### Eclipse Workspace Patch 1.0
#P ispobjecttest
Index: src/string/api.c
===================================================================
--- src/string/api.c	(revision 41260)
+++ src/string/api.c	(working copy)
@@ -92,6 +92,8 @@
     if (PObj_is_cowed_TESTALL(s)) {
         STRING for_alloc;
 
+        POBJ_set_check_magic(&for_alloc);
+
         /* Create new pool data for this header to use,
          * independent of the original COW data */
         PObj_constant_CLEAR(s);
Index: src/gc/system.c
===================================================================
--- src/gc/system.c	(revision 41260)
+++ src/gc/system.c	(working copy)
@@ -454,13 +454,19 @@
                 /* ...so ensure that Parrot_gc_mark_PObj_alive checks PObj_on_free_list_FLAG
                  * before adding it to the next_for_GC list, to have
                  * vtable->mark() called. */
-                Parrot_gc_mark_PObj_alive(interp, (PObj *)ptr);
+#  ifdef PObj_do_is_pobj_check
+                if (!PObj_is_live_or_free_TESTALL((PObj *)ptr))
+#  endif
+                    Parrot_gc_mark_PObj_alive(interp, (PObj *)ptr);
             }
             else if (buffer_min <= ptr && ptr < buffer_max &&
                     is_buffer_ptr(interp, (void *)ptr)) {
                 /* ...and since Parrot_gc_mark_PObj_alive doesn't care about bufstart, it
                  * doesn't really matter if it sets a flag */
-                Parrot_gc_mark_PObj_alive(interp, (PObj *)ptr);
+#  ifdef PObj_do_is_pobj_check
+                if (!PObj_is_live_or_free_TESTALL((PObj *)ptr))
+#  endif
+                    Parrot_gc_mark_PObj_alive(interp, (PObj *)ptr);
             }
         }
     }
Index: src/gc/api.c
===================================================================
--- src/gc/api.c	(revision 41260)
+++ src/gc/api.c	(working copy)
@@ -198,6 +198,8 @@
     /* TODO: Have each core register a ->pobject_lives function pointer in the
        Arenas struct, and call that pointer directly instead of having a messy
        set of #if preparser conditions. */
+    POBJ_PARROT_ASSERT_check_is_pobj(obj);
+
 #if PARROT_GC_GMS
     do {
         if (!PObj_live_TEST(obj) && \
@@ -341,6 +343,8 @@
     pmc->vtable         = NULL;
     PMC_data(pmc)       = NULL;
 
+    POBJ_set_check_magic(pmc);
+
     return pmc;
 }
 
@@ -358,7 +362,11 @@
 Parrot_gc_free_pmc_header(PARROT_INTERP, ARGMOD(PMC *pmc))
 {
     ASSERT_ARGS(Parrot_gc_free_pmc_header)
-    Small_Object_Pool * const pool = (PObj_constant_TEST(pmc)) ?
+    Small_Object_Pool * pool;
+
+    POBJ_PARROT_ASSERT_check_is_pobj(pmc);
+
+    pool = (PObj_constant_TEST(pmc)) ?
         interp->arena_base->constant_pmc_pool : interp->arena_base->pmc_pool;
 
     Parrot_pmc_destroy(interp, pmc);
@@ -383,6 +391,8 @@
 {
     ASSERT_ARGS(Parrot_gc_free_pmc_sync)
 
+    POBJ_PARROT_ASSERT_check_is_pobj(p);
+
     if (PObj_is_PMC_shared_TEST(p) && PMC_sync(p)) {
         MUTEX_DESTROY(PMC_sync(p)->pmc_lock);
         mem_internal_free(PMC_sync(p));
@@ -407,6 +417,8 @@
 {
     ASSERT_ARGS(Parrot_gc_add_pmc_sync)
 
+    POBJ_PARROT_ASSERT_check_is_pobj(pmc);
+
     /* This mutex already exists, leave it alone. */
     if (PMC_sync(pmc))
         return;
@@ -453,6 +465,8 @@
     PObj_get_FLAGS(string) |=
         flags | PObj_is_string_FLAG | PObj_is_COWable_FLAG | PObj_live_FLAG;
 
+    POBJ_set_check_magic(string);
+
     return string;
 }
 
@@ -470,8 +484,11 @@
 Parrot_gc_free_string_header(PARROT_INTERP, ARGMOD(STRING *s))
 {
     ASSERT_ARGS(Parrot_gc_free_string_header)
+
+    POBJ_PARROT_ASSERT_check_is_pobj(s);
+
     if (!PObj_constant_TEST(s)) {
-        Small_Object_Pool * const pool = interp->arena_base->string_header_pool;
+        Small_Object_Pool * pool = interp->arena_base->string_header_pool;
         pool->add_free_object(interp, pool, s);
     }
 }
@@ -495,10 +512,15 @@
 Parrot_gc_new_bufferlike_header(PARROT_INTERP, size_t size)
 {
     ASSERT_ARGS(Parrot_gc_new_bufferlike_header)
+    Buffer *buffer;
 
