C++ HandleScript::analysis方法代码示例

bool
TypeInferenceOracle::propertyReadIdempotent(HandleScript script, jsbytecode *pc, HandleId id)
{
    if (script->analysis()->getCode(pc).notIdempotent)
        return false;

    if (id != MakeTypeId(cx, id))
        return false;

    StackTypeSet *types = script->analysis()->poppedTypes(pc, 0);
    if (!types || types->unknownObject())
        return false;

    for (unsigned i = 0; i < types->getObjectCount(); i++) {
        if (types->getSingleObject(i))
            return false;

        if (TypeObject *obj = types->getTypeObject(i)) {
            if (obj->unknownProperties())
                return false;

            // Check if the property has been reconfigured or is a getter.
            HeapTypeSet *propertyTypes = obj->getProperty(cx, id, false);
            if (!propertyTypes || propertyTypes->isOwnProperty(cx, obj, true))
                return false;
        }
    }

    return true;
}

bool
TypeInferenceOracle::elementReadIsTypedArray(HandleScript script, jsbytecode *pc, int *arrayType)
{
    // Check whether the object is a typed array and index is int32 or double.
    StackTypeSet *obj = script->analysis()->poppedTypes(pc, 1);
    StackTypeSet *id = DropUnrooted(script)->analysis()->poppedTypes(pc, 0);

    JSValueType idType = id->getKnownTypeTag();
    if (idType != JSVAL_TYPE_INT32 && idType != JSVAL_TYPE_DOUBLE)
        return false;

    *arrayType = obj->getTypedArrayType();
    if (*arrayType == TypedArray::TYPE_MAX)
        return false;

    JS_ASSERT(*arrayType >= 0 && *arrayType < TypedArray::TYPE_MAX);

    // Unlike dense arrays, the types of elements in typed arrays are not
    // guaranteed to be present in the object's type, and we need to use
    // knowledge about the possible contents of the array vs. the types
    // that have been read out of it to figure out how to do the load.
    types::TypeSet *result = propertyRead(script, pc);
    if (*arrayType == TypedArray::TYPE_FLOAT32 || *arrayType == TypedArray::TYPE_FLOAT64) {
        if (!result->hasType(types::Type::DoubleType()))
            return false;
    } else {
        if (!result->hasType(types::Type::Int32Type()))
            return false;
    }

    return true;
}

bool
TypeInferenceOracle::inObjectIsDenseNativeWithoutExtraIndexedProperties(HandleScript script, jsbytecode *pc)
{
    // Check whether the object is a native and index is int32 or double.
    StackTypeSet *id = script->analysis()->poppedTypes(pc, 1);
    StackTypeSet *obj = script->analysis()->poppedTypes(pc, 0);

    JSValueType idType = id->getKnownTypeTag();
    if (idType != JSVAL_TYPE_INT32 && idType != JSVAL_TYPE_DOUBLE)
        return false;

    Class *clasp = obj->getKnownClass();
    if (!clasp || !clasp->isNative())
        return false;

    return !types::TypeCanHaveExtraIndexedProperties(cx, obj);
}

bool
TypeInferenceOracle::elementWriteIsDenseNative(HandleScript script, jsbytecode *pc)
{
    // Check whether the object is a dense array and index is int32 or double.
    StackTypeSet *obj = script->analysis()->poppedTypes(pc, 2);
    StackTypeSet *id = script->analysis()->poppedTypes(pc, 1);

    JSValueType idType = id->getKnownTypeTag();
    if (idType != JSVAL_TYPE_INT32 && idType != JSVAL_TYPE_DOUBLE)
        return false;

    Class *clasp = obj->getKnownClass();
    if (!clasp || !clasp->isNative())
        return false;

    return obj->convertDoubleElements(cx) != StackTypeSet::AmbiguousDoubleConversion;
}

bool
TypeInferenceOracle::canInlineCall(HandleScript caller, jsbytecode *pc)
{
    JS_ASSERT(types::IsInlinableCall(pc));

    JSOp op = JSOp(*pc);
    Bytecode *code = caller->analysis()->maybeCode(pc);

    // For foo.apply(this, arguments), the caller is foo and not the js_fun_apply function.
    // Ignore code->monitoredTypes, as we know the caller is foo
    if (op != JSOP_FUNAPPLY && code->monitoredTypes)
        return false;

    // Gets removed in Bug 796114
    if (caller->analysis()->typeBarriers(cx, pc))
        return false;

    return true;
}

bool
TypeInferenceOracle::elementWriteIsDenseNative(HandleScript script, jsbytecode *pc)
{
    return elementWriteIsDenseNative(script->analysis()->poppedTypes(pc, 2),
                                     script->analysis()->poppedTypes(pc, 1));
}