Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!apple!ames!think!barmar
From: barmar@think.COM (Barry Margolin)
Newsgroups: comp.lang.c
Subject: Re: pointer representation (was: Re: effect of free())
Message-ID: <29171@news.Think.COM>
Date: 11 Sep 89 03:25:01 GMT
References: <319@cubmol.BIO.COLUMBIA.EDU> <3756@buengc.BU.EDU> <11021@smoke.BRL.MIL> <2075@munnari.oz.au>
Sender: news@Think.COM
Organization: Thinking Machines Corporation, Cambridge MA, USA
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In article <2075@munnari.oz.au> ok@cs.mu.oz.au (Richard O'Keefe) writes:
>  My point is that optimising compilers
>generally assume that "equals may be subsituted for equals" (that's what
>equality is all about), so that *correct* source code is very likely to be
>incorrectly *optimised*.

If the optimizer for an architecture where pointers may compare equal
but not be completely equivalent were to perform such a
transformation, it would be a buggy optimizer.  You appear to be
assuming a system-independent optimizer; what you've done is point out
why such a thing is not really a good idea.

Barry Margolin
Thinking Machines Corp.

barmar@think.com
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