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8165489: Missing G1 barrier in Unsafe_GetObjectVolatile

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Add missing barrier, sharing code with Unsafe_GetObject.

Reviewed-by: kbarrett, mgerdin, pliden
This commit is contained in:
Martin Doerr 2016-09-06 13:01:27 +02:00
parent b56e8054a3
commit 38eb4a4f6f
1 changed files with 29 additions and 27 deletions
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56
hotspot/src/share/vm/prims/unsafe.cpp
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@ -272,6 +272,31 @@ public:
// 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].
@ -286,34 +311,9 @@ UNSAFE_ENTRY(jobject, Unsafe_GetObject(JNIEnv *env, jobject unsafe, jobject obj,
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)) {
@ -344,6 +344,8 @@ UNSAFE_ENTRY(jobject, Unsafe_GetObjectVolatile(JNIEnv *env, jobject unsafe, jobj
(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