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// --------
// unused:22 hash:31 -->| unused_gap:4 age:4 self-fwd:1 lock:2 (normal object)
//
// 64 bits (with compact headers):
// -------------------------------
! // klass:22 hash:31 -->| unused_gap:4 age:4 self-fwd:1 lock:2 (normal object)
//
// - hash contains the identity hash value: largest value is
// 31 bits, see os::random(). Also, 64-bit vm's require
// a hash value no bigger than 32 bits because they will not
// properly generate a mask larger than that: see library_call.cpp
//
// - the two lock bits are used to describe three states: locked/unlocked and monitor.
//
// [ptr | 00] locked ptr points to real header on stack (stack-locking in use)
// [header | 00] locked locked regular object header (fast-locking in use)
// [header | 01] unlocked regular object header
// --------
// unused:22 hash:31 -->| unused_gap:4 age:4 self-fwd:1 lock:2 (normal object)
//
// 64 bits (with compact headers):
// -------------------------------
! // klass:22 unused_gap:29 hash:2 -->| unused_gap:4 age:4 self-fwd:1 lock:2 (normal object)
//
// - hash contains the identity hash value: largest value is
// 31 bits, see os::random(). Also, 64-bit vm's require
// a hash value no bigger than 32 bits because they will not
// properly generate a mask larger than that: see library_call.cpp
//
+ // - With +UseCompactObjectHeaders:
+ // hashctrl bits indicate if object has been hashed:
+ // 00 - never hashed
+ // 01 - hashed, but not expanded by GC: will recompute hash
+ // 10 - not hashed, but expanded; special state used only by CDS to deal with scratch classes
+ // 11 - hashed and expanded by GC, and hashcode has been installed in hidden field
+ //
+ // When identityHashCode() is called, the transitions work as follows:
+ // 00 - set the hashctrl bits to 01, and compute the identity hash
+ // 01 - recompute idendity hash. When GC encounters 01 when moving an object, it will allocate an extra word, if
+ // necessary, for the object copy, and install 11.
+ // 11 - read hashcode from field
+ //
// - the two lock bits are used to describe three states: locked/unlocked and monitor.
//
// [ptr | 00] locked ptr points to real header on stack (stack-locking in use)
// [header | 00] locked locked regular object header (fast-locking in use)
// [header | 01] unlocked regular object header
return !operator==(other);
}
// Conversion
uintptr_t value() const { return _value; }
// Constants
static const int age_bits = 4;
static const int lock_bits = 2;
static const int self_fwd_bits = 1;
static const int max_hash_bits = BitsPerWord - age_bits - lock_bits - self_fwd_bits;
static const int hash_bits = max_hash_bits > 31 ? 31 : max_hash_bits;
static const int unused_gap_bits = LP64_ONLY(4) NOT_LP64(0); // Reserved for Valhalla.
static const int lock_shift = 0;
static const int self_fwd_shift = lock_shift + lock_bits;
static const int age_shift = self_fwd_shift + self_fwd_bits;
static const int hash_shift = age_shift + age_bits + unused_gap_bits;
static const uintptr_t lock_mask = right_n_bits(lock_bits);
static const uintptr_t lock_mask_in_place = lock_mask << lock_shift;
static const uintptr_t self_fwd_mask = right_n_bits(self_fwd_bits);
static const uintptr_t self_fwd_mask_in_place = self_fwd_mask << self_fwd_shift;
static const uintptr_t age_mask = right_n_bits(age_bits);
static const uintptr_t age_mask_in_place = age_mask << age_shift;
static const uintptr_t hash_mask = right_n_bits(hash_bits);
static const uintptr_t hash_mask_in_place = hash_mask << hash_shift;
#ifdef _LP64
// Used only with compact headers:
// We store the (narrow) Klass* in the bits 43 to 64.
