From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 14862 invoked by alias); 2 Dec 2009 16:11:06 -0000 Mailing-List: contact archer-help@sourceware.org; run by ezmlm Sender: Precedence: bulk List-Post: List-Help: List-Subscribe: List-Id: Received: (qmail 14850 invoked by uid 22791); 2 Dec 2009 16:11:04 -0000 X-SWARE-Spam-Status: No, hits=-2.3 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS,SPF_PASS X-Spam-Check-By: sourceware.org Date: Wed, 02 Dec 2009 16:11:00 -0000 From: Dodji Seketeli To: Tom Tromey Cc: Cary Coutant , GDB/Archer list Subject: Re: [RFC] Proposal for a new DWARF name index section Message-ID: <20091202161049.GD4450@tintin.torimasen.com> References: <4A7FE28D.4050901@redhat.com> <4A8D8868.3010302@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-08-17) X-SW-Source: 2009-q4/txt/msg00070.txt.bz2 On Tue, Dec 01, 2009 at 12:13:47PM (-0700), Tom Tromey wrote: > The biggest fixable performance problem in the current reader is > actually computing the hash codes for the strings from the > .debug_gnu_index section. So, I've been thinking about putting the hash > code directly into the section. FWIW, from a G++ pov, I think it'd be tempted to say "let's try to implement this and see how much GDB gains" so that we can have data to make an educated choice. So I'd be on the "yes, let's try side" of the story here. > > The other problem I've noticed is name canonicalization. This past > year, we changed gdb to canonicalize names in its symbol tables, and to > canonicalize user input before doing lookups. This lets gdb return the > right answer even when the order of modifiers varies. This change > slowed down DWARF reading, and it occurred to me that it would also > substantially slow down index reading. So, I would also like to change > the .debug_gnu_index spec to specify how names are to be canonicalized. Just to be sure I understand. How saying _how_ the strings are to be canonicalized is going to speed up significantly GDB's processing? I would have have thought that the killer gain would come from the producing directly what the consumer expects. I guess I am missing something. Dodji