[PATCH v4 04/11] [gdb/tui] Fix buglet in tui_find_disassembly_address

[Tom de Vries <tdevries@suse.de>]

In commit 72535eb14bd ("[gdb/tui] Fix segfault in
tui_find_disassembly_address"), in a loop in tui_find_disassembly_address I added:
...
 	  /* Disassemble forward.  */
 	  next_addr = tui_disassemble (gdbarch, asm_lines, new_low, max_lines);
+	  if (asm_lines.empty ())
+	    break;
 	  last_addr = asm_lines.back ().addr;
...

In retrospect, I think I missed something there.

After the loop, new_low may be returned:
...
  if (asm_lines.size () < max_lines)
    {
      if (!possible_new_low.has_value ())
	return new_low;
...
so we'd be returning an address from where in fact we can't disassemble.

Fix this by reverting to prev_low in this case.
---
 gdb/tui/tui-disasm.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/gdb/tui/tui-disasm.c b/gdb/tui/tui-disasm.c
index a6cf12ba9c2..c242614be45 100644
--- a/gdb/tui/tui-disasm.c
+++ b/gdb/tui/tui-disasm.c
@@ -251,7 +251,10 @@ tui_find_disassembly_address (struct gdbarch *gdbarch, CORE_ADDR pc, int from)
       /* Disassemble forward.  */
       next_addr = tui_disassemble (gdbarch, asm_lines, new_low, max_lines);
       if (asm_lines.empty ())
-	break;
+	{
+	  new_low = prev_low;
+	  break;
+	}
       last_addr = asm_lines.back ().addr;
 
       /* If disassembling from the current value of NEW_LOW reached PC
-- 
2.51.0