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*/
#ifndef SHARE_OOPS_MARKWORD_HPP
#define SHARE_OOPS_MARKWORD_HPP
+ #include "gc/shared/gc_globals.hpp"
#include "metaprogramming/integralConstant.hpp"
#include "metaprogramming/primitiveConversions.hpp"
#include "oops/oopsHierarchy.hpp"
#include "runtime/globals.hpp"
// 64 bits:
// --------
// unused:25 hash:31 -->| unused_gap:1 age:4 biased_lock:1 lock:2 (normal object)
// JavaThread*:54 epoch:2 unused_gap:1 age:4 biased_lock:1 lock:2 (biased object)
//
+ // 64 bits (with compact headers):
+ // -------------------------------
+ // nklass:32 hash:25 -->| unused_gap:1 age:4 self-fwded: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
// [header | 0 | 01] unlocked regular object header
! // [ptr | 10] monitor inflated lock (header is wapped out)
// [ptr | 11] marked used to mark an object
! // [0 ............ 0| 00] inflating inflation in progress
//
// We assume that stack/thread pointers have the lowest two bits cleared.
//
// - INFLATING() is a distinguished markword value of all zeros that is
// used when inflating an existing stack-lock into an ObjectMonitor.
// See below for is_being_inflated() and INFLATING().
class BasicLock;
class ObjectMonitor;
class JavaThread;
class outputStream;
class markWord {
private:
uintptr_t _value;
//
// - the two lock bits are used to describe three states: locked/unlocked and monitor.
//
// [ptr | 00] locked ptr points to real header on stack
// [header | 0 | 01] unlocked regular object header
! // [ptr | 10] monitor inflated lock (header is swapped out)
// [ptr | 11] marked used to mark an object
! // [0 ............ 0| 00] inflating inflation in progress (stack-locking in use)
//
// We assume that stack/thread pointers have the lowest two bits cleared.
//
// - INFLATING() is a distinguished markword value of all zeros that is
// used when inflating an existing stack-lock into an ObjectMonitor.
// See below for is_being_inflated() and INFLATING().
class BasicLock;
class ObjectMonitor;
class JavaThread;
+ class Klass;
class outputStream;
class markWord {
private:
uintptr_t _value;
// Constants
static const int age_bits = 4;
static const int lock_bits = 2;
static const int biased_lock_bits = 1;
! static const int max_hash_bits = BitsPerWord - age_bits - lock_bits - biased_lock_bits;
static const int hash_bits = max_hash_bits > 31 ? 31 : max_hash_bits;
static const int unused_gap_bits = LP64_ONLY(1) NOT_LP64(0);
static const int epoch_bits = 2;
// The biased locking code currently requires that the age bits be
// contiguous to the lock bits.
static const int lock_shift = 0;
static const int biased_lock_shift = lock_bits;
! static const int age_shift = lock_bits + biased_lock_bits;
static const int unused_gap_shift = age_shift + age_bits;
static const int hash_shift = unused_gap_shift + unused_gap_bits;
static const int epoch_shift = hash_shift;
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 biased_lock_mask = right_n_bits(lock_bits + biased_lock_bits);
static const uintptr_t biased_lock_mask_in_place= biased_lock_mask << lock_shift;
static const uintptr_t biased_lock_bit_in_place = 1 << biased_lock_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 epoch_mask = right_n_bits(epoch_bits);
static const uintptr_t epoch_mask_in_place = epoch_mask << epoch_shift;
static const uintptr_t hash_mask = right_n_bits(hash_bits);
static const uintptr_t hash_mask_in_place = hash_mask << hash_shift;
// Alignment of JavaThread pointers encoded in object header required by biased locking
static const size_t biased_lock_alignment = 2 << (epoch_shift + epoch_bits);
static const uintptr_t locked_value = 0;
// Constants
static const int age_bits = 4;
static const int lock_bits = 2;
static const int biased_lock_bits = 1;
! static const int self_forwarded_bits = 1;
+ static const int max_hash_bits = BitsPerWord - age_bits - lock_bits - self_forwarded_bits;
static const int hash_bits = max_hash_bits > 31 ? 31 : max_hash_bits;
+ static const int hash_bits_compact = max_hash_bits > 25 ? 25 : max_hash_bits;
+ // Used only without compact headers.
static const int unused_gap_bits = LP64_ONLY(1) NOT_LP64(0);
static const int epoch_bits = 2;
+ #ifdef _LP64
+ // Used only with compact headers.
