/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/*
* GC-internal definition of relocation overlay used while moving cells.
*/
#ifndef gc_RelocationOverlay_h
#define gc_RelocationOverlay_h
#include "mozilla/Assertions.h"
#include <stdint.h>
#include "gc/Cell.h"
namespace js {
namespace gc {
/*
* This structure overlays a Cell that has been moved and provides a way to find
* its new location. It's used during generational and compacting GC.
*/
class RelocationOverlay :
public Cell {
public:
/* The location the cell has been moved to, stored in the cell header. */
Cell* forwardingAddress()
const {
MOZ_ASSERT(isForwarded());
return reinterpret_cast<Cell*>(header_.getForwardingAddress());
}
protected:
/* A list entry to track all relocated things. */
RelocationOverlay* next_;
explicit RelocationOverlay(Cell* dst);
public:
static const RelocationOverlay* fromCell(
const Cell* cell) {
return static_cast<
const RelocationOverlay*>(cell);
}
static RelocationOverlay* fromCell(Cell* cell) {
return static_cast<RelocationOverlay*>(cell);
}
static RelocationOverlay* forwardCell(Cell* src, Cell* dst);
void setNext(RelocationOverlay* next) {
MOZ_ASSERT(isForwarded());
next_ = next;
}
RelocationOverlay* next()
const {
MOZ_ASSERT(isForwarded());
return next_;
}
};
}
// namespace gc
}
// namespace js
#endif /* gc_RelocationOverlay_h */
