153 lines
4.7 KiB
C++
153 lines
4.7 KiB
C++
/*
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* Copyright (C) 2010-2019 Apple Inc. All Rights Reserved.
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*
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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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* are met:
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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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*
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* THIS SOFTWARE IS PROVIDED BY APPLE 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 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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*
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*/
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#pragma once
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#include <algorithm>
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#include <wtf/StackPointer.h>
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#include <wtf/ThreadingPrimitives.h>
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namespace WTF {
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class StackBounds {
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WTF_MAKE_FAST_ALLOCATED;
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public:
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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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static constexpr size_t DefaultReservedZone = 64 * 1024;
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static constexpr StackBounds emptyBounds() { return StackBounds(); }
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#if HAVE(STACK_BOUNDS_FOR_NEW_THREAD)
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// This function is only effective for newly created threads. In some platform, it returns a bogus value for the main thread.
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static StackBounds newThreadStackBounds(PlatformThreadHandle);
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#endif
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static StackBounds currentThreadStackBounds()
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{
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auto result = currentThreadStackBoundsInternal();
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result.checkConsistency();
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return result;
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}
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void* origin() const
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{
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ASSERT(m_origin);
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return m_origin;
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}
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void* end() const
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{
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ASSERT(m_bound);
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return m_bound;
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}
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size_t size() const
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{
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return static_cast<char*>(m_origin) - static_cast<char*>(m_bound);
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}
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bool isEmpty() const { return !m_origin; }
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bool contains(void* p) const
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{
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if (isEmpty())
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return false;
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return (m_origin >= p) && (p > m_bound);
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}
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void* recursionLimit(size_t minReservedZone = DefaultReservedZone) const
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{
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checkConsistency();
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return static_cast<char*>(m_bound) + minReservedZone;
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}
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void* recursionLimit(char* startOfUserStack, size_t maxUserStack, size_t reservedZoneSize) const
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{
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checkConsistency();
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if (maxUserStack < reservedZoneSize)
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reservedZoneSize = maxUserStack;
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size_t maxUserStackWithReservedZone = maxUserStack - reservedZoneSize;
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char* endOfStackWithReservedZone = reinterpret_cast<char*>(m_bound) + reservedZoneSize;
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if (startOfUserStack < endOfStackWithReservedZone)
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return endOfStackWithReservedZone;
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size_t availableUserStack = startOfUserStack - endOfStackWithReservedZone;
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if (maxUserStackWithReservedZone > availableUserStack)
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maxUserStackWithReservedZone = availableUserStack;
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return startOfUserStack - maxUserStackWithReservedZone;
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}
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StackBounds withSoftOrigin(void* origin) const
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{
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ASSERT(contains(origin));
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return StackBounds(origin, m_bound);
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}
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private:
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StackBounds(void* origin, void* end)
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: m_origin(origin)
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, m_bound(end)
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{
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ASSERT(isGrowingDownwards());
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}
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constexpr StackBounds()
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: m_origin(nullptr)
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, m_bound(nullptr)
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{
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}
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inline bool isGrowingDownwards() const
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{
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ASSERT(m_origin && m_bound);
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return m_bound <= m_origin;
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}
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WTF_EXPORT_PRIVATE static StackBounds currentThreadStackBoundsInternal();
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void checkConsistency() const
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{
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#if ASSERT_ENABLED
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void* currentPosition = currentStackPointer();
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ASSERT(m_origin != m_bound);
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ASSERT(currentPosition < m_origin && currentPosition > m_bound);
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#endif
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}
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void* m_origin;
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void* m_bound;
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friend class StackStats;
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};
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} // namespace WTF
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using WTF::StackBounds;
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