[RFC,v6] PR gdb/13860: make -interpreter-exec console "list" behave more like "list".

  Hi!

I'm sending out a different fix for this one, below.
Quoting previous patch for context.

On 03/04/2014 06:32 PM, Tom Tromey wrote:
> From: Pedro Alves <palves@redhat.com>
> 
> Patch 3 in this series made me notice that "list" behaves differently
> in CLI vs MI.  Particularly:
> 
>   >./gdb -nx -q ./testsuite/gdb.mi/mi-cli
>   Reading symbols from /home/pedro/gdb/mygit/build/gdb/testsuite/gdb.mi/mi-cli...done.
>   (gdb) start
>   Temporary breakpoint 1 at 0x40054d: file ../../../src/gdb/testsuite/gdb.mi/basics.c, line 62.
>   Starting program: /home/pedro/gdb/mygit/build/gdb/testsuite/gdb.mi/mi-cli
> 
>   Temporary breakpoint 1, main () at ../../../src/gdb/testsuite/gdb.mi/basics.c:62
>   62        callee1 (2, "A string argument.", 3.5);
>   (gdb) list
>   57      {
>   58      }
>   59
>   60      main ()
>   61      {
>   62        callee1 (2, "A string argument.", 3.5);
>   63        callee1 (2, "A string argument.", 3.5);
>   64
>   65        do_nothing (); /* Hello, World! */
>   66
>   (gdb)
> 
> Note the list started at line 57.  IOW, the program stopped at line
> 62, and GDB centered the list on that.
> 
> compare with:
> 
>   >./gdb -nx -q ./testsuite/gdb.mi/mi-cli -i=mi
>   =thread-group-added,id="i1"
>   ~"Reading symbols from /home/pedro/gdb/mygit/build/gdb/testsuite/gdb.mi/mi-cli..."
>   ~"done.\n"
>   (gdb)
>   start
>   &"start\n"
>   ~"Temporary breakpoint 1 at 0x40054d: file ../../../src/gdb/testsuite/gdb.mi/basics.c, line 62.\n"
>   =breakpoint-created,bkpt={number="1",type="breakpoint",disp="del",enabled="y",addr="0x000000000040054d",func="main",file="../../../src/gdb/testsuite/gdb.mi/basics.c",fullname="/home/pedro/gdb/mygit/src/gdb/testsuite/gdb.mi/basics.c",line="62",times="0",original-location="main"}
>   ~"Starting program: /home/pedro/gdb/mygit/build/gdb/testsuite/gdb.mi/mi-cli \n"
>   =thread-group-started,id="i1",pid="14221"
>   =thread-created,id="1",group-id="i1"
>   ^running
>   *running,thread-id="all"
>   (gdb)
>   =library-loaded,id="/lib64/ld-linux-x86-64.so.2",target-name="/lib64/ld-linux-x86-64.so.2",host-name="/lib64/ld-linux-x86-64.so.2",symbols-loaded="0",thread-group="i1"
>   =library-loaded,id="/lib64/libm.so.6",target-name="/lib64/libm.so.6",host-name="/lib64/libm.so.6",symbols-loaded="0",thread-group="i1"
>   =library-loaded,id="/lib64/libc.so.6",target-name="/lib64/libc.so.6",host-name="/lib64/libc.so.6",symbols-loaded="0",thread-group="i1"
>   =breakpoint-modified,bkpt={number="1",type="breakpoint",disp="del",enabled="y",addr="0x000000000040054d",func="main",file="../../../src/gdb/testsuite/gdb.mi/basics.c",fullname="/home/pedro/gdb/mygit/src/gdb/testsuite/gdb.mi/basics.c",line="62",times="1",original-location="main"}
>   ~"\nTemporary breakpoint "
>   ~"1, main () at ../../../src/gdb/testsuite/gdb.mi/basics.c:62\n"
>   ~"62\t  callee1 (2, \"A string argument.\", 3.5);\n"
>   *stopped,reason="breakpoint-hit",disp="del",bkptno="1",frame={addr="0x000000000040054d",func="main",args=[],file="../../../src/gdb/testsuite/gdb.mi/basics.c",fullname="/home/pedro/gdb/mygit/src/gdb/testsuite/gdb.mi/basics.c",line="62"},thread-id="1",stopped-threads="all",core="0"
>   =breakpoint-deleted,id="1"
>   (gdb)
>   -interpreter-exec console list
>   ~"62\t  callee1 (2, \"A string argument.\", 3.5);\n"
>   ~"63\t  callee1 (2, \"A string argument.\", 3.5);\n"
>   ~"64\t\n"
>   ~"65\t  do_nothing (); /* Hello, World! */\n"
>   ~"66\t\n"
>   ~"67\t  callme (1);\n"
>   ~"68\t  callme (2);\n"
>   ~"69\t\n"
>   ~"70\t  return 0;\n"
>   ~"71\t}\n"
>   ^done
>   (gdb)
> 
> Here the list starts at line 62, where the program was stopped.
> 
> This happens because print_stack_frame, called from both normal_stop
> and mi_on_normal_stop, is the function responsible for setting the
> current sal from the selected frame, overrides the PRINT_WHAT
> argument, and only after that does it decide whether to center the
> current sal line or not, based on the overriden value, and it will
> always decide false.
> 
> (The print_stack_frame call in mi_on_normal_stop is a little different
> from the call in normal_stop, in that it is an unconditional
> SRC_AND_LOC call.  The next patch will make those uniform.)
> 
> Tested on x86_64 Fedora 16, no regressions.
> 
> 2013-10-30  Pedro Alves  <palves@redhat.com>
> 
> 	* stack.c (print_stack_frame): Compute CENTER before overriding
> 	PRINT_WHAT.
> 
> 2013-10-30  Pedro Alves  <palves@redhat.com>
> 
> 	* gdb.mi/mi-cli.exp: Adjust expected output of "list".
> ---
>  gdb/ChangeLog                   | 5 +++++
>  gdb/stack.c                     | 4 ++--
>  gdb/testsuite/ChangeLog         | 4 ++++
>  gdb/testsuite/gdb.mi/mi-cli.exp | 2 +-
>  4 files changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/gdb/stack.c b/gdb/stack.c
> index da7d977..6fd2be9 100644
> --- a/gdb/stack.c
> +++ b/gdb/stack.c
> @@ -160,14 +160,14 @@ print_stack_frame (struct frame_info *frame, int print_level,
>  {
>    volatile struct gdb_exception e;
>  
> +  int center = (print_what == SRC_LINE || print_what == SRC_AND_LOC);
> +
>    /* For mi, alway print location and address.  */
>    if (ui_out_is_mi_like_p (current_uiout))
>      print_what = LOC_AND_ADDRESS;
>  
>    TRY_CATCH (e, RETURN_MASK_ERROR)
>      {
> -      int center = (print_what == SRC_LINE || print_what == SRC_AND_LOC);
> -
>        print_frame_info (frame, print_level, print_what, 1 /* print_args */,
>  			set_current_sal);
>        if (set_current_sal)
> diff --git a/gdb/testsuite/gdb.mi/mi-cli.exp b/gdb/testsuite/gdb.mi/mi-cli.exp
> index 5657be6..016f54f 100644
> --- a/gdb/testsuite/gdb.mi/mi-cli.exp
> +++ b/gdb/testsuite/gdb.mi/mi-cli.exp
> @@ -91,7 +91,7 @@ mi_gdb_test "-interpreter-exec console \"set listsize 1\"" \
>  
>  # {.*\~"32[ \t(\\t)]*callee1.*\\n".*\^done }
>  mi_gdb_test "-interpreter-exec console \"list\"" \
> -  ".*\~\"$line_main_body\[\\\\t \]*callee1.*;\\\\n\".*\\^done" \
> +  ".*\~\"57\\\\t\{\\\\n\".*\\^done" \
>    "-interpreter-exec console \"list\""

