[PATCH 4/6] gdb/tui: Fix 'layout asm' before the inferior has started

Andrew Burgess
2020-01-07T11:52:33Z

Currently if a user starts the tui with 'layout asm' then they will be
presented with the 'src' layout.

What happens is:

1. Layout command enables TUI, selecting the SRC layout by default.

2. As part of tui_enable we call tui_display_main, which calls
tui_get_begin_asm_address, which calls
set_default_source_symtab_and_line. This changes core GDBs
current symtab and line, which triggers a call to the symtab
changed hook tui_symtab_changed, which sets the flag
from_source_symtab.

3. Back in the layout command, the layout is changed from SRC to
ASM. After this the layout command completes and we return to
core GDB which prints the prompt, however...

4. The before prompt hook is called which sees the
from_source_symtab flag is set and forces the SRC window to be
displayed. This switches us back to SRC view.

The solution I propose here is to delay installing the hooks into core
GDB until after we have finished setting up the tui and selecting the
default frame to view. In this way we effectively ignore the first
symtab changed event triggered when making main the default symtab.

gdb/ChangeLog:

* tui/tui.c (tui_enable): Register tui hooks after calling
tui_display_main.

gdb/testsuite/ChangeLog:

* gdb.tui/tui-layout-asm.exp: New file.

Change-Id: I858ab81a17ffb4aa72deb3f36c3755228a9c9d9a
---
gdb/ChangeLog | 5 +++++
gdb/testsuite/ChangeLog | 4 ++++
gdb/testsuite/gdb.tui/tui-layout-asm.exp | 34 ++++++++++++++++++++++++++++++++
gdb/tui/tui.c | 10 ++++++----
4 files changed, 49 insertions(+), 4 deletions(-)
create mode 100644 gdb/testsuite/gdb.tui/tui-layout-asm.exp

diff --git a/gdb/testsuite/gdb.tui/tui-layout-asm.exp b/gdb/testsuite/gdb.tui/tui-layout-asm.exp
new file mode 100644
index 00000000000..cec2735764e
--- /dev/null
+++ b/gdb/testsuite/gdb.tui/tui-layout-asm.exp
@@ -0,0 +1,34 @@
+# Copyright 2020 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+# Ensure that 'layout asm' before starting the inferior puts us in the
+# asm layout and displays the disassembly for main.
+
+load_lib "tuiterm.exp"
+
+standard_testfile tui-layout.c
+
+if {[build_executable "failed to prepare" ${testfile} ${srcfile}] == -1} {
+ return -1
+}
+
+Term::clean_restart 24 80 $testfile
+if {![Term::prepare_for_tui]} {
+ unsupported "TUI not supported"
+}
+
+# This puts us into TUI mode, and should display the ASM window.
+Term::command "layout asm"
+Term::check_box_contents "check asm box contents" 0 0 80 15 " "
diff --git a/gdb/tui/tui.c b/gdb/tui/tui.c
index 7ff5825ece2..99d30a55a15 100644
--- a/gdb/tui/tui.c
+++ b/gdb/tui/tui.c
@@ -489,10 +489,6 @@ tui_enable (void)
clearok (stdscr, TRUE);
}

- /* Install the TUI specific hooks. */
- tui_install_hooks ();
- rl_startup_hook = tui_rl_startup_hook;
-
if (tui_update_variables ())
tui_rehighlight_all ();

@@ -513,6 +509,12 @@ tui_enable (void)
else
tui_display_main ();

+ /* Install the TUI specific hooks. This must be done after the call to
+ tui_display_main so that we don't detect the symtab changed event it
+ can cause. */
+ tui_install_hooks ();
+ rl_startup_hook = tui_rl_startup_hook;
+
/* Restore TUI keymap. */
tui_set_key_mode (tui_current_key_mode);

--
2.14.5