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* Copyright (C) 2010 Apple Inc. All Rights Reserved.
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// isSafeToRecurse() / recursionLimit() tests (by default)
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// that we are at least this far from the end of the stack.
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// This 64k number was picked because a sampling of stack usage differences
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// between consecutive entries into one of the Interpreter::execute...()
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// functions was seen to be as high as 27k. Hence, 64k is chosen as a
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// conservative availability value that is not too large but comfortably
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// exceeds 27k with some buffer for error.
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const static size_t s_defaultAvailabilityDelta = 64 * 1024;
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static StackBounds currentThreadStackBounds()
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bounds.checkConsistency();
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void* currentPosition = ¤tPosition;
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return currentPosition;
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return isGrowingDownward()
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? static_cast<char*>(m_origin) - static_cast<char*>(m_bound)
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: static_cast<char*>(m_bound) - static_cast<char*>(m_origin);
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void* recursionLimit(size_t minAvailableDelta = s_defaultAvailabilityDelta) const
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return isGrowingDownward()
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? static_cast<char*>(m_bound) + minAvailableDelta
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: static_cast<char*>(m_bound) - minAvailableDelta;
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bool isSafeToRecurse(size_t minAvailableDelta = s_defaultAvailabilityDelta) const
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return isGrowingDownward()
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? current() >= recursionLimit(minAvailableDelta)
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: current() <= recursionLimit(minAvailableDelta);
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bool isGrowingDownward() const
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ASSERT(m_origin && m_bound);
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return m_origin > m_bound;
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void checkConsistency() const
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void* currentPosition = ¤tPosition;
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ASSERT(m_origin != m_bound);
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ASSERT(isGrowingDownward()
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? (currentPosition < m_origin && currentPosition > m_bound)
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: (currentPosition > m_origin && currentPosition < m_bound));
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friend class StackStats;
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using WTF::StackBounds;