[3/3] Remove flickering from the TUI

diff --git a/gdb/tui/tui-command.c b/gdb/tui/tui-command.c
index 5f676b2e659..ca0e8f612bd 100644
--- a/gdb/tui/tui-command.c
+++ b/gdb/tui/tui-command.c
@@ -70,7 +70,7 @@  tui_refresh_cmd_win (void)
 {
   WINDOW *w = TUI_CMD_WIN->handle.get ();
 
-  wrefresh (w);
+  tui_wrefresh (w);
 
   /* FIXME: It's not clear why this is here.
      It was present in the original tui_puts code and is kept in order to
diff --git a/gdb/tui/tui-data.h b/gdb/tui/tui-data.h
index 2a822487fce..25a23860ef8 100644
--- a/gdb/tui/tui-data.h
+++ b/gdb/tui/tui-data.h
@@ -99,6 +99,13 @@  public:
     return handle != nullptr;
   }
 
+  /* Disable output until the next call to doupdate.  */
+  virtual void no_refresh ()
+  {
+    if (handle != nullptr)
+      wnoutrefresh (handle.get ());
+  }
+
   /* Window handle.  */
   std::unique_ptr<WINDOW, curses_deleter> handle;
   /* Type of window.  */
diff --git a/gdb/tui/tui-layout.c b/gdb/tui/tui-layout.c
index bd2e6aee651..740178ca083 100644
--- a/gdb/tui/tui-layout.c
+++ b/gdb/tui/tui-layout.c
@@ -113,6 +113,8 @@  tui_set_layout (enum tui_layout_type layout_type)
 
   if (new_layout != cur_layout)
     {
+      tui_suppress_output suppress;
+
       show_layout (new_layout);
 
       /* Now determine where focus should be.  */
diff --git a/gdb/tui/tui-regs.c b/gdb/tui/tui-regs.c
index 85c7a31b0b6..cfcd80b7745 100644
--- a/gdb/tui/tui-regs.c
+++ b/gdb/tui/tui-regs.c
@@ -381,7 +381,7 @@  tui_data_window::erase_data_content (const char *prompt)
 	x_pos = half_width - strlen (prompt);
       mvwaddstr (handle.get (), (height / 2), x_pos, (char *) prompt);
     }
-  wrefresh (handle.get ());
+  tui_wrefresh (handle.get ());
 }
 
 /* See tui-regs.h.  */
@@ -434,6 +434,14 @@  tui_data_window::refresh_window ()
     win.refresh_window ();
 }
 
+void
+tui_data_window::no_refresh ()
+{
+  tui_gen_win_info::no_refresh ();
+  for (auto &&win : m_regs_content)
+    win.no_refresh ();
+}
+
 /* This function check all displayed registers for changes in values,
    given a particular frame.  If the values have changed, they are
    updated with the new value and highlighted.  */
@@ -502,7 +510,7 @@  tui_data_item_window::refresh_window ()
 	 windows, which according to the ncurses man pages aren't well
 	 supported.  */
       touchwin (handle.get ());
-      wrefresh (handle.get ());
+      tui_wrefresh (handle.get ());
     }
 }
 
@@ -574,6 +582,8 @@  tui_reg_command (const char *args, int from_tty)
       /* Make sure the curses mode is enabled.  */
       tui_enable ();
 
+      tui_suppress_output suppress;
+
       /* Make sure the register window is visible.  If not, select an
 	 appropriate layout.  We need to do this before trying to run the
 	 'next' or 'prev' commands.  */
diff --git a/gdb/tui/tui-regs.h b/gdb/tui/tui-regs.h
index 92df6183677..3ba4b28ddf6 100644
--- a/gdb/tui/tui-regs.h
+++ b/gdb/tui/tui-regs.h
@@ -70,6 +70,8 @@  struct tui_data_window : public tui_win_info
 
   void refresh_window () override;
 
