98 lines
3.1 KiB
C++
98 lines
3.1 KiB
C++
/*
|
|
* Copyright (c) 2017, 2019, 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_ZFORWARDINGENTRY_HPP
|
|
#define SHARE_GC_Z_ZFORWARDINGENTRY_HPP
|
|
|
|
#include "gc/z/zBitField.hpp"
|
|
#include "memory/allocation.hpp"
|
|
#include "metaprogramming/primitiveConversions.hpp"
|
|
|
|
//
|
|
// Forwarding entry layout
|
|
// -----------------------
|
|
//
|
|
// 6 4 4
|
|
// 3 6 5 1 0
|
|
// +--------------------+--------------------------------------------------+-+
|
|
// |11111111 11111111 11|111111 11111111 11111111 11111111 11111111 1111111|1|
|
|
// +--------------------+--------------------------------------------------+-+
|
|
// | | |
|
|
// | | 0-0 Populated Flag (1-bits) *
|
|
// | |
|
|
// | * 45-1 To Object Offset (45-bits)
|
|
// |
|
|
// * 63-46 From Object Index (18-bits)
|
|
//
|
|
|
|
class ZForwardingEntry {
|
|
friend class PrimitiveConversions;
|
|
|
|
private:
|
|
typedef ZBitField<uint64_t, bool, 0, 1> field_populated;
|
|
typedef ZBitField<uint64_t, size_t, 1, 45> field_to_offset;
|
|
typedef ZBitField<uint64_t, size_t, 46, 18> field_from_index;
|
|
|
|
uint64_t _entry;
|
|
|
|
public:
|
|
ZForwardingEntry() :
|
|
_entry(0) {}
|
|
|
|
ZForwardingEntry(size_t from_index, size_t to_offset) :
|
|
_entry(field_populated::encode(true) |
|
|
field_to_offset::encode(to_offset) |
|
|
field_from_index::encode(from_index)) {}
|
|
|
|
bool populated() const {
|
|
return field_populated::decode(_entry);
|
|
}
|
|
|
|
size_t to_offset() const {
|
|
return field_to_offset::decode(_entry);
|
|
}
|
|
|
|
size_t from_index() const {
|
|
return field_from_index::decode(_entry);
|
|
}
|
|
};
|
|
|
|
// Needed to allow atomic operations on ZForwardingEntry
|
|
template <>
|
|
struct PrimitiveConversions::Translate<ZForwardingEntry> : public TrueType {
|
|
typedef ZForwardingEntry Value;
|
|
typedef uint64_t Decayed;
|
|
|
|
static Decayed decay(Value v) {
|
|
return v._entry;
|
|
}
|
|
|
|
static Value recover(Decayed d) {
|
|
ZForwardingEntry entry;
|
|
entry._entry = d;
|
|
return entry;
|
|
}
|
|
};
|
|
|
|
#endif // SHARE_GC_Z_ZFORWARDINGENTRY_HPP
|