Beispiel #1
0
bool Structure::prototypeChainMayInterceptStoreTo(JSGlobalData& globalData, PropertyName propertyName)
{
    unsigned i = propertyName.asIndex();
    if (i != PropertyName::NotAnIndex)
        return anyObjectInChainMayInterceptIndexedAccesses();
    
    for (Structure* current = this; ;) {
        JSValue prototype = current->storedPrototype();
        if (prototype.isNull())
            return false;
        
        current = prototype.asCell()->structure();
        
        unsigned attributes;
        JSCell* specificValue;
        PropertyOffset offset = current->get(globalData, propertyName, attributes, specificValue);
        if (!JSC::isValidOffset(offset))
            continue;
        
        if (attributes & (ReadOnly | Accessor))
            return true;
        
        return false;
    }
}
GetByIdStatus GetByIdStatus::computeFromLLInt(CodeBlock* profiledBlock, unsigned bytecodeIndex, Identifier& ident)
{
    UNUSED_PARAM(profiledBlock);
    UNUSED_PARAM(bytecodeIndex);
    UNUSED_PARAM(ident);
#if ENABLE(LLINT)
    Instruction* instruction = profiledBlock->instructions().begin() + bytecodeIndex;
    
    if (instruction[0].u.opcode == LLInt::getOpcode(llint_op_get_array_length))
        return GetByIdStatus(NoInformation, false);

    Structure* structure = instruction[4].u.structure.get();
    if (!structure)
        return GetByIdStatus(NoInformation, false);
    
    unsigned attributesIgnored;
    JSCell* specificValue;
    PropertyOffset offset = structure->get(
        *profiledBlock->vm(), ident, attributesIgnored, specificValue);
    if (structure->isDictionary())
        specificValue = 0;
    if (!isValidOffset(offset))
        return GetByIdStatus(NoInformation, false);
    
    return GetByIdStatus(Simple, false, StructureSet(structure), offset, specificValue);
#else
    return GetByIdStatus(NoInformation, false);
#endif
}
Beispiel #3
0
GetByIdStatus GetByIdStatus::computeFromLLInt(CodeBlock* profiledBlock, unsigned bytecodeIndex, Identifier& ident)
{
    UNUSED_PARAM(profiledBlock);
    UNUSED_PARAM(bytecodeIndex);
    UNUSED_PARAM(ident);
#if ENABLE(LLINT)
    Instruction* instruction = profiledBlock->instructions().begin() + bytecodeIndex;
    
    if (instruction[0].u.opcode == llint_op_method_check)
        instruction++;

    Structure* structure = instruction[4].u.structure.get();
    if (!structure)
        return GetByIdStatus(NoInformation, false);
    
    unsigned attributesIgnored;
    JSCell* specificValue;
    size_t offset = structure->get(
        *profiledBlock->globalData(), ident, attributesIgnored, specificValue);
    if (offset == notFound)
        return GetByIdStatus(NoInformation, false);
    
    return GetByIdStatus(Simple, false, StructureSet(structure), offset, specificValue);
#else
    return GetByIdStatus(NoInformation, false);
#endif
}
PutByIdStatus PutByIdStatus::computeFromLLInt(CodeBlock* profiledBlock, unsigned bytecodeIndex, Identifier& ident)
{
    UNUSED_PARAM(profiledBlock);
    UNUSED_PARAM(bytecodeIndex);
    UNUSED_PARAM(ident);
#if ENABLE(LLINT)
    Instruction* instruction = profiledBlock->instructions().begin() + bytecodeIndex;

    Structure* structure = instruction[4].u.structure.get();
    if (!structure)
        return PutByIdStatus(NoInformation, 0, 0, 0, invalidOffset);
    
    if (instruction[0].u.opcode == LLInt::getOpcode(llint_op_put_by_id)
        || instruction[0].u.opcode == LLInt::getOpcode(llint_op_put_by_id_out_of_line)) {
        PropertyOffset offset = structure->get(*profiledBlock->vm(), ident);
        if (!isValidOffset(offset))
            return PutByIdStatus(NoInformation, 0, 0, 0, invalidOffset);
        
        return PutByIdStatus(SimpleReplace, structure, 0, 0, offset);
    }
    
    ASSERT(structure->transitionWatchpointSetHasBeenInvalidated());
    
