src/hotspot/share/oops/oop.inline.hpp

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * 2 along with this work; if not, write to the Free Software Foundation,
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#ifndef SHARE_VM_OOPS_OOP_INLINE_HPP
#define SHARE_VM_OOPS_OOP_INLINE_HPP

#include "gc/shared/collectedHeap.hpp"
#include "memory/metaspaceShared.hpp"
#include "oops/access.inline.hpp"
#include "oops/arrayKlass.hpp"
#include "oops/arrayOop.hpp"
#include "oops/compressedOops.inline.hpp"
#include "oops/klass.inline.hpp"
#include "oops/markOop.inline.hpp"
#include "oops/oop.hpp"
#include "runtime/atomic.hpp"
#include "runtime/orderAccess.hpp"
#include "runtime/os.hpp"
#include "utilities/align.hpp"
#include "utilities/macros.hpp"

// Implementation of all inlined member functions defined in oop.hpp
// We need a separate file to avoid circular references

markOop  oopDesc::mark()      const {
  uintptr_t v = HeapAccess<MO_VOLATILE>::load_at(as_oop(), mark_offset_in_bytes());
  return markOop(v);
}

markOop  oopDesc::mark_raw()  const {
  return Atomic::load(&_mark);;
}

markOop* oopDesc::mark_addr_raw() const {
  return (markOop*) &_mark;
}

void oopDesc::set_mark(markOop m) {
  HeapAccess<MO_VOLATILE>::store_at(as_oop(), mark_offset_in_bytes(), m.value());
}

void oopDesc::set_mark_raw(markOop m) {
  Atomic::store(m, &_mark);
}

void oopDesc::set_mark_raw(HeapWord* mem, markOop m) {
  *(markOop*)(((char*)mem) + mark_offset_in_bytes()) = m;
}

void oopDesc::release_set_mark(markOop m) {
  HeapAccess<MO_RELEASE>::store_at(as_oop(), mark_offset_in_bytes(), m.value());
}

markOop oopDesc::cas_set_mark(markOop new_mark, markOop old_mark) {
  uintptr_t v = HeapAccess<>::atomic_cmpxchg_at(new_mark.value(), as_oop(), mark_offset_in_bytes(), old_mark.value());
  return markOop(v);
}

markOop oopDesc::cas_set_mark_raw(markOop new_mark, markOop old_mark, atomic_memory_order order) {
  return Atomic::cmpxchg(new_mark, &_mark, old_mark, order);
}

void oopDesc::init_mark() {
  set_mark(markOop::prototype_for_object(this));
}

void oopDesc::init_mark_raw() {
  set_mark_raw(markOop::prototype_for_object(this));
}

Klass* oopDesc::klass() const {
  if (UseCompressedClassPointers) {
    return Klass::decode_klass_not_null(_metadata._compressed_klass);
  } else {
    return _metadata._klass;
  }
}

Klass* oopDesc::klass_or_null() const volatile {
  if (UseCompressedClassPointers) {
    return Klass::decode_klass(_metadata._compressed_klass);
  } else {
    return _metadata._klass;
  }
}

Klass* oopDesc::klass_or_null_acquire() const volatile {
  if (UseCompressedClassPointers) {
    // Workaround for non-const load_acquire parameter.
    const volatile narrowKlass* addr = &_metadata._compressed_klass;
    volatile narrowKlass* xaddr = const_cast<volatile narrowKlass*>(addr);
    return Klass::decode_klass(OrderAccess::load_acquire(xaddr));
  } else {
    return OrderAccess::load_acquire(&_metadata._klass);
  }
}

Klass** oopDesc::klass_addr(HeapWord* mem) {
  // Only used internally and with CMS and will not work with
  // UseCompressedOops
  assert(!UseCompressedClassPointers, "only supported with uncompressed klass pointers");
  ByteSize offset = byte_offset_of(oopDesc, _metadata._klass);
  return (Klass**) (((char*)mem) + in_bytes(offset));
}

narrowKlass* oopDesc::compressed_klass_addr(HeapWord* mem) {
  assert(UseCompressedClassPointers, "only called by compressed klass pointers");
  ByteSize offset = byte_offset_of(oopDesc, _metadata._compressed_klass);
  return (narrowKlass*) (((char*)mem) + in_bytes(offset));
}

