view src/share/vm/oops/oop.hpp @ 13584:2dfe246179c0

author dholmes
date Wed, 20 Sep 2017 23:55:35 -0400
parents 23d7878acfb7 12817e44b856
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 * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
 * 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 if you need additional information or have any
 * questions.


#include "gc/shared/specialized_oop_closures.hpp"
#include "memory/iterator.hpp"
#include "memory/memRegion.hpp"
#include "oops/metadata.hpp"
#include "utilities/macros.hpp"

// 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

// store into oop with store check
template <class T> inline void oop_store(T* p, oop v);
template <class T> inline void oop_store(volatile T* p, oop v);

extern bool always_do_update_barrier;

// Forward declarations.
class OopClosure;
class ScanClosure;
class FastScanClosure;
class FilteringClosure;
class BarrierSet;
class CMSIsAliveClosure;

class PSPromotionManager;
class ParCompactionManager;

class oopDesc {
  friend class VMStructs;
  friend class JVMCIVMStructs;
  volatile markOop _mark;
  union _metadata {
    Klass*      _klass;
    narrowKlass _compressed_klass;
  } _metadata;

  // Fast access to barrier set. Must be initialized.
  static BarrierSet* _bs;

  markOop  mark()      const { return _mark; }
  markOop* mark_addr() const { return (markOop*) &_mark; }

  void set_mark(volatile markOop m) { _mark = m; }

  inline void release_set_mark(markOop m);
  inline markOop cas_set_mark(markOop new_mark, markOop old_mark);

  // 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 volatile;
  inline Klass* klass_or_null_acquire() const volatile;
  inline Klass** klass_addr();
  inline narrowKlass* compressed_klass_addr();

  inline void set_klass(Klass* k);
  inline void release_set_klass(Klass* k);

  // For klass field compression
  inline int klass_gap() const;
  inline void set_klass_gap(int z);
  // For when the klass pointer is being used as a linked list "next" field.
  inline void set_klass_to_list_ptr(oop k);
  inline oop list_ptr_from_klass();

  // size of object header, aligned to platform wordSize
  static 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
  inline int 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 int size_given_klass(Klass* klass);

  // type test operations (inlined in oop.inline.hpp)
  inline bool is_instance()            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_array_noinline()             const;
  bool is_objArray_noinline()          const;
  bool is_typeArray_noinline()         const;

  // field addresses in oop
  inline void*      field_base(int offset)          const;

  inline jbyte*     byte_field_addr(int offset)     const;
  inline jchar*     char_field_addr(int offset)     const;
  inline jboolean*  bool_field_addr(int offset)     const;
  inline jint*      int_field_addr(int offset)      const;
  inline jshort*    short_field_addr(int offset)    const;
  inline jlong*     long_field_addr(int offset)     const;
  inline jfloat*    float_field_addr(int offset)    const;
  inline jdouble*   double_field_addr(int offset)   const;
  inline Metadata** metadata_field_addr(int offset) const;

  // Need this as public for garbage collection.
  template <class T> inline T* obj_field_addr(int offset) const;

  // Needed for javaClasses
  inline address* address_field_addr(int offset) const;

  inline static bool is_null(oop obj)       { return obj == NULL; }
  inline static bool is_null(narrowOop obj) { return obj == 0; }

  // Decode an oop pointer from a narrowOop if compressed.
  // These are overloaded for oop and narrowOop as are the other functions
  // below so that they can be called in template functions.
  static inline oop decode_heap_oop_not_null(oop v) { return v; }
  static inline oop decode_heap_oop_not_null(narrowOop v);
  static inline oop decode_heap_oop(oop v) { return v; }
  static inline oop decode_heap_oop(narrowOop v);

  // Encode an oop pointer to a narrow oop. The or_null versions accept
  // null oop pointer, others do not in order to eliminate the
  // null checking branches.
  static inline narrowOop encode_heap_oop_not_null(oop v);
  static inline narrowOop encode_heap_oop(oop v);

  // Load an oop out of the Java heap as is without decoding.
  // Called by GC to check for null before decoding.
  static inline narrowOop load_heap_oop(narrowOop* p) { return *p; }
  static inline oop       load_heap_oop(oop* p)       { return *p; }

  // Load an oop out of Java heap and decode it to an uncompressed oop.
  static inline oop load_decode_heap_oop_not_null(narrowOop* p);
  static inline oop load_decode_heap_oop_not_null(oop* p) { return *p; }
  static inline oop load_decode_heap_oop(narrowOop* p);
  static inline oop load_decode_heap_oop(oop* p) { return *p; }

  // Store already encoded heap oop into the heap.
  static inline void store_heap_oop(narrowOop* p, narrowOop v) { *p = v; }
  static inline void store_heap_oop(oop* p, oop v)             { *p = v; }

  // Encode oop if UseCompressedOops and store into the heap.
  static inline void encode_store_heap_oop_not_null(narrowOop* p, oop v);
  static inline void encode_store_heap_oop_not_null(oop* p, oop v) { *p = v; }
  static inline void encode_store_heap_oop(narrowOop* p, oop v);
  static inline void encode_store_heap_oop(oop* p, oop v) { *p = v; }

  static inline void release_store_heap_oop(volatile narrowOop* p, narrowOop v);
  static inline void release_store_heap_oop(volatile oop* p, oop v);

  static inline void release_encode_store_heap_oop_not_null(volatile narrowOop* p, oop v);
  static inline void release_encode_store_heap_oop_not_null(volatile oop* p, oop v);
  static inline void release_encode_store_heap_oop(volatile narrowOop* p, oop v);
  static inline void release_encode_store_heap_oop(volatile oop* p, oop v);

  static inline oop atomic_exchange_oop(oop exchange_value, volatile HeapWord *dest);
  static inline oop atomic_compare_exchange_oop(oop exchange_value,
                                                volatile HeapWord *dest,
                                                oop compare_value,
                                                bool prebarrier = false);

