gdb: make user-created frames reinflatable

This patch teaches frame_info_ptr to reinflate user-created frames
(frames created through create_new_frame, with the "select-frame view"
command).

Before this patch, frame_info_ptr doesn't support reinflating
user-created frames, because it currently reinflates by getting the
current target frame (for frame 0) or frame_find_by_id (for other
frames).  To reinflate a user-created frame, we need to call
create_new_frame, to make it lookup an existing user-created frame, or
otherwise create one.

So, in prepare_reinflate, get the frame id even if the frame has level
0, if it is user-created.  In reinflate, if the saved frame id is user
create it, call create_new_frame.

In order to test this, I initially enhanced the gdb.base/frame-view.exp
test added by the previous patch by setting a pretty-printer for the
type of the function parameters, in which we do an inferior call.  This
causes print_frame_args to not reinflate its frame (which is a
user-created one) properly.  On one machine (my Arch Linux one), it
properly catches the bug, as the frame is not correctly restored after
printing the first parameter, so it messes up the second parameter:

    frame
    #0  baz (z1=hahaha, z2=<error reading variable: frame address is not available.>) at /home/simark/src/binutils-gdb/gdb/testsuite/gdb.base/frame-view.c:40
    40        return z1.m + z2.n;
    (gdb) FAIL: gdb.base/frame-view.exp: with_pretty_printer=true: frame
    frame
    #0  baz (z1=hahaha, z2=<error reading variable: frame address is not available.>) at /home/simark/src/binutils-gdb/gdb/testsuite/gdb.base/frame-view.c:40
    40        return z1.m + z2.n;
    (gdb) FAIL: gdb.base/frame-view.exp: with_pretty_printer=true: frame again

However, on another machine (my Ubuntu 22.04 one), it just passes fine,
without the appropriate fix.  I then thought about writing a selftest
for that, it's more reliable.  I left the gdb.base/frame-view.exp pretty
printer test there, it's already written, and we never know, it might
catch some unrelated issue some day.

Change-Id: I5849baf77991fc67a15bfce4b5e865a97265b386
Reviewed-By: Bruno Larsen <blarsen@redhat.com>

1 files changed, 80 insertions, 0 deletions

diff --git a/gdb/unittests/frame_info_ptr-selftests.c b/gdb/unittests/frame_info_ptr-selftests.c
new file mode 100644
index 0000000..edf1b9f
--- /dev/null
+++ b/gdb/unittests/frame_info_ptr-selftests.c
@@ -0,0 +1,80 @@
+/* Self tests for frame_info_ptr.
+
+   Copyright (C) 2022 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   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/>.  */
+
+#include "defs.h"
+
+#include "frame.h"
+#include "gdbsupport/selftest.h"
+#include "scoped-mock-context.h"
+#include "test-target.h"
+
+namespace selftests {
+
+static void
+validate_user_created_frame (frame_id id)
+{
+  SELF_CHECK (id.stack_status == FID_STACK_VALID);
+  SELF_CHECK (id.stack_addr == 0x1234);
+  SELF_CHECK (id.code_addr_p);
+  SELF_CHECK (id.code_addr == 0x5678);
+}
+
+static frame_info_ptr
+user_created_frame_callee (frame_info_ptr frame)
+{
+  validate_user_created_frame (get_frame_id (frame));
+
+  frame.prepare_reinflate ();
+  reinit_frame_cache ();
+  frame.reinflate ();
+
+  validate_user_created_frame (get_frame_id (frame));
+
+  return frame;
+}
+
+static void
+test_user_created_frame ()
+{
+  scoped_mock_context<test_target_ops> mock_context
+    (current_inferior ()->gdbarch);
+  frame_info_ptr frame = create_new_frame (0x1234, 0x5678);
+
+  validate_user_created_frame (get_frame_id (frame));
+
+  /* Pass the frame to a callee, which calls reinit_frame_cache.  This lets us
+     validate that the reinflation in both the callee and caller restore the
+     same frame_info object.  */
+  frame.prepare_reinflate ();
+  frame_info_ptr callees_frame_info = user_created_frame_callee (frame);
+  frame.reinflate ();
+
+  validate_user_created_frame (get_frame_id (frame));
+  SELF_CHECK (frame.get () == callees_frame_info.get ());
+}
+
+} /* namespace selftests */
+
+void _initialize_frame_info_ptr_selftests ();
+void
+_initialize_frame_info_ptr_selftests ()
+{
+  selftests::register_test ("frame_info_ptr_user",
+			    selftests::test_user_created_frame);
+}