
Surely this has been discovered and fixed by now!]
	Tom Truscott

main()
{
	register char *s;
	register int a, b;

	s = "\1\2\3\4";

	a = (s[0] + s[1]);
	s += 2;
	b = (s[0] + s[1]);
	printf("%d %d\n", a, b);

	a = s[1];
	s--;
	b = s[1];
	printf("%d %d\n", a, b);
}