8269897: Shenandoah: Resolve UNKNOWN access strength, where possible
Backport-of: 7ac08161a8b2080ed054bc00a30d6f694ece4df3
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.hpp b/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.hpp
index 38b447a..a4353df 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.hpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.hpp
@@ -54,11 +54,11 @@
static bool need_keep_alive_barrier(DecoratorSet decorators, BasicType type);
static bool is_strong_access(DecoratorSet decorators) {
- return (decorators & (ON_WEAK_OOP_REF | ON_PHANTOM_OOP_REF | ON_UNKNOWN_OOP_REF)) == 0;
+ return (decorators & (ON_WEAK_OOP_REF | ON_PHANTOM_OOP_REF)) == 0;
}
static bool is_weak_access(DecoratorSet decorators) {
- return (decorators & (ON_WEAK_OOP_REF | ON_UNKNOWN_OOP_REF)) != 0;
+ return (decorators & ON_WEAK_OOP_REF) != 0;
}
static bool is_phantom_access(DecoratorSet decorators) {
@@ -90,8 +90,6 @@
inline void satb_enqueue(oop value);
inline void iu_barrier(oop obj);
- template <DecoratorSet decorators>
- inline void keep_alive_if_weak(oop value);
inline void keep_alive_if_weak(DecoratorSet decorators, oop value);
inline void enqueue(oop obj);
@@ -101,8 +99,17 @@
template <class T>
inline oop load_reference_barrier_mutator(oop obj, T* load_addr);
- template <DecoratorSet decorators, class T>
- inline oop load_reference_barrier(oop obj, T* load_addr);
+ template <class T>
+ inline oop load_reference_barrier(DecoratorSet decorators, oop obj, T* load_addr);
+
+ template <typename T>
+ inline oop oop_load(DecoratorSet decorators, T* addr);
+
+ template <typename T>
+ inline oop oop_cmpxchg(DecoratorSet decorators, T* addr, oop compare_value, oop new_value);
+
+ template <typename T>
+ inline oop oop_xchg(DecoratorSet decorators, T* addr, oop new_value);
private:
template <class T>
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.inline.hpp b/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.inline.hpp
index d0beb4c..ed6a921 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.inline.hpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.inline.hpp
@@ -99,21 +99,21 @@
return obj;
}
-template <DecoratorSet decorators, class T>
-inline oop ShenandoahBarrierSet::load_reference_barrier(oop obj, T* load_addr) {
+template <class T>
+inline oop ShenandoahBarrierSet::load_reference_barrier(DecoratorSet decorators, oop obj, T* load_addr) {
if (obj == NULL) {
return NULL;
}
// Prevent resurrection of unreachable phantom (i.e. weak-native) references.
- if (HasDecorator<decorators, ON_PHANTOM_OOP_REF>::value &&
+ if ((decorators & ON_PHANTOM_OOP_REF) != 0 &&
_heap->is_concurrent_weak_root_in_progress() &&
!_heap->marking_context()->is_marked(obj)) {
return NULL;
}
// Prevent resurrection of unreachable weak references.
- if ((HasDecorator<decorators, ON_WEAK_OOP_REF>::value || HasDecorator<decorators, ON_UNKNOWN_OOP_REF>::value) &&
+ if ((decorators & ON_WEAK_OOP_REF) != 0 &&
_heap->is_concurrent_weak_root_in_progress() &&
!_heap->marking_context()->is_marked_strong(obj)) {
return NULL;
@@ -121,7 +121,7 @@
// Prevent resurrection of unreachable objects that are visited during
// concurrent class-unloading.
- if (HasDecorator<decorators, AS_NO_KEEPALIVE>::value &&
+ if ((decorators & AS_NO_KEEPALIVE) != 0 &&
_heap->is_evacuation_in_progress() &&
!_heap->marking_context()->is_marked(obj)) {
return obj;
@@ -184,45 +184,64 @@
}
}
-template <DecoratorSet decorators>
-inline void ShenandoahBarrierSet::keep_alive_if_weak(oop value) {
- 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) {
- satb_enqueue(value);
- }
+template <typename T>
+inline oop ShenandoahBarrierSet::oop_load(DecoratorSet decorators, T* addr) {
+ oop value = RawAccess<>::oop_load(addr);
+ value = load_reference_barrier(decorators, value, addr);
+ keep_alive_if_weak(decorators, value);
+ return value;
+}
+
+template <typename T>
+inline oop ShenandoahBarrierSet::oop_cmpxchg(DecoratorSet decorators, T* addr, oop compare_value, oop new_value) {
+ iu_barrier(new_value);
+ oop res;
+ oop expected = compare_value;
+ do {
+ compare_value = expected;
+ res = RawAccess<>::oop_atomic_cmpxchg(addr, compare_value, new_value);
+ expected = res;
+ } while ((compare_value != expected) && (resolve_forwarded(compare_value) == resolve_forwarded(expected)));
+
+ // Note: We don't need a keep-alive-barrier here. We already enqueue any loaded reference for SATB anyway,
+ // because it must be the previous value.
