/* * Copyright (C) 2017 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. ``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 * 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. */ #pragma once #if ENABLE(WEBASSEMBLY) #include "Options.h" #include <wtf/Atomics.h> #include <wtf/StdLibExtras.h> namespace JSC { namespace Wasm { // This class manages the tier up counts for Wasm binaries. The main interesting thing about // wasm tiering up counts is that the least significant bit indicates if the tier up has already // started. Also, wasm code does not atomically update this count. This is because we // don't care too much if the countdown is slightly off. The tier up trigger is atomic, however, // so tier up will be triggered exactly once. class TierUpCount { WTF_MAKE_NONCOPYABLE(TierUpCount); public: TierUpCount() : m_count(Options::webAssemblyOMGTierUpCount()) , m_tierUpStarted(false) { } TierUpCount(TierUpCount&& other) { ASSERT(other.m_count == Options::webAssemblyOMGTierUpCount()); m_count = other.m_count; } static uint32_t loopDecrement() { return Options::webAssemblyLoopDecrement(); } static uint32_t functionEntryDecrement() { return Options::webAssemblyFunctionEntryDecrement(); } bool shouldStartTierUp() { return !m_tierUpStarted.exchange(true); } int32_t count() { return bitwise_cast<int32_t>(m_count); } private: uint32_t m_count; Atomic<bool> m_tierUpStarted; }; } } // namespace JSC::Wasm #endif // ENABLE(WEBASSEMBLY)