Looking again at this, I think there's a deeper issue here.  This "list"
is the first source listing after a breakpoint stop, and "set listsize 1".
The breakpoint is at line 62.  Why would we list line 57 (and only
that line) ?  The issue is with the line centering done too soon.  We should
be a little more lazy here, like in the patch below.

Let me know what you think.

---------
[PATCH] PR gdb/13860: make -interpreter-exec console "list" behave
 more like "list".

I noticed that "list" behaves differently in CLI vs MI.  Particularly:

  $ ./gdb -nx -q ./testsuite/gdb.mi/mi-cli
  Reading symbols from /home/pedro/gdb/mygit/build/gdb/testsuite/gdb.mi/mi-cli...done.
  (gdb) start
  Temporary breakpoint 1 at 0x40054d: file ../../../src/gdb/testsuite/gdb.mi/basics.c, line 62.
  Starting program: /home/pedro/gdb/mygit/build/gdb/testsuite/gdb.mi/mi-cli

  Temporary breakpoint 1, main () at ../../../src/gdb/testsuite/gdb.mi/basics.c:62
  62        callee1 (2, "A string argument.", 3.5);
  (gdb) list
  57      {
  58      }
  59
  60      main ()
  61      {
  62        callee1 (2, "A string argument.", 3.5);
  63        callee1 (2, "A string argument.", 3.5);
  64
  65        do_nothing (); /* Hello, World! */
  66
  (gdb)

Note the list started at line 57.  IOW, the program stopped at line
62, and GDB centered the list on that.

compare with:

  $ ./gdb -nx -q ./testsuite/gdb.mi/mi-cli -i=mi
  =thread-group-added,id="i1"
  ~"Reading symbols from /home/pedro/gdb/mygit/build/gdb/testsuite/gdb.mi/mi-cli..."
  ~"done.\n"
  (gdb)
  start
  &"start\n"
...
 ~"\nTemporary breakpoint "
  ~"1, main () at ../../../src/gdb/testsuite/gdb.mi/basics.c:62\n"
  ~"62\t  callee1 (2, \"A string argument.\", 3.5);\n"
  *stopped,reason="breakpoint-hit",disp="del",bkptno="1",frame={addr="0x000000000040054d",func="main",args=[],file="../../../src/gdb/testsuite/gdb.mi/basics.c",fullname="/home/pedro/gdb/mygit/src/gdb/testsuite/gdb.mi/basics.c",line="62"},thread-id="1",stopped-threads="all",core="0"
  =breakpoint-deleted,id="1"
  (gdb)
  -interpreter-exec console list
  ~"62\t  callee1 (2, \"A string argument.\", 3.5);\n"
  ~"63\t  callee1 (2, \"A string argument.\", 3.5);\n"
  ~"64\t\n"
  ~"65\t  do_nothing (); /* Hello, World! */\n"
  ~"66\t\n"
  ~"67\t  callme (1);\n"
  ~"68\t  callme (2);\n"
  ~"69\t\n"
  ~"70\t  return 0;\n"
  ~"71\t}\n"
  ^done
  (gdb)

Here the list starts at line 62, where the program was stopped.

This happens because print_stack_frame, called from both normal_stop
and mi_on_normal_stop, is the function responsible for setting the
current sal from the selected frame, overrides the PRINT_WHAT
argument, and only after that does it decide whether to center the
current sal line or not, based on the overriden value, and it will
always decide false.

(The print_stack_frame call in mi_on_normal_stop is a little different
from the call in normal_stop, in that it is an unconditional
SRC_AND_LOC call.  A future patch will make those uniform.)

A previous version of this patch made MI uniform with CLI here, by
making print_stack_frame also center when MI is active.  That changed
the output of a "list" command in mi-cli.exp, to expect line 57
instead of 62, as per the example above.

However, looking deeper, that list in question is the first "list"
after the program stops, and right after the stop, before the "list",
the test did "set listsize 1".  Let's try the same thing with the CLI:

 (gdb) start
 62        callee1 (2, "A string argument.", 3.5);
 (gdb) set listsize 1
 (gdb) list
 57      {

Huh, that's unexpected.  Why the 57?  It's because print_stack_frame,
called in reaction to the breakpoint stop, expecting the next "list"
to show 10 lines (the listsize at the time) around line 62, sets the
lines listed range to 57-67 (62 +/- 5).  If the user changes the
listsize before "list", why would we still show that range?  Looks
bogus to me.

So the fix for this whole issue should be delay trying to center the
listing to until actually listing, so that the correct listsize can be
taken into account.  This makes MI and CLI uniform too, as it deletes
the center code from print_stack_frame.

A series of tests are added to list.exp to cover this.  mi-cli.exp was
after all correct all along, but it now gains an additional test that
lists lines with listsize 10, to ensure the centering is consistent
with CLI's.

One related Python test changed related output -- it's a test that
prints the line number after stopping for a breakpoint, similar to the
new list.exp tests.  Previously we'd print the stop line minus 5 (due
to the premature centering), now we print the stop line.  I think
that's a good change.

Tested on x86_64 Fedora 17.

gdb/
2014-03-18  Pedro Alves  <palves@redhat.com>

	* cli/cli-cmds.c (list_command): Handle the first "list" after the
	current source line having changed.
	* frame.h (set_current_sal_from_frame): Remove 'center' parameter.
	* infrun.c (normal_stop): Adjust call to
	set_current_sal_from_frame.
	* source.c (clear_lines_listed_range): New function.
	(set_current_source_symtab_and_line, identify_source_line): Clear
	the lines listed range.
	(line_info): Handle the first "info line" after the current source
	line having changed.
	* stack.c (print_stack_frame): Remove center handling.
	(set_current_sal_from_frame): Remove 'center' parameter.  Don't
	center sal.line.