+  void no_refresh () override;
+
   const char *name () const override
   {
     return DATA_NAME;
diff --git a/gdb/tui/tui-wingeneral.c b/gdb/tui/tui-wingeneral.c
index 17be3e23e9a..091cd73986e 100644
--- a/gdb/tui/tui-wingeneral.c
+++ b/gdb/tui/tui-wingeneral.c
@@ -30,13 +30,51 @@ 
 
 #include "gdb_curses.h"
 
+/* This is true if we're currently suppressing output, via
+   wnoutrefresh.  This is needed in case we create a new window while
+   in this mode.  */
+
+static bool suppress_output;
+
+/* See tui-data.h.  */
+
+tui_suppress_output::tui_suppress_output ()
+  : m_saved_suppress (suppress_output)
+{
+  suppress_output = true;
+
+  for (const auto &win : all_tui_windows ())
+    win->no_refresh ();
+}
+
+/* See tui-data.h.  */
+
+tui_suppress_output::~tui_suppress_output ()
+{
+  suppress_output = m_saved_suppress;
+  if (!suppress_output)
+    doupdate ();
+
+  for (const auto &win : all_tui_windows ())
+    win->refresh_window ();
+}
+
+/* See tui-data.h.  */
+
+void
+tui_wrefresh (WINDOW *win)
+{
+  if (!suppress_output)
+    wrefresh (win);
+}
+
 /* See tui-data.h.  */
 
 void
 tui_gen_win_info::refresh_window ()
 {
   if (handle != NULL)
-    wrefresh (handle.get ());
+    tui_wrefresh (handle.get ());
 }
 
 /* Draw a border arround the window.  */
@@ -133,7 +171,11 @@  tui_gen_win_info::make_window ()
 {
   handle.reset (newwin (height, width, y, x));
   if (handle != NULL)
-    scrollok (handle.get (), TRUE);
+    {
+      if (suppress_output)
+	wnoutrefresh (handle.get ());
+      scrollok (handle.get (), TRUE);
+    }
 }
 
 void
diff --git a/gdb/tui/tui-wingeneral.h b/gdb/tui/tui-wingeneral.h
index 9995250ce9a..982a9364516 100644
--- a/gdb/tui/tui-wingeneral.h
+++ b/gdb/tui/tui-wingeneral.h
@@ -33,4 +33,27 @@  extern void tui_unhighlight_win (struct tui_win_info *);
 extern void tui_highlight_win (struct tui_win_info *);
 extern void tui_refresh_all ();
 
+/* An RAII class that suppresses output on construction (calling
+   wnoutrefresh on the existing windows), and then flushes the output
+   (via doupdate) when destroyed.  */
+
+class tui_suppress_output
+{
+public:
+
+  tui_suppress_output ();
+  ~tui_suppress_output ();
+
+  DISABLE_COPY_AND_ASSIGN (tui_suppress_output);
+
+private:
+
+  /* Save the state of the suppression global.  */
+  bool m_saved_suppress;
+};
+
+/* Call wrefresh on the given window.  However, if output is being
+   suppressed via tui_suppress_output, do not call wrefresh.  */
+extern void tui_wrefresh (WINDOW *win);
+
 #endif /* TUI_TUI_WINGENERAL_H */
diff --git a/gdb/tui/tui.c b/gdb/tui/tui.c
index 6fdfa4579f1..b0d31c3bc0c 100644
--- a/gdb/tui/tui.c
+++ b/gdb/tui/tui.c
@@ -30,6 +30,7 @@ 
 #include "tui/tui-regs.h"
 #include "tui/tui-stack.h"
 #include "tui/tui-win.h"
+#include "tui/tui-wingeneral.h"
 #include "tui/tui-winsource.h"
 #include "tui/tui-source.h"
 #include "target.h"
@@ -575,6 +576,7 @@  tui_disable_command (const char *args, int from_tty)
 void
 tui_show_assembly (struct gdbarch *gdbarch, CORE_ADDR addr)
 {
+  tui_suppress_output suppress;
   tui_add_win_to_layout (DISASSEM_WIN);
   tui_update_source_windows_with_addr (gdbarch, addr);
 }