http://sourceware.org/ml/gdb-patches/2011-08/msg00283.html
Subject: [patch] TUI: Permit stepi on stripped code

Hi,

nick <cinolt> on #gdb@freenode complained one cannot stepi on stripped binary.

echo -e '#include<unistd.h>\nint main(void){return alarm(0);}'|gcc -Wall -s -x c -;./gdbtui ./a.out -nx -ex 'layout asm' -ex 'b alarm' -ex r -ex fini
will:
	0x7ffff7ae25c0 <alarm>          mov    $0x25,%eax
	-------------------------------------------------
	(gdb) p/x $pc
	$1 = 0x4004d2
	(gdb) stepi
	No function contains program counter for selected frame.
	(gdb) p/x $pc
	$2 = 0x4004d2

That is the window still displays stale content, stepi does not work at all.

#0  throw_verror (error=GENERIC_ERROR, fmt=0xe73d20 "No function contains program counter for selected frame.", ap=0x7fffdbd3b0a8) at exceptions.c:400
#1  in error (string=0xe73d20 "No function contains program counter for selected frame.") at utils.c:780
#2  in tui_show_frame_info (fi=0x3eca1e0) at ./tui/tui-stack.c:383
#3  in tui_selected_frame_level_changed_hook (level=0) at ./tui/tui-hooks.c:218
#4  in select_frame (fi=0x3eca1e0) at frame.c:1396
#5  in restore_selected_frame (a_frame_id=..., frame_level=0) at thread.c:1049
#6  in do_restore_current_thread_cleanup (arg=0x456dca0) at thread.c:1116
#7  in do_my_cleanups (pmy_chain=0x1c865f0, old_chain=0x456de90) at utils.c:515
#8  in do_cleanups (old_chain=0x456de90) at utils.c:497
#9  in insert_breakpoint_locations () at breakpoint.c:2021
#10 in insert_breakpoints () at breakpoint.c:1919
#11 in proceed (addr=18446744073709551615, siggnal=TARGET_SIGNAL_DEFAULT, step=1) at infrun.c:2156
#12 in step_once (skip_subroutines=0, single_inst=1, count=1, thread=-1) at infcmd.c:1068
#13 in step_1 (skip_subroutines=0, single_inst=1, count_string=0x0) at infcmd.c:903
#14 in stepi_command (count_string=0x0, from_tty=1) at infcmd.c:839

With the fix stepi works and the window correctly displays:
	0x4004d2        pop    %rbp                
	-------------------------------------------------

I haven't found any TUI testsuite.

I will check it in (after regression testing(?)) in some time.


Thanks,
Jan


gdb/
2011-08-14  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Fix TUI stepi on code without symbols.
	* tui/tui-stack.c (tui_show_frame_info): Remove error, set LOW for
	current PC instead.

--- a/gdb/tui/tui-stack.c
+++ b/gdb/tui/tui-stack.c
@@ -380,8 +380,11 @@ tui_show_frame_info (struct frame_info *fi)
 	    {
 	      if (find_pc_partial_function (get_frame_pc (fi), (char **) NULL,
 					    &low, (CORE_ADDR) 0) == 0)
-		error (_("No function contains program "
-			 "counter for selected frame."));
+		{
+		  /* There is no symbol available for current PC.  There is no
+		     safe way how to "disassemble backwards".  */
+		  low = get_frame_pc (fi);
+		}
 	      else
 		low = tui_get_low_disassembly_address (get_frame_arch (fi),
 						       low, get_frame_pc (fi));