Klass** oopDesc::klass_addr() {
  return klass_addr((HeapWord*)this);
}

narrowKlass* oopDesc::compressed_klass_addr() {
  return compressed_klass_addr((HeapWord*)this);
}

#define CHECK_SET_KLASS(k)                                                \
  do {                                                                    \
    assert(Universe::is_bootstrapping() || k != NULL, "NULL Klass");      \
    assert(Universe::is_bootstrapping() || k->is_klass(), "not a Klass"); \
  } while (0)

void oopDesc::set_klass(Klass* k) {
  CHECK_SET_KLASS(k);
  if (UseCompressedClassPointers) {
    *compressed_klass_addr() = Klass::encode_klass_not_null(k);
  } else {
    *klass_addr() = k;
  }
}

void oopDesc::release_set_klass(HeapWord* mem, Klass* klass) {
  CHECK_SET_KLASS(klass);
  if (UseCompressedClassPointers) {
    OrderAccess::release_store(compressed_klass_addr(mem),
                               Klass::encode_klass_not_null(klass));
  } else {
    OrderAccess::release_store(klass_addr(mem), klass);
  }
}

#undef CHECK_SET_KLASS

int oopDesc::klass_gap() const {
  return *(int*)(((intptr_t)this) + klass_gap_offset_in_bytes());
}

void oopDesc::set_klass_gap(HeapWord* mem, int v) {
  if (UseCompressedClassPointers) {
    *(int*)(((char*)mem) + klass_gap_offset_in_bytes()) = v;
  }
}

void oopDesc::set_klass_gap(int v) {
  set_klass_gap((HeapWord*)this, v);
}

void oopDesc::set_klass_to_list_ptr(oop k) {
  // This is only to be used during GC, for from-space objects, so no
  // barrier is needed.
  if (UseCompressedClassPointers) {
    _metadata._compressed_klass = (narrowKlass)CompressedOops::encode(k);  // may be null (parnew overflow handling)
  } else {
    _metadata._klass = (Klass*)(address)k;
  }
}

oop oopDesc::list_ptr_from_klass() {
  // This is only to be used during GC, for from-space objects.
  if (UseCompressedClassPointers) {
    return CompressedOops::decode((narrowOop)_metadata._compressed_klass);
  } else {
    // Special case for GC
    return (oop)(address)_metadata._klass;
  }
}

bool oopDesc::is_a(Klass* k) const {
  return klass()->is_subtype_of(k);
}

int oopDesc::size()  {
  return size_given_klass(klass());
}

int oopDesc::size_given_klass(Klass* klass)  {
  int lh = klass->layout_helper();
  int s;

  // lh is now a value computed at class initialization that may hint
  // at the size.  For instances, this is positive and equal to the
  // size.  For arrays, this is negative and provides log2 of the
  // array element size.  For other oops, it is zero and thus requires
  // a virtual call.
  //
  // We go to all this trouble because the size computation is at the
  // heart of phase 2 of mark-compaction, and called for every object,
  // alive or dead.  So the speed here is equal in importance to the
  // speed of allocation.

  if (lh > Klass::_lh_neutral_value) {
    if (!Klass::layout_helper_needs_slow_path(lh)) {
      s = lh >> LogHeapWordSize;  // deliver size scaled by wordSize
    } else {
      s = klass->oop_size(this);
    }
  } else if (lh <= Klass::_lh_neutral_value) {
    // The most common case is instances; fall through if so.
    if (lh < Klass::_lh_neutral_value) {
      // Second most common case is arrays.  We have to fetch the
      // length of the array, shift (multiply) it appropriately,
      // up to wordSize, add the header, and align to object size.
      size_t size_in_bytes;
      size_t array_length = (size_t) ((arrayOop)this)->length();
      size_in_bytes = array_length << Klass::layout_helper_log2_element_size(lh);
      size_in_bytes += Klass::layout_helper_header_size(lh);

