From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 20303 invoked by alias); 1 May 2009 17:32:49 -0000 Received: (qmail 20294 invoked by uid 22791); 1 May 2009 17:32:48 -0000 X-SWARE-Spam-Status: No, hits=-1.5 required=5.0 tests=AWL,BAYES_00,J_CHICKENPOX_34,J_CHICKENPOX_36,J_CHICKENPOX_37,SPF_HELO_PASS,SPF_PASS X-Spam-Check-By: sourceware.org Received: from mx2.redhat.com (HELO mx2.redhat.com) (66.187.237.31) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Fri, 01 May 2009 17:32:41 +0000 Received: from int-mx2.corp.redhat.com (int-mx2.corp.redhat.com [172.16.27.26]) by mx2.redhat.com (8.13.8/8.13.8) with ESMTP id n41HWI1X028256; Fri, 1 May 2009 13:32:18 -0400 Received: from ns3.rdu.redhat.com (ns3.rdu.redhat.com [10.11.255.199]) by int-mx2.corp.redhat.com (8.13.1/8.13.1) with ESMTP id n41HWHmx013060; Fri, 1 May 2009 13:32:17 -0400 Received: from host0.dyn.jankratochvil.net (sebastian-int.corp.redhat.com [172.16.52.221]) by ns3.rdu.redhat.com (8.13.8/8.13.8) with ESMTP id n41HWFIF024722; Fri, 1 May 2009 13:32:16 -0400 Received: from host0.dyn.jankratochvil.net (localhost [127.0.0.1]) by host0.dyn.jankratochvil.net (8.14.3/8.14.3) with ESMTP id n41HWEmW001222; Fri, 1 May 2009 19:32:14 +0200 Received: (from jkratoch@localhost) by host0.dyn.jankratochvil.net (8.14.3/8.14.3/Submit) id n41HWCMH001215; Fri, 1 May 2009 19:32:12 +0200 Date: Fri, 01 May 2009 17:32:00 -0000 From: Jan Kratochvil To: Joel Brobecker Cc: Tom Tromey , gdb-patches@sourceware.org Subject: Re: [patch] Fix internal error on breaking at a multi-locations caller Message-ID: <20090501173212.GA31331@host0.dyn.jankratochvil.net> References: <20090309220736.GA27259@host0.dyn.jankratochvil.net> <20090428203235.GG31821@adacore.com> <20090501091942.GA8465@host0.dyn.jankratochvil.net> <20090501154759.GF10734@adacore.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090501154759.GF10734@adacore.com> User-Agent: Mutt/1.5.19 (2009-01-05) X-IsSubscribed: yes 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 X-SW-Source: 2009-05/txt/msg00034.txt.bz2 On Fri, 01 May 2009 17:47:59 +0200, Joel Brobecker wrote: > I think Tom must be pretty busy right now :), I have no news on that issue. :-) > Based on that, "break" in my opinion should be equivalent to "break *PC" > where PC is the current frame's PC. So, I think that the correct way > to fix this is to set the "explicit_pc" flag in the sal. Attached. If you do not agree with the fix credit I am willing to fully accept it as I agree with this change. > I also understand the reason why you think a warning might help, > especially since I had a different intuitive perception of what > the argument-less command was doing. As I was surprised of the change requested by Tom Tromey I share the feeling there is no agreement on the intuitive expectation on side-effects of the parameter-less `break' command. > But I think that such a warning would quickly become more annoying than > anything if the user knows precisely the meaning of his command. Just my general opinion on this matter: In such cases there should be a GDB variable to turn it off in the power user's `~/.gdbinit' file. Reading the GDB manual should not be a prerequisite for starting GDB. > Nonetheless, I think we can treat the two issues separately. We can > fix the problem first with a one-liner, and then we can discuss the > idea of a warning if you think it might be useful. As I found out in this discussion it is not clear what the side-effects should be and as I do not think newbie GDB users are aware the parameter-less `break' command feature exists at all I no longer have any objections. Regression tested on x86_64-unknown-linux-gnu. Thanks, Jan gdb/ 2009-05-01 Joel Brobecker Jan