gdb/testsuite/
2014-03-18  Pedro Alves  <palves@redhat.com>

	* gdb.base/list.exp (build_pattern, test_list): New procedures.
	Use them to test variations of "list" after reaching a breakpoint.
	* gdb.mi/mi-cli.exp (line_main_callme_2): New global.
	Test "list" with listsize 10 after reaching a breakpoint.
	* gdb.python/python.exp (decode_line current location line
	number): Adjust expected line number.
---
 gdb/cli/cli-cmds.c                  | 21 +++++++++
 gdb/frame.h                         |  5 +-
 gdb/infrun.c                        |  2 +-
 gdb/source.c                        | 26 ++++++++--
 gdb/source.h                        |  7 +--
 gdb/stack.c                         | 14 ++----
 gdb/testsuite/gdb.base/list.exp     | 94 +++++++++++++++++++++++++++++++++++++
 gdb/testsuite/gdb.mi/mi-cli.exp     | 20 ++++++++
 gdb/testsuite/gdb.python/python.exp |  5 +-
 9 files changed, 171 insertions(+), 23 deletions(-)
  

On 03/18/2014 04:04 PM, Pedro Alves wrote:

> Looking again at this, I think there's a deeper issue here.  This "list"
> is the first source listing after a breakpoint stop, and "set listsize 1".
> The breakpoint is at line 62.  Why would we list line 57 (and only
> that line) ?  The issue is with the line centering done too soon.  We should
> be a little more lazy here, like in the patch below.
> 
> Let me know what you think.

Tom told me off list he's OK with this version.

I've pushed it in.

Pedro Alves

> 
> ---------
> [PATCH] PR gdb/13860: make -interpreter-exec console "list" behave
>  more like "list".
> 
> I noticed that "list" behaves differently in CLI vs MI.  Particularly:
> 
>   $ ./gdb -nx -q ./testsuite/gdb.mi/mi-cli
>   Reading symbols from /home/pedro/gdb/mygit/build/gdb/testsuite/gdb.mi/mi-cli...done.
>   (gdb) start
>   Temporary breakpoint 1 at 0x40054d: file ../../../src/gdb/testsuite/gdb.mi/basics.c, line 62.
>   Starting program: /home/pedro/gdb/mygit/build/gdb/testsuite/gdb.mi/mi-cli
> 
>   Temporary breakpoint 1, main () at ../../../src/gdb/testsuite/gdb.mi/basics.c:62
>   62        callee1 (2, "A string argument.", 3.5);
>   (gdb) list
>   57      {
>   58      }
>   59
>   60      main ()
>   61      {
>   62        callee1 (2, "A string argument.", 3.5);
>   63        callee1 (2, "A string argument.", 3.5);
>   64
>   65        do_nothing (); /* Hello, World! */
>   66
>   (gdb)
> 
> Note the list started at line 57.  IOW, the program stopped at line
> 62, and GDB centered the list on that.
> 
> compare with:
> 
>   $ ./gdb -nx -q ./testsuite/gdb.mi/mi-cli -i=mi
>   =thread-group-added,id="i1"
>   ~"Reading symbols from /home/pedro/gdb/mygit/build/gdb/testsuite/gdb.mi/mi-cli..."
>   ~"done.\n"
>   (gdb)
>   start
>   &"start\n"
> ...
>  ~"\nTemporary breakpoint "
>   ~"1, main () at ../../../src/gdb/testsuite/gdb.mi/basics.c:62\n"
>   ~"62\t  callee1 (2, \"A string argument.\", 3.5);\n"
>   *stopped,reason="breakpoint-hit",disp="del",bkptno="1",frame={addr="0x000000000040054d",func="main",args=[],file="../../../src/gdb/testsuite/gdb.mi/basics.c",fullname="/home/pedro/gdb/mygit/src/gdb/testsuite/gdb.mi/basics.c",line="62"},thread-id="1",stopped-threads="all",core="0"
>   =breakpoint-deleted,id="1"
>   (gdb)
>   -interpreter-exec console list
>   ~"62\t  callee1 (2, \"A string argument.\", 3.5);\n"
>   ~"63\t  callee1 (2, \"A string argument.\", 3.5);\n"
>   ~"64\t\n"
>   ~"65\t  do_nothing (); /* Hello, World! */\n"
>   ~"66\t\n"
>   ~"67\t  callme (1);\n"
>   ~"68\t  callme (2);\n"
>   ~"69\t\n"
>   ~"70\t  return 0;\n"
>   ~"71\t}\n"
>   ^done
>   (gdb)
> 
> Here the list starts at line 62, where the program was stopped.
> 
> This happens because print_stack_frame, called from both normal_stop
> and mi_on_normal_stop, is the function responsible for setting the
> current sal from the selected frame, overrides the PRINT_WHAT
> argument, and only after that does it decide whether to center the
> current sal line or not, based on the overriden value, and it will
> always decide false.
> 
> (The print_stack_frame call in mi_on_normal_stop is a little different
> from the call in normal_stop, in that it is an unconditional
> SRC_AND_LOC call.  A future patch will make those uniform.)
> 
> A previous version of this patch made MI uniform with CLI here, by
> making print_stack_frame also center when MI is active.  That changed
> the output of a "list" command in mi-cli.exp, to expect line 57
> instead of 62, as per the example above.
> 
> However, looking deeper, that list in question is the first "list"
> after the program stops, and right after the stop, before the "list",
> the test did "set listsize 1".  Let's try the same thing with the CLI:
> 
>  (gdb) start
>  62        callee1 (2, "A string argument.", 3.5);
>  (gdb) set listsize 1
>  (gdb) list
>  57      {
> 
> Huh, that's unexpected.  Why the 57?  It's because print_stack_frame,
> called in reaction to the breakpoint stop, expecting the next "list"
> to show 10 lines (the listsize at the time) around line 62, sets the
> lines listed range to 57-67 (62 +/- 5).  If the user changes the
> listsize before "list", why would we still show that range?  Looks
> bogus to me.
> 
> So the fix for this whole issue should be delay trying to center the
> listing to until actually listing, so that the correct listsize can be
> taken into account.  This makes MI and CLI uniform too, as it deletes
> the center code from print_stack_frame.
> 
> A series of tests are added to list.exp to cover this.  mi-cli.exp was
> after all correct all along, but it now gains an additional test that
> lists lines with listsize 10, to ensure the centering is consistent
> with CLI's.
> 
> One related Python test changed related output -- it's a test that
> prints the line number after stopping for a breakpoint, similar to the
> new list.exp tests.  Previously we'd print the stop line minus 5 (due
> to the premature centering), now we print the stop line.  I think
> that's a good change.
> 
> Tested on x86_64 Fedora 17.
> 
> gdb/
> 2014-03-18  Pedro Alves  <palves@redhat.com>
> 
> 	* cli/cli-cmds.c (list_command): Handle the first "list" after the
> 	current source line having changed.
> 	* frame.h (set_current_sal_from_frame): Remove 'center' parameter.
> 	* infrun.c (normal_stop): Adjust call to
> 	set_current_sal_from_frame.
> 	* source.c (clear_lines_listed_range): New function.