    ASSERT(instruction[0].u.opcode == LLInt::getOpcode(llint_op_put_by_id_transition_direct)
           || instruction[0].u.opcode == LLInt::getOpcode(llint_op_put_by_id_transition_normal)
           || instruction[0].u.opcode == LLInt::getOpcode(llint_op_put_by_id_transition_direct_out_of_line)
           || instruction[0].u.opcode == LLInt::getOpcode(llint_op_put_by_id_transition_normal_out_of_line));
    
    Structure* newStructure = instruction[6].u.structure.get();
    StructureChain* chain = instruction[7].u.structureChain.get();
    ASSERT(newStructure);
    ASSERT(chain);
    
    PropertyOffset offset = newStructure->get(*profiledBlock->vm(), ident);
    if (!isValidOffset(offset))
        return PutByIdStatus(NoInformation, 0, 0, 0, invalidOffset);
    
    return PutByIdStatus(SimpleTransition, structure, newStructure, chain, offset);
#else
    return PutByIdStatus(NoInformation, 0, 0, 0, invalidOffset);
#endif
}
void GetByIdStatus::computeForChain(GetByIdStatus& result, CodeBlock* profiledBlock, Identifier& ident, Structure* structure)
{
#if ENABLE(JIT) && ENABLE(VALUE_PROFILER)
    // Validate the chain. If the chain is invalid, then currently the best thing
    // we can do is to assume that TakesSlow is true. In the future, it might be
    // worth exploring reifying the structure chain from the structure we've got
    // instead of using the one from the cache, since that will do the right things
    // if the structure chain has changed. But that may be harder, because we may
    // then end up having a different type of access altogether. And it currently
    // does not appear to be worth it to do so -- effectively, the heuristic we
    // have now is that if the structure chain has changed between when it was
    // cached on in the baseline JIT and when the DFG tried to inline the access,
    // then we fall back on a polymorphic access.
    Structure* currentStructure = structure;
    JSObject* currentObject = 0;
    for (unsigned i = 0; i < result.m_chain.size(); ++i) {
        ASSERT(!currentStructure->isDictionary());
        currentObject = asObject(currentStructure->prototypeForLookup(profiledBlock));
        currentStructure = result.m_chain[i];
        if (currentObject->structure() != currentStructure)
            return;
    }
        
    ASSERT(currentObject);
        
    unsigned attributesIgnored;
    JSCell* specificValue;
        
    result.m_offset = currentStructure->get(
        *profiledBlock->vm(), ident, attributesIgnored, specificValue);
    if (currentStructure->isDictionary())
        specificValue = 0;
    if (!isValidOffset(result.m_offset))
        return;
        
    result.m_structureSet.add(structure);
    result.m_specificValue = JSValue(specificValue);
#else
    UNUSED_PARAM(result);
    UNUSED_PARAM(profiledBlock);
    UNUSED_PARAM(ident);
    UNUSED_PARAM(structure);
    UNREACHABLE_FOR_PLATFORM();
#endif
}
GetByIdStatus GetByIdStatus::computeFor(CodeBlock* profiledBlock, unsigned bytecodeIndex, Identifier& ident)
{
    UNUSED_PARAM(profiledBlock);
    UNUSED_PARAM(bytecodeIndex);
    UNUSED_PARAM(ident);
#if ENABLE(JIT) && ENABLE(VALUE_PROFILER)
    if (!profiledBlock->numberOfStructureStubInfos())
        return computeFromLLInt(profiledBlock, bytecodeIndex, ident);
    
    // First check if it makes either calls, in which case we want to be super careful, or
    // if it's not set at all, in which case we punt.
    StructureStubInfo& stubInfo = profiledBlock->getStubInfo(bytecodeIndex);
    if (!stubInfo.seen)
        return computeFromLLInt(profiledBlock, bytecodeIndex, ident);
    
    if (stubInfo.resetByGC)
        return GetByIdStatus(TakesSlowPath, true);

