< prev index next > src/hotspot/share/oops/markWord.hpp
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*/
#ifndef SHARE_OOPS_MARKWORD_HPP
#define SHARE_OOPS_MARKWORD_HPP
+ #include "gc/shared/gc_globals.hpp"
#include "metaprogramming/primitiveConversions.hpp"
#include "oops/oopsHierarchy.hpp"
#include "runtime/globals.hpp"
#include <type_traits>
//
// 64 bits:
// --------
// unused:25 hash:31 -->| unused_gap:1 age:4 unused_gap:1 lock:2 (normal 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
//
uintptr_t value() const { return _value; }
// Constants
static const int age_bits = 4;
static const int lock_bits = 2;
! static const int first_unused_gap_bits = 1;
! static const int max_hash_bits = BitsPerWord - age_bits - lock_bits - first_unused_gap_bits;
static const int hash_bits = max_hash_bits > 31 ? 31 : max_hash_bits;
! static const int second_unused_gap_bits = LP64_ONLY(1) NOT_LP64(0);
static const int lock_shift = 0;
! static const int age_shift = lock_bits + first_unused_gap_bits;
! static const int hash_shift = age_shift + age_bits + second_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 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 locked_value = 0;
static const uintptr_t unlocked_value = 1;
static const uintptr_t monitor_value = 2;
static const uintptr_t marked_value = 3;
uintptr_t value() const { return _value; }
// Constants
static const int age_bits = 4;
static const int lock_bits = 2;
! 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);
+ #ifdef _LP64
+ // Used only with compact headers.
+ static const int klass_bits = 32;
+ #endif
static const int lock_shift = 0;
! static const int self_forwarded_shift = lock_shift + lock_bits;
! static const int age_shift = self_forwarded_shift + self_forwarded_bits;
+ static const int hash_shift = age_shift + age_bits + 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 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_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 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
+ // Used only with compact headers.
+ static const uintptr_t klass_mask = right_n_bits(klass_bits);
+ static const 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;
: (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 {
! 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);
: (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 narrowKlass narrow_klass() const;
+ inline markWord set_narrow_klass(narrowKlass nklass) const;
+ inline markWord set_klass(Klass* 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() { 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 std::true_type {
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