| /* |
| * Copyright (C) 2010 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 COMPUTER, INC. ``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 COMPUTER, INC. OR |
| * 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 StackBounds_h |
| #define StackBounds_h |
| |
| namespace WTF { |
| |
| class StackBounds { |
| // isSafeToRecurse() / recursionLimit() tests (by default) |
| // that we are at least this far from the end of the stack. |
| // |
| // This 64k number was picked because a sampling of stack usage differences |
| // between consecutive entries into one of the Interpreter::execute...() |
| // functions was seen to be as high as 27k. Hence, 64k is chosen as a |
| // conservative availability value that is not too large but comfortably |
| // exceeds 27k with some buffer for error. |
| const static size_t s_defaultAvailabilityDelta = 64 * 1024; |
| |
| public: |
| StackBounds() |
| : m_origin(0) |
| , m_bound(0) |
| { |
| } |
| |
| static StackBounds currentThreadStackBounds() |
| { |
| StackBounds bounds; |
| bounds.initialize(); |
| bounds.checkConsistency(); |
| return bounds; |
| } |
| |
| void* origin() const |
| { |
| ASSERT(m_origin); |
| return m_origin; |
| } |
| |
| void* current() const |
| { |
| checkConsistency(); |
| void* currentPosition = ¤tPosition; |
| return currentPosition; |
| } |
| |
| size_t size() const |
| { |
| return isGrowingDownward() |
| ? static_cast<char*>(m_origin) - static_cast<char*>(m_bound) |
| : static_cast<char*>(m_bound) - static_cast<char*>(m_origin); |
| } |
| |
| void* recursionLimit(size_t minAvailableDelta = s_defaultAvailabilityDelta) const |
| { |
| checkConsistency(); |
| return isGrowingDownward() |
| ? static_cast<char*>(m_bound) + minAvailableDelta |
| : static_cast<char*>(m_bound) - minAvailableDelta; |
| } |
| |
| bool isSafeToRecurse(size_t minAvailableDelta = s_defaultAvailabilityDelta) const |
| { |
| checkConsistency(); |
| return isGrowingDownward() |
| ? current() >= recursionLimit(minAvailableDelta) |
| : current() <= recursionLimit(minAvailableDelta); |
| } |
| |
| private: |
| void initialize(); |
| |
| |
| bool isGrowingDownward() const |
| { |
| ASSERT(m_origin && m_bound); |
| #if OS(WINCE) |
| return m_origin > m_bound; |
| #else |
| return true; |
| #endif |
| } |
| |
| void checkConsistency() const |
| { |
| #if !ASSERT_DISABLED |
| void* currentPosition = ¤tPosition; |
| ASSERT(m_origin != m_bound); |
| ASSERT(isGrowingDownward() |
| ? (currentPosition < m_origin && currentPosition > m_bound) |
| : (currentPosition > m_origin && currentPosition < m_bound)); |
| #endif |
| } |
| |
| void* m_origin; |
| void* m_bound; |
| |
| friend class StackStats; |
| }; |
| |
| } // namespace WTF |
| |
| using WTF::StackBounds; |
| |
| #endif |