/*
* Copyright (C) 2011 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.
*/
#include <ctime>
#include "object.h"
#include "array-inl.h"
#include "art_field-inl.h"
#include "art_field.h"
#include "class-inl.h"
#include "class.h"
#include "class_linker-inl.h"
#include "dex/descriptors_names.h"
#include "dex/dex_file-inl.h"
#include "gc/accounting/card_table-inl.h"
#include "gc/heap-inl.h"
#include "handle_scope-inl.h"
#include "iftable-inl.h"
#include "monitor.h"
#include "object-inl.h"
#include "object-refvisitor-inl.h"
#include "object_array-inl.h"
#include "runtime.h"
#include "throwable.h"
#include "well_known_classes.h"
namespace art {
namespace mirror {
Atomic<uint32_t> Object::hash_code_seed(987654321U + std::time(nullptr));
class CopyReferenceFieldsWithReadBarrierVisitor {
public:
explicit CopyReferenceFieldsWithReadBarrierVisitor(ObjPtr<Object> dest_obj)
: dest_obj_(dest_obj) {}
void operator()(ObjPtr<Object> obj, MemberOffset offset, bool /* is_static */) const
ALWAYS_INLINE REQUIRES_SHARED(Locks::mutator_lock_) {
// GetFieldObject() contains a RB.
ObjPtr<Object> ref = obj->GetFieldObject<Object>(offset);
// No WB here as a large object space does not have a card table
// coverage. Instead, cards will be marked separately.
dest_obj_->SetFieldObjectWithoutWriteBarrier<false, false>(offset, ref);
}
void operator()(ObjPtr<mirror::Class> klass, ObjPtr<mirror::Reference> ref) const
ALWAYS_INLINE REQUIRES_SHARED(Locks::mutator_lock_) {
// Copy java.lang.ref.Reference.referent which isn't visited in
// Object::VisitReferences().
DCHECK(klass->IsTypeOfReferenceClass());
this->operator()(ref, mirror::Reference::ReferentOffset(), false);
}
// Unused since we don't copy class native roots.
void VisitRootIfNonNull(mirror::CompressedReference<mirror::Object>* root ATTRIBUTE_UNUSED)
const {}
void VisitRoot(mirror::CompressedReference<mirror::Object>* root ATTRIBUTE_UNUSED) const {}
private:
const ObjPtr<Object> dest_obj_;
};
ObjPtr<Object> Object::CopyObject(ObjPtr<mirror::Object> dest,
ObjPtr<mirror::Object> src,
size_t num_bytes) {
// Copy instance data. Don't assume memcpy copies by words (b/32012820).
{
const size_t offset = sizeof(Object);
uint8_t* src_bytes = reinterpret_cast<uint8_t*>(src.Ptr()) + offset;
uint8_t* dst_bytes = reinterpret_cast<uint8_t*>(dest.Ptr()) + offset;
num_bytes -= offset;
DCHECK_ALIGNED(src_bytes, sizeof(uintptr_t));
DCHECK_ALIGNED(dst_bytes, sizeof(uintptr_t));
// Use word sized copies to begin.
while (num_bytes >= sizeof(uintptr_t)) {
reinterpret_cast<Atomic<uintptr_t>*>(dst_bytes)->store(
reinterpret_cast<Atomic<uintptr_t>*>(src_bytes)->load(std::memory_order_relaxed),
std::memory_order_relaxed);
src_bytes += sizeof(uintptr_t);
dst_bytes += sizeof(uintptr_t);
num_bytes -= sizeof(uintptr_t);
}
// Copy possible 32 bit word.
if (sizeof(uintptr_t) != sizeof(uint32_t) && num_bytes >= sizeof(uint32_t)) {
reinterpret_cast<Atomic<uint32_t>*>(dst_bytes)->store(
reinterpret_cast<Atomic<uint32_t>*>(src_bytes)->load(std::memory_order_relaxed),
std::memory_order_relaxed);
src_bytes += sizeof(uint32_t);
dst_bytes += sizeof(uint32_t);
num_bytes -= sizeof(uint32_t);
}
// Copy remaining bytes, avoid going past the end of num_bytes since there may be a redzone
// there.
