From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 29949 invoked by alias); 8 Jul 2015 12:48:29 -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 29940 invoked by uid 89); 8 Jul 2015 12:48:28 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.7 required=5.0 tests=AWL,BAYES_00,KAM_LAZY_DOMAIN_SECURITY,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=no version=3.3.2 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 (AES256-GCM-SHA384 encrypted) ESMTPS; Wed, 08 Jul 2015 12:48:27 +0000 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) by mx1.redhat.com (Postfix) with ESMTPS id AF28DA380C; Wed, 8 Jul 2015 12:48:26 +0000 (UTC) Received: from [127.0.0.1] (ovpn01.gateway.prod.ext.ams2.redhat.com [10.39.146.11]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t68CmPVG005574; Wed, 8 Jul 2015 08:48:25 -0400 Message-ID: <559D1C18.4070008@redhat.com> Date: Wed, 08 Jul 2015 12:48:00 -0000 From: Pedro Alves User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: Patrick Palka CC: "gdb-patches@sourceware.org" Subject: Re: [PATCH] tui: replace deprecated_register_changed_hook with observer References: <1436145432-6502-1-git-send-email-patrick@parcs.ath.cx> <559D0C63.3000200@redhat.com> In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-SW-Source: 2015-07/txt/msg00203.txt.bz2 On 07/08/2015 01:30 PM, Patrick Palka wrote: > On Wed, Jul 8, 2015 at 7:41 AM, Pedro Alves wrote: >> On 07/06/2015 02:17 AM, Patrick Palka wrote: >>> This is a straightforward replacement of the TUI's use of the >>> aforementioned hook with the register_changed observer. Since this was >>> the only user of the hook, this patch also removes the hook. >>> >>> [ I am not sure if the changes to the function tui_register_changed are >>> correct. In particular, the inputted frame argument is now passed down >>> to tui_check_data_values instead of the frame returned by >>> get_selected_frame. The frame argument passed to each register_changed >>> observer corresponds to the VALUE_FRAME_ID of the register being >>> modified within a register assignment, e.g. the $rax in "print $rax = >>> FOO". When would the frame corresponding to the VALUE_FRAME_ID of a >>> register not be the currently selected frame? ] >>> >> >> Grepping for value_assign callers finds e.g., varobjs: >> >> varobj.c: val = value_assign (var->value, value); >> >> Adding an assertion like this: >> >> @@ -1169,6 +1169,7 @@ value_assign (struct value *toval, struct value *fromval) >> } >> } >> >> + gdb_assert (frame == get_selected_frame (NULL)); >> observer_notify_register_changed (frame, value_reg); >> if (deprecated_register_changed_hook) >> deprecated_register_changed_hook (-1); >> >> and playing with varobjs shows the assertion failing: >> >> (gdb) interpreter-exec mi "-var-create - * $rax" >> ^done,name="var1",numchild="0",value="6295640",type="int64_t",has_more="0" >> (gdb) up >> #1 0x000000000040082a in thread_function0 (arg=0x0) at threads.c:69 >> 69 usleep (1); /* Loop increment. */ >> (gdb) up >> #2 0x0000003616a07ee5 in start_thread (arg=0x7ffff7fc1700) at pthread_create.c:309 >> 309 THREAD_SETMEM (pd, result, CALL_THREAD_FCT (pd)); >> (gdb) interpreter-exec mi "-var-assign var1 1" >> ~"/home/pedro/gdb/mygit/build/../src/gdb/valops.c:1172: internal-error: value_assign: Assertion `frame == get_selected_frame (NULL)' failed.\nA problem internal to GDB has been detected,\nfurther debugging may prove unreliable.\nQuit this debugging session? (y or n) " >> >> The TUI doesn't use MI, but there are probably other similar cases >> in the tree. E.g., I'd assume you can create a register Value with Python, >> and then assign to it when the selected frame is not >> the register's frame. > > Ah okay.. So it seems to me that if the frame argument != > get_selected_frame, then we should not update the register window at > all since the register window is supposed to show the register values > of the currently selected frame. Yes, I think so. > Or instead, just ignore the frame argument and always pass > get_selected_frame to tui_check_data_values, even if frame != > get_selected_frame. Seems to me that this is the safest option. That'd be a 1-1 with the current code. Though, I believe that results in spuriously clearing the highlight of previously changed registers (of the selected frame), because nothing will have changed. So seems like the other option actually fixes a bug. Thanks, Pedro Alves