[PATCH] Avoid depending on destructor order

[Thomas Neumann]

> 
>     +static const bool in_shutdown = false;
> 
> I'll let Jason or others decide if this is the right solution.  It seems 
> that in_shutdown also could be declared outside the #ifdef and 
> initialized as "false".

sure, either is fine. Moving it outside the #ifdef wastes one byte in 
the executable (while the compiler can eliminate the const), but it does 
not really matter.

I have verified that the patch below fixes builds for both fast-path and 
non-fast-path builds. But if you prefer I will move the in_shutdown 
definition instead.

Best

Thomas

PS: in_shutdown is an int here instead of a bool because non-fast-path 
builds do not include stdbool. Not a good reason, of course, but I 
wanted to keep the patch minimal and it makes no difference in practice.


     When using the atomic fast path deregistering can fail during
     program shutdown if the lookup structures are already destroyed.
     The assert in __deregister_frame_info_bases takes that into
     account. In the non-fast-path case however is not aware of
     program shutdown, which caused a compiler error on such platforms.
     We fix that by introducing a constant for in_shutdown in
     non-fast-path builds.

     libgcc/ChangeLog:
             * unwind-dw2-fde.c: Introduce a constant for in_shutdown
             for the non-fast-path case.

diff --git a/libgcc/unwind-dw2-fde.c b/libgcc/unwind-dw2-fde.c
index d237179f4ea..0bcd5061d76 100644
--- a/libgcc/unwind-dw2-fde.c
+++ b/libgcc/unwind-dw2-fde.c
@@ -67,6 +67,8 @@ static void
  init_object (struct object *ob);

  #else
+/* Without fast path frame deregistration must always succeed.  */
+static const int in_shutdown = 0;

  /* The unseen_objects list contains objects that have been registered
     but not yet categorized in any way.  The seen_objects list has had