  // Access to fields in a instanceOop through these methods.
  inline oop obj_field(int offset) const;
  inline void obj_field_put(int offset, oop value);
  inline void obj_field_put_raw(int offset, oop value);
  inline void obj_field_put_volatile(int offset, oop value);

  inline Metadata* metadata_field(int offset) const;
  inline void metadata_field_put(int offset, Metadata* value);

  inline Metadata* metadata_field_acquire(int offset) const;
  inline void release_metadata_field_put(int offset, Metadata* value);

  inline jbyte byte_field(int offset) const;
  inline void byte_field_put(int offset, jbyte contents);

  inline jchar char_field(int offset) const;
  inline void char_field_put(int offset, jchar contents);

  inline jboolean bool_field(int offset) const;
  inline void bool_field_put(int offset, jboolean contents);

  inline jint int_field(int offset) const;
  inline void int_field_put(int offset, jint contents);

  inline jshort short_field(int offset) const;
  inline void short_field_put(int offset, jshort contents);

  inline jlong long_field(int offset) const;
  inline void long_field_put(int offset, jlong contents);

  inline jfloat float_field(int offset) const;
  inline void float_field_put(int offset, jfloat contents);

  inline jdouble double_field(int offset) const;
  inline void double_field_put(int offset, jdouble contents);

  inline address address_field(int offset) const;
  inline void address_field_put(int offset, address contents);

  inline oop obj_field_acquire(int offset) const;
  inline void release_obj_field_put(int offset, oop value);

  inline jbyte byte_field_acquire(int offset) const;
  inline void release_byte_field_put(int offset, jbyte contents);

  inline jchar char_field_acquire(int offset) const;
  inline void release_char_field_put(int offset, jchar contents);

  inline jboolean bool_field_acquire(int offset) const;
  inline void release_bool_field_put(int offset, jboolean contents);

  inline jint int_field_acquire(int offset) const;
  inline void release_int_field_put(int offset, jint contents);

  inline jshort short_field_acquire(int offset) const;
  inline void release_short_field_put(int offset, jshort contents);

  inline jlong long_field_acquire(int offset) const;
  inline void release_long_field_put(int offset, jlong contents);

  inline jfloat float_field_acquire(int offset) const;
  inline void release_float_field_put(int offset, jfloat contents);

  inline jdouble double_field_acquire(int offset) const;
  inline void release_double_field_put(int offset, jdouble contents);

  inline address address_field_acquire(int offset) const;
  inline 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
  void verify_on(outputStream* st);
  void verify();

  // locking operations
  inline bool is_locked()   const;
  inline bool is_unlocked() const;
  inline bool has_bias_pattern() 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);
#ifndef PRODUCT
  inline bool is_unlocked_oop() const;

  // garbage collection
  inline bool is_gc_marked() const;

  inline bool is_scavengable() const;

  // Forward pointer operations for scavenge
  inline bool is_forwarded() const;

  inline void forward_to(oop p);
  inline bool cas_forward_to(oop p, markOop compare);

  // 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);

  inline oop forwardee() const;

  // Age of object during scavenge
  inline uint age() const;
  inline void incr_age();

  // mark-sweep support
  void follow_body(int begin, int end);

  // Fast access to barrier set
  static BarrierSet* bs()            { return _bs; }
  static void set_bs(BarrierSet* bs) { _bs = bs; }

  // Garbage Collection support

  // Parallel Compact
  inline void pc_follow_contents(ParCompactionManager* cm);
  inline void pc_update_contents(ParCompactionManager* cm);
  // Parallel Scavenge
  inline void ps_push_contents(PSPromotionManager* pm);

  // iterators, returns size of object
#define OOP_ITERATE_DECL(OopClosureType, nv_suffix)                     \
  inline void oop_iterate(OopClosureType* blk);                         \
  inline void oop_iterate(OopClosureType* blk, MemRegion mr);  // Only in mr.


#define OOP_ITERATE_SIZE_DECL(OopClosureType, nv_suffix)                \
  inline int oop_iterate_size(OopClosureType* blk);                     \
  inline int oop_iterate_size(OopClosureType* blk, MemRegion mr);  // Only in mr.



#define OOP_ITERATE_BACKWARDS_DECL(OopClosureType, nv_suffix)  \
  inline void oop_iterate_backwards(OopClosureType* blk);



  inline int oop_iterate_no_header(OopClosure* bk);
  inline int oop_iterate_no_header(OopClosure* bk, MemRegion mr);

  // identity hash; returns the identity hash key (computes it if necessary)
  // NOTE with the introduction of UseBiasedLocking that identity_hash() might reach a
  // safepoint if called on a biased object. Calling code must be aware of that.
  inline intptr_t identity_hash();
  intptr_t slow_identity_hash();

  // Alternate hashing code if string table is rehashed
  unsigned int new_hash(juint seed);

  // marks are forwarded to stack when object is locked
  inline bool    has_displaced_mark() const;
  inline markOop displaced_mark() const;
  inline void    set_displaced_mark(markOop m);

  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);

  static bool is_archive_object(oop p) NOT_CDS_JAVA_HEAP_RETURN_(false);