[PATCH 1/1] gdb: set the cache information in 'get_prev_frame_maybe_check_cycle'

[Stephan Rohr <stephan.rohr@intel.com>]

From: "Rohr, Stephan" <stephan.rohr@intel.com>

'get_prev_frame_maybe_check_cycle' retrieves the previous frame and
computes the frame id.  At this point, the frame id is not cached yet,
which prevents the frame from being reinflated once the frane cache is
flushed.  Explicitly update the cache information before returning
'prev_frame' so the frame can be reinflated properly.

The 'up' command invokes the following sequence.

  1. Build the 'prev_frame' and eventually calls
     'get_prev_frame_maybe_check_cycle'.  The frame_id is only computed
     for the raw frame pointer, the wrapping 'frame_info_ptr' it not
     updated.
  2. Printing the frame calls 'do_print_frame_info'.
  3. If a pretty-printer runs an inferior call, the frame cache is
     flushed.
  4. This triggers the assertion when reinflating the frame_info_ptr.

Extend the 'gdb.python/pretty-print-call-by-hand.exp' testcase to cover
this use-case.
---
 gdb/frame.c                                    | 18 +++++++++++++++++-
 gdb/frame.h                                    |  4 ++++
 .../gdb.python/pretty-print-call-by-hand.exp   |  2 ++
 3 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/gdb/frame.c b/gdb/frame.c
index 4137e1d5edd..1d4e231ea81 100644
--- a/gdb/frame.c
+++ b/gdb/frame.c
@@ -2332,6 +2332,12 @@ get_prev_frame_maybe_check_cycle (const frame_info_ptr &this_frame)
       throw;
     }
 
+  /* No cycle and the frame is added to the frame stash, update the cache
+     information to ensure the frame can be reinflated after the cache is
+     flushed.  */
+  if (prev_frame)
+    prev_frame.update_cache ();
+
   return prev_frame;
 }
 
@@ -3431,7 +3437,17 @@ frame_info_ptr::frame_info_ptr (struct frame_info *ptr)
   if (m_ptr == nullptr)
     return;
 
-  m_cached_level = ptr->level;
+  update_cache ();
+}
+
+/* See frame-info-ptr.h.  */
+
+void
+frame_info_ptr::update_cache ()
+{
+  gdb_assert (m_ptr != nullptr);
+
+  m_cached_level = m_ptr->level;
 
   if (m_cached_level != 0 || m_ptr->this_id.value.user_created_p)
     m_cached_id = m_ptr->this_id.value;
diff --git a/gdb/frame.h b/gdb/frame.h
index f6553fb7b6d..897518371b2 100644
--- a/gdb/frame.h
+++ b/gdb/frame.h
@@ -332,6 +332,10 @@ class frame_info_ptr : public intrusive_list_node<frame_info_ptr>
     m_ptr = nullptr;
   }
 
+  /* Update the cached copies of frame_id and the frame level based on the
+     underlying pointer.   */
+  void update_cache ();
+
 private:
   /* We sometimes need to construct frame_info_ptr objects around the
      sentinel_frame, which has level -1.  Therefore, make the invalid frame
diff --git a/gdb/testsuite/gdb.python/pretty-print-call-by-hand.exp b/gdb/testsuite/gdb.python/pretty-print-call-by-hand.exp
index 52162fc9952..a2a29c4d0f8 100644
--- a/gdb/testsuite/gdb.python/pretty-print-call-by-hand.exp
+++ b/gdb/testsuite/gdb.python/pretty-print-call-by-hand.exp
@@ -108,6 +108,8 @@ with_test_prefix "frame movement down" {
 with_test_prefix "frame movement up" {
     if { [start_test "TAG: final frame"] == 0 } {
 	gdb_test "up" [multi_line "#1 .*in g \\(mt=mytype is .*\\, depth=1\\).*" ".*first frame.*"]
+	gdb_test "p f ()" " = 2"
+	gdb_test "frame" [multi_line "#1 .*in g \\(mt=mytype is .*\\, depth=1\\).*" ".*first frame.*"]
     }
 }
 
-- 
2.43.0

Intel Deutschland GmbH

Registered Address: Dornacher Strasse 1, 85622 Feldkirchen, Germany
Tel: +49 89 991 430, www.intel.de
Managing Directors: Harry Demas, Jeffrey Schneiderman, Yin Chong Sorrell
Chairperson of the Supervisory Board: Nicole Lau
Registered Seat: Munich
Commercial Register: Amtsgericht Muenchen HRB 186928