Add class flags to class to help GC scanning
Reduces GC time and pauses by reducing the number of loads required
to scan an object.
Average total GC time before on EvaluateAndApplyChanges (EAAC): 7.452s
After: 7.144s
Average GC pause times before on EAAC: 860.67us
After: 722.75us
Adding the class flags field cause a memory increase of ~24k system
wide on low memory devices.
Change-Id: I3f04212d5787bfbf5e55026584d149f55476105e
diff --git a/runtime/mirror/class_flags.h b/runtime/mirror/class_flags.h
new file mode 100644
index 0000000..6c15639
--- /dev/null
+++ b/runtime/mirror/class_flags.h
@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2015 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_MIRROR_CLASS_FLAGS_H_
+#define ART_RUNTIME_MIRROR_CLASS_FLAGS_H_
+
+#include <stdint.h>
+
+namespace art {
+namespace mirror {
+
+// Object types stored in class to help GC with faster object marking.
+static constexpr uint32_t kClassFlagNormal = 0x00000000;
+// Only normal objects which have no reference fields, e.g. string or primitive array or normal
+// class instance.
+static constexpr uint32_t kClassFlagNoReferenceFields = 0x00000001;
+static constexpr uint32_t kClassFlagString = 0x00000004;
+static constexpr uint32_t kClassFlagObjectArray = 0x00000008;
+static constexpr uint32_t kClassFlagClass = 0x00000010;
+
+// class is ClassLoader or one of its subclasses
+static constexpr uint32_t kClassFlagClassLoader = 0x00000020;
+
+// class is a soft/weak/phantom ref
+static constexpr uint32_t kClassFlagSoftReference = 0x00000040;
+// class is a weak reference
+static constexpr uint32_t kClassFlagWeakReference = 0x00000080;
+// class is a finalizer reference
+static constexpr uint32_t kClassFlagFinalizerReference = 0x00000100;
+// class is a phantom reference
+static constexpr uint32_t kClassFlagPhantomReference = 0x00000200;
+
+static constexpr uint32_t kClassFlagReference =
+ kClassFlagSoftReference |
+ kClassFlagWeakReference |
+ kClassFlagFinalizerReference |
+ kClassFlagPhantomReference;
+
+} // namespace mirror
+} // namespace art
+
+#endif // ART_RUNTIME_MIRROR_CLASS_FLAGS_H_
+