fix assert in __deregister_frame_info_bases

The assertion in __deregister_frame_info_bases assumes that for every
frame something was inserted into the lookup data structure by
__register_frame_info_bases. Unfortunately, this does not necessarily
hold true as the btree_insert call in __register_frame_info_bases will
not insert anything for empty ranges. Therefore, we need to explicitly
account for such empty ranges in the assertion as `ob` will be a null
pointer for such ranges, hence causing the assertion to fail.

Signed-off-by: Sören Tempel <soeren@soeren-tempel.net>
libgcc/ChangeLog:
	* unwind-dw2-fde.c: Accept empty ranges when deregistering frames.

diff --git a/libgcc/unwind-dw2-fde.c b/libgcc/unwind-dw2-fde.c
index 7b74c391ced1b70990736161a22c9adcea524a04..8683a65aa025a798888413802f16b203999a65a6 100644 (file)
--- a/libgcc/unwind-dw2-fde.c
+++ b/libgcc/unwind-dw2-fde.c
@@ -278,7 +278,9 @@ __deregister_frame_info_bases (const void *begin)
   __gthread_mutex_unlock (&object_mutex);
 #endif
 
-  gcc_assert (in_shutdown || ob);
+  // If we didn't find anything in the lookup data structures then they
+  // were either already destroyed or we tried to remove an empty range.
+  gcc_assert (in_shutdown || ((range[1] - range[0]) == 0 || ob));
   return (void *) ob;
 }