From: Tom Tromey <tromey@redhat.com>
To: Jeff Law <law@redhat.com>
Cc: gcc-patches <gcc-patches@gcc.gnu.org>
Subject: Re: RFA: New pass to delete unexecutable paths in the CFG
Date: Mon, 07 Nov 2011 14:16:00 -0000 [thread overview]
Message-ID: <m3sjm0nind.fsf@fleche.redhat.com> (raw)
In-Reply-To: <4EB7AAF6.6060702@redhat.com> (Jeff Law's message of "Mon, 07 Nov 2011 02:55:02 -0700")
>>>>> "Jeff" == Jeff Law <law@redhat.com> writes:
Jeff> First, it's perfectly fine to have a NULL pointer dereference in a
Jeff> program as long as that code is never executed. Once the code is
Jeff> executed, we've entered the realm of undefined behavior.
Jeff> Thus in a conforming program we can safely assume that a provable NULL
Jeff> pointer dereference can never be executed at runtime. This implies
Jeff> there is a path through the CFG that is unexecutable.
IIUC, then this isn't true for Java. In Java the attempt to dereference
NULL throws a NullPointerException, which can be caught, etc. It isn't
undefined.
Tom
next prev parent reply other threads:[~2011-11-07 13:53 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-07 9:58 Jeff Law
2011-11-07 10:19 ` Jakub Jelinek
2011-11-07 10:21 ` Richard Guenther
2011-11-07 10:30 ` Richard Guenther
2011-11-07 19:20 ` Jeff Law
2011-11-07 16:14 ` Jeff Law
2011-11-07 16:30 ` Richard Guenther
2011-11-07 16:57 ` Kai Tietz
2011-11-07 19:03 ` Jeff Law
2011-11-08 11:50 ` Paolo Bonzini
2011-11-08 19:48 ` Jeff Law
2011-11-08 20:38 ` Paolo Bonzini
2011-11-08 20:59 ` Jeff Law
2011-11-09 8:37 ` Paolo Bonzini
2011-11-09 18:11 ` Jeff Law
2011-11-09 18:12 ` Jakub Jelinek
2011-11-09 22:45 ` Paolo Bonzini
2011-11-10 19:27 ` Jeff Law
2011-11-07 19:14 ` Jeff Law
2011-11-07 14:16 ` Tom Tromey [this message]
2011-11-07 15:54 ` Jeff Law
2011-11-07 15:54 ` Richard Guenther
2011-11-07 19:09 ` Jeff Law
2011-11-07 22:34 ` Richard Guenther
2011-11-08 20:02 ` Jeff Law
2011-11-09 9:50 ` Richard Guenther
2011-11-09 17:43 ` Jeff Law
2011-11-07 15:55 ` Tom Tromey
2011-11-07 17:01 ` Paolo Bonzini
2011-11-15 7:52 ` RFA: disable -fdelete-null-pointer-checks for Java Jeff Law
2011-11-07 19:05 ` RFA: New pass to delete unexecutable paths in the CFG Jeff Law
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