Source/JavaScriptCore/ftl/FTLJITCode.cpp

/*
 * Copyright (C) 2013-2018 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 "FTLJITCode.h"

#if ENABLE(FTL_JIT)

#include "FTLState.h"
#include "JSCPtrTag.h"

namespace JSC { namespace FTL {

using namespace B3;

JITCode::JITCode()
    : JSC::JITCode(JITType::FTLJIT)
    , common(/* isUnlinked */ false)
{
}

JITCode::~JITCode()
{
    if (FTL::shouldDumpDisassembly()) {
        if (m_b3Code || m_arityCheckEntrypoint) {
            dataLog("Destroying FTL JIT code at ");
            CommaPrinter comma;
            if (m_b3Code)
                dataLog(comma, m_b3Code);
            if (m_arityCheckEntrypoint)
                dataLog(comma, m_arityCheckEntrypoint);
            dataLog("\n");
        }
    }
}

void JITCode::initializeB3Code(CodeRef<JSEntryPtrTag> b3Code)
{
    m_b3Code = b3Code;
}

void JITCode::initializeB3Byproducts(std::unique_ptr<OpaqueByproducts> byproducts)
{
    m_b3Byproducts = WTFMove(byproducts);
}

void JITCode::initializeAddressForCall(CodePtr<JSEntryPtrTag> address)
{
    m_addressForCall = address;
}

void JITCode::initializeArityCheckEntrypoint(CodeRef<JSEntryPtrTag> entrypoint)
{
    m_arityCheckEntrypoint = entrypoint;
}

JITCode::CodePtr<JSEntryPtrTag> JITCode::addressForCall(ArityCheckMode arityCheck)
{
    switch (arityCheck) {
    case ArityCheckNotRequired:
        return m_addressForCall;
    case MustCheckArity:
        return m_arityCheckEntrypoint.code();
    }
    RELEASE_ASSERT_NOT_REACHED();
    return CodePtr<JSEntryPtrTag>();
}

void* JITCode::executableAddressAtOffset(size_t offset)
{
    if (!offset)
        return m_addressForCall.executableAddress();

    char* executableAddress = m_addressForCall.untaggedExecutableAddress<char*>();
    return tagCodePtr<JSEntryPtrTag>(executableAddress + offset);
}

void* JITCode::dataAddressAtOffset(size_t)
{
    // We can't patch FTL code, yet. Even if we did, it's not clear that we would do so
    // through this API.
    RELEASE_ASSERT_NOT_REACHED();
    return nullptr;
}

unsigned JITCode::offsetOf(void*)
{
    // We currently don't have visibility into the FTL code.
    RELEASE_ASSERT_NOT_REACHED();
    return 0;
}

size_t JITCode::size()
{
    // We don't know the size of FTL code, yet. Make a wild guess. This is mostly used for
    // GC load estimates.
    return 1000;
}

bool JITCode::contains(void*)
{
    // We have no idea what addresses the FTL code contains, yet.
    RELEASE_ASSERT_NOT_REACHED();
    return false;
}

JITCode* JITCode::ftl()
{
    return this;
}

DFG::CommonData* JITCode::dfgCommon()
{
    return &common;
}

void JITCode::shrinkToFit(const ConcurrentJSLocker&)
{
    common.shrinkToFit();
    m_osrExit.shrinkToFit();
    osrExitDescriptors.shrinkToFit();
    lazySlowPaths.shrinkToFit();
}

void JITCode::validateReferences(const TrackedReferences& trackedReferences)
{
    common.validateReferences(trackedReferences);
    
    for (OSRExit& exit : m_osrExit)
        exit.m_descriptor->validateReferences(trackedReferences);
}

RegisterSet JITCode::liveRegistersToPreserveAtExceptionHandlingCallSite(CodeBlock*, CallSiteIndex callSiteIndex)
{
    for (OSRExit& exit : m_osrExit) {
        if (exit.m_exceptionHandlerCallSiteIndex.bits() == callSiteIndex.bits()) {
            RELEASE_ASSERT(exit.isExceptionHandler());
            RELEASE_ASSERT(exit.isGenericUnwindHandler());
            return ValueRep::usedRegisters(exit.m_valueReps);
        }
    }
    return { };
}

std::optional<CodeOrigin> JITCode::findPC(CodeBlock* codeBlock, void* pc)
{
    for (OSRExit& exit : m_osrExit) {
        if (ExecutableMemoryHandle* handle = exit.m_code.executableMemory()) {
            if (handle->start().untaggedPtr() <= pc && pc < handle->end().untaggedPtr())
                return std::optional<CodeOrigin>(exit.m_codeOriginForExitProfile);
        }
    }

    for (std::unique_ptr<LazySlowPath>& lazySlowPath : lazySlowPaths) {
        if (ExecutableMemoryHandle* handle = lazySlowPath->stub().executableMemory()) {
            if (handle->start().untaggedPtr() <= pc && pc < handle->end().untaggedPtr())
                return std::optional<CodeOrigin>(codeBlock->codeOrigin(lazySlowPath->callSiteIndex()));
        }
    }

    return std::nullopt;
}

} } // namespace JSC::FTL

#endif // ENABLE(FTL_JIT)