Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!uflorida!haven!adm!smoke!gwyn
From: gwyn@smoke.BRL.MIL (Doug Gwyn)
Newsgroups: comp.lang.c
Subject: Re: effect of free()
Message-ID: <10976@smoke.BRL.MIL>
Date: 8 Sep 89 10:49:48 GMT
References: <319@cubmol.BIO.COLUMBIA.EDU> <3756@buengc.BU.EDU> <10971@smoke.BRL.MIL> <2054@munnari.oz.au>
Reply-To: gwyn@brl.arpa (Doug Gwyn)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 13

In article <2054@munnari.oz.au> ok@cs.mu.oz.au (Richard O'Keefe) writes:
>So what's so special about other (pointer values that may not be
>dereferenced)?

You'll never grasp what we're trying to say so long as you try to interpret
it in terms of conventional architectures, because we're talking about a
hardware trap that occurs NOT when an invalid pointer is used to REFERENCE
an object, by when the invalid pointer itself is merely INSPECTED.  This
occurs only for certain special architectures, such as "tagged" ones.  It
can be a useful software reliability feature when properly exploited, which
is why SWARD-like designs may well implement it.

You won't have the problem we're talking about on your VAX or Macintosh.