// These are for bit-precise extraction of the narrow Klass* from the 64-bit Markword
! static constexpr int klass_offset_in_bytes = 4;
! static constexpr int klass_shift = hash_shift + hash_bits;
- static constexpr int klass_shift_at_offset = klass_shift - klass_offset_in_bytes * BitsPerByte;
- static constexpr int klass_bits = 22;
static constexpr uintptr_t klass_mask = right_n_bits(klass_bits);
static constexpr uintptr_t klass_mask_in_place = klass_mask << klass_shift;
#endif
static const uintptr_t locked_value = 0;
static const uintptr_t unlocked_value = 1;
static const uintptr_t monitor_value = 2;
static const uintptr_t marked_value = 3;
static const uintptr_t no_hash = 0 ; // no hash value assigned
static const uintptr_t no_hash_in_place = (uintptr_t)no_hash << hash_shift;
static const uintptr_t no_lock_in_place = unlocked_value;
return !operator==(other);
}
// Conversion
uintptr_t value() const { return _value; }
+ uint32_t value32() const { return (uint32_t)_value; }
// Constants
static const int age_bits = 4;
static const int lock_bits = 2;
static const int self_fwd_bits = 1;
static const int max_hash_bits = BitsPerWord - age_bits - lock_bits - self_fwd_bits;
static const int hash_bits = max_hash_bits > 31 ? 31 : max_hash_bits;
static const int unused_gap_bits = LP64_ONLY(4) NOT_LP64(0); // Reserved for Valhalla.
+ static const int hashctrl_bits = 2;
static const int lock_shift = 0;
static const int self_fwd_shift = lock_shift + lock_bits;
static const int age_shift = self_fwd_shift + self_fwd_bits;
static const int hash_shift = age_shift + age_bits + unused_gap_bits;
+ static const int hashctrl_shift = age_shift + age_bits + unused_gap_bits;
static const uintptr_t lock_mask = right_n_bits(lock_bits);
static const uintptr_t lock_mask_in_place = lock_mask << lock_shift;
static const uintptr_t self_fwd_mask = right_n_bits(self_fwd_bits);
static const uintptr_t self_fwd_mask_in_place = self_fwd_mask << self_fwd_shift;
static const uintptr_t age_mask = right_n_bits(age_bits);
static const uintptr_t age_mask_in_place = age_mask << age_shift;
static const uintptr_t hash_mask = right_n_bits(hash_bits);
static const uintptr_t hash_mask_in_place = hash_mask << hash_shift;
+ static const uintptr_t hashctrl_mask = right_n_bits(hashctrl_bits);
+ static const uintptr_t hashctrl_mask_in_place = hashctrl_mask << hashctrl_shift;
+ static const uintptr_t hashctrl_hashed_mask_in_place = ((uintptr_t)1) << hashctrl_shift;
+ static const uintptr_t hashctrl_expanded_mask_in_place = ((uintptr_t)2) << hashctrl_shift;
#ifdef _LP64
// Used only with compact headers:
// We store the (narrow) Klass* in the bits 43 to 64.
// These are for bit-precise extraction of the narrow Klass* from the 64-bit Markword
! static constexpr int klass_shift = hashctrl_shift + hashctrl_bits;
! static constexpr int klass_bits = 19;
static constexpr uintptr_t klass_mask = right_n_bits(klass_bits);
static constexpr uintptr_t klass_mask_in_place = klass_mask << klass_shift;
#endif
static const uintptr_t locked_value = 0;
static const uintptr_t unlocked_value = 1;
static const uintptr_t monitor_value = 2;
static const uintptr_t marked_value = 3;
+ static const uintptr_t forward_expanded_value = 0b111;
static const uintptr_t no_hash = 0 ; // no hash value assigned
static const uintptr_t no_hash_in_place = (uintptr_t)no_hash << hash_shift;
static const uintptr_t no_lock_in_place = unlocked_value;
}
bool is_unlocked() const {
return (mask_bits(value(), lock_mask_in_place) == unlocked_value);
}
bool is_marked() const {
! return (mask_bits(value(), lock_mask_in_place) == marked_value);
}
bool is_forwarded() const {
// Returns true for normal forwarded (0b011) and self-forwarded (0b1xx).
return mask_bits(value(), lock_mask_in_place | self_fwd_mask_in_place) >= static_cast<intptr_t>(marked_value);
}
bool is_neutral() const { // Not locked, or marked - a "clean" neutral state
return (mask_bits(value(), lock_mask_in_place) == unlocked_value);
}
// Special temporary state of the markWord while being inflated.