+ res = load_reference_barrier(decorators, res, reinterpret_cast<T*>(NULL));
+ satb_enqueue(res);
+ return res;
+}
+
+template <typename T>
+inline oop ShenandoahBarrierSet::oop_xchg(DecoratorSet decorators, T* addr, oop new_value) {
+ iu_barrier(new_value);
+ oop previous = RawAccess<>::oop_atomic_xchg(addr, new_value);
+ // Note: We don't need a keep-alive-barrier here. We already enqueue any loaded reference for SATB anyway,
+ // because it must be the previous value.
+ previous = load_reference_barrier<T>(decorators, previous, reinterpret_cast<T*>(NULL));
+ satb_enqueue(previous);
+ return previous;
}
template <DecoratorSet decorators, typename BarrierSetT>
template <typename T>
inline oop ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_load_not_in_heap(T* addr) {
- oop value = Raw::oop_load_not_in_heap(addr);
- if (value != NULL) {
- ShenandoahBarrierSet *const bs = ShenandoahBarrierSet::barrier_set();
- value = bs->load_reference_barrier<decorators, T>(value, addr);
- bs->keep_alive_if_weak<decorators>(value);
- }
- return value;
+ assert((decorators & ON_UNKNOWN_OOP_REF) == 0, "must be absent");
+ ShenandoahBarrierSet* const bs = ShenandoahBarrierSet::barrier_set();
+ return bs->oop_load(decorators, addr);
}
template <DecoratorSet decorators, typename BarrierSetT>
template <typename T>
inline oop ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_load_in_heap(T* addr) {
- oop value = Raw::oop_load_in_heap(addr);
- ShenandoahBarrierSet *const bs = ShenandoahBarrierSet::barrier_set();
- value = bs->load_reference_barrier<decorators, T>(value, addr);
- bs->keep_alive_if_weak<decorators>(value);
- return value;
+ assert((decorators & ON_UNKNOWN_OOP_REF) == 0, "must be absent");
+ ShenandoahBarrierSet* const bs = ShenandoahBarrierSet::barrier_set();
+ return bs->oop_load(decorators, addr);
}
template <DecoratorSet decorators, typename BarrierSetT>
inline oop ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_load_in_heap_at(oop base, ptrdiff_t offset) {
- oop value = Raw::oop_load_in_heap_at(base, offset);
- ShenandoahBarrierSet *const bs = ShenandoahBarrierSet::barrier_set();
+ ShenandoahBarrierSet* const bs = ShenandoahBarrierSet::barrier_set();
DecoratorSet resolved_decorators = AccessBarrierSupport::resolve_possibly_unknown_oop_ref_strength<decorators>(base, offset);
- value = bs->load_reference_barrier<decorators>(value, AccessInternal::oop_field_addr<decorators>(base, offset));
- bs->keep_alive_if_weak(resolved_decorators, value);
- return value;
+ return bs->oop_load(resolved_decorators, AccessInternal::oop_field_addr<decorators>(base, offset));
}
template <DecoratorSet decorators, typename BarrierSetT>
@@ -254,59 +273,49 @@
template <DecoratorSet decorators, typename BarrierSetT>
template <typename T>
inline oop ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_atomic_cmpxchg_not_in_heap(T* addr, oop compare_value, oop new_value) {
+ assert((decorators & (AS_NO_KEEPALIVE | ON_UNKNOWN_OOP_REF)) == 0, "must be absent");
ShenandoahBarrierSet* bs = ShenandoahBarrierSet::barrier_set();
- bs->iu_barrier(new_value);
-
- oop res;
- oop expected = compare_value;
- do {
- compare_value = expected;
- res = Raw::oop_atomic_cmpxchg(addr, compare_value, new_value);
- expected = res;
- } while ((compare_value != expected) && (resolve_forwarded(compare_value) == resolve_forwarded(expected)));
-
- // Note: We don't need a keep-alive-barrier here. We already enqueue any loaded reference for SATB anyway,
- // because it must be the previous value.
- res = ShenandoahBarrierSet::barrier_set()->load_reference_barrier<decorators, T>(res, NULL);
- bs->satb_enqueue(res);
- return res;
+ return bs->oop_cmpxchg(decorators, addr, compare_value, new_value);
}
template <DecoratorSet decorators, typename BarrierSetT>
template <typename T>
inline oop ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_atomic_cmpxchg_in_heap(T* addr, oop compare_value, oop new_value) {
- return oop_atomic_cmpxchg_not_in_heap(addr, compare_value, new_value);
+ assert((decorators & (AS_NO_KEEPALIVE | ON_UNKNOWN_OOP_REF)) == 0, "must be absent");
+ ShenandoahBarrierSet* bs = ShenandoahBarrierSet::barrier_set();
+ return bs->oop_cmpxchg(decorators, addr, compare_value, new_value);
}
template <DecoratorSet decorators, typename BarrierSetT>
inline oop ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_atomic_cmpxchg_in_heap_at(oop base, ptrdiff_t offset, oop compare_value, oop new_value) {
- return oop_atomic_cmpxchg_in_heap(AccessInternal::oop_field_addr<decorators>(base, offset), compare_value, new_value);
+ assert((decorators & AS_NO_KEEPALIVE) == 0, "must be absent");
+ ShenandoahBarrierSet* bs = ShenandoahBarrierSet::barrier_set();
+ DecoratorSet resolved_decorators = AccessBarrierSupport::resolve_possibly_unknown_oop_ref_strength<decorators>(base, offset);
+ return bs->oop_cmpxchg(resolved_decorators, AccessInternal::oop_field_addr<decorators>(base, offset), compare_value, new_value);
}
template <DecoratorSet decorators, typename BarrierSetT>
template <typename T>
inline oop ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_atomic_xchg_not_in_heap(T* addr, oop new_value) {
+ assert((decorators & (AS_NO_KEEPALIVE | ON_UNKNOWN_OOP_REF)) == 0, "must be absent");
ShenandoahBarrierSet* bs = ShenandoahBarrierSet::barrier_set();
- bs->iu_barrier(new_value);
-
- oop previous = Raw::oop_atomic_xchg(addr, new_value);
-
- // Note: We don't need a keep-alive-barrier here. We already enqueue any loaded reference for SATB anyway,
- // because it must be the previous value.
