webkitgtk-2.16.5HEADwebkitgtk-2.16.5master

1 files changed, 330 insertions, 0 deletions

diff --git a/Source/JavaScriptCore/jit/JITWorklist.cpp b/Source/JavaScriptCore/jit/JITWorklist.cpp
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+++ b/Source/JavaScriptCore/jit/JITWorklist.cpp
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+/*
+ * Copyright (C) 2016 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. 
+ */
+
+#include "config.h"
+#include "JITWorklist.h"
+
+#if ENABLE(JIT)
+
+#include "JIT.h"
+#include "JSCInlines.h"
+#include "VMInlines.h"
+
+namespace JSC {
+
+class JITWorklist::Plan : public ThreadSafeRefCounted<JITWorklist::Plan> {
+public:
+    Plan(CodeBlock* codeBlock, unsigned loopOSREntryBytecodeOffset)
+        : m_codeBlock(codeBlock)
+        , m_jit(codeBlock->vm(), codeBlock, loopOSREntryBytecodeOffset)
+    {
+        m_jit.doMainThreadPreparationBeforeCompile();
+    }
+    
+    void compileInThread()
+    {
+        m_jit.compileWithoutLinking(JITCompilationCanFail);
+        
+        LockHolder locker(m_lock);
+        m_isFinishedCompiling = true;
+    }
+    
+    void finalize()
+    {
+        CompilationResult result = m_jit.link();
+        switch (result) {
+        case CompilationFailed:
+            CODEBLOCK_LOG_EVENT(m_codeBlock, "delayJITCompile", ("compilation failed"));
+            if (Options::verboseOSR())
+                dataLogF("    JIT compilation failed.\n");
+            m_codeBlock->dontJITAnytimeSoon();
+            m_codeBlock->m_didFailJITCompilation = true;
+            return;
+        case CompilationSuccessful:
+            if (Options::verboseOSR())
+                dataLogF("    JIT compilation successful.\n");
+            m_codeBlock->ownerScriptExecutable()->installCode(m_codeBlock);
+            m_codeBlock->jitSoon();
+            return;
+        default:
+            RELEASE_ASSERT_NOT_REACHED();
+            return;
+        }
+    }
+    
+    CodeBlock* codeBlock() { return m_codeBlock; }
+    VM* vm() { return m_codeBlock->vm(); }
+    
+    bool isFinishedCompiling()
+    {
+        LockHolder locker(m_lock);
+        return m_isFinishedCompiling;
+    }
+    
+    static void compileNow(CodeBlock* codeBlock, unsigned loopOSREntryBytecodeOffset)
+    {
+        Plan plan(codeBlock, loopOSREntryBytecodeOffset);
+        plan.compileInThread();
+        plan.finalize();
+    }
+    
+private:
+    CodeBlock* m_codeBlock;
+    JIT m_jit;
+    Lock m_lock;
+    bool m_isFinishedCompiling { false };
+};
+
+class JITWorklist::Thread : public AutomaticThread {
+public:
+    Thread(const AbstractLocker& locker, JITWorklist& worklist)
+        : AutomaticThread(locker, worklist.m_lock, worklist.m_condition)
+        , m_worklist(worklist)
+    {
+        m_worklist.m_numAvailableThreads++;
+    }
+    
+protected:
+    PollResult poll(const AbstractLocker&) override
+    {
+        RELEASE_ASSERT(m_worklist.m_numAvailableThreads);
+        
+        if (m_worklist.m_queue.isEmpty())
+            return PollResult::Wait;
+        
+        m_myPlans = WTFMove(m_worklist.m_queue);
+        m_worklist.m_numAvailableThreads--;
+        return PollResult::Work;
+    }
+    
+    WorkResult work() override
+    {
+        RELEASE_ASSERT(!m_myPlans.isEmpty());
+        
+        for (RefPtr<Plan>& plan : m_myPlans) {
+            plan->compileInThread();
+            plan = nullptr;
+            
+            // Make sure that the main thread realizes that we just compiled something. Notifying
+            // a condition is basically free if nobody is waiting.
+            LockHolder locker(*m_worklist.m_lock);
+            m_worklist.m_condition->notifyAll(locker);
+        }
+        
+        m_myPlans.clear();
+        
+        LockHolder locker(*m_worklist.m_lock);
+        m_worklist.m_numAvailableThreads++;
+        return WorkResult::Continue;
+    }
+    
+private:
+    JITWorklist& m_worklist;
+    Plans m_myPlans;
+};
+
+JITWorklist::JITWorklist()
+    : m_lock(Box<Lock>::create())
+    , m_condition(AutomaticThreadCondition::create())
+{
+    LockHolder locker(*m_lock);
+    m_thread = new Thread(locker, *this);
+}
+
+JITWorklist::~JITWorklist()
+{
+    UNREACHABLE_FOR_PLATFORM();
+}
+
+bool JITWorklist::completeAllForVM(VM& vm)
+{
+    bool result = false;
+    DeferGC deferGC(vm.heap);
+    for (;;) {
+        Vector<RefPtr<Plan>, 32> myPlans;
+        {
+            LockHolder locker(*m_lock);
+            for (;;) {
+                bool didFindUnfinishedPlan = false;
+                m_plans.removeAllMatching(
+                    [&] (RefPtr<Plan>& plan) {
+                        if (plan->vm() != &vm)
+                            return false;
+                        if (!plan->isFinishedCompiling()) {
+                            didFindUnfinishedPlan = true;
+                            return false;
+                        }
+                        myPlans.append(WTFMove(plan));
+                        return true;
+                    });
+                
+                // If we found plans then we should finalize them now.
