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/object-inl.h b/runtime/mirror/object-inl.h
index 586ae30..702a0f4 100644
--- a/runtime/mirror/object-inl.h
+++ b/runtime/mirror/object-inl.h
@@ -24,6 +24,7 @@
#include "atomic.h"
#include "array-inl.h"
#include "class.h"
+#include "class_flags.h"
#include "class_linker.h"
#include "class_loader-inl.h"
#include "lock_word-inl.h"
@@ -1010,20 +1011,43 @@
const JavaLangRefVisitor& ref_visitor) {
mirror::Class* klass = GetClass<kVerifyFlags>();
visitor(this, ClassOffset(), false);
- if (klass == Class::GetJavaLangClass()) {
- AsClass<kVerifyNone>()->VisitReferences(klass, visitor);
- } else if (klass->IsArrayClass() || klass->IsStringClass()) {
- if (klass->IsObjectArrayClass<kVerifyNone>()) {
- AsObjectArray<mirror::Object, kVerifyNone>()->VisitReferences(visitor);
- }
- } else if (klass->IsClassLoaderClass()) {
- mirror::ClassLoader* class_loader = AsClassLoader<kVerifyFlags>();
- class_loader->VisitReferences<kVerifyFlags>(klass, visitor);
- } else {
+ const uint32_t class_flags = klass->GetClassFlags<kVerifyNone>();
+ if (LIKELY(class_flags == kClassFlagNormal)) {
DCHECK(!klass->IsVariableSize());
VisitInstanceFieldsReferences(klass, visitor);
- if (UNLIKELY(klass->IsTypeOfReferenceClass<kVerifyNone>())) {
- ref_visitor(klass, AsReference());
+ DCHECK(!klass->IsClassClass());
+ } else {
+ if ((class_flags & kClassFlagNoReferenceFields) == 0) {
+ DCHECK(!klass->IsStringClass());
+ if (class_flags == kClassFlagClass) {
+ DCHECK(klass->IsClassClass());
+ AsClass<kVerifyNone>()->VisitReferences(klass, visitor);
+ } else if (class_flags == kClassFlagObjectArray) {
+ DCHECK(klass->IsObjectArrayClass());
+ AsObjectArray<mirror::Object, kVerifyNone>()->VisitReferences(visitor);
+ } else if ((class_flags & kClassFlagReference) != 0) {
+ VisitInstanceFieldsReferences(klass, visitor);
+ ref_visitor(klass, AsReference());
+ } else {
+ mirror::ClassLoader* const class_loader = AsClassLoader<kVerifyFlags>();
+ class_loader->VisitReferences<kVerifyFlags>(klass, visitor);
+ }
+ } else if (kIsDebugBuild) {
+ CHECK(!klass->IsClassClass());
+ CHECK(!klass->IsObjectArrayClass());
+ // String still has instance fields for reflection purposes but these don't exist in
+ // actual string instances.
+ if (!klass->IsStringClass()) {
+ size_t total_reference_instance_fields = 0;
+ mirror::Class* super_class = klass;
+ do {
+ total_reference_instance_fields += super_class->NumReferenceInstanceFields();
+ super_class = super_class->GetSuperClass();
+ } while (super_class != nullptr);
+ // The only reference field should be the object's class. This field is handled at the
+ // beginning of the function.
+ CHECK_EQ(total_reference_instance_fields, 1u);
+ }
}
}
}