while (num_bytes > 0) {
reinterpret_cast<Atomic<uint8_t>*>(dst_bytes)->store(
reinterpret_cast<Atomic<uint8_t>*>(src_bytes)->load(std::memory_order_relaxed),
std::memory_order_relaxed);
src_bytes += sizeof(uint8_t);
dst_bytes += sizeof(uint8_t);
num_bytes -= sizeof(uint8_t);
}
}
if (kUseReadBarrier) {
// We need a RB here. After copying the whole object above, copy references fields one by one
// again with a RB to make sure there are no from space refs. TODO: Optimize this later?
CopyReferenceFieldsWithReadBarrierVisitor visitor(dest);
src->VisitReferences(visitor, visitor);
}
// Perform write barriers on copied object references.
ObjPtr<Class> c = src->GetClass();
if (c->IsArrayClass()) {
if (!c->GetComponentType()->IsPrimitive()) {
ObjPtr<ObjectArray<Object>> array = dest->AsObjectArray<Object>();
WriteBarrier::ForArrayWrite(dest, 0, array->GetLength());
}
} else {
WriteBarrier::ForEveryFieldWrite(dest);
}
return dest;
}
// An allocation pre-fence visitor that copies the object.
class CopyObjectVisitor {
public:
CopyObjectVisitor(Handle<Object>* orig, size_t num_bytes)
: orig_(orig), num_bytes_(num_bytes) {}
void operator()(ObjPtr<Object> obj, size_t usable_size ATTRIBUTE_UNUSED) const
REQUIRES_SHARED(Locks::mutator_lock_) {
Object::CopyObject(obj, orig_->Get(), num_bytes_);
}
private:
Handle<Object>* const orig_;
const size_t num_bytes_;
DISALLOW_COPY_AND_ASSIGN(CopyObjectVisitor);
};
ObjPtr<Object> Object::Clone(Thread* self) {
CHECK(!IsClass()) << "Can't clone classes.";
// Object::SizeOf gets the right size even if we're an array. Using c->AllocObject() here would
// be wrong.
gc::Heap* heap = Runtime::Current()->GetHeap();
size_t num_bytes = SizeOf();
StackHandleScope<1> hs(self);
Handle<Object> this_object(hs.NewHandle(this));
ObjPtr<Object> copy;
CopyObjectVisitor visitor(&this_object, num_bytes);
if (heap->IsMovableObject(this)) {
copy = heap->AllocObject<true>(self, GetClass(), num_bytes, visitor);
} else {
copy = heap->AllocNonMovableObject<true>(self, GetClass(), num_bytes, visitor);
}
if (this_object->GetClass()->IsFinalizable()) {
heap->AddFinalizerReference(self, ©);
}
return copy;
}
uint32_t Object::GenerateIdentityHashCode() {
uint32_t expected_value, new_value;
do {
expected_value = hash_code_seed.load(std::memory_order_relaxed);
new_value = expected_value * 1103515245 + 12345;
} while (!hash_code_seed.CompareAndSetWeakRelaxed(expected_value, new_value) ||
(expected_value & LockWord::kHashMask) == 0);
return expected_value & LockWord::kHashMask;
}
void Object::SetHashCodeSeed(uint32_t new_seed) {
hash_code_seed.store(new_seed, std::memory_order_relaxed);
}
int32_t Object::IdentityHashCode() {
ObjPtr<Object> current_this = this; // The this pointer may get invalidated by thread suspension.
while (true) {
LockWord lw = current_this->GetLockWord(false);
switch (lw.GetState()) {
case LockWord::kUnlocked: {
// Try to compare and swap in a new hash, if we succeed we will return the hash on the next
// loop iteration.
LockWord hash_word = LockWord::FromHashCode(GenerateIdentityHashCode(), lw.GCState());
DCHECK_EQ(hash_word.GetState(), LockWord::kHashCode);
// Use a strong CAS to prevent spurious failures since these can make the boot image
// non-deterministic.
if (current_this->CasLockWord(lw, hash_word, CASMode::kStrong, std::memory_order_relaxed)) {
return hash_word.GetHashCode();
}
break;
}
case LockWord::kThinLocked: {
// Inflate the thin lock to a monitor and stick the hash code inside of the monitor. May
// fail spuriously.