Kratochvil Fix internal error on breaking at a multi-locations caller source line. * breakpoint.c (parse_breakpoint_sals): Set EXPLICIT_PC for the `break' command with no parameters. gdb/testsuite/ 2009-05-01 Jan Kratochvil * gdb.cp/expand-sals.exp, gdb.cp/expand-sals.cc: New. --- gdb/breakpoint.c 29 Apr 2009 19:31:58 -0000 1.392 +++ gdb/breakpoint.c 1 May 2009 16:45:49 -0000 @@ -5488,6 +5475,13 @@ parse_breakpoint_sals (char **address, sal.line = default_breakpoint_line; sal.symtab = default_breakpoint_symtab; sal.section = find_pc_overlay (sal.pc); + + /* In the case of breaking at the caller line (right after the + calling instruction) GDB should use neither the first instruction + of the source line (before the calling instruction) nor any other + existing locations (function instances) for that source line. */ + sal.explicit_pc = 1; + sals->sals[0] = sal; sals->nelts = 1; } --- /dev/null 1 Jan 1970 00:00:00 -0000 +++ gdb/testsuite/gdb.cp/expand-sals.cc 1 May 2009 16:45:50 -0000 @@ -0,0 +1,53 @@ +/* This testcase is part of GDB, the GNU debugger. + + Copyright (C) 2009 Free Software Foundation, Inc. + + This file is part of GDB. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + +int +func () +{ + return 42; /* func-line */ +} + +volatile int global_x; + +class A +{ +public: + A () + { + global_x = func (); /* caller-line */ + } +}; + +/* class B is here just to make the `func' calling line above having multiple + instances - multiple locations. Template cannot be used as its instances + would have different function names which get discarded by GDB + expand_line_sal_maybe. */ + +class B : public A +{ +}; + +int +main (void) +{ + A a; + B b; + + return 0; /* exit-line */ +} --- /dev/null 1 Jan 1970 00:00:00 -0000 +++ gdb/testsuite/gdb.cp/expand-sals.exp 1 May 2009 16:45:50 -0000 @@ -0,0 +1,83 @@ +# Copyright 2009 Free Software Foundation, Inc. + +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 3 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see . + +if { [skip_cplus_tests] } { continue } + +set srcfile expand-sals.cc +if { [prepare_for_testing expand-sals.exp expand-sals $srcfile {debug c++}] } { + return -1 +} +if ![runto_main] { + return -1 +} + +gdb_breakpoint [gdb_get_line_number "exit-line"] + +gdb_breakpoint [gdb_get_line_number "func-line"] +gdb_continue_to_breakpoint "func" ".*func-line.*" + +gdb_test "up" "caller-line.*" + +# PC should not be at the boundary of source lines to make the original bug +# exploitable. + +set test "p/x \$pc" +set pc {} +gdb_test_multiple $test $test { + -re "\\$\[0-9\]+ = (0x\[0-9a-f\]+)\r\n$gdb_prompt $" { + set pc $expect_out(1,string) + pass $test + } +} + +set test "info line" +set end {} +gdb_test_multiple $test $test { + -re "Line \[0-9\]+ of .* starts at address 0x\[0-9a-f\]+.* and ends at (0x\[0-9a-f\]+).*\\.\r\n$gdb_prompt $" { + set end $expect_out(1,string) + pass $test + } +} + +set test "caller line has trailing code" +if {$pc != $end} { + pass $test +} else { + fail $test +} + +# Original problem was an internal error here. +set test "break" +gdb_test_multiple $test $test { + -re "Breakpoint \[0-9\]+ at .*, line \[0-9\]+\\. \\(\[2-9\] locations\\)\r\n$gdb_prompt $" { + fail $test + } + -re "Breakpoint \[0-9\]+ at .*, line \[0-9\]+\\.\r\n$gdb_prompt $" { + pass $test + } +} + +gdb_continue_to_breakpoint "caller" ".*caller-line.*" + +# Test GDB caught this return call and not the next one through B::B() +gdb_test "bt" \ + "#0 \[^\r\n\]* A \[^\r\n\]*\r\n#1 \[^\r\n\]* main \[^\r\n\]*" \ + "bt from A" + +gdb_continue_to_breakpoint "next caller func" ".*func-line.*" + +# Verify GDB really could not catch any other breakpoint location. + +gdb_continue_to_breakpoint "uncaught return" ".*exit-line.*"