// Code that looks at mark outside a lock need to take this into account.
bool is_being_inflated() const { return (value() == 0); }
// Distinguished markword value - used when inflating over
}
bool is_unlocked() const {
return (mask_bits(value(), lock_mask_in_place) == unlocked_value);
}
bool is_marked() const {
! return (value() & (self_fwd_mask_in_place | lock_mask_in_place)) > monitor_value;
}
bool is_forwarded() const {
// Returns true for normal forwarded (0b011) and self-forwarded (0b1xx).
return mask_bits(value(), lock_mask_in_place | self_fwd_mask_in_place) >= static_cast<intptr_t>(marked_value);
}
bool is_neutral() const { // Not locked, or marked - a "clean" neutral state
return (mask_bits(value(), lock_mask_in_place) == unlocked_value);
}
+ markWord set_forward_expanded() {
+ assert((value() & (lock_mask_in_place | self_fwd_mask_in_place)) == marked_value, "must be normal-forwarded here");
+ return markWord(value() | forward_expanded_value);
+ }
+ bool is_forward_expanded() {
+ return (value() & (lock_mask_in_place | self_fwd_mask_in_place)) == forward_expanded_value;
+ }
+
// Special temporary state of the markWord while being inflated.
// Code that looks at mark outside a lock need to take this into account.
bool is_being_inflated() const { return (value() == 0); }
// Distinguished markword value - used when inflating over
// Fast-locking does not use INFLATING.
static markWord INFLATING() { return zero(); } // inflate-in-progress
// Should this header be preserved during GC?
bool must_be_preserved() const {
! return (!is_unlocked() || !has_no_hash());
}
// WARNING: The following routines are used EXCLUSIVELY by
// synchronization functions. They are not really gc safe.
// They must get updated if markWord layout get changed.
// Fast-locking does not use INFLATING.
static markWord INFLATING() { return zero(); } // inflate-in-progress
// Should this header be preserved during GC?
bool must_be_preserved() const {
! return UseCompactObjectHeaders ? !is_unlocked() : (!is_unlocked() || !has_no_hash());
}
// WARNING: The following routines are used EXCLUSIVELY by
// synchronization functions. They are not really gc safe.
// They must get updated if markWord layout get changed.
return (lockbits & unlocked_value) == 0;
}
markWord displaced_mark_helper() const;
void set_displaced_mark_helper(markWord m) const;
markWord copy_set_hash(intptr_t hash) const {
+ assert(!UseCompactObjectHeaders, "Do not use with compact i-hash");
uintptr_t tmp = value() & (~hash_mask_in_place);
tmp |= ((hash & hash_mask) << hash_shift);
return markWord(tmp);
}
// it is only used to be stored into BasicLock as the
markWord set_has_monitor() const {
return markWord((value() & ~lock_mask_in_place) | monitor_value);
}
// used to encode pointers during GC
! markWord clear_lock_bits() const { return markWord(value() & ~lock_mask_in_place); }
// age operations
markWord set_marked() { return markWord((value() & ~lock_mask_in_place) | marked_value); }
markWord set_unmarked() { return markWord((value() & ~lock_mask_in_place) | unlocked_value); }
markWord set_has_monitor() const {
return markWord((value() & ~lock_mask_in_place) | monitor_value);
}
// used to encode pointers during GC
! markWord clear_lock_bits() const { return markWord(value() & ~(lock_mask_in_place | self_fwd_mask_in_place)); }
// age operations
markWord set_marked() { return markWord((value() & ~lock_mask_in_place) | marked_value); }
markWord set_unmarked() { return markWord((value() & ~lock_mask_in_place) | unlocked_value); }
}
markWord incr_age() const { return age() == max_age ? markWord(_value) : set_age(age() + 1); }
// hash operations
intptr_t hash() const {
return mask_bits(value() >> hash_shift, hash_mask);
}
bool has_no_hash() const {
! return hash() == no_hash;
}
inline Klass* klass() const;
inline Klass* klass_or_null() const;
inline Klass* klass_without_asserts() const;
inline narrowKlass narrow_klass() const;
inline markWord set_narrow_klass(narrowKlass narrow_klass) const;
// Prototype mark for initialization
static markWord prototype() {
! return markWord( no_hash_in_place | no_lock_in_place );
}
// Debugging
void print_on(outputStream* st, bool print_monitor_info = true) const;
}
markWord incr_age() const { return age() == max_age ? markWord(_value) : set_age(age() + 1); }
// hash operations
intptr_t hash() const {
+ assert(!UseCompactObjectHeaders, "only without compact i-hash");
return mask_bits(value() >> hash_shift, hash_mask);
}
bool has_no_hash() const {
! if (UseCompactObjectHeaders) {
+ return !is_hashed();
+ } else {
+ return hash() == no_hash;
+ }
+ }
+
+ inline bool is_hashed_not_expanded() const {
+ assert(UseCompactObjectHeaders, "only with compact i-hash");
+ return (value() & hashctrl_mask_in_place) == hashctrl_hashed_mask_in_place;
+ }
+ inline markWord set_hashed_not_expanded() const {
+ assert(UseCompactObjectHeaders, "only with compact i-hash");
+ return markWord((value() & ~hashctrl_mask_in_place) | hashctrl_hashed_mask_in_place);
+ }
+
+ inline bool is_hashed_expanded() const {
+ assert(UseCompactObjectHeaders, "only with compact i-hash");
+ return (value() & hashctrl_mask_in_place) == (hashctrl_hashed_mask_in_place | hashctrl_expanded_mask_in_place);
+ }
+ inline markWord set_hashed_expanded() const {
+ assert(UseCompactObjectHeaders, "only with compact i-hash");
+ return markWord((value() & ~hashctrl_mask_in_place) | (hashctrl_hashed_mask_in_place | hashctrl_expanded_mask_in_place));
+ }
+
+ // This is a special hashctrl state (11) that is only used
+ // during CDS archive dumping. There we allocate 'scratch mirrors' for
+ // each real mirror klass. We allocate those scratch mirrors
+ // in a pre-extended form, but without being hashed. When the
+ // real mirror gets hashed, then we turn the scratch mirror into
+ // hashed_moved state, otherwise we leave it in that special state
+ // which indicates that the archived copy will be allocated in the
+ // unhashed form.
