| /* |
| * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package jdk.nashorn.internal.runtime.linker; |
| |
| import static jdk.nashorn.internal.lookup.Lookup.MH; |
| |
| import java.lang.invoke.MethodHandle; |
| import java.lang.invoke.MethodHandles; |
| import java.lang.ref.WeakReference; |
| import jdk.dynalink.CallSiteDescriptor; |
| import jdk.dynalink.linker.LinkRequest; |
| import jdk.nashorn.api.scripting.JSObject; |
| import jdk.nashorn.internal.objects.Global; |
| import jdk.nashorn.internal.runtime.JSType; |
| import jdk.nashorn.internal.runtime.Property; |
| import jdk.nashorn.internal.runtime.PropertyMap; |
| import jdk.nashorn.internal.runtime.ScriptFunction; |
| import jdk.nashorn.internal.runtime.ScriptObject; |
| import jdk.nashorn.internal.runtime.options.Options; |
| |
| /** |
| * Constructor of method handles used to guard call sites. |
| */ |
| public final class NashornGuards { |
| private static final MethodHandle IS_MAP = findOwnMH("isMap", boolean.class, ScriptObject.class, PropertyMap.class); |
| private static final MethodHandle IS_MAP_SCRIPTOBJECT = findOwnMH("isMap", boolean.class, Object.class, PropertyMap.class); |
| private static final MethodHandle IS_SCRIPTOBJECT = findOwnMH("isScriptObject", boolean.class, Object.class); |
| private static final MethodHandle IS_NOT_JSOBJECT = findOwnMH("isNotJSObject", boolean.class, Object.class); |
| private static final MethodHandle SAME_OBJECT = findOwnMH("sameObject", boolean.class, Object.class, WeakReference.class); |
| //TODO - maybe put this back in ScriptFunction instead of the ClassCastException.class relinkage |
| //private static final MethodHandle IS_SCRIPTFUNCTION = findOwnMH("isScriptFunction", boolean.class, Object.class); |
| |
| private static final boolean CCE_ONLY = Options.getBooleanProperty("nashorn.cce"); |
| |
| // don't create me! |
| private NashornGuards() { |
| } |
| |
| /** |
| * Given a callsite descriptor and a link request, determine whether we should use an instanceof |
| * check explicitly for the guard if needed, or if we should link it with a try/catch ClassCastException |
| * combinator as its relink criteria - i.e. relink when CCE is thrown. |
| * |
| * @param desc callsite descriptor |
| * @param request link request |
| * @return true of explicit instanceof check is needed |
| */ |
| public static boolean explicitInstanceOfCheck(final CallSiteDescriptor desc, final LinkRequest request) { |
| //THIS is currently true, as the inliner encounters several problems with sun.misc.ValueConversions.castReference |
| //otherwise. We should only use the exception based relink where we have no choice, and the result is faster code, |
| //for example in the NativeArray, TypedArray, ContinuousArray getters. For the standard callsite, it appears that |
| //we lose performance rather than gain it, due to JVM issues. :-( |
| return !CCE_ONLY; |
| } |
| |
| /** |
| * Returns a guard that does an instanceof ScriptObject check on the receiver |
| * @return guard |
| */ |
| public static MethodHandle getScriptObjectGuard() { |
| return IS_SCRIPTOBJECT; |
| } |
| |
| /** |
| * Get the guard that checks if an item is not a {@code JSObject} |
| * @return method handle for guard |
| */ |
| public static MethodHandle getNotJSObjectGuard() { |
| return IS_NOT_JSOBJECT; |
| } |
| |
| /** |
| * Returns a guard that does an instanceof ScriptObject check on the receiver |
| * @param explicitInstanceOfCheck - if false, then this is a nop, because it's all the guard does |
| * @return guard |
| */ |
| public static MethodHandle getScriptObjectGuard(final boolean explicitInstanceOfCheck) { |
| return explicitInstanceOfCheck ? IS_SCRIPTOBJECT : null; |
| } |
| |
| /** |
| * Get the guard that checks if a {@link PropertyMap} is equal to |
| * a known map, using reference comparison |
| * |
| * @param explicitInstanceOfCheck true if we should do an explicit script object instanceof check instead of just casting |
| * @param map The map to check against. This will be bound to the guard method handle |
| * |
| * @return method handle for guard |
| */ |
| public static MethodHandle getMapGuard(final PropertyMap map, final boolean explicitInstanceOfCheck) { |
| return MH.insertArguments(explicitInstanceOfCheck ? IS_MAP_SCRIPTOBJECT : IS_MAP, 1, map); |
| } |
| |
| /** |
| * Determine whether the given callsite needs a guard. |
| * @param property the property, or null |
| * @param desc the callsite descriptor |
