From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 1649 invoked by alias); 5 May 2011 11:08:07 -0000 Received: (qmail 1640 invoked by uid 22791); 5 May 2011 11:08:06 -0000 X-SWARE-Spam-Status: No, hits=-2.3 required=5.0 tests=AWL,BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,RCVD_IN_DNSWL_LOW,RFC_ABUSE_POST X-Spam-Check-By: sourceware.org Received: from mail-wy0-f175.google.com (HELO mail-wy0-f175.google.com) (74.125.82.175) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 05 May 2011 11:07:50 +0000 Received: by wye20 with SMTP id 20so1795154wye.20 for ; Thu, 05 May 2011 04:07:49 -0700 (PDT) MIME-Version: 1.0 Received: by 10.227.98.9 with SMTP id o9mr2386612wbn.25.1304593669312; Thu, 05 May 2011 04:07:49 -0700 (PDT) Received: by 10.227.20.74 with HTTP; Thu, 5 May 2011 04:07:49 -0700 (PDT) In-Reply-To: References: <20110504202659.AD3CFECC6@topo.tor.corp.google.com> Date: Thu, 05 May 2011 11:25:00 -0000 Message-ID: Subject: Re: [pph] Add streamer hook for preloading common nodes (issue4478043) From: Richard Guenther To: Diego Novillo Cc: reply@codereview.appspotmail.com, crowl@google.com, gcc-patches@gcc.gnu.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-IsSubscribed: yes 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 X-SW-Source: 2011-05/txt/msg00398.txt.bz2 On Thu, May 5, 2011 at 1:03 PM, Diego Novillo wrote: > On Thu, May 5, 2011 at 05:06, Richard Guenther > wrote: > >> I think we should move away from pre-loading the streamer cache, that >> has caused enough trouble when the common nodes are originating from >> different Frontends and when compiling units with different flags which >> happen to change those nodes (think of the hoops we jump through >> to support that for -f[un]signed-char). > > Sure, though that's not an issue for pph. =A0PPH images are generated > and consumed by one front end. > > Pre-loading common nodes in C++ gives us: > > 1- Smaller pph images > 2- Ability to do pointer comparison against common nodes. > > #1 saves us from saving a few hundred nodes in each pph image. =A0But #2 > is a stronger requirement. =A0How do you think we could do #2 without > pre-loading? For LTO we have type-merging for that, and we'd continue to pre-load the type merger with the (LTO frontend specific) common tree nodes. I suppose you are not doing any merging at all? If so pre-loading those nodes makes indeed sense (given you have a way to reject PPH images when flags such as -f[un]signed-char differ ...). Richard. > > Diego. >