Thread* self = Thread::Current();
StackHandleScope<1> hs(self);
Handle<mirror::Object> h_this(hs.NewHandle(current_this));
Monitor::InflateThinLocked(self, h_this, lw, GenerateIdentityHashCode());
// A GC may have occurred when we switched to kBlocked.
current_this = h_this.Get();
break;
}
case LockWord::kFatLocked: {
// Already inflated, return the hash stored in the monitor.
Monitor* monitor = lw.FatLockMonitor();
DCHECK(monitor != nullptr);
return monitor->GetHashCode();
}
case LockWord::kHashCode: {
return lw.GetHashCode();
}
default: {
LOG(FATAL) << "Invalid state during hashcode " << lw.GetState();
UNREACHABLE();
}
}
}
}
void Object::CheckFieldAssignmentImpl(MemberOffset field_offset, ObjPtr<Object> new_value) {
ObjPtr<Class> c = GetClass();
Runtime* runtime = Runtime::Current();
if (runtime->GetClassLinker() == nullptr || !runtime->IsStarted() ||
!runtime->GetHeap()->IsObjectValidationEnabled() || !c->IsResolved()) {
return;
}
for (ObjPtr<Class> cur = c; cur != nullptr; cur = cur->GetSuperClass()) {
for (ArtField& field : cur->GetIFields()) {
if (field.GetOffset().Int32Value() == field_offset.Int32Value()) {
CHECK_NE(field.GetTypeAsPrimitiveType(), Primitive::kPrimNot);
// TODO: resolve the field type for moving GC.
ObjPtr<mirror::Class> field_type =
kMovingCollector ? field.LookupResolvedType() : field.ResolveType();
if (field_type != nullptr) {
CHECK(field_type->IsAssignableFrom(new_value->GetClass()));
}
return;
}
}
}
if (c->IsArrayClass()) {
// Bounds and assign-ability done in the array setter.
return;
}
if (IsClass()) {
for (ArtField& field : AsClass()->GetSFields()) {
if (field.GetOffset().Int32Value() == field_offset.Int32Value()) {
CHECK_NE(field.GetTypeAsPrimitiveType(), Primitive::kPrimNot);
// TODO: resolve the field type for moving GC.
ObjPtr<mirror::Class> field_type =
kMovingCollector ? field.LookupResolvedType() : field.ResolveType();
if (field_type != nullptr) {
CHECK(field_type->IsAssignableFrom(new_value->GetClass()));
}
return;
}
}
}
LOG(FATAL) << "Failed to find field for assignment to " << reinterpret_cast<void*>(this)
<< " of type " << c->PrettyDescriptor() << " at offset " << field_offset;
UNREACHABLE();
}
ArtField* Object::FindFieldByOffset(MemberOffset offset) {
return IsClass() ? ArtField::FindStaticFieldWithOffset(AsClass(), offset.Uint32Value())
: ArtField::FindInstanceFieldWithOffset(GetClass(), offset.Uint32Value());
}
std::string Object::PrettyTypeOf(ObjPtr<mirror::Object> obj) {
return (obj == nullptr) ? "null" : obj->PrettyTypeOf();
}
std::string Object::PrettyTypeOf() {
// From-space version is the same as the to-space version since the dex file never changes.
// Avoiding the read barrier here is important to prevent recursive AssertToSpaceInvariant
// issues.
ObjPtr<mirror::Class> klass = GetClass<kDefaultVerifyFlags, kWithoutReadBarrier>();
if (klass == nullptr) {
return "(raw)";
}
std::string temp;
std::string result(PrettyDescriptor(klass->GetDescriptor(&temp)));
if (klass->IsClassClass()) {
result += "<" + PrettyDescriptor(AsClass()->GetDescriptor(&temp)) + ">";
}
return result;
}
} // namespace mirror
} // namespace art