More non-null assertions in spaces.

Author: wks

src/policy/copyspace.rs

@@ -217,6 +217,7 @@ impl<VM: VMBinding> CopySpace<VM> {
         worker: &mut GCWorker<VM>,
     ) -> ObjectReference {
         trace!("copyspace.trace_object(, {:?}, {:?})", object, semantics,);
+        debug_assert!(!object.is_null());
 
         // If this is not from space, we do not need to trace it (the object has been copied to the tosapce)
         if !self.is_from_space() {

src/policy/immix/immixspace.rs

@@ -184,6 +184,7 @@ impl<VM: VMBinding> crate::policy::gc_work::PolicyTraceObject<VM> for ImmixSpace
         copy: Option<CopySemantics>,
         worker: &mut GCWorker<VM>,
     ) -> ObjectReference {
+        debug_assert!(!object.is_null());
         if KIND == TRACE_KIND_TRANSITIVE_PIN {
             self.trace_object_without_moving(queue, object)
         } else if KIND == TRACE_KIND_DEFRAG {

src/policy/immortalspace.rs

@@ -187,6 +187,7 @@ impl<VM: VMBinding> ImmortalSpace<VM> {
         queue: &mut Q,
         object: ObjectReference,
     ) -> ObjectReference {
+        debug_assert!(!object.is_null());
         #[cfg(feature = "vo_bit")]
         debug_assert!(
             crate::util::metadata::vo_bit::is_vo_bit_set::<VM>(object),

src/policy/largeobjectspace.rs

@@ -189,6 +189,7 @@ impl<VM: VMBinding> LargeObjectSpace<VM> {
         queue: &mut Q,
         object: ObjectReference,
     ) -> ObjectReference {
+        debug_assert!(!object.is_null());
         #[cfg(feature = "vo_bit")]
         debug_assert!(
             crate::util::metadata::vo_bit::is_vo_bit_set::<VM>(object),

src/policy/markcompactspace.rs

@@ -130,6 +130,7 @@ impl<VM: VMBinding> crate::policy::gc_work::PolicyTraceObject<VM> for MarkCompac
         _copy: Option<CopySemantics>,
         _worker: &mut GCWorker<VM>,
     ) -> ObjectReference {
+        debug_assert!(!object.is_null());
         debug_assert!(
             KIND != TRACE_KIND_TRANSITIVE_PIN,
             "MarkCompact does not support transitive pin trace."