| * @return true if a guard should be used for this callsite |
| */ |
| static boolean needsGuard(final Property property, final CallSiteDescriptor desc) { |
| return property == null || property.isConfigurable() |
| || property.isBound() || property.hasDualFields() |
| || !NashornCallSiteDescriptor.isFastScope(desc) || property.canChangeType(); |
| } |
| |
| /** |
| * Get the guard for a property access. This returns an identity guard for non-configurable global properties |
| * and a map guard for everything else. |
| * |
| * @param sobj the first object in the prototype chain |
| * @param property the property |
| * @param desc the callsite descriptor |
| * @param explicitInstanceOfCheck true if we should do an explicit script object instanceof check instead of just casting |
| * @return method handle for guard |
| */ |
| public static MethodHandle getGuard(final ScriptObject sobj, final Property property, final CallSiteDescriptor desc, final boolean explicitInstanceOfCheck) { |
| if (!needsGuard(property, desc)) { |
| return null; |
| } |
| if (NashornCallSiteDescriptor.isScope(desc) && sobj.isScope()) { |
| if (property != null && property.isBound() && !property.canChangeType()) { |
| // This is a declared top level variables in main script or eval, use identity guard. |
| return getIdentityGuard(sobj); |
| } |
| if (!(sobj instanceof Global) && (property == null || property.isConfigurable())) { |
| // Undeclared variables in nested evals need stronger guards |
| return combineGuards(getIdentityGuard(sobj), getMapGuard(sobj.getMap(), explicitInstanceOfCheck)); |
| } |
| } |
| return getMapGuard(sobj.getMap(), explicitInstanceOfCheck); |
| } |
| |
| |
| /** |
| * Get a guard that checks referential identity of the current object. |
| * |
| * @param sobj the self object |
| * @return true if same self object instance |
| */ |
| public static MethodHandle getIdentityGuard(final ScriptObject sobj) { |
| return MH.insertArguments(SAME_OBJECT, 1, new WeakReference<>(sobj)); |
| } |
| |
| /** |
| * Get a guard that checks if in item is a JS string. |
| * |
| * @return method handle for guard |
| */ |
| public static MethodHandle getStringGuard() { |
| return JSType.IS_STRING.methodHandle(); |
| } |
| |
| /** |
| * Get a guard that checks if in item is a JS number. |
| * |
| * @return method handle for guard |
| */ |
| public static MethodHandle getNumberGuard() { |
| return JSType.IS_NUMBER.methodHandle(); |
| } |
| |
| /** |
| * Combine two method handles of type {@code (Object)boolean} using logical AND. |
| * |
| * @param guard1 the first guard |
| * @param guard2 the second guard, only invoked if guard1 returns true |
| * @return true if both guard1 and guard2 returned true |
| */ |
| public static MethodHandle combineGuards(final MethodHandle guard1, final MethodHandle guard2) { |
| if (guard1 == null) { |
| return guard2; |
| } else if (guard2 == null) { |
| return guard1; |
| } else { |
| return MH.guardWithTest(guard1, guard2, MH.dropArguments(MH.constant(boolean.class, false), 0, Object.class)); |
| } |
| } |
| |
| @SuppressWarnings("unused") |
| private static boolean isScriptObject(final Object self) { |
| return self instanceof ScriptObject; |
| } |
| |
| @SuppressWarnings("unused") |
| private static boolean isScriptObject(final Class<? extends ScriptObject> clazz, final Object self) { |
| return clazz.isInstance(self); |
| } |
| |
| @SuppressWarnings("unused") |
| private static boolean isMap(final ScriptObject self, final PropertyMap map) { |
| return self.getMap() == map; |
| } |
| |
| @SuppressWarnings("unused") |
| private static boolean isNotJSObject(final Object self) { |
| return !(self instanceof JSObject); |
| } |
| |
| @SuppressWarnings("unused") |
| private static boolean isMap(final Object self, final PropertyMap map) { |
| return self instanceof ScriptObject && ((ScriptObject)self).getMap() == map; |
| } |
| |
| |
| @SuppressWarnings("unused") |
| private static boolean sameObject(final Object self, final WeakReference<ScriptObject> ref) { |
| return self == ref.get(); |
| } |
| |
| @SuppressWarnings("unused") |
| private static boolean isScriptFunction(final Object self) { |
| return self instanceof ScriptFunction; |
| } |
| |
| private static MethodHandle findOwnMH(final String name, final Class<?> rtype, final Class<?>... types) { |
| return MH.findStatic(MethodHandles.lookup(), NashornGuards.class, name, MH.type(rtype, types)); |
| } |
| } |