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/*
* Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#ifndef SHARE_OOPS_OOP_HPP
#define SHARE_OOPS_OOP_HPP
#include "memory/iterator.hpp"
#include "memory/memRegion.hpp"
#include "oops/accessDecorators.hpp"
#include "oops/markWord.hpp"
#include "oops/metadata.hpp"
#include "runtime/atomic.hpp"
#include "utilities/globalDefinitions.hpp"
#include "utilities/macros.hpp"
#include <type_traits>
// oopDesc is the top baseclass for objects classes. The {name}Desc classes describe
// the format of Java objects so the fields can be accessed from C++.
// oopDesc is abstract.
// (see oopHierarchy for complete oop class hierarchy)
//
// no virtual functions allowed
// Forward declarations.
class OopClosure;
class FilteringClosure;
class PSPromotionManager;
class ParCompactionManager;
class oopDesc {
friend class VMStructs;
friend class JVMCIVMStructs;
private:
volatile markWord _mark;
union _metadata {
Klass* _klass;
narrowKlass _compressed_klass;
} _metadata;
// There may be ordering constraints on the initialization of fields that
// make use of the C++ copy/assign incorrect.
NONCOPYABLE(oopDesc);
public:
// Must be trivial; see verifying static assert after the class.
oopDesc() = default;
inline markWord mark() const;
inline markWord mark_acquire() const;
inline markWord* mark_addr() const;
inline void set_mark(markWord m);
static inline void set_mark(HeapWord* mem, markWord m);
inline void release_set_mark(markWord m);
inline markWord cas_set_mark(markWord new_mark, markWord old_mark);
inline markWord cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order);
// Used only to re-initialize the mark word (e.g., of promoted
// objects during a GC) -- requires a valid klass pointer
inline void init_mark();
inline Klass* klass() const;
inline Klass* klass_or_null() const;
inline Klass* klass_or_null_acquire() const;
void set_narrow_klass(narrowKlass nk) NOT_CDS_JAVA_HEAP_RETURN;
inline void set_klass(Klass* k);
static inline void release_set_klass(HeapWord* mem, Klass* k);
// For klass field compression
static inline void set_klass_gap(HeapWord* mem, int z);
// size of object header, aligned to platform wordSize
static constexpr int header_size() { return sizeof(oopDesc)/HeapWordSize; }
// Returns whether this is an instance of k or an instance of a subclass of k
inline bool is_a(Klass* k) const;
// Returns the actual oop size of the object in machine words
inline size_t size();
// Sometimes (for complicated concurrency-related reasons), it is useful
// to be able to figure out the size of an object knowing its klass.
inline size_t size_given_klass(Klass* klass);
// type test operations (inlined in oop.inline.hpp)
inline bool is_instance() const;
inline bool is_instanceRef() const;
inline bool is_stackChunk() const;
inline bool is_array() const;
inline bool is_objArray() const;
inline bool is_typeArray() const;
// type test operations that don't require inclusion of oop.inline.hpp.
bool is_instance_noinline() const;
bool is_instanceRef_noinline() const;
bool is_stackChunk_noinline() const;
bool is_array_noinline() const;
bool is_objArray_noinline() const;
bool is_typeArray_noinline() const;
protected:
inline oop as_oop() const { return const_cast<oopDesc*>(this); }
public:
template<typename T>
inline T* field_addr(int offset) const;
template <typename T> inline size_t field_offset(T* p) const;
// Standard compare function returns negative value if o1 < o2
// 0 if o1 == o2
// positive value if o1 > o2
inline static int compare(oop o1, oop o2) {
void* o1_addr = (void*)o1;
void* o2_addr = (void*)o2;
if (o1_addr < o2_addr) {
return -1;
} else if (o1_addr > o2_addr) {
return 1;
} else {
return 0;
}
}
// Access to fields in a instanceOop through these methods.