     Small_Object_Pool * const pool = get_bufferlike_pool(interp, size);
 
-    return get_free_buffer(interp, pool);
+    buffer = (Buffer*)get_free_buffer(interp, pool);
+
+    POBJ_set_check_magic(buffer);
+
+    return buffer;
 }
 
 /*
@@ -529,6 +551,8 @@
         memset(buffer + 1, 0,
                 pool->object_size - sizeof (Buffer) - GC_HEADER_SIZE);
 
+    POBJ_set_check_magic(buffer);
+
     return buffer;
 }
 
@@ -549,7 +573,11 @@
     size_t size)
 {
     ASSERT_ARGS(Parrot_gc_free_bufferlike_header)
-    Small_Object_Pool * const pool = get_bufferlike_pool(interp, size);
+    Small_Object_Pool * pool;
+
+    POBJ_PARROT_ASSERT_check_is_pobj(obj);
+
+    pool = get_bufferlike_pool(interp, size);
     pool->add_free_object(interp, pool, obj);
 }
 
@@ -574,6 +602,8 @@
     size_t new_size;
     char *mem;
 
+    POBJ_PARROT_ASSERT_check_is_pobj(buffer);
+
     Buffer_buflen(buffer) = 0;
     Buffer_bufstart(buffer) = NULL;
     new_size = aligned_size(buffer, size);
@@ -611,6 +641,8 @@
     Memory_Pool * const pool = interp->arena_base->memory_pool;
     size_t new_size, needed, old_size;
 
+    POBJ_PARROT_ASSERT_check_is_pobj(buffer);
+
     /*
      * we don't shrink buffers
      */
@@ -682,6 +714,8 @@
     Memory_Pool *pool;
     char        *mem;
 
+    POBJ_PARROT_ASSERT_check_is_pobj(str);
+
     Buffer_buflen(str)   = 0;
     Buffer_bufstart(str) = NULL;
 
@@ -725,8 +759,11 @@
     size_t copysize;
     char *mem, *oldmem;
     size_t new_size, needed, old_size;
+    Memory_Pool * pool;
 
-    Memory_Pool * const pool =
+    POBJ_PARROT_ASSERT_check_is_pobj(str);
+
+    pool =
         PObj_constant_TEST(str)
             ? interp->arena_base->constant_string_pool
             : interp->arena_base->memory_pool;
Index: include/parrot/pobj.h
===================================================================
--- include/parrot/pobj.h	(revision 41260)
+++ include/parrot/pobj.h	(working copy)
@@ -15,17 +15,36 @@
 
 #include "parrot/config.h"
 
+/* To enable test which test whether the object which are entered into the gc functions
+   are indeed pobject enable this define */
+#define PObj_do_is_pobj_check 1
+
 /* Parrot Object - base class for all others */
 typedef struct pobj_t {
     Parrot_UInt flags;
+#ifdef PObj_do_is_pobj_check
+    Parrot_UInt is_pobj_test;
+#endif
 } PObj;
 
 typedef struct buffer_t {
     Parrot_UInt flags;
+#ifdef PObj_do_is_pobj_check
+    Parrot_UInt is_pobj_test;
+#endif
     void *     _bufstart;
     size_t     _buflen;
 } Buffer;
 
+#ifdef PObj_do_is_pobj_check
+#  define is_pobj_check_magic 0xcecaacec
+#  define POBJ_set_check_magic(pobj)              (pobj)->is_pobj_test = is_pobj_check_magic
+#  define POBJ_PARROT_ASSERT_check_is_pobj(pobj)  PARROT_ASSERT((pobj)->is_pobj_test == is_pobj_check_magic)
+#else
+#  define POBJ_set_check_magic(pobj)
+#  define POBJ_PARROT_ASSERT_check_is_pobj(pobj)
+#endif
+
 #define Buffer_bufstart(buffer)    (buffer)->_bufstart
 #define Buffer_buflen(buffer)      (buffer)->_buflen
 
@@ -81,6 +100,9 @@
 
 struct parrot_string_t {
     Parrot_UInt flags;
+#ifdef PObj_do_is_pobj_check
+    Parrot_UInt is_pobj_test;
+#endif
     void *     _bufstart;
     size_t     _buflen;
     char       *strstart;
@@ -98,6 +120,9 @@
 /* note that cache and flags are isomorphic with Buffer and PObj */
 struct PMC {
     Parrot_UInt     flags;
+#ifdef PObj_do_is_pobj_check
+    Parrot_UInt     is_pobj_test;
+#endif
     VTABLE         *vtable;
     DPOINTER       *data;