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/*
* Copyright (C) 2015 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef CellState_h
#define CellState_h
namespace JSC {
enum class CellState : uint8_t {
// The object is black as far as this GC is concerned. When not in GC, this just means that it's an
// old gen object. Note that we deliberately arrange OldBlack to be zero, so that the store barrier on
// a target object "from" is just:
//
// if (!from->cellState())
// slowPath(from);
//
// There is a bunch of code in the LLInt and JITs that rely on this being the case. You'd have to
// change a lot of code if you ever wanted the store barrier to be anything but a non-zero check on
// cellState.
OldBlack = 0,
// The object is in eden. During GC, this means that the object has not been marked yet.
NewWhite = 1,
// The object is grey - i.e. it will be scanned - but it either belongs to old gen (if this is eden
// GC) or it is grey a second time in this current GC (because a concurrent store barrier requested
// re-greying).
OldGrey = 2,
// The object is grey - i.e. it will be scanned - and this is the first time in this GC that we are
// going to scan it. If this is an eden GC, this also means that the object is in eden.
NewGrey = 3
};
} // namespace JSC
#endif // CellState_h
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