Source/JavaScriptCore/dfg/DFGOSRExitCompiler.cpp

/*
 * Copyright (C) 2011 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 "DFGOSRExitCompiler.h"

#if ENABLE(DFG_JIT)

#include "CallFrame.h"
#include "LinkBuffer.h"
#include "RepatchBuffer.h"

namespace JSC { namespace DFG {

extern "C" {

void compileOSRExit(ExecState* exec)
{
    CodeBlock* codeBlock = exec->codeBlock();
    
    ASSERT(codeBlock);
    ASSERT(codeBlock->getJITType() == JITCode::DFGJIT);
    
    JSGlobalData* globalData = &exec->globalData();
    
    uint32_t exitIndex = globalData->osrExitIndex;
    OSRExit& exit = codeBlock->osrExit(exitIndex);
    
    // Make sure all code on our inline stack is JIT compiled. This is necessary since
    // we may opt to inline a code block even before it had ever been compiled by the
    // JIT, but our OSR exit infrastructure currently only works if the target of the
    // OSR exit is JIT code. This could be changed since there is nothing particularly
    // hard about doing an OSR exit into the interpreter, but for now this seems to make
    // sense in that if we're OSR exiting from inlined code of a DFG code block, then
    // probably it's a good sign that the thing we're exiting into is hot. Even more
    // interestingly, since the code was inlined, it may never otherwise get JIT
    // compiled since the act of inlining it may ensure that it otherwise never runs.
    for (CodeOrigin codeOrigin = exit.m_codeOrigin; codeOrigin.inlineCallFrame; codeOrigin = codeOrigin.inlineCallFrame->caller) {
        static_cast<FunctionExecutable*>(codeOrigin.inlineCallFrame->executable.get())
            ->baselineCodeBlockFor(codeOrigin.inlineCallFrame->isCall ? CodeForCall : CodeForConstruct)
            ->jitCompile(*globalData);
    }
    
    SpeculationRecovery* recovery = 0;
    if (exit.m_recoveryIndex)
        recovery = &codeBlock->speculationRecovery(exit.m_recoveryIndex - 1);

#if DFG_ENABLE(DEBUG_VERBOSE)
    dataLog("Generating OSR exit #%u (bc#%u, @%u, %s) for code block %p.\n", exitIndex, exit.m_codeOrigin.bytecodeIndex, exit.m_nodeIndex, exitKindToString(exit.m_kind), codeBlock);
#endif

    {
        AssemblyHelpers jit(globalData, codeBlock);
        OSRExitCompiler exitCompiler(jit);

        jit.jitAssertHasValidCallFrame();
        exitCompiler.compileExit(exit, recovery);
        
        LinkBuffer patchBuffer(*globalData, &jit, codeBlock);
        exit.m_code = patchBuffer.finalizeCode();

#if DFG_ENABLE(DEBUG_VERBOSE)
        dataLog("OSR exit code at [%p, %p).\n", patchBuffer.debugAddress(), static_cast<char*>(patchBuffer.debugAddress()) + patchBuffer.debugSize());
#endif
    }
    
    {
        RepatchBuffer repatchBuffer(codeBlock);
        repatchBuffer.relink(exit.m_check.codeLocationForRepatch(codeBlock), CodeLocationLabel(exit.m_code.code()));
    }
    
    globalData->osrExitJumpDestination = exit.m_code.code().executableAddress();
}

} // extern "C"

void OSRExitCompiler::handleExitCounts(const OSRExit& exit)
{
    m_jit.add32(AssemblyHelpers::TrustedImm32(1), AssemblyHelpers::AbsoluteAddress(&exit.m_count));
    
    m_jit.move(AssemblyHelpers::TrustedImmPtr(m_jit.codeBlock()), GPRInfo::regT0);
    
    AssemblyHelpers::JumpList tooFewFails;
    
    if (exit.m_kind == InadequateCoverage) {
        // Proceed based on the assumption that we can profitably optimize this code once
        // it has executed enough times.
        
        m_jit.load32(AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfForcedOSRExitCounter()), GPRInfo::regT2);
        m_jit.load32(AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfSpeculativeSuccessCounter()), GPRInfo::regT1);
        m_jit.add32(AssemblyHelpers::TrustedImm32(1), GPRInfo::regT2);
        m_jit.add32(AssemblyHelpers::TrustedImm32(-1), GPRInfo::regT1);
        m_jit.store32(GPRInfo::regT2, AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfForcedOSRExitCounter()));
        m_jit.store32(GPRInfo::regT1, AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfSpeculativeSuccessCounter()));
        
        tooFewFails.append(m_jit.branch32(AssemblyHelpers::BelowOrEqual, GPRInfo::regT2, AssemblyHelpers::TrustedImm32(Options::forcedOSRExitCountForReoptimization)));
    } else {
        // Proceed based on the assumption that we can handle these exits so long as they
        // don't get too frequent.
        
        m_jit.load32(AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfSpeculativeFailCounter()), GPRInfo::regT2);
        m_jit.load32(AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfSpeculativeSuccessCounter()), GPRInfo::regT1);
        m_jit.add32(AssemblyHelpers::TrustedImm32(1), GPRInfo::regT2);
        m_jit.add32(AssemblyHelpers::TrustedImm32(-1), GPRInfo::regT1);
        m_jit.store32(GPRInfo::regT2, AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfSpeculativeFailCounter()));
        m_jit.store32(GPRInfo::regT1, AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfSpeculativeSuccessCounter()));
    
        m_jit.move(AssemblyHelpers::TrustedImmPtr(m_jit.baselineCodeBlock()), GPRInfo::regT0);
    
        tooFewFails.append(m_jit.branch32(AssemblyHelpers::BelowOrEqual, GPRInfo::regT2, AssemblyHelpers::TrustedImm32(m_jit.codeBlock()->largeFailCountThreshold())));
        m_jit.mul32(AssemblyHelpers::TrustedImm32(Options::desiredSpeculativeSuccessFailRatio), GPRInfo::regT2, GPRInfo::regT2);
    
        tooFewFails.append(m_jit.branch32(AssemblyHelpers::BelowOrEqual, GPRInfo::regT2, GPRInfo::regT1));
    }

    // Reoptimize as soon as possible.
    m_jit.store32(AssemblyHelpers::TrustedImm32(0), AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfJITExecuteCounter()));
    m_jit.store32(AssemblyHelpers::TrustedImm32(0), AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfJITExecutionActiveThreshold()));
    AssemblyHelpers::Jump doneAdjusting = m_jit.jump();
    
    tooFewFails.link(&m_jit);
    
    // Adjust the execution counter such that the target is to only optimize after a while.
    int32_t targetValue =
        ExecutionCounter::applyMemoryUsageHeuristicsAndConvertToInt(
            m_jit.baselineCodeBlock()->counterValueForOptimizeAfterLongWarmUp(),
            m_jit.baselineCodeBlock());
    m_jit.store32(AssemblyHelpers::TrustedImm32(-targetValue), AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfJITExecuteCounter()));
    m_jit.store32(AssemblyHelpers::TrustedImm32(targetValue), AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfJITExecutionActiveThreshold()));
    m_jit.store32(AssemblyHelpers::TrustedImm32(ExecutionCounter::formattedTotalCount(targetValue)), AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfJITExecutionTotalCount()));
    
    doneAdjusting.link(&m_jit);
}

} } // namespace JSC::DFG

#endif // ENABLE(DFG_JIT)