Re: [rfa/testsuite] gdb1250.exp, new test script

[Daniel Jacobowitz <drow at mvista dot com>]

On Tue, Jul 15, 2003 at 12:13:57PM -0400, Michael Elizabeth Chastain wrote:
> Rats, I said I would do this yesterday.  Here it is: a new test script
> for PR gdb/1250.
> 
>   http://sources.redhat.com/gdb/bugs/1250
> 
> This is the bug where gdb loses its marbles when backtracing through a
> function which calls a noreturn function such as 'abort'.  The calling
> function has no epilog after the call to 'abort', so when gdb looks at
> the frame for that function, gdb sees the first instruction of the
> *next* function and uses information for that function instead.
> 
> This happens in gdb.base/corefile.exp but I think it is nice to have a
> specific test for it.
> 
> I tested this on native i686-pc-linux-gnu with gdb HEAD, gcc 2.95.3 and
> v3, dwarf-2 and stabs+.
> 
> It PASSed with gcc 2.95.3 because gcc 2.95.3 does not optimize away the
> epilog.  I think that this is okay.  The gdb user really just wants to
> put breakpoints on things like 'abort' and 'exit' and have it work, and
> if it works because the compiler is simple, that is okay.
> 
> It KFAILed with all the gcc 3.3's that I used.
> 
> I would like to commit this to HEAD, wait a few days or a week, and then
> commit it to gdb_6_0-branch.
> 
> OK to commit?

You misspelled exiting as "exitting".  Other than that, it looks fine
(with ChangeLog); please check it in on HEAD.  I'm not sure about the
branch.

> 
> Michael C
> 
> ===
> 
> # Copyright 2003 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 2 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, write to the Free Software
> # Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  
> 
> # Tests for PR gdb/1250.
> # 2003-07-15  Michael Chastain <mec@shout.net>
> 
> # This file is part of the gdb testsuite.
> 
> if $tracelevel then {
>         strace $tracelevel
>         }
> 
> #
> # test running programs
> #
> set prms_id 0
> set bug_id 0
> 
> set testfile "gdb1250"
> set srcfile ${testfile}.c
> set binfile ${objdir}/${subdir}/${testfile}
> 
> if  { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug}] != "" } {
>      gdb_suppress_entire_file "Testcase compile failed, so all tests in this file will automatically fail."
> }
> 
> gdb_exit
> gdb_start
> gdb_reinitialize_dir $srcdir/$subdir
> gdb_load ${binfile}
> 
> if ![runto abort] then {
>     perror "couldn't run to breakpoint"
>     continue
> }
> 
> # See http://sources.redhat.com/gdb/bugs/1250
> #
> # In a nutshell: the function 'beta' ends with a call to 'abort', which
> # is a noreturn function.  So the last instruction of 'beta' is a call
> # to 'abort'.  When gdb looks for information about the caller of
> # 'beta', it looks at the instruction after the call to 'abort' -- which
> # is the first instruction of 'alpha'!  So gdb uses the wrong frame
> # information.  It thinks that the test program is in 'alpha' and that
> # the prologue "push %ebp / mov %esp,%ebp" has not been executed yet,
> # and grabs the wrong values.
> #
> # By the nature of the bug, it could pass if the C compiler is not smart
> # enough to implement 'abort' as a noreturn function.  This is okay.
> # The real point is that users often put breakpoints on noreturn
> # functions such as 'abort' or some kind of exitting function, and those
> # breakpoints should work.
> 
> gdb_test_multiple "backtrace" "backtrace from abort" {
>     -re "#0.*abort.*\r\n#1.*beta.*\r\n#2.*alpha.*\r\n#3.*main.*\r\n$gdb_prompt $" {
> 	pass "backtrace from abort"
>     }
>     -re "#0.*abort.*\r\n#1.*beta.*\r\n$gdb_prompt $" {
> 	# This happens with gdb HEAD as of 2003-07-13, with gcc 3.3,
> 	# binutils 2.14, either -gdwarf-2 or -gstabs+, on native
> 	# i686-pc-linux-gnu.
> 	#
> 	# gdb gets 'abort' and 'beta' right and then goes into the
> 	# weeds.
> 	kfail "gdb/1250" "backtrace from abort"
>     }
> }
> 
> ===
> 
> /* Test program for stack trace through noreturn function.
> 
>    Copyright 2003 Free Software Foundation, Inc.
> 
>    This file is part of the gdb testsuite.
> 
>    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 2 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, write to the Free Software
>    Foundation, Inc., 59 Temple Place - Suite 330,
>    Boston, MA 02111-1307, USA.
>  
>    This file was written by Michael Elizabeth Chastain (mec@shout.net).  */
> 
> #include <stdlib.h>
> 
> int global = 0;
> 
> void gamma (int *parray)
> {
>   return;
> }
> 
> void beta ()
> {
>   int array [4];
>   array [0] = global++;
>   array [1] = global++;
>   array [2] = global++;
>   array [3] = global++;
>   gamma (array);
>   abort ();
> }
> 
> int alpha ()
> {
>   global++;
>   beta ();
>   return 0;
> }
> 
> int main ()
> {
>   int i;
>   global++;
>   i = alpha ();
>   return i;
> }
> 

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer