[Bug gdb/28426] Step reverse over line with multiple executable statements

["blarsen at redhat dot com" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=28426

B. Larsen <blarsen at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |blarsen at redhat dot com

--- Comment #3 from B. Larsen <blarsen at redhat dot com> ---
As explained by Pedro Alves in this email thread
(https://sourceware.org/pipermail/gdb-patches/2023-January/196110.html), it is
possible to reproduce this bug in x86_64, with a modified reproducer. Consider
the following code:

void func1 ()
{
}

void func 2 ()
{
}

int main ()
{
  int v = 0;
  func 1 (); func 2 ();
  return v;
}

and the debug session:

(gdb) start
Temporary breakpoint 1 at 0x40111c: file t.c, line 10.
Starting program: /home/blarsen/Documents/downstream_build/gdb/reverse 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".

Temporary breakpoint 1, main () at t.c:10
10          int v = 0;
(gdb) record
(gdb) n
11          func1 (); func2 ();
(gdb) 
12          return v;
(gdb) rn
11          func1 (); func2 ();
(gdb) 
11          func1 (); func2 ();
(gdb) rn

No more reverse-execution history.
main () at t.c:10
10          int v = 0;
(gdb) 


Without a line before the `func1 (); func2 ()` GDB mistakenly reports that
we've reached the end of the recorded history, but that is an unrelated bug.
Compiling the example program with no column information, we get instead the
following session:

(gdb) start
Temporary breakpoint 1 at 0x40111c: file t.c, line 10.
Starting program: /home/blarsen/Documents/downstream_build/gdb/reverse 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".

Temporary breakpoint 1, main () at t.c:10
10          int v = 0;
(gdb) record
(gdb) n
11          func1 (); func2 ();
(gdb) 
12          return v;
(gdb) rn
11          func1 (); func2 ();
(gdb) 

No more reverse-execution history.
main () at t.c:10
10          int v = 0;
(gdb)

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