Add intrinsic for Reference.get()
Added an intrinsic function for Reference.get(). Return immediately
without going through JNI if the slow path is not currently in use.
Otherwise, branch off to the the existing JNI function.
Approximately 47x speedup for cases where slow path is not enabled.
Change-Id: I13ad65a356fe4e104d8d83980694dc2740d7d039
diff --git a/runtime/gc/reference_processor-inl.h b/runtime/gc/reference_processor-inl.h
new file mode 100644
index 0000000..f619a15
--- /dev/null
+++ b/runtime/gc/reference_processor-inl.h
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ART_RUNTIME_GC_REFERENCE_PROCESSOR_INL_H_
+#define ART_RUNTIME_GC_REFERENCE_PROCESSOR_INL_H_
+
+#include "reference_processor.h"
+
+namespace art {
+namespace gc {
+
+inline bool ReferenceProcessor::SlowPathEnabled() {
+ return mirror::Reference::GetJavaLangRefReference()->GetSlowPathEnabled();
+}
+
+} // namespace gc
+} // namespace art
+
+#endif // ART_RUNTIME_GC_REFERENCE_PROCESSOR_INL_H_
diff --git a/runtime/gc/reference_processor.cc b/runtime/gc/reference_processor.cc
index e52bc1f..62d9e68 100644
--- a/runtime/gc/reference_processor.cc
+++ b/runtime/gc/reference_processor.cc
@@ -17,7 +17,9 @@
#include "reference_processor.h"
#include "mirror/object-inl.h"
+#include "mirror/reference.h"
#include "mirror/reference-inl.h"
+#include "reference_processor-inl.h"
#include "reflection.h"
#include "ScopedLocalRef.h"
#include "scoped_thread_state_change.h"
@@ -27,18 +29,17 @@
namespace gc {
ReferenceProcessor::ReferenceProcessor()
- : process_references_args_(nullptr, nullptr, nullptr), slow_path_enabled_(false),
+ : process_references_args_(nullptr, nullptr, nullptr),
preserving_references_(false), lock_("reference processor lock", kReferenceProcessorLock),
condition_("reference processor condition", lock_) {
}
void ReferenceProcessor::EnableSlowPath() {
- Locks::mutator_lock_->AssertExclusiveHeld(Thread::Current());
- slow_path_enabled_ = true;
+ mirror::Reference::GetJavaLangRefReference()->SetSlowPathEnabled(true);
}
void ReferenceProcessor::DisableSlowPath(Thread* self) {
- slow_path_enabled_ = false;
+ mirror::Reference::GetJavaLangRefReference()->SetSlowPathEnabled(false);
condition_.Broadcast(self);
}
@@ -46,11 +47,11 @@
mirror::Object* const referent = reference->GetReferent();
// If the referent is null then it is already cleared, we can just return null since there is no
// scenario where it becomes non-null during the reference processing phase.
- if (LIKELY(!slow_path_enabled_) || referent == nullptr) {
+ if (UNLIKELY(!SlowPathEnabled()) || referent == nullptr) {
return referent;
}
MutexLock mu(self, lock_);
- while (slow_path_enabled_) {
+ while (SlowPathEnabled()) {
mirror::HeapReference<mirror::Object>* const referent_addr =
reference->GetReferentReferenceAddr();
// If the referent became cleared, return it. Don't need barrier since thread roots can't get
@@ -117,7 +118,7 @@
process_references_args_.is_marked_callback_ = is_marked_callback;
process_references_args_.mark_callback_ = mark_object_callback;
process_references_args_.arg_ = arg;
- CHECK_EQ(slow_path_enabled_, concurrent) << "Slow path must be enabled iff concurrent";
+ CHECK_EQ(SlowPathEnabled(), concurrent) << "Slow path must be enabled iff concurrent";
}
// Unless required to clear soft references with white references, preserve some white referents.
if (!clear_soft_references) {
diff --git a/runtime/gc/reference_processor.h b/runtime/gc/reference_processor.h
index 2771ea8..91328a3 100644
--- a/runtime/gc/reference_processor.h
+++ b/runtime/gc/reference_processor.h
@@ -30,6 +30,7 @@
namespace mirror {
class Object;
class Reference;
+class ReferenceClass;
} // namespace mirror
namespace gc {
@@ -49,6 +50,7 @@
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_)
LOCKS_EXCLUDED(lock_);
+ // The slow path bool is contained in the reference class object, can only be set once
// Only allow setting this with mutators suspended so that we can avoid using a lock in the
// GetReferent fast path as an optimization.
void EnableSlowPath() EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_);
@@ -60,7 +62,7 @@
IsHeapReferenceMarkedCallback* is_marked_callback, void* arg)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
void UpdateRoots(IsMarkedCallback* callback, void* arg)
- SHARED_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_);
+ SHARED_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_);
private:
class ProcessReferencesArgs {
@@ -75,8 +77,10 @@
MarkObjectCallback* mark_callback_;
void* arg_;
};
+ bool SlowPathEnabled() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Called by ProcessReferences.
- void DisableSlowPath(Thread* self) EXCLUSIVE_LOCKS_REQUIRED(lock_);
+ void DisableSlowPath(Thread* self) EXCLUSIVE_LOCKS_REQUIRED(lock_)
+ SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// If we are preserving references it means that some dead objects may become live, we use start
// and stop preserving to block mutators using GetReferrent from getting access to these
// referents.
@@ -84,8 +88,6 @@
void StopPreservingReferences(Thread* self) LOCKS_EXCLUDED(lock_);
// Process args, used by the GetReferent to return referents which are already marked.
ProcessReferencesArgs process_references_args_ GUARDED_BY(lock_);
- // Boolean for whether or not we need to go slow path in GetReferent.
- volatile bool slow_path_enabled_;
// Boolean for whether or not we are preserving references (either soft references or finalizers).
// If this is true, then we cannot return a referent (see comment in GetReferent).
bool preserving_references_ GUARDED_BY(lock_);