[pypy-svn] pypy default: Add more precise asserts, designed to catch most cases where 'obj' is nonsense (it points inside an object, where there is a pointer).

[arigo]

Author: Armin Rigo <arigo at tunes.org>
Branch: 
Changeset: r42190:375a03b5f02e
Date: 2011-02-20 14:17 +0100
http://bitbucket.org/pypy/pypy/changeset/375a03b5f02e/

Log:	Add more precise asserts, designed to catch most cases where 'obj'
	is nonsense (it points inside an object, where there is a pointer).

diff --git a/pypy/rpython/memory/gc/minimark.py b/pypy/rpython/memory/gc/minimark.py
--- a/pypy/rpython/memory/gc/minimark.py
+++ b/pypy/rpython/memory/gc/minimark.py
@@ -108,6 +108,8 @@
 GCFLAG_HAS_CARDS    = first_gcflag << 5
 GCFLAG_CARDS_SET    = first_gcflag << 6     # <- at least one card bit is set
 
+TID_MASK            = (first_gcflag << 7) - 1
+
 
 FORWARDSTUB = lltype.GcStruct('forwarding_stub',
                               ('forw', llmemory.Address))
@@ -820,9 +822,13 @@
         that can never be set on a young object -- except if tid == -42.
         """
         assert self.is_in_nursery(obj)
-        result = (self.header(obj).tid & GCFLAG_FINALIZATION_ORDERING != 0)
+        tid = self.header(obj).tid
+        result = (tid & GCFLAG_FINALIZATION_ORDERING != 0)
         if result:
-            ll_assert(self.header(obj).tid == -42, "bogus header for young obj")
+            ll_assert(tid == -42, "bogus header for young obj")
+        else:
+            ll_assert(tid != 0, "bogus header (1)")
+            ll_assert(tid & ~TID_MASK == 0, "bogus header (2)")
         return result
 
     def get_forwarding_address(self, obj):