From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 16564 invoked by alias); 14 Oct 2015 15:22:07 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Received: (qmail 16555 invoked by uid 89); 14 Oct 2015 15:22:06 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.7 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS,T_RP_MATCHES_RCVD autolearn=ham version=3.3.2 X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-GCM-SHA384 encrypted) ESMTPS; Wed, 14 Oct 2015 15:22:05 +0000 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (Postfix) with ESMTPS id 796FE344EC3; Wed, 14 Oct 2015 15:22:04 +0000 (UTC) Received: from localhost.localdomain (ovpn-113-105.phx2.redhat.com [10.3.113.105]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t9EFM3Qi029350; Wed, 14 Oct 2015 11:22:03 -0400 Subject: Re: [PATCH 8/9] Add TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID To: Richard Henderson , Richard Biener References: <1444280375-20866-1-git-send-email-rth@redhat.com> <1444280375-20866-9-git-send-email-rth@redhat.com> <5616DBBE.9080309@redhat.com> <561C41DD.5000505@redhat.com> <561D27EE.8030608@redhat.com> <561D7095.8080401@redhat.com> Cc: GCC Patches From: Jeff Law Message-ID: <561E731B.3020803@redhat.com> Date: Wed, 14 Oct 2015 15:22:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <561D7095.8080401@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-IsSubscribed: yes X-SW-Source: 2015-10/txt/msg01373.txt.bz2 On 10/13/2015 02:59 PM, Richard Henderson wrote: > On 10/14/2015 02:49 AM, Jeff Law wrote: >> The problem here is we don't know what address space the *0 is going >> to hit, >> right? > > Correct, not before we do the walk of stmt to see what's present. So the address space information isn't part of the address? I must admit I haven't looked at how that stuff is being implemented. > >> Isn't that also an issue for code generation as well? > > What sort of problem are you thinking of? I haven't seen one yet. If the address space information was supposed to be carried in the address itself, then we'd need the address to be distinct from NULL_POINTER_NODE. It sounds to me like you're carrying address space information outside the address itself, which avoid those issues. However, it does mean that the path isolation code needs some kind of adjustment to distinguish between *0 that will fault and *0 which hits a different address space and may not fault. jeff