+ static const int klass_bits = 32;
+ #endif
// The biased locking code currently requires that the age bits be
// contiguous to the lock bits.
static const int lock_shift = 0;
static const int biased_lock_shift = lock_bits;
! static const int self_forwarded_shift = lock_shift + lock_bits;
+ static const int age_shift = self_forwarded_shift + self_forwarded_bits;
static const int unused_gap_shift = age_shift + age_bits;
static const int hash_shift = unused_gap_shift + unused_gap_bits;
+ static const int hash_shift_compact = age_shift + age_bits;
+ #ifdef _LP64
+ // Used only with compact headers.
+ static const int klass_shift = hash_shift_compact + hash_bits_compact;
+ #endif
static const int epoch_shift = hash_shift;
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 biased_lock_mask = right_n_bits(lock_bits + biased_lock_bits);
static const uintptr_t biased_lock_mask_in_place= biased_lock_mask << lock_shift;
static const uintptr_t biased_lock_bit_in_place = 1 << biased_lock_shift;
+ static const uintptr_t self_forwarded_mask = right_n_bits(self_forwarded_bits);
+ static const uintptr_t self_forwarded_mask_in_place = self_forwarded_mask << self_forwarded_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 epoch_mask = right_n_bits(epoch_bits);
static const uintptr_t epoch_mask_in_place = epoch_mask << epoch_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 hash_mask_compact = right_n_bits(hash_bits_compact);
+ static const uintptr_t hash_mask_compact_in_place = hash_mask_compact << hash_shift_compact;
+
+ #ifdef _LP64
+ static const uintptr_t klass_mask = right_n_bits(klass_bits);
+ static const uintptr_t klass_mask_in_place = klass_mask << klass_shift;
+ #endif
// Alignment of JavaThread pointers encoded in object header required by biased locking
static const size_t biased_lock_alignment = 2 << (epoch_shift + epoch_bits);
static const uintptr_t locked_value = 0;
// an existing stack-lock. 0 indicates the markword is "BUSY".
// Lockword mutators that use a LD...CAS idiom should always
// check for and avoid overwriting a 0 value installed by some
// other thread. (They should spin or block instead. The 0 value
// is transient and *should* be short-lived).
+ // Fast-locking does not use INFLATING.
static markWord INFLATING() { return zero(); } // inflate-in-progress
// Should this header be preserved during GC?
inline bool must_be_preserved(const oopDesc* obj) const;
// They must get updated if markWord layout get changed.
markWord set_unlocked() const {
return markWord(value() | unlocked_value);
}
bool has_locker() const {
! return ((value() & lock_mask_in_place) == locked_value);
}
BasicLock* locker() const {
assert(has_locker(), "check");
return (BasicLock*) value();
}
bool has_monitor() const {
return ((value() & monitor_value) != 0);
}
ObjectMonitor* monitor() const {
assert(has_monitor(), "check");
// Use xor instead of &~ to provide one extra tag-bit check.
return (ObjectMonitor*) (value() ^ monitor_value);
}
bool has_displaced_mark_helper() const {
! return ((value() & unlocked_value) == 0);
}
markWord displaced_mark_helper() const;
void set_displaced_mark_helper(markWord m) const;
markWord copy_set_hash(intptr_t hash) const {
! 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
// indicator that the lock is using heavyweight monitor
static markWord unused_mark() {
return markWord(marked_value);
// They must get updated if markWord layout get changed.