> 	(set_current_source_symtab_and_line, identify_source_line): Clear
> 	the lines listed range.
> 	(line_info): Handle the first "info line" after the current source
> 	line having changed.
> 	* stack.c (print_stack_frame): Remove center handling.
> 	(set_current_sal_from_frame): Remove 'center' parameter.  Don't
> 	center sal.line.
> 
> gdb/testsuite/
> 2014-03-18  Pedro Alves  <palves@redhat.com>
> 
> 	* gdb.base/list.exp (build_pattern, test_list): New procedures.
> 	Use them to test variations of "list" after reaching a breakpoint.
> 	* gdb.mi/mi-cli.exp (line_main_callme_2): New global.
> 	Test "list" with listsize 10 after reaching a breakpoint.
> 	* gdb.python/python.exp (decode_line current location line
> 	number): Adjust expected line number.
> ---
>  gdb/cli/cli-cmds.c                  | 21 +++++++++
>  gdb/frame.h                         |  5 +-
>  gdb/infrun.c                        |  2 +-
>  gdb/source.c                        | 26 ++++++++--
>  gdb/source.h                        |  7 +--
>  gdb/stack.c                         | 14 ++----
>  gdb/testsuite/gdb.base/list.exp     | 94 +++++++++++++++++++++++++++++++++++++
>  gdb/testsuite/gdb.mi/mi-cli.exp     | 20 ++++++++
>  gdb/testsuite/gdb.python/python.exp |  5 +-
>  9 files changed, 171 insertions(+), 23 deletions(-)
> 
> diff --git a/gdb/cli/cli-cmds.c b/gdb/cli/cli-cmds.c
> index bfcd975..5c6129d 100644
> --- a/gdb/cli/cli-cmds.c
> +++ b/gdb/cli/cli-cmds.c
> @@ -874,6 +874,27 @@ list_command (char *arg, int from_tty)
>      {
>        set_default_source_symtab_and_line ();
>        cursal = get_current_source_symtab_and_line ();
> +
> +      /* If this is the first "list" since we've set the current
> +	 source line, center the listing around that line.  */
> +      if (get_first_line_listed () == 0)
> +	{
> +	  int first;
> +
> +	  first = max (cursal.line - get_lines_to_list () / 2, 1);
> +
> +	  /* A small special case --- if listing backwards, and we
> +	     should list only one line, list the preceding line,
> +	     instead of the exact line we've just shown after e.g.,
> +	     stopping for a breakpoint.  */
> +	  if (arg != NULL && arg[0] == '-'
> +	      && get_lines_to_list () == 1 && first > 1)
> +	    first -= 1;
> +
> +	  print_source_lines (cursal.symtab, first,
> +			      first + get_lines_to_list (), 0);
> +	  return;
> +	}
>      }
>  
>    /* "l" or "l +" lists next ten lines.  */
> diff --git a/gdb/frame.h b/gdb/frame.h
> index e451a93..6a75f0d 100644
> --- a/gdb/frame.h
> +++ b/gdb/frame.h
> @@ -388,10 +388,9 @@ extern void find_frame_sal (struct frame_info *frame,
>  			    struct symtab_and_line *sal);
>  
>  /* Set the current source and line to the location given by frame
> -   FRAME, if possible.  When CENTER is true, adjust so the relevant
> -   line is in the center of the next 'list'.  */
> +   FRAME, if possible.  */
>  
> -void set_current_sal_from_frame (struct frame_info *, int);
> +void set_current_sal_from_frame (struct frame_info *);
>  
>  /* Return the frame base (what ever that is) (DEPRECATED).
>  
> diff --git a/gdb/infrun.c b/gdb/infrun.c
> index b7c0969..3d3ba55 100644
> --- a/gdb/infrun.c
> +++ b/gdb/infrun.c
> @@ -6091,7 +6091,7 @@ normal_stop (void)
>       display the frame below, but the current SAL will be incorrect
>       during a user hook-stop function.  */
>    if (has_stack_frames () && !stop_stack_dummy)
> -    set_current_sal_from_frame (get_current_frame (), 1);
> +    set_current_sal_from_frame (get_current_frame ());
>  
>    /* Let the user/frontend see the threads as stopped.  */
>    do_cleanups (old_chain);
> diff --git a/gdb/source.c b/gdb/source.c
> index c112765..c77a4f4 100644
> --- a/gdb/source.c
> +++ b/gdb/source.c
> @@ -133,7 +133,9 @@ show_filename_display_string (struct ui_file *file, int from_tty,
>  
>  static int last_line_listed;
>  
> -/* First line number listed by last listing command.  */
> +/* First line number listed by last listing command.  If 0, then no
> +   source lines have yet been listed since the last time the current
> +   source line was changed.  */
>  
>  static int first_line_listed;
>  
> @@ -153,6 +155,16 @@ get_first_line_listed (void)
>    return first_line_listed;
>  }
>  
> +/* Clear line listed range.  This makes the next "list" center the
> +   printed source lines around the current source line.  */
> +
> +static void
> +clear_lines_listed_range (void)
> +{
> +  first_line_listed = 0;
> +  last_line_listed = 0;
> +}
> +
>  /* Return the default number of lines to print with commands like the
>     cli "list".  The caller of print_source_lines must use this to
>     calculate the end line and use it in the call to print_source_lines
> @@ -220,6 +232,9 @@ set_current_source_symtab_and_line (const struct symtab_and_line *sal)
>    current_source_symtab = sal->symtab;
>    current_source_line = sal->line;
>  
> +  /* Force the next "list" to center around the current line.  */
