From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 6915 invoked by alias); 6 Apr 2006 13:45:33 -0000 Received: (qmail 6907 invoked by uid 22791); 6 Apr 2006 13:45:33 -0000 X-Spam-Check-By: sourceware.org Received: from zigzag.lvk.cs.msu.su (HELO zigzag.lvk.cs.msu.su) (158.250.17.23) by sourceware.org (qpsmtpd/0.31) with ESMTP; Thu, 06 Apr 2006 13:45:31 +0000 Received: from Debian-exim by zigzag.lvk.cs.msu.su with spam-scanned (Exim 4.50) id 1FRUne-0005kd-JV for gdb@sources.redhat.com; Thu, 06 Apr 2006 17:45:27 +0400 Received: from zigzag.lvk.cs.msu.su ([158.250.17.23]) by zigzag.lvk.cs.msu.su with esmtp (Exim 4.50) id 1FRUnV-0005in-3i; Thu, 06 Apr 2006 17:45:17 +0400 From: Vladimir Prus To: Jim Ingham , GDB List Subject: Re: MI: type prefixes for values Date: Thu, 06 Apr 2006 14:05:00 -0000 User-Agent: KMail/1.7.2 References: <200602171724.03824.ghost@cs.msu.su> <200604061703.26246.ghost@cs.msu.su> <20060406133546.GB25088@nevyn.them.org> In-Reply-To: <20060406133546.GB25088@nevyn.them.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200604061745.16585.ghost@cs.msu.su> Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org X-SW-Source: 2006-04/txt/msg00060.txt.bz2 On Thursday 06 April 2006 17:35, Daniel Jacobowitz wrote: > On Thu, Apr 06, 2006 at 05:03:25PM +0400, Vladimir Prus wrote: > > I was thinking about this more, and still not 100% sure how Xcode can do > > this. Do you mean that Xcode takes a stack trace when the varobj was > > created, and deletes varobj whenever it sees that stack became shorter? > > > > The case I'm not sure about is this: > > > > 1. main calls 'a' which calls 'b' which bits breakpoint. > > 2 varobj is created for local var of 'b' > > 3. Users says 'continue'. > > 4. 'b' exists and then 'a' calls 'b' again and breakpoint is > > hit again. > > > > However, this second time it's not guaranteed that stack frame of 'b' is > > at the same address as it was the last time -- maybe 'a' has pushed > > something on stack. How do you detect this case? > > Either b's stack frame is at the same address - in which case the > varobj is still valid - or else it isn't, in which case the frame id > has changed. I did not know that GDB exposes frame ID in any way, and Jim has mentioned that it's XCode that does the magic, not gdb. Is there some command to print frame id that I've missed? > > > Note, however, that the varobj's do remember their frames, so if you > > > tried to evaluate one that was no longer on the stack, the varobj > > > would report "out of scope". > > > > Would be great to add this in FSF version. > > It's already there: > > /* The frame for this expression */ > struct frame_id frame; > > c_value_of_root will always fail if the frame is gone. Sorry, does not seems to work this way here. For the following program: void foo() { int i = 10; ++i; } int main() { foo(); } I get this session: (gdb) -break-insert a.cpp:5 ^done,bkpt={...... (gdb) -exec-run ^running (gdb) *stopped,reason="breakpoint-hit",frame={addr="0x080483a1",func="foo" (gdb) -var-create TMP * i ^done,name="TMP",numchild="0",type="int" (gdb) -var-evaluate-expression TMP ^done,value="10" (gdb) -exec-finish ^running (gdb) *stopped,reason="function-finished",frame={addr="0x080483bd",func="main", (gdb) -var-evaluate-expression TMP ^done,value="10" (gdb) There's no indication that 'TMP' varobj belongs to the stack frame we've already left. This is with vanilla 6.4. - Volodya