From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 14992 invoked by alias); 13 May 2003 21:27:58 -0000 Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org Received: (qmail 14832 invoked from network); 13 May 2003 21:27:57 -0000 Received: from unknown (HELO frothingslosh.sfbay.redhat.com) (66.187.237.200) by sources.redhat.com with SMTP; 13 May 2003 21:27:57 -0000 Received: from frothingslosh.sfbay.redhat.com (localhost.localdomain [127.0.0.1]) by frothingslosh.sfbay.redhat.com (8.12.8/8.12.8) with ESMTP id h4DLOQNm008390; Tue, 13 May 2003 14:24:26 -0700 Received: (from rth@localhost) by frothingslosh.sfbay.redhat.com (8.12.8/8.12.8/Submit) id h4DLOQ3l008388; Tue, 13 May 2003 14:24:26 -0700 X-Authentication-Warning: frothingslosh.sfbay.redhat.com: rth set sender to rth@redhat.com using -f Date: Tue, 13 May 2003 21:27:00 -0000 From: Richard Henderson To: Geoff Keating Cc: Mike Stump , Jason Merrill , gcc@gcc.gnu.org Subject: Re: __attribute__((cleanup(function)) versus try/finally Message-ID: <20030513212426.GD8273@redhat.com> Mail-Followup-To: Richard Henderson , Geoff Keating , Mike Stump , Jason Merrill , gcc@gcc.gnu.org References: <20030508204622.GB6901@redhat.com> <82B7548E-81A4-11D7-BD07-003065A77310@apple.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4i X-SW-Source: 2003-05/txt/msg01366.txt.bz2 On Mon, May 12, 2003 at 05:07:36PM -0700, Geoff Keating wrote: > For instance, much of the information in the tables is included in the > object code (nearly all of it in the case of routines that don't > actually have cleanups). It wouldn't be that hard to write a routine > that, given a return address, can determine what registers need to be > restored and from where in 90% of the cases by looking at the object > code; those routines (in the 90%) can have an abbreviated EH entry > that just says "use the object code", and the remaining 10% could have > a real EH entry. If you have an entry at all, it means you know the extent of the function being described. So you know where the entry point is. So no searching for that. You'd just read forward from the start. However, if you make the prologue regular enough that code reading is going to work, you're talking about *maybe* 2 bytes per saved register in the EH information, at which point I disbelieve that we're saving enough data space to make this worthwhile. r~