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/*
* Copyright (c) 2017, 2021, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* 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 www.oracle.com if you need additional information or have any
* questions.
*/
#ifndef SHARE_GC_Z_ZMARKSTACKENTRY_HPP
#define SHARE_GC_Z_ZMARKSTACKENTRY_HPP
#include "gc/z/zBitField.hpp"
#include "memory/allocation.hpp"
//
// Mark stack entry layout
// -----------------------
//
// Object entry
// ------------
//
// 6
// 3 5 4 3 2 1 0
// +------------------------------------------------------------------+-+-+-+-+-+
// |11111111 11111111 11111111 11111111 11111111 11111111 11111111 111|1|1|1|1|1|
// +------------------------------------------------------------------+-+-+-+-+-+
// | | | | | |
// | 4-4 Mark Flag (1-bit) * | | | |
// | | | | |
// | 3-3 Increment Live Flag (1-bit) * | | |
// | | | |
// | 2-2 Follow Flag (1-bit) * | |
// | | |
// | 1-1 Partial Array Flag (1-bit) * |
// | |
// | 0-0 Final Flag (1-bit) *
// |
// * 63-5 Object Address (59-bits)
//
//
// Partial array entry
// -------------------
//
// 6 3 3
// 3 2 1 2 1 0
// +------------------------------------+---------------------------------+-+-+
// |11111111 11111111 11111111 11111111 |11111111 11111111 11111111 111111|1|1|
// +------------------------------------+---------------------------------+-+-+
// | | | |
// | | 1-1 Partial Array Flag (1-bit) * |
// | | |
// | | 0-0 Final Flag (1-bit) *
// | |
// | * 31-2 Partial Array Length (30-bits)
// |
// * 63-32 Partial Array Address Offset (32-bits)
//
class ZMarkStackEntry {
private:
typedef ZBitField<uint64_t, bool, 0, 1> field_finalizable;
typedef ZBitField<uint64_t, bool, 1, 1> field_partial_array;
typedef ZBitField<uint64_t, bool, 2, 1> field_follow;
typedef ZBitField<uint64_t, bool, 3, 1> field_inc_live;
typedef ZBitField<uint64_t, bool, 4, 1> field_mark;
typedef ZBitField<uint64_t, uintptr_t, 5, 59> field_object_address;
typedef ZBitField<uint64_t, size_t, 2, 30> field_partial_array_length;
typedef ZBitField<uint64_t, size_t, 32, 32> field_partial_array_offset;
uint64_t _entry;
public:
ZMarkStackEntry() {
// This constructor is intentionally left empty and does not initialize
// _entry to allow it to be optimized out when instantiating ZMarkStack,
// which has a long array of ZMarkStackEntry elements, but doesn't care
// what _entry is initialized to.
}
ZMarkStackEntry(uintptr_t object_address, bool mark, bool inc_live, bool follow, bool finalizable) :
_entry(field_object_address::encode(object_address) |
field_mark::encode(mark) |
field_inc_live::encode(inc_live) |
field_follow::encode(follow) |
field_partial_array::encode(false) |
field_finalizable::encode(finalizable)) {}
ZMarkStackEntry(size_t partial_array_offset, size_t partial_array_length, bool finalizable) :
_entry(field_partial_array_offset::encode(partial_array_offset) |
field_partial_array_length::encode(partial_array_length) |
field_partial_array::encode(true) |
field_finalizable::encode(finalizable)) {}
bool finalizable() const {
return field_finalizable::decode(_entry);
}
bool partial_array() const {
return field_partial_array::decode(_entry);
}
size_t partial_array_offset() const {
return field_partial_array_offset::decode(_entry);
}
size_t partial_array_length() const {
return field_partial_array_length::decode(_entry);
}
bool follow() const {
return field_follow::decode(_entry);
}
bool inc_live() const {
return field_inc_live::decode(_entry);
}
bool mark() const {
return field_mark::decode(_entry);
}
uintptr_t object_address() const {
return field_object_address::decode(_entry);
}
};
#endif // SHARE_GC_Z_ZMARKSTACKENTRY_HPP
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