+ inline bool is_not_hashed_expanded() const {
+ assert(UseCompactObjectHeaders, "only with compact i-hash");
+ return (value() & hashctrl_mask_in_place) == hashctrl_expanded_mask_in_place;
+ }
+ inline markWord set_not_hashed_expanded() const {
+ assert(UseCompactObjectHeaders, "only with compact i-hash");
+ return markWord((value() & ~hashctrl_mask_in_place) | hashctrl_expanded_mask_in_place);
+ }
+ // Return true when object is either hashed_moved or not_hashed_moved.
+ inline bool is_expanded() const {
+ assert(UseCompactObjectHeaders, "only with compact i-hash");
+ return (value() & hashctrl_expanded_mask_in_place) != 0;
+ }
+ inline bool is_hashed() const {
+ assert(UseCompactObjectHeaders, "only with compact i-hash");
+ return (value() & hashctrl_hashed_mask_in_place) != 0;
+ }
+
+ inline markWord copy_hashctrl_from(markWord m) const {
+ if (UseCompactObjectHeaders) {
+ return markWord((value() & ~hashctrl_mask_in_place) | (m.value() & hashctrl_mask_in_place));
+ } else {
+ return markWord(value());
+ }
}
inline Klass* klass() const;
inline Klass* klass_or_null() const;
inline Klass* klass_without_asserts() const;
inline narrowKlass narrow_klass() const;
inline markWord set_narrow_klass(narrowKlass narrow_klass) const;
+ #ifdef _LP64
+ inline int array_length() { return checked_cast<int>(value() >> 32); }
+ #endif
+
// Prototype mark for initialization
static markWord prototype() {
! if (UseCompactObjectHeaders) {
+ return markWord(no_lock_in_place);
+ } else {
+ return markWord(no_hash_in_place | no_lock_in_place);
+ }
}
// Debugging
void print_on(outputStream* st, bool print_monitor_info = true) const;
// Recover address of oop from encoded form used in mark
inline void* decode_pointer() const { return (void*)clear_lock_bits().value(); }
inline bool is_self_forwarded() const {
NOT_LP64(assert(LockingMode != LM_LEGACY, "incorrect with LM_LEGACY on 32 bit");)
! return mask_bits(value(), self_fwd_mask_in_place) != 0;
}
inline markWord set_self_forwarded() const {
NOT_LP64(assert(LockingMode != LM_LEGACY, "incorrect with LM_LEGACY on 32 bit");)
return markWord(value() | self_fwd_mask_in_place);
// Recover address of oop from encoded form used in mark
inline void* decode_pointer() const { return (void*)clear_lock_bits().value(); }
inline bool is_self_forwarded() const {
NOT_LP64(assert(LockingMode != LM_LEGACY, "incorrect with LM_LEGACY on 32 bit");)
! // Match 100, 101, 110 but not 111.
+ return mask_bits(value() + 1, (lock_mask_in_place | self_fwd_mask_in_place)) > 4;
}
inline markWord set_self_forwarded() const {
NOT_LP64(assert(LockingMode != LM_LEGACY, "incorrect with LM_LEGACY on 32 bit");)
return markWord(value() | self_fwd_mask_in_place);
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