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src/share/vm/prims/unsafe.cpp
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rev 11983 : 8165489: Missing G1 barrier in Unsafe_GetObjectVolatile
Reviewed-by: kbarrett, mgerdin
@@ -270,10 +270,35 @@
#endif
};
// Get/PutObject must be special-cased, since it works with handles.
+// We could be accessing the referent field in a reference
+// object. If G1 is enabled then we need to register non-null
+// referent with the SATB barrier.
+
+#if INCLUDE_ALL_GCS
+static bool is_java_lang_ref_Reference_access(oop o, jlong offset) {
+ if (offset == java_lang_ref_Reference::referent_offset && o != NULL) {
+ Klass* k = o->klass();
+ if (InstanceKlass::cast(k)->reference_type() != REF_NONE) {
+ assert(InstanceKlass::cast(k)->is_subclass_of(SystemDictionary::Reference_klass()), "sanity");
+ return true;
+ }
+ }
+ return false;
+}
+#endif
+
+static void ensure_satb_referent_alive(oop o, jlong offset, oop v) {
+#if INCLUDE_ALL_GCS
+ if (UseG1GC && v != NULL && is_java_lang_ref_Reference_access(o, offset)) {
+ G1SATBCardTableModRefBS::enqueue(v);
+ }
+#endif
+}
+
// These functions allow a null base pointer with an arbitrary address.
// But if the base pointer is non-null, the offset should make some sense.
// That is, it should be in the range [0, MAX_OBJECT_SIZE].
UNSAFE_ENTRY(jobject, Unsafe_GetObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) {
oop p = JNIHandles::resolve(obj);
@@ -284,38 +309,13 @@
v = oopDesc::decode_heap_oop(n);
} else {
v = *(oop*)index_oop_from_field_offset_long(p, offset);
}
- jobject ret = JNIHandles::make_local(env, v);
+ ensure_satb_referent_alive(p, offset, v);
-#if INCLUDE_ALL_GCS
- // We could be accessing the referent field in a reference
- // object. If G1 is enabled then we need to register non-null
- // referent with the SATB barrier.
- if (UseG1GC) {
- bool needs_barrier = false;
-
- if (ret != NULL) {
- if (offset == java_lang_ref_Reference::referent_offset && obj != NULL) {
- oop o = JNIHandles::resolve(obj);
- Klass* k = o->klass();
- if (InstanceKlass::cast(k)->reference_type() != REF_NONE) {
- assert(InstanceKlass::cast(k)->is_subclass_of(SystemDictionary::Reference_klass()), "sanity");
- needs_barrier = true;
- }
- }
- }
-
- if (needs_barrier) {
- oop referent = JNIHandles::resolve(ret);
- G1SATBCardTableModRefBS::enqueue(referent);
- }
- }
-#endif // INCLUDE_ALL_GCS
-
- return ret;
+ return JNIHandles::make_local(env, v);
} UNSAFE_END
UNSAFE_ENTRY(void, Unsafe_PutObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject x_h)) {
oop x = JNIHandles::resolve(x_h);
oop p = JNIHandles::resolve(obj);
@@ -342,10 +342,12 @@
(void)const_cast<oop&>(v = oopDesc::decode_heap_oop(n));
} else {
(void)const_cast<oop&>(v = *(volatile oop*) addr);
}
+ ensure_satb_referent_alive(p, offset, v);
+
OrderAccess::acquire();
return JNIHandles::make_local(env, v);
} UNSAFE_END
UNSAFE_ENTRY(void, Unsafe_PutObjectVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject x_h)) {
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