> +  clear_lines_listed_range ();
> +
>    return cursal;
>  }
>  
> @@ -1294,9 +1309,8 @@ identify_source_line (struct symtab *s, int line, int mid_statement,
>  		   mid_statement, get_objfile_arch (s->objfile), pc);
>  
>    current_source_line = line;
> -  first_line_listed = line;
> -  last_line_listed = line;
>    current_source_symtab = s;
> +  clear_lines_listed_range ();
>    return 1;
>  }
>  
> @@ -1488,7 +1502,11 @@ line_info (char *arg, int from_tty)
>      {
>        sal.symtab = current_source_symtab;
>        sal.pspace = current_program_space;
> -      sal.line = last_line_listed;
> +      if (last_line_listed != 0)
> +	sal.line = last_line_listed;
> +      else
> +	sal.line = current_source_line;
> +
>        sals.nelts = 1;
>        sals.sals = (struct symtab_and_line *)
>  	xmalloc (sizeof (struct symtab_and_line));
> diff --git a/gdb/source.h b/gdb/source.h
> index 61826ea..ad74df9 100644
> --- a/gdb/source.h
> +++ b/gdb/source.h
> @@ -62,9 +62,10 @@ extern const char *symtab_to_filename_for_display (struct symtab *symtab);
>     lines.  */
>  extern void find_source_lines (struct symtab *s, int desc);
>  
> -/* Return the first line listed by print_source_lines.
> -   Used by command interpreters to request listing from
> -   a previous point.  */
> +/* Return the first line listed by print_source_lines.  Used by
> +   command interpreters to request listing from a previous point.  If
> +   0, then no source lines have yet been listed since the last time
> +   the current source line was changed.  */
>  extern int get_first_line_listed (void);
>  
>  /* Return the default number of lines to print with commands like the
> diff --git a/gdb/stack.c b/gdb/stack.c
> index da7d977..0c6923d 100644
> --- a/gdb/stack.c
> +++ b/gdb/stack.c
> @@ -166,12 +166,10 @@ print_stack_frame (struct frame_info *frame, int print_level,
>  
>    TRY_CATCH (e, RETURN_MASK_ERROR)
>      {
> -      int center = (print_what == SRC_LINE || print_what == SRC_AND_LOC);
> -
>        print_frame_info (frame, print_level, print_what, 1 /* print_args */,
>  			set_current_sal);
>        if (set_current_sal)
> -	set_current_sal_from_frame (frame, center);
> +	set_current_sal_from_frame (frame);
>      }
>  }
>  
> @@ -716,17 +714,13 @@ print_frame_args (struct symbol *func, struct frame_info *frame,
>     line is in the center of the next 'list'.  */
>  
>  void
> -set_current_sal_from_frame (struct frame_info *frame, int center)
> +set_current_sal_from_frame (struct frame_info *frame)
>  {
>    struct symtab_and_line sal;
>  
>    find_frame_sal (frame, &sal);
> -  if (sal.symtab)
> -    {
> -      if (center)
> -        sal.line = max (sal.line - get_lines_to_list () / 2, 1);
> -      set_current_source_symtab_and_line (&sal);
> -    }
> +  if (sal.symtab != NULL)
> +    set_current_source_symtab_and_line (&sal);
>  }
>  
>  /* If ON, GDB will display disassembly of the next source line when
> diff --git a/gdb/testsuite/gdb.base/list.exp b/gdb/testsuite/gdb.base/list.exp
> index 12b2c94..67eef12 100644
> --- a/gdb/testsuite/gdb.base/list.exp
> +++ b/gdb/testsuite/gdb.base/list.exp
> @@ -529,4 +529,98 @@ if [ set_listsize 10 ] then {
>      test_only_end
>  }
>  
> +# Follows tests that require execution.
> +
> +# Build source listing pattern based on a line range spec string.  The
> +# range can be specificed as "START-END" indicating all lines in range
> +# (inclusive); or just "LINE", indicating just that line.
> +
> +proc build_pattern { range_spec } {
> +    global line_re
> +
> +    set range_list [split $range_spec -]
> +    set range_list_len [llength $range_list]
> +
> +    set range_start [lindex $range_list 0]
> +    if { $range_list_len > 2 || $range_list_len < 1} {
> +	error "invalid range spec string: $range_spec"
> +    } elseif { $range_list_len == 2 } {
> +	set range_end [lindex $range_list 1]
> +    } else {
> +	set range_end $range_start
> +    }
> +
> +    for {set i $range_start} {$i <= $range_end} {incr i} {
> +	append pattern "\r\n$i\[ \t\]\[^\r\n\]*"
> +    }
> +
> +    verbose -log "pattern $pattern"
> +    return $pattern
> +}
> +
> +# Test "list" command invocations right after stopping for an event.
> +# COMMAND is the actual list command, including arguments.  LISTSIZE1
> +# and LISTSIZE2 are the listsizes set just before and after running
> +# the program to the stop point.  COMMAND is issued twice.  The first
> +# time, the lines specificed by LINERANGE1 are expected; the second
> +# time, the lines specified by LINERANGE2 are expected.
> +
> +proc test_list {command listsize1 listsize2 linerange1 linerange2} {
> +    with_test_prefix "$command after stop: $listsize1, $listsize2" {
> +	global binfile
> +
> +	clean_restart $binfile
> +	if ![runto_main] then {
> +	    fail "Can't run to main"
> +	    return
> +	}
> +
> +	# Test changing the listsize both before nexting, and after