      // This code could be simplified, but by keeping array_header_in_bytes
      // in units of bytes and doing it this way we can round up just once,
      // skipping the intermediate round to HeapWordSize.
      s = (int)(align_up(size_in_bytes, MinObjAlignmentInBytes) / HeapWordSize);

      // ParNew (used by CMS), UseParallelGC and UseG1GC can change the length field
      // of an "old copy" of an object array in the young gen so it indicates
      // the grey portion of an already copied array. This will cause the first
      // disjunct below to fail if the two comparands are computed across such
      // a concurrent change.
      // ParNew also runs with promotion labs (which look like int
      // filler arrays) which are subject to changing their declared size
      // when finally retiring a PLAB; this also can cause the first disjunct
      // to fail for another worker thread that is concurrently walking the block
      // offset table. Both these invariant failures are benign for their
      // current uses; we relax the assertion checking to cover these two cases below:
      //     is_objArray() && is_forwarded()   // covers first scenario above
      //  || is_typeArray()                    // covers second scenario above
      // If and when UseParallelGC uses the same obj array oop stealing/chunking
      // technique, we will need to suitably modify the assertion.
      assert((s == klass->oop_size(this)) ||
             (Universe::heap()->is_gc_active() &&
              ((is_typeArray() && UseConcMarkSweepGC) ||
               (is_objArray()  && is_forwarded() && (UseConcMarkSweepGC || UseParallelGC || UseG1GC)))),
             "wrong array object size");
    } else {
      // Must be zero, so bite the bullet and take the virtual call.
      s = klass->oop_size(this);
    }
  }

  assert(s > 0, "Oop size must be greater than zero, not %d", s);
  assert(is_object_aligned(s), "Oop size is not properly aligned: %d", s);
  return s;
}

bool oopDesc::is_instance()  const { return klass()->is_instance_klass();  }
bool oopDesc::is_array()     const { return klass()->is_array_klass();     }
bool oopDesc::is_objArray()  const { return klass()->is_objArray_klass();  }
bool oopDesc::is_typeArray() const { return klass()->is_typeArray_klass(); }

void*    oopDesc::field_addr_raw(int offset)     const { return reinterpret_cast<void*>(cast_from_oop<intptr_t>(as_oop()) + offset); }
void*    oopDesc::field_addr(int offset)         const { return Access<>::resolve(as_oop())->field_addr_raw(offset); }

template <class T>
T*       oopDesc::obj_field_addr_raw(int offset) const { return (T*) field_addr_raw(offset); }

template <typename T>
size_t   oopDesc::field_offset(T* p) const { return pointer_delta((void*)p, (void*)this, 1); }

template <DecoratorSet decorators>
inline oop  oopDesc::obj_field_access(int offset) const             { return HeapAccess<decorators>::oop_load_at(as_oop(), offset); }
inline oop  oopDesc::obj_field(int offset) const                    { return HeapAccess<>::oop_load_at(as_oop(), offset);  }

inline void oopDesc::obj_field_put(int offset, oop value)           { HeapAccess<>::oop_store_at(as_oop(), offset, value); }

inline jbyte oopDesc::byte_field(int offset) const                  { return HeapAccess<>::load_at(as_oop(), offset);  }
inline void  oopDesc::byte_field_put(int offset, jbyte value)       { HeapAccess<>::store_at(as_oop(), offset, value); }

inline jchar oopDesc::char_field(int offset) const                  { return HeapAccess<>::load_at(as_oop(), offset);  }
inline void  oopDesc::char_field_put(int offset, jchar value)       { HeapAccess<>::store_at(as_oop(), offset, value); }

inline jboolean oopDesc::bool_field(int offset) const               { return HeapAccess<>::load_at(as_oop(), offset);                }
inline void     oopDesc::bool_field_put(int offset, jboolean value) { HeapAccess<>::store_at(as_oop(), offset, jboolean(value & 1)); }

