[binutils-gdb] gdb/tui: avoid extra refresh_window on horizontal scroll

[Andrew Burgess <aburgess@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=d2a5ea5622ec7a2a3e255186c88d69812f148913

commit d2a5ea5622ec7a2a3e255186c88d69812f148913
Author: Andrew Burgess <aburgess@redhat.com>
Date:   Thu Jan 5 12:18:05 2023 +0000

    gdb/tui: avoid extra refresh_window on horizontal scroll
    
    While working on the previous patches I noticed that in some cases I
    was seeing two calls to tui_source_window_base::refresh_window when
    scrolling the window horizontally.
    
    The two calls would trigger in for the tui-disasm-long-lines.exp test
    when the pad needed to be refilled.  The two called both come from
    tui_source_window_base::show_source_content.  The first call is nested
    within check_and_display_highlight_if_needed, while the second call is
    done directly at the end of show_source_content.
    
    The check_and_display_highlight_if_needed is being used to draw the
    window box to the window, this is needed here because
    show_source_content is what gets called when the window needs
    updating, e.g. after a resize.  We could potentially do the boxing in
    refresh_window, but then we'd be doing it each time we scroll, even
    though the box doesn't need changing in this case.
    
    However, we can move the check_and_display_highlight_if_needed to be
    the last thing done in show_source_content, this means that we can
    rely on the refresh_window call within it to be our single refresh
    call.
    
    There should be no user visible changes after this commit.

Diff:
---
 gdb/tui/tui-winsource.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/gdb/tui/tui-winsource.c b/gdb/tui/tui-winsource.c
index 6e22638ec74..50efa80576f 100644
--- a/gdb/tui/tui-winsource.c
+++ b/gdb/tui/tui-winsource.c
@@ -348,8 +348,6 @@ tui_source_window_base::show_source_content ()
 {
   gdb_assert (!m_content.empty ());
 
-  check_and_display_highlight_if_needed ();
-
   /* The pad should be at least as wide as the window, but ideally, as wide
      as the content, however, for some very wide content this might not be
      possible.  */
@@ -399,7 +397,11 @@ tui_source_window_base::show_source_content ()
   for (int lineno = 0; lineno < m_content.size (); lineno++)
     show_source_line (lineno);
 
-  refresh_window ();
+  /* Calling check_and_display_highlight_if_needed will call refresh_window
+     (so long as the current window can be boxed), which will ensure that
+     the newly loaded window content is copied to the screen.  */
+  gdb_assert (can_box ());
+  check_and_display_highlight_if_needed ();
 }
 
 tui_source_window_base::tui_source_window_base ()