+                if (!myPlans.isEmpty())
+                    break;
+                
+                // If we don't find plans, then we're either done or we need to wait, depending on
+                // whether we found some unfinished plans.
+                if (!didFindUnfinishedPlan)
+                    return result;
+                
+                m_condition->wait(*m_lock);
+            }
+        }
+        
+        RELEASE_ASSERT(!myPlans.isEmpty());
+        result = true;
+        finalizePlans(myPlans);
+    }
+}
+
+void JITWorklist::poll(VM& vm)
+{
+    DeferGC deferGC(vm.heap);
+    Plans myPlans;
+    {
+        LockHolder locker(*m_lock);
+        m_plans.removeAllMatching(
+            [&] (RefPtr<Plan>& plan) {
+                if (plan->vm() != &vm)
+                    return false;
+                if (!plan->isFinishedCompiling())
+                    return false;
+                myPlans.append(WTFMove(plan));
+                return true;
+            });
+    }
+    
+    finalizePlans(myPlans);
+}
+
+void JITWorklist::compileLater(CodeBlock* codeBlock, unsigned loopOSREntryBytecodeOffset)
+{
+    DeferGC deferGC(codeBlock->vm()->heap);
+    RELEASE_ASSERT(codeBlock->jitType() == JITCode::InterpreterThunk);
+    
+    if (codeBlock->m_didFailJITCompilation) {
+        codeBlock->dontJITAnytimeSoon();
+        return;
+    }
+    
+    if (!Options::useConcurrentJIT()) {
+        Plan::compileNow(codeBlock, loopOSREntryBytecodeOffset);
+        return;
+    }
+    
+    codeBlock->jitSoon();
+
+    {
+        LockHolder locker(*m_lock);
+        
+        if (m_planned.contains(codeBlock))
+            return;
+        
+        if (m_numAvailableThreads) {
+            m_planned.add(codeBlock);
+            RefPtr<Plan> plan = adoptRef(new Plan(codeBlock, loopOSREntryBytecodeOffset));
+            m_plans.append(plan);
+            m_queue.append(plan);
+            m_condition->notifyAll(locker);
+            return;
+        }
+    }
+
+    // Compiling on the main thread if the helper thread isn't available is a defense against this
+    // pathology:
+    //
+    // 1) Do something that is allowed to take a while, like load a giant piece of initialization
+    //    code. This plans the compile of the init code, but doesn't finish it. It will take a
+    //    while.
+    //
+    // 2) Do something that is supposed to be quick. Now all baseline compiles, and so all DFG and
+    //    FTL compiles, of everything is blocked on the long-running baseline compile of that
+    //    initialization code.
+    //
+    // The single-threaded concurrent JIT has this tendency to convoy everything while at the same
+    // time postponing when it happens, which means that the convoy delays are less predictable.
+    // This works around the issue. If the concurrent JIT thread is convoyed, we revert to main
+    // thread compiles. This is probably not as good as if we had multiple JIT threads. Maybe we
+    // can do that someday.
+    Plan::compileNow(codeBlock, loopOSREntryBytecodeOffset);
+}
+
+void JITWorklist::compileNow(CodeBlock* codeBlock, unsigned loopOSREntryBytecodeOffset)
+{
+    DeferGC deferGC(codeBlock->vm()->heap);
+    if (codeBlock->jitType() != JITCode::InterpreterThunk)
+        return;
+    
+    bool isPlanned;
+    {
+        LockHolder locker(*m_lock);
+        isPlanned = m_planned.contains(codeBlock);
+    }
+    
+    if (isPlanned) {
+        RELEASE_ASSERT(Options::useConcurrentJIT());
+        // This is expensive, but probably good enough.
+        completeAllForVM(*codeBlock->vm());
+    }
+    
+    // Now it might be compiled!
+    if (codeBlock->jitType() != JITCode::InterpreterThunk)
+        return;
+    
+    // We do this in case we had previously attempted, and then failed, to compile with the
+    // baseline JIT.
+    codeBlock->resetJITData();
+    
+    // OK, just compile it.
+    JIT::compile(codeBlock->vm(), codeBlock, JITCompilationMustSucceed, loopOSREntryBytecodeOffset);
+    codeBlock->ownerScriptExecutable()->installCode(codeBlock);
+}
+
+void JITWorklist::finalizePlans(Plans& myPlans)
+{
+    for (RefPtr<Plan>& plan : myPlans) {
+        plan->finalize();
+        
+        LockHolder locker(*m_lock);
+        m_planned.remove(plan->codeBlock());
+    }
+}
+
+JITWorklist* JITWorklist::instance()
+{
+    static JITWorklist* worklist;
+    static std::once_flag once;
+    std::call_once(
+        once,
+        [] {
+            worklist = new JITWorklist();
+        });
+    return worklist;
+}
+
+} // namespace JSC
+
+#endif // ENABLE(JIT)
+