From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 6989 invoked by alias); 27 Feb 2004 03:03:12 -0000 Mailing-List: contact gdb-patches-help@sources.redhat.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sources.redhat.com Received: (qmail 6902 invoked from network); 27 Feb 2004 03:03:11 -0000 Received: from unknown (HELO nevyn.them.org) (66.93.172.17) by sources.redhat.com with SMTP; 27 Feb 2004 03:03:11 -0000 Received: from drow by nevyn.them.org with local (Exim 4.30 #1 (Debian)) id 1AwYHO-0006Jh-Rj; Thu, 26 Feb 2004 22:03:10 -0500 Date: Fri, 27 Feb 2004 03:03:00 -0000 From: Daniel Jacobowitz To: Jim Blandy Cc: gdb-patches@sources.redhat.com, Elena Zannoni Subject: Re: [RFA/dwarf] Optimize partial DIE reading for uninteresting DIEs Message-ID: <20040227030310.GA24230@nevyn.them.org> Mail-Followup-To: Jim Blandy , gdb-patches@sources.redhat.com, Elena Zannoni References: <20040225030644.GA5167@nevyn.them.org> <20040226231255.GC8487@nevyn.them.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.1i X-SW-Source: 2004-02/txt/msg00797.txt.bz2 On Thu, Feb 26, 2004 at 09:58:32PM -0500, Jim Blandy wrote: > > Daniel Jacobowitz writes: > > You're mistaken about the expense. In particular read_unsigned_leb128 > > is much slower than skip_uleb128 because of the computations to build > > the result; IIRC variable shifts are expensive. Yes, this was measured > > with an optimized build and a non-intrusive profiler. There's also the > > different memory access patterns. > > No kidding. I'm amazed. Okay. > > > Most of the speedup comes from not reading in the attribute values, > > though. > > If what you say above is so, then two distinct versions of the > attribute traversal are clearly called for. > > It would be interesting to compare profiling results between two GDB's > that differ only in whether they use your attribute skipper or the > attribute value reader. For this patch, the changes were pretty small. For the larger change, with just partial symbol table reading, read_unsigned_leb128 dropped way down and skip_leb128 didn't climb equally far up. Let me reproduce those results, though. Something seems suspicious. -- Daniel Jacobowitz MontaVista Software Debian GNU/Linux Developer