From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 70044 invoked by alias); 24 Nov 2017 04:54:50 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 70024 invoked by uid 89); 24 Nov 2017 04:54:49 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.7 required=5.0 tests=BAYES_00,KB_WAM_FROM_NAME_SINGLEWORD,SPF_HELO_PASS,T_RP_MATCHES_RCVD autolearn=no version=3.3.2 spammy= 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 ESMTP; Fri, 24 Nov 2017 04:54:48 +0000 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 79B3DC0587D7; Fri, 24 Nov 2017 04:54:47 +0000 (UTC) Received: from localhost (unused-10-15-17-193.yyz.redhat.com [10.15.17.193]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3EFD9600C8; Fri, 24 Nov 2017 04:54:47 +0000 (UTC) From: Sergio Durigan Junior To: Pedro Alves Cc: Yao Qi , Joel Brobecker , "gdb-patches\@sourceware.org" Subject: Re: [PATCH v2] Add support for the --readnever command-line option (DWARF only) References: <1467838463-15786-1-git-send-email-brobecker@adacore.com> <87o9ntddb6.fsf_-_@redhat.com> <2cb6d01b-b40b-0a73-2df4-65f4e2094731@redhat.com> <87efoodi79.fsf@redhat.com> Date: Fri, 24 Nov 2017 04:54:00 -0000 In-Reply-To: (Pedro Alves's message of "Thu, 23 Nov 2017 17:29:01 +0000") Message-ID: <87a7zc9syx.fsf@redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-IsSubscribed: yes X-SW-Source: 2017-11/txt/msg00589.txt.bz2 On Thursday, November 23 2017, Pedro Alves wrote: > On 11/23/2017 05:21 PM, Sergio Durigan Junior wrote: > >>>> +This option is currently limited to debug information in DWARF format. >>>> +For all other format, this option has no effect. >>> >>> How hard would it be to just make it work? There's only stabs and mdebug >>> left, I think? There should be a single a function somewhere that we can >>> add an early return. And then we don't need to document this limitation... >>> >>> For example, in elf_symfile_read, we could just skip the elf_locate_sections >>> call. In coffread.c we could skip reading stabs right after >>> bfd_map_over_sections (abfd, coff_locate_sections....); >>> >>> Looking for: >>> >>> $ grep -h "^[a-z]*_build_psymtabs" gdb/ >>> coffstab_build_psymtabs (struct objfile *objfile, >>> elfstab_build_psymtabs (struct objfile *objfile, asection *stabsect, >>> stabsect_build_psymtabs (struct objfile *objfile, char *stab_name, >>> mdebug_build_psymtabs (minimal_symbol_reader &reader, >>> elfmdebug_build_psymtabs (struct objfile *objfile, >>> >>> finds all the relevant places. >>> >>> Maybe it wouldn't be that hard to make this be an objfile flag >>> afterall (like OBJF_READNOW is). That'd make it possible >>> to add the location "-readnever" counterpart switch to add-symbol-file >>> too, BTW: > > I meant "logical" instead of "location". I was staring at > gdb/location.c at that time. :-P > >>> >>> symfile.c: if (strcmp (arg, "-readnow") == 0) >>> symfile.c: else if (strcmp (arg, "-readnow") == 0) >> >> Hm, I'll look into this. Just to make it clear: the idea is to have >> both a --readnever global option and also a OBJF_READNEVER specific to >> each objfile? > > Sure, the idea is to do something similar to what's done for --readnow. Sorry, but I guess I need a few more details on this. The way I understand the code at elf_symfile_read, the very first thing to do would be to check if OBJF_READNEVER is set and return early if it is. But it seems that you're proposing something a bit different when you say that we should "... just skip the elf_locate_sections call." It doesn't seem to me that is worth continuing on that function if OBJF_READNEVER is present. As for the *_build_psymtabs functions, I am doing exactly that: if objfile->flags contains OBJF_READNEVER, then just return and do nothing. The patch is almost ready for resubmission (well, I still need to figure out how to test the --readnow && --readnever scenario), but I want to make sure I got this part right. Thanks, -- Sergio GPG key ID: 237A 54B1 0287 28BF 00EF 31F4 D0EB 7628 65FC 5E36 Please send encrypted e-mail if possible http://sergiodj.net/