- previous = ShenandoahBarrierSet::barrier_set()->load_reference_barrier<decorators, T>(previous, NULL);
- bs->satb_enqueue(previous);
- return previous;
+ return bs->oop_xchg(decorators, addr, new_value);
}
template <DecoratorSet decorators, typename BarrierSetT>
template <typename T>
inline oop ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_atomic_xchg_in_heap(T* addr, oop new_value) {
- return oop_atomic_xchg_not_in_heap(addr, new_value);
+ assert((decorators & (AS_NO_KEEPALIVE | ON_UNKNOWN_OOP_REF)) == 0, "must be absent");
+ ShenandoahBarrierSet* bs = ShenandoahBarrierSet::barrier_set();
+ return bs->oop_xchg(decorators, addr, new_value);
}
template <DecoratorSet decorators, typename BarrierSetT>
inline oop ShenandoahBarrierSet::AccessBarrier<decorators, BarrierSetT>::oop_atomic_xchg_in_heap_at(oop base, ptrdiff_t offset, oop new_value) {
- return oop_atomic_xchg_in_heap(AccessInternal::oop_field_addr<decorators>(base, offset), new_value);
+ assert((decorators & AS_NO_KEEPALIVE) == 0, "must be absent");
+ ShenandoahBarrierSet* bs = ShenandoahBarrierSet::barrier_set();
+ DecoratorSet resolved_decorators = AccessBarrierSupport::resolve_possibly_unknown_oop_ref_strength<decorators>(base, offset);
+ return bs->oop_xchg(resolved_decorators, AccessInternal::oop_field_addr<decorators>(base, offset), new_value);
}
// Clone barrier support
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahRuntime.cpp b/src/hotspot/share/gc/shenandoah/shenandoahRuntime.cpp
index 2a8de1f..223ceb0 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahRuntime.cpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahRuntime.cpp
@@ -68,17 +68,17 @@
JRT_END
JRT_LEAF(oopDesc*, ShenandoahRuntime::load_reference_barrier_weak(oopDesc * src, oop* load_addr))
- return (oopDesc*) ShenandoahBarrierSet::barrier_set()->load_reference_barrier<ON_WEAK_OOP_REF, oop>(oop(src), load_addr);
+ return (oopDesc*) ShenandoahBarrierSet::barrier_set()->load_reference_barrier<oop>(ON_WEAK_OOP_REF, oop(src), load_addr);
JRT_END
JRT_LEAF(oopDesc*, ShenandoahRuntime::load_reference_barrier_weak_narrow(oopDesc * src, narrowOop* load_addr))
- return (oopDesc*) ShenandoahBarrierSet::barrier_set()->load_reference_barrier<ON_WEAK_OOP_REF, narrowOop>(oop(src), load_addr);
+ return (oopDesc*) ShenandoahBarrierSet::barrier_set()->load_reference_barrier<narrowOop>(ON_WEAK_OOP_REF, oop(src), load_addr);
JRT_END
JRT_LEAF(oopDesc*, ShenandoahRuntime::load_reference_barrier_phantom(oopDesc * src, oop* load_addr))
- return (oopDesc*) ShenandoahBarrierSet::barrier_set()->load_reference_barrier<ON_PHANTOM_OOP_REF, oop>(oop(src), load_addr);
+ return (oopDesc*) ShenandoahBarrierSet::barrier_set()->load_reference_barrier<oop>(ON_PHANTOM_OOP_REF, oop(src), load_addr);
JRT_END
JRT_LEAF(oopDesc*, ShenandoahRuntime::load_reference_barrier_phantom_narrow(oopDesc * src, narrowOop* load_addr))
- return (oopDesc*) ShenandoahBarrierSet::barrier_set()->load_reference_barrier<ON_PHANTOM_OOP_REF, narrowOop>(oop(src), load_addr);
+ return (oopDesc*) ShenandoahBarrierSet::barrier_set()->load_reference_barrier<narrowOop>(ON_PHANTOM_OOP_REF, oop(src), load_addr);
JRT_END