> +	# stopping, but before listing.  Only the second listsize
> +	# change should affect which lines are listed.
> +	gdb_test_no_output "set listsize $listsize1"
> +	gdb_test "next" "foo \\(.*"
> +	gdb_test_no_output "set listsize $listsize2"
> +
> +	set pattern1 [build_pattern $linerange1]
> +	set pattern2 [build_pattern $linerange2]
> +	gdb_test "$command" "${pattern1}" "$command #1"
> +	gdb_test "$command" "${pattern2}" "$command #2"
> +    }
> +}
> +
> +
> +# The first "list" should center the listing around line 8, the stop
> +# line.
> +test_list "list" 1 10 "3-12" "13-22"
> +
> +# Likewise.
> +test_list "list" 10 10 "3-12" "13-22"
> +
> +# Likewise, but show only one line.  IOW, the first list should show
> +# line 8.  Note how the listsize is 10 at the time of the stop, but
> +# before any listing had been requested.  That should not affect the
> +# line range that is first listed.
> +test_list "list" 10 1 "8" "9"
> +
> +# Likewise, but show two lines.
> +test_list "list" 10 2 "7-8" "9-10"
> +
> +# Three lines.
> +test_list "list" 10 3 "7-9" "10-12"
> +
> +# Now test backwards.  Just like "list", the first "list -" should
> +# center the listing around the stop line.
> +test_list "list -" 10 10 "3-12" "2"
> +
> +# Likewise, but test showing 3 lines at a time.
> +test_list "list -" 10 3 "7-9" "4-6"
> +
> +# 2 lines at a time.
> +test_list "list -" 10 2 "7-8" "5-6"
> +
> +# Test listing one line one.  This case is a little special, and
> +# starts showing the previous line immediately.
> +test_list "list -" 10 1 "7" "6"
> +
>  remote_exec build "rm -f list0.h"
> diff --git a/gdb/testsuite/gdb.mi/mi-cli.exp b/gdb/testsuite/gdb.mi/mi-cli.exp
> index 5657be6..566d64d 100644
> --- a/gdb/testsuite/gdb.mi/mi-cli.exp
> +++ b/gdb/testsuite/gdb.mi/mi-cli.exp
> @@ -65,6 +65,7 @@ set line_main_head    [gdb_get_line_number "main ("]
>  set line_main_body    [expr $line_main_head + 2]
>  set line_main_hello   [gdb_get_line_number "Hello, World!"]
>  set line_main_return  [expr $line_main_hello + 2]
> +set line_main_callme_2 [expr $line_main_return + 1]
>  set line_callee4_head [gdb_get_line_number "callee4 ("]
>  set line_callee4_body [expr $line_callee4_head + 2]
>  set line_callee4_next [expr $line_callee4_body + 1]
> @@ -184,6 +185,25 @@ mi_gdb_test "-interpreter-exec console \"list\"" \
>    "\~\"$line_main_return\[\\\\t ]*callme \\(1\\);\\\\n\".*\\^done" \
>    "-interpreter-exec console \"list\" at basics.c:\$line_main_return"
>  
> +mi_gdb_test "600-break-insert -t basics.c:$line_main_callme_2" \
> +	{600\^done,bkpt=.number="4",type="breakpoint".*\}} \
> +	"-break-insert -t basics.c:\$line_main_callme_2"
> +
> +mi_execute_to "exec-continue" "breakpoint-hit" "main" "" ".*basics.c" \
> +    $line_main_callme_2 { "" "disp=\"del\"" } \
> +    "-exec-continue to line \$line_main_callme_2"
> +
> +# Restore the listsize back to the default.
> +mi_gdb_test "-interpreter-exec console \"set listsize 10\"" \
> +  ".*=cmd-param-changed,param=\"listsize\",value=\"10\".*\\^done" \
> +  "-interpreter-exec console \"set listsize 10\""
> +
> +# "list" should show 10 lines centered on where the program stopped.
> +set first_list_line [expr $line_main_callme_2 - 5]
> +mi_gdb_test "-interpreter-exec console \"list\"" \
> +    ".*\~\"$first_list_line.*\\^done" \
> +    "-interpreter-exec console \"list\" at basics.c:\$line_main_return"
> +
>  mi_gdb_test "-interpreter-exec console \"help set args\"" \
>    {\~"Set argument list to give program being debugged when it is started\.\\nFollow this command with any number of args, to be passed to the program\.".*\^done} \
>    "-interpreter-exec console \"help set args\""
> diff --git a/gdb/testsuite/gdb.python/python.exp b/gdb/testsuite/gdb.python/python.exp
> index a470427..2b7d78e 100644
> --- a/gdb/testsuite/gdb.python/python.exp
> +++ b/gdb/testsuite/gdb.python/python.exp
> @@ -168,7 +168,8 @@ if ![runto_main] then {
>      return 0
>  }
>  
> -runto [gdb_get_line_number "Break to end."]
> +set lineno [gdb_get_line_number "Break to end."]
> +runto $lineno
>  
>  # Test gdb.decode_line.
>  gdb_test "python gdb.decode_line(\"main.c:43\")" \
> @@ -179,7 +180,7 @@ gdb_test "python print (len(symtab))" "2" "Test decode_line current location"
>  gdb_test "python print (symtab\[0\])" "None" "Test decode_line expression parse"
>  gdb_test "python print (len(symtab\[1\]))" "1" "Test decode_line current location"
>  gdb_test "python print (symtab\[1\]\[0\].symtab)" ".*gdb.python/python.c.*" "Test decode_line current locationn filename"
> -gdb_test "python print (symtab\[1\]\[0\].line)" "22" "Test decode_line current location line number"
> +gdb_test "python print (symtab\[1\]\[0\].line)" "$lineno" "Test decode_line current location line number"
>  
>  gdb_py_test_silent_cmd "python symtab = gdb.decode_line(\"python.c:26 if foo\")" "test decode_line python.c:26" 1
>  gdb_test "python print (len(symtab))" "2" "Test decode_line python.c:26 length"
>