[PATCH] Destroy allocated values when exiting GDB (was: Re: [PATCH] Merge handle_inferior_event and handle_inferior_event_1)

[Sergio Durigan Junior <sergiodj@redhat.com>]

On Thursday, March 28 2019, Pedro Alves wrote:

> On 03/27/2019 12:57 PM, Tom Tromey wrote:
>> Sergio> I did that, and we (Pedro, Mark, Frank and I) did a session of
>> Sergio> collective investigation.  I summarized what we found here:
>> Sergio>   https://bugzilla.redhat.com/show_bug.cgi?id=1690120#c25
>> 
>> Thanks, that's very interesting.
>> I suppose either better control over the order of destruction is needed,
>> or maybe finalize_python should clear gdb_python_initialized and then
>> this should be checked in xmethod destructor.
> I think the former is better.  I think we should put an 
>   all_values.clear ();
> call in quit_force, before the do_final_cleanups call.  Even
> better, add a new finalize_values function next to
> _initialize_values, and call that.

How does this look?

From b88067edfb2289cd5af3c9b8984b0b0354c965db Mon Sep 17 00:00:00 2001
From: Sergio Durigan Junior <sergiodj@redhat.com>
Date: Fri, 29 Mar 2019 17:34:54 -0400
Subject: [PATCH] Destroy allocated values when exiting GDB

When the user exits GDB, we might still have some allocated values in
the chain, which, in specific scenarios, can cause problems when GDB
attempts to destroy them in "quit_force".  For example, see the bug
reported at:

  https://bugzilla.redhat.com/show_bug.cgi?id=1690120

And the thread starting at:

  https://sourceware.org/ml/gdb-patches/2019-03/msg00475.html
  Message-ID: <87r2azkhmq.fsf@redhat.com>

In order to avoid that, and to be more aware of our allocated
resources, this commit implements a new function "finalize_values" and
calls it from inside "quit_force".

Tested by the BuildBot.

2019-03-29  Sergio Durigan Junior  <sergiodj@redhat.com>
	    Pedro Alves  <palves@redhat.com>

	* top.c (quit_force): Call 'finalize_values'.
	* value.c (finalize_values): New function.
	* value.h (finalize_values): Declare.
---
 gdb/top.c   | 3 +++
 gdb/value.c | 8 ++++++++
 gdb/value.h | 4 ++++
 3 files changed, 15 insertions(+)

diff --git a/gdb/top.c b/gdb/top.c
index b10b0649e9..ffbe8e517f 100644
--- a/gdb/top.c
+++ b/gdb/top.c
@@ -1672,6 +1672,9 @@ quit_force (int *exit_arg, int from_tty)
     }
   END_CATCH
 
+  /* Destroy any values currently allocated.  */
+  finalize_values ();
+
   /* Do any final cleanups before exiting.  */
   TRY
     {
diff --git a/gdb/value.c b/gdb/value.c
index dc297dfe0f..bcfc084e09 100644
--- a/gdb/value.c
+++ b/gdb/value.c
@@ -4132,3 +4132,11 @@ prevents future values, larger than this size, from being allocated."),
 			    selftests::test_insert_into_bit_range_vector);
 #endif
 }
+
+/* See value.h.  */
+
+void
+finalize_values ()
+{
+  all_values.clear ();
+}
diff --git a/gdb/value.h b/gdb/value.h
index d3905cc354..7853950ca3 100644
--- a/gdb/value.h
+++ b/gdb/value.h
@@ -1189,4 +1189,8 @@ extern struct value *call_xmethod (struct value *method,
 extern int value_union_variant (struct type *union_type,
 				const gdb_byte *contents);
 
+/* Destroy the values currently allocated.  This is mostly called when
+   GDB is exiting (e.g., on quit_force).  */
+extern void finalize_values ();
+
 #endif /* !defined (VALUE_H) */
-- 
2.17.2