From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 11601 invoked by alias); 24 Oct 2014 20:09:22 -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 11589 invoked by uid 89); 24 Oct 2014 20:09:22 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.7 required=5.0 tests=AWL,BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS,SPF_PASS autolearn=ham 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; Fri, 24 Oct 2014 20:09:20 +0000 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s9OK9DhF028859 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Fri, 24 Oct 2014 16:09:13 -0400 Received: from [127.0.0.1] (ovpn01.gateway.prod.ext.ams2.redhat.com [10.39.146.11]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id s9OK99Aq027804; Fri, 24 Oct 2014 16:09:10 -0400 Message-ID: <544AB1E5.8030509@redhat.com> Date: Fri, 24 Oct 2014 20:09:00 -0000 From: Pedro Alves User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.1.1 MIME-Version: 1.0 To: Martin Galvan CC: gdb-patches@sourceware.org, Doug Evans , Eli Zaretskii , Ulrich Weigand , Daniel Gutson Subject: Re: [PATCH] Python API: Add gdb.is_in_prologue and gdb.is_in_epilogue. References: <1413986485-4673-1-git-send-email-martin.galvan@tallertechnologies.com> <544822D6.8020606@redhat.com> <544828BB.9040900@redhat.com> <544A68B1.9000909@redhat.com> In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-SW-Source: 2014-10/txt/msg00674.txt.bz2 On 10/24/2014 08:49 PM, Martin Galvan wrote: > On Fri, Oct 24, 2014 at 11:56 AM, Pedro Alves wrote: >> On 10/23/2014 06:36 PM, Martin Galvan wrote: >>>>> Some targets have code at address 0. Seems like we may be exposing a >>>>> bad interface for these targets here? >>> I used 0 because in_prologue expects it to be non-zero. If it's 0 and >>> we have no debugging info, it'll always return true: >>> >>> /* We don't even have minsym information, so fall back to using >>> func_start, if given. */ >>> if (! func_start) >>> return 1; /* We *might* be in a prologue. */ >> >> Design mistakes in the internal APIs shouldn't be exposed to a public >> API. I'd even suggest that whatever Python API we end up with, it'd >> be good to make the internal API match it. >> >>> >>> Again, I did it because of the way in_prologue works, but as Eli said >>> this would probably be better handled with a Python exception or a >>> message of some kind. >> >> Not sure an exception makes sense given the function's >> interface. Say in the future another optional parameter is added. >> What would you do then? What of old code that passed in func_start >> but not that new argument? Those might not expect an exception. >> So for the case of the new argument not being specified, we'd >> have to return 1, which is right -- the PC _might_ be pointing >> at a prologue. > > I probably didn't make myself clear-- I wasn't talking about using > in_prologue directly anymore, but to follow its approach in the API > function. Of course it wouldn't make sense to put Python exception > raising directly inside in_prologue. That concern with about clients of the Python API, and if another optional parameter is added to the Python API. > >> But, how exactly were you planning using the gdb.is_in_prologue >> function? GDB itself doesn't use this to determine whether locals >> are valid, only gdbarch_in_function_epilogue_p/gdb.is_in_epilogue. > > Well, I followed the code while testing a rather simple function and > noticed that handle_step_into_function is very similar (in terms of > the approach) to in_prologue plus some address corrections and setting > a breakpoint to proceed to. The API function needs only the address > calculation part. > > What if: > 1) I split handle_step_into_function in the address calc part and > the brakpoint insertion part, > moving the address calc to a new function (publicly available from infrun.h). > 2) I expose such function to the Python API. > > Would that be accepted? Would you want to see a patch? > > Please keep in mind that what I actually need is not really messing > with the prologue, but to know where the local variables are > accessible. If I could simply use DWARF info to accomplish that then I > wouldn't even touch the prologue at all. Hmm, how is this different from simply doing "break function" ? GDB sets function breakpoints after the prologue already. A "step" into a function should stop at the exact same address as if the user did "b function; c" to run to said function. So, when you detect that you stepped into a function, you could just set the breakpoint by function name? Thanks, Pedro Alves