    PolymorphicAccessStructureList* list;
    int listSize;
    switch (stubInfo.accessType) {
    case access_get_by_id_self_list:
        list = stubInfo.u.getByIdSelfList.structureList;
        listSize = stubInfo.u.getByIdSelfList.listSize;
        break;
    case access_get_by_id_proto_list:
        list = stubInfo.u.getByIdProtoList.structureList;
        listSize = stubInfo.u.getByIdProtoList.listSize;
        break;
    default:
        list = 0;
        listSize = 0;
        break;
    }
    for (int i = 0; i < listSize; ++i) {
        if (!list->list[i].isDirect)
            return GetByIdStatus(MakesCalls, true);
    }
    
    // Next check if it takes slow case, in which case we want to be kind of careful.
    if (profiledBlock->likelyToTakeSlowCase(bytecodeIndex))
        return GetByIdStatus(TakesSlowPath, true);
    
    // Finally figure out if we can derive an access strategy.
    GetByIdStatus result;
    result.m_wasSeenInJIT = true; // This is interesting for bytecode dumping only.
    switch (stubInfo.accessType) {
    case access_unset:
        return computeFromLLInt(profiledBlock, bytecodeIndex, ident);
        
    case access_get_by_id_self: {
        Structure* structure = stubInfo.u.getByIdSelf.baseObjectStructure.get();
        unsigned attributesIgnored;
        JSCell* specificValue;
        result.m_offset = structure->get(
            *profiledBlock->vm(), ident, attributesIgnored, specificValue);
        if (structure->isDictionary())
            specificValue = 0;
        
        if (isValidOffset(result.m_offset)) {
            result.m_structureSet.add(structure);
            result.m_specificValue = JSValue(specificValue);
        }
        
        if (isValidOffset(result.m_offset))
            ASSERT(result.m_structureSet.size());
        break;
    }
        
    case access_get_by_id_self_list: {
        for (int i = 0; i < listSize; ++i) {
            ASSERT(list->list[i].isDirect);
            
            Structure* structure = list->list[i].base.get();
            if (result.m_structureSet.contains(structure))
                continue;
            
            unsigned attributesIgnored;
            JSCell* specificValue;
            PropertyOffset myOffset = structure->get(
                *profiledBlock->vm(), ident, attributesIgnored, specificValue);
            if (structure->isDictionary())
                specificValue = 0;
            
            if (!isValidOffset(myOffset)) {
                result.m_offset = invalidOffset;
                break;
            }
                    
            if (!i) {
                result.m_offset = myOffset;
                result.m_specificValue = JSValue(specificValue);
            } else if (result.m_offset != myOffset) {
                result.m_offset = invalidOffset;
                break;
            } else if (result.m_specificValue != JSValue(specificValue))
                result.m_specificValue = JSValue();
            
            result.m_structureSet.add(structure);
        }
                    
        if (isValidOffset(result.m_offset))
            ASSERT(result.m_structureSet.size());
        break;
    }
        
    case access_get_by_id_proto: {
        if (!stubInfo.u.getByIdProto.isDirect)
            return GetByIdStatus(MakesCalls, true);
        result.m_chain.append(stubInfo.u.getByIdProto.prototypeStructure.get());
        computeForChain(
            result, profiledBlock, ident,
            stubInfo.u.getByIdProto.baseObjectStructure.get());
        break;
    }
        
    case access_get_by_id_chain: {
        if (!stubInfo.u.getByIdChain.isDirect)
            return GetByIdStatus(MakesCalls, true);
        for (unsigned i = 0; i < stubInfo.u.getByIdChain.count; ++i)
            result.m_chain.append(stubInfo.u.getByIdChain.chain->head()[i].get());
        computeForChain(
            result, profiledBlock, ident,
            stubInfo.u.getByIdChain.baseObjectStructure.get());
        break;
    }
        
    default:
        ASSERT(!isValidOffset(result.m_offset));
        break;
    }
    
    if (!isValidOffset(result.m_offset)) {
        result.m_state = TakesSlowPath;
        result.m_structureSet.clear();
        result.m_chain.clear();
        result.m_specificValue = JSValue();
    } else
        result.m_state = Simple;
    
    return result;
#else // ENABLE(JIT)
    return GetByIdStatus(NoInformation, false);
#endif // ENABLE(JIT)
}