inline jshort oopDesc::short_field(int offset) const                { return HeapAccess<>::load_at(as_oop(), offset);  }
inline void   oopDesc::short_field_put(int offset, jshort value)    { HeapAccess<>::store_at(as_oop(), offset, value); }

inline jint oopDesc::int_field(int offset) const                    { return HeapAccess<>::load_at(as_oop(), offset);  }
inline void oopDesc::int_field_put(int offset, jint value)          { HeapAccess<>::store_at(as_oop(), offset, value); }

inline jlong oopDesc::long_field(int offset) const                  { return HeapAccess<>::load_at(as_oop(), offset);  }
inline void  oopDesc::long_field_put(int offset, jlong value)       { HeapAccess<>::store_at(as_oop(), offset, value); }

inline jfloat oopDesc::float_field(int offset) const                { return HeapAccess<>::load_at(as_oop(), offset);  }
inline void   oopDesc::float_field_put(int offset, jfloat value)    { HeapAccess<>::store_at(as_oop(), offset, value); }

inline jdouble oopDesc::double_field(int offset) const              { return HeapAccess<>::load_at(as_oop(), offset);  }
inline void    oopDesc::double_field_put(int offset, jdouble value) { HeapAccess<>::store_at(as_oop(), offset, value); }

bool oopDesc::is_locked() const {
  return mark().is_locked();
}

bool oopDesc::is_unlocked() const {
  return mark().is_unlocked();
}

bool oopDesc::has_bias_pattern() const {
  return mark().has_bias_pattern();
}

bool oopDesc::has_bias_pattern_raw() const {
  return mark_raw().has_bias_pattern();
}

// Used only for markSweep, scavenging
bool oopDesc::is_gc_marked() const {
  return mark_raw().is_marked();
}

// Used by scavengers
bool oopDesc::is_forwarded() const {
  // The extra heap check is needed since the obj might be locked, in which case the
  // mark would point to a stack location and have the sentinel bit cleared
  return mark_raw().is_marked();
}

// Used by scavengers
void oopDesc::forward_to(oop p) {
  assert(check_obj_alignment(p),
         "forwarding to something not aligned");
  assert(Universe::heap()->is_in_reserved(p),
         "forwarding to something not in heap");
  assert(!MetaspaceShared::is_archive_object(oop(this)) &&
         !MetaspaceShared::is_archive_object(p),
         "forwarding archive object");
  markOop m = markOop::encode_pointer_as_mark(p);
  assert(m.decode_pointer() == p, "encoding must be reversable");
  set_mark_raw(m);
}

// Used by parallel scavengers
bool oopDesc::cas_forward_to(oop p, markOop compare, atomic_memory_order order) {
  assert(check_obj_alignment(p),
         "forwarding to something not aligned");
  assert(Universe::heap()->is_in_reserved(p),
         "forwarding to something not in heap");
  markOop m = markOop::encode_pointer_as_mark(p);
  assert(m.decode_pointer() == p, "encoding must be reversable");
  return cas_set_mark_raw(m, compare, order) == compare;
}

oop oopDesc::forward_to_atomic(oop p, atomic_memory_order order) {
  markOop oldMark = mark_raw();
  markOop forwardPtrMark = markOop::encode_pointer_as_mark(p);
  markOop curMark;

  assert(forwardPtrMark.decode_pointer() == p, "encoding must be reversable");
  assert(sizeof(markOop) == sizeof(intptr_t), "CAS below requires this.");

  while (!oldMark.is_marked()) {
    curMark = cas_set_mark_raw(forwardPtrMark, oldMark, order);
    assert(is_forwarded(), "object should have been forwarded");
    if (curMark == oldMark) {
      return NULL;
    }
    // If the CAS was unsuccessful then curMark->is_marked()
    // should return true as another thread has CAS'd in another
    // forwarding pointer.
    oldMark = curMark;
  }
  return forwardee();
}

// Note that the forwardee is not the same thing as the displaced_mark.
// The forwardee is used when copying during scavenge and mark-sweep.
// It does need to clear the low two locking- and GC-related bits.
oop oopDesc::forwardee() const {
  return (oop) mark_raw().decode_pointer();
}

