# HG changeset patch
# User zgu
# Date 1597152345 14400
#      Tue Aug 11 09:25:45 2020 -0400
# Node ID dd065f121770077e2fd69f657ecb614d7329effb
# Parent  efe48e82100516f409a3d7a6ea2dfd30ef0fa638
8251359: Shenandoah: filter null oops before calling enqueue/SATB barrier

diff --git a/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.inline.hpp b/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.inline.hpp
--- a/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.inline.hpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.inline.hpp
@@ -77,6 +77,7 @@
 }
 
 inline void ShenandoahBarrierSet::enqueue(oop obj) {
+  assert(!CompressedOops::is_null(obj), "checked by caller");
   assert(_satb_mark_queue_set.is_active(), "only get here when SATB active");
 
   // Filter marked objects before hitting the SATB queues. The same predicate would
@@ -116,6 +117,7 @@
 
 inline void ShenandoahBarrierSet::keep_alive_if_weak(DecoratorSet decorators, oop value) {
   assert((decorators & ON_UNKNOWN_OOP_REF) == 0, "Reference strength must be known");
+  assert(!CompressedOops::is_null(value), "checked by caller");
   const bool on_strong_oop_ref = (decorators & ON_STRONG_OOP_REF) != 0;
   const bool peek              = (decorators & AS_NO_KEEPALIVE) != 0;
   if (!peek && !on_strong_oop_ref) {
@@ -125,6 +127,7 @@
 
 template <DecoratorSet decorators>
 inline void ShenandoahBarrierSet::keep_alive_if_weak(oop value) {
+  assert(!CompressedOops::is_null(value), "checked by caller");
   assert((decorators & ON_UNKNOWN_OOP_REF) == 0, "Reference strength must be known");
   if (!HasDecorator<decorators, ON_STRONG_OOP_REF>::value &&
       !HasDecorator<decorators, AS_NO_KEEPALIVE>::value) {
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp b/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp
--- a/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp
@@ -1325,7 +1325,7 @@
 
 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
 void ShenandoahHeap::keep_alive(oop obj) {
-  if (is_concurrent_mark_in_progress()) {
+  if (is_concurrent_mark_in_progress() && !CompressedOops::is_null(obj)) {
     ShenandoahBarrierSet::barrier_set()->enqueue(obj);
   }
 }