markWord set_unlocked() const {
return markWord(value() | unlocked_value);
}
bool has_locker() const {
! assert(LockingMode == LM_LEGACY, "should only be called with legacy stack locking");
+ return (value() & lock_mask_in_place) == locked_value;
}
BasicLock* locker() const {
assert(has_locker(), "check");
return (BasicLock*) value();
}
+
+ bool is_fast_locked() const {
+ assert(LockingMode == LM_LIGHTWEIGHT, "should only be called with new lightweight locking");
+ return (value() & lock_mask_in_place) == locked_value;
+ }
+ markWord set_fast_locked() const {
+ return markWord(value() & ~lock_mask_in_place);
+ }
+
bool has_monitor() const {
return ((value() & monitor_value) != 0);
}
ObjectMonitor* monitor() const {
assert(has_monitor(), "check");
// Use xor instead of &~ to provide one extra tag-bit check.
return (ObjectMonitor*) (value() ^ monitor_value);
}
bool has_displaced_mark_helper() const {
! intptr_t lockbits = value() & lock_mask_in_place;
+ return LockingMode == LM_LIGHTWEIGHT ? lockbits == monitor_value // monitor?
+ : (lockbits & unlocked_value) == 0; // monitor | stack-locked?
}
markWord displaced_mark_helper() const;
void set_displaced_mark_helper(markWord m) const;
markWord copy_set_hash(intptr_t hash) const {
! if (UseCompactObjectHeaders) {
! uintptr_t tmp = value() & (~hash_mask_compact_in_place);
! tmp |= ((hash & hash_mask_compact) << hash_shift_compact);
+ return markWord(tmp);
+ } else {
+ 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
// indicator that the lock is using heavyweight monitor
static markWord unused_mark() {
return markWord(marked_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;
}
// Prototype mark for initialization
static markWord prototype() {
return markWord( no_hash_in_place | no_lock_in_place );
}
}
markWord incr_age() const { return age() == max_age ? markWord(_value) : set_age(age() + 1); }
// hash operations
intptr_t hash() const {
! if (UseCompactObjectHeaders) {
+ return mask_bits(value() >> hash_shift_compact, hash_mask_compact);
+ } else {
+ return mask_bits(value() >> hash_shift, hash_mask);
+ }
}
bool has_no_hash() const {
return hash() == no_hash;
}
+ #ifdef _LP64
+ inline markWord actual_mark() const;
+ inline Klass* klass() const;
+ inline Klass* klass_or_null() const;
+ inline Klass* safe_klass() const;
+ inline markWord set_klass(const Klass* klass) const;
+ inline narrowKlass narrow_klass() const;
+ inline markWord set_narrow_klass(const narrowKlass klass) const;
+ #endif
+
// Prototype mark for initialization
static markWord prototype() {
return markWord( no_hash_in_place | no_lock_in_place );
}
// Prepare address of oop for placement into mark
inline static markWord encode_pointer_as_mark(void* p) { return from_pointer(p).set_marked(); }
// Recover address of oop from encoded form used in mark
inline void* decode_pointer() { if (UseBiasedLocking && has_bias_pattern()) return NULL; return (void*)clear_lock_bits().value(); }
+
+ #ifdef _LP64
+ inline bool self_forwarded() const {
+ bool self_fwd = mask_bits(value(), self_forwarded_mask_in_place) != 0;
+ assert(!self_fwd || UseAltGCForwarding, "Only set self-fwd bit when using alt GC forwarding");
+ return self_fwd;
+ }
+
+ inline markWord set_self_forwarded() const {
+ assert(UseAltGCForwarding, "Only call this with alt GC forwarding");
+ return markWord(value() | self_forwarded_mask_in_place | marked_value);
+ }
+ #endif
};
// Support atomic operations.
template<>
struct PrimitiveConversions::Translate<markWord> : public TrueType {
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