template<DecoratorSet decorators>
oop obj_field_access(int offset) const;
oop obj_field(int offset) const;
void obj_field_put(int offset, oop value);
void obj_field_put_raw(int offset, oop value);
void obj_field_put_volatile(int offset, oop value);
template<DecoratorSet decorators>
void obj_field_put_access(int offset, oop value);
Metadata* metadata_field(int offset) const;
void metadata_field_put(int offset, Metadata* value);
Metadata* metadata_field_acquire(int offset) const;
void release_metadata_field_put(int offset, Metadata* value);
jbyte byte_field(int offset) const;
void byte_field_put(int offset, jbyte contents);
jchar char_field(int offset) const;
void char_field_put(int offset, jchar contents);
jboolean bool_field(int offset) const;
void bool_field_put(int offset, jboolean contents);
jboolean bool_field_volatile(int offset) const;
void bool_field_put_volatile(int offset, jboolean contents);
jint int_field(int offset) const;
void int_field_put(int offset, jint contents);
jshort short_field(int offset) const;
void short_field_put(int offset, jshort contents);
jlong long_field(int offset) const;
void long_field_put(int offset, jlong contents);
jfloat float_field(int offset) const;
void float_field_put(int offset, jfloat contents);
jdouble double_field(int offset) const;
void double_field_put(int offset, jdouble contents);
address address_field(int offset) const;
void address_field_put(int offset, address contents);
oop obj_field_acquire(int offset) const;
void release_obj_field_put(int offset, oop value);
jbyte byte_field_acquire(int offset) const;
void release_byte_field_put(int offset, jbyte contents);
jchar char_field_acquire(int offset) const;
void release_char_field_put(int offset, jchar contents);
jboolean bool_field_acquire(int offset) const;
void release_bool_field_put(int offset, jboolean contents);
jint int_field_acquire(int offset) const;
void release_int_field_put(int offset, jint contents);
jshort short_field_acquire(int offset) const;
void release_short_field_put(int offset, jshort contents);
jlong long_field_acquire(int offset) const;
void release_long_field_put(int offset, jlong contents);
jfloat float_field_acquire(int offset) const;
void release_float_field_put(int offset, jfloat contents);
jdouble double_field_acquire(int offset) const;
void release_double_field_put(int offset, jdouble contents);
address address_field_acquire(int offset) const;
void release_address_field_put(int offset, address contents);
// printing functions for VM debugging
void print_on(outputStream* st) const; // First level print
void print_value_on(outputStream* st) const; // Second level print.
void print_address_on(outputStream* st) const; // Address printing
// printing on default output stream
void print();
void print_value();
void print_address();
// return the print strings
char* print_string();
char* print_value_string();
// verification operations
static void verify_on(outputStream* st, oopDesc* oop_desc);
static void verify(oopDesc* oopDesc);
// locking operations
inline bool is_locked() const;
inline bool is_unlocked() const;
// asserts and guarantees
static bool is_oop(oop obj, bool ignore_mark_word = false);
static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
// garbage collection
inline bool is_gc_marked() const;
// Forward pointer operations for scavenge
inline bool is_forwarded() const;
void verify_forwardee(oop forwardee) NOT_DEBUG_RETURN;
inline void forward_to(oop p);
// Like "forward_to", but inserts the forwarding pointer atomically.
// Exactly one thread succeeds in inserting the forwarding pointer, and
// this call returns "NULL" for that thread; any other thread has the
// value of the forwarding pointer returned and does not modify "this".
inline oop forward_to_atomic(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
inline oop forwardee() const;
// Age of object during scavenge
inline uint age() const;
inline void incr_age();
template <typename OopClosureType>
inline void oop_iterate(OopClosureType* cl);
template <typename OopClosureType>
inline void oop_iterate(OopClosureType* cl, MemRegion mr);
template <typename OopClosureType>
inline size_t oop_iterate_size(OopClosureType* cl);
template <typename OopClosureType>
inline size_t oop_iterate_size(OopClosureType* cl, MemRegion mr);
template <typename OopClosureType>
inline void oop_iterate_backwards(OopClosureType* cl);
template <typename OopClosureType>
inline void oop_iterate_backwards(OopClosureType* cl, Klass* klass);
inline static bool is_instanceof_or_null(oop obj, Klass* klass);
// identity hash; returns the identity hash key (computes it if necessary)
inline intptr_t identity_hash();
intptr_t slow_identity_hash();
inline bool fast_no_hash_check();
// marks are forwarded to stack when object is locked
inline bool has_displaced_mark() const;
inline markWord displaced_mark() const;
inline void set_displaced_mark(markWord m);
// Checks if the mark word needs to be preserved
inline bool mark_must_be_preserved() const;
inline bool mark_must_be_preserved(markWord m) const;
static bool has_klass_gap();
// for code generation
static int mark_offset_in_bytes() { return offset_of(oopDesc, _mark); }
static int klass_offset_in_bytes() { return offset_of(oopDesc, _metadata._klass); }
static int klass_gap_offset_in_bytes() {
assert(has_klass_gap(), "only applicable to compressed klass pointers");
return klass_offset_in_bytes() + sizeof(narrowKlass);
}
// for error reporting
static void* load_klass_raw(oop obj);
static void* load_oop_raw(oop obj, int offset);
DEBUG_ONLY(bool size_might_change();)
};
// An oopDesc is not initialized via a constructor. Space is allocated in
// the Java heap, and static functions provided here on HeapWord* are used
// to fill in certain parts of that memory. The allocated memory is then
// treated as referring to an oopDesc. For that to be valid, the oopDesc
// class must have a trivial default constructor (C++14 3.8/1).
static_assert(std::is_trivially_default_constructible<oopDesc>::value, "required");
#endif // SHARE_OOPS_OOP_HPP
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