// Note that the forwardee is not the same thing as the displaced_mark.
// The forwardee is used when copying during scavenge and mark-sweep.
// It does need to clear the low two locking- and GC-related bits.
oop oopDesc::forwardee_acquire() const {
  return (oop) OrderAccess::load_acquire(&_mark).decode_pointer();
}

// The following method needs to be MT safe.
uint oopDesc::age() const {
  assert(!is_forwarded(), "Attempt to read age from forwarded mark");
  if (has_displaced_mark_raw()) {
    return displaced_mark_raw().age();
  } else {
    return mark_raw().age();
  }
}

void oopDesc::incr_age() {
  assert(!is_forwarded(), "Attempt to increment age of forwarded mark");
  if (has_displaced_mark_raw()) {
    set_displaced_mark_raw(displaced_mark_raw().incr_age());
  } else {
    set_mark_raw(mark_raw().incr_age());
  }
}

#if INCLUDE_PARALLELGC
void oopDesc::pc_follow_contents(ParCompactionManager* cm) {
  klass()->oop_pc_follow_contents(this, cm);
}

void oopDesc::pc_update_contents(ParCompactionManager* cm) {
  Klass* k = klass();
  if (!k->is_typeArray_klass()) {
    // It might contain oops beyond the header, so take the virtual call.
    k->oop_pc_update_pointers(this, cm);
  }
  // Else skip it.  The TypeArrayKlass in the header never needs scavenging.
}

void oopDesc::ps_push_contents(PSPromotionManager* pm) {
  Klass* k = klass();
  if (!k->is_typeArray_klass()) {
    // It might contain oops beyond the header, so take the virtual call.
    k->oop_ps_push_contents(this, pm);
  }
  // Else skip it.  The TypeArrayKlass in the header never needs scavenging.
}
#endif // INCLUDE_PARALLELGC

template <typename OopClosureType>
void oopDesc::oop_iterate(OopClosureType* cl) {
  OopIteratorClosureDispatch::oop_oop_iterate(cl, this, klass());
}

template <typename OopClosureType>
void oopDesc::oop_iterate(OopClosureType* cl, MemRegion mr) {
  OopIteratorClosureDispatch::oop_oop_iterate(cl, this, klass(), mr);
}

template <typename OopClosureType>
int oopDesc::oop_iterate_size(OopClosureType* cl) {
  Klass* k = klass();
  int size = size_given_klass(k);
  OopIteratorClosureDispatch::oop_oop_iterate(cl, this, k);
  return size;
}

template <typename OopClosureType>
int oopDesc::oop_iterate_size(OopClosureType* cl, MemRegion mr) {
  Klass* k = klass();
  int size = size_given_klass(k);
  OopIteratorClosureDispatch::oop_oop_iterate(cl, this, k, mr);
  return size;
}

template <typename OopClosureType>
void oopDesc::oop_iterate_backwards(OopClosureType* cl) {
  OopIteratorClosureDispatch::oop_oop_iterate_backwards(cl, this, klass());
}

bool oopDesc::is_instanceof_or_null(oop obj, Klass* klass) {
  return obj == NULL || obj->klass()->is_subtype_of(klass);
}

intptr_t oopDesc::identity_hash() {
  // Fast case; if the object is unlocked and the hash value is set, no locking is needed
  // Note: The mark must be read into local variable to avoid concurrent updates.
  markOop mrk = mark();
  if (mrk.is_unlocked() && !mrk.has_no_hash()) {
    return mrk.hash();
  } else if (mrk.is_marked()) {
    return mrk.hash();
  } else {
    return slow_identity_hash();
  }
}

bool oopDesc::has_displaced_mark_raw() const {
  return mark_raw().has_displaced_mark_helper();
}

markOop oopDesc::displaced_mark_raw() const {
  return mark_raw().displaced_mark_helper();
}

void oopDesc::set_displaced_mark_raw(markOop m) {
  mark_raw().set_displaced_mark_helper(m);
}

#endif // SHARE_VM_OOPS_OOP_INLINE_HPP