Re: [PATCH] Avoid depending on destructor order

[Thomas Neumann <neumann@in.tum.de>]

Hi Iain,

> You might also want to include Rainer’s patch,
> 
> AFAIR patches to fix bootstrap are allowed to proceed as an exception to
> the usual rules,

I was not aware of that. I have pushed the patch below now (including 
Rainer's change), I will update the code if requested.

Best

Thomas

     fix assert in __deregister_frame_info_bases

     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.
     We also drop the destructor priority, as it is not supported on
     all platforms and we no longer rely upon the priority anyway.

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

diff --git a/libgcc/unwind-dw2-fde.c b/libgcc/unwind-dw2-fde.c
index d237179f4ea..3c0cc654ec0 100644
--- a/libgcc/unwind-dw2-fde.c
+++ b/libgcc/unwind-dw2-fde.c
@@ -51,7 +51,7 @@ static struct btree registered_frames;
  static bool in_shutdown;

  static void
-release_registered_frames (void) __attribute__ ((destructor (110)));
+release_registered_frames (void) __attribute__ ((destructor));
  static void
  release_registered_frames (void)
  {
@@ -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