1 /* 2 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package jdk.nashorn.internal.runtime; 27 28 import static jdk.nashorn.internal.lookup.Lookup.MH; 29 import static jdk.nashorn.internal.runtime.ECMAErrors.referenceError; 30 import static jdk.nashorn.internal.runtime.JSType.getAccessorTypeIndex; 31 32 import java.lang.invoke.MethodHandle; 33 import java.lang.invoke.SwitchPoint; 34 import jdk.dynalink.CallSiteDescriptor; 35 import jdk.dynalink.linker.GuardedInvocation; 36 import jdk.dynalink.linker.LinkRequest; 37 import jdk.nashorn.internal.runtime.linker.NashornCallSiteDescriptor; 38 import jdk.nashorn.internal.runtime.linker.NashornGuards; 39 40 /** 41 * Instances of this class are quite ephemeral; they only exist for the duration of an invocation of 42 * {@link ScriptObject#findSetMethod(CallSiteDescriptor, jdk.dynalink.linker.LinkRequest)} and 43 * serve as the actual encapsulation of the algorithm for creating an appropriate property setter method. 44 */ 45 final class SetMethodCreator { 46 // See constructor parameters for description of fields 47 private final ScriptObject sobj; 48 private final PropertyMap map; 49 private final FindProperty find; 50 private final CallSiteDescriptor desc; 51 private final Class<?> type; 52 private final LinkRequest request; 53 54 /** 55 * Creates a new property setter method creator. 56 * @param sobj the object for which we're creating the property setter 57 * @param find a result of a {@link ScriptObject#findProperty(Object, boolean)} on the object for the property we 58 * want to create a setter for. Can be null if the property does not yet exist on the object. 59 * @param desc the descriptor of the call site that triggered the property setter lookup 60 * @param request the link request 61 */ 62 SetMethodCreator(final ScriptObject sobj, final FindProperty find, final CallSiteDescriptor desc, final LinkRequest request) { 63 this.sobj = sobj; 64 this.map = sobj.getMap(); 65 this.find = find; 66 this.desc = desc; 67 this.type = desc.getMethodType().parameterType(1); 68 this.request = request; 69 } 70 71 private String getName() { 72 return NashornCallSiteDescriptor.getOperand(desc); 73 } 74 75 private PropertyMap getMap() { 76 return map; 77 } 78 79 /** 80 * Creates the actual guarded invocation that represents the dynamic setter method for the property. 81 * @return the actual guarded invocation that represents the dynamic setter method for the property. 82 */ 83 GuardedInvocation createGuardedInvocation(final SwitchPoint builtinSwitchPoint) { 84 return createSetMethod(builtinSwitchPoint).createGuardedInvocation(); 85 } 86 87 /** 88 * This class encapsulates the results of looking up a setter method; it's basically a triple of a method handle, 89 * a Property object, and flags for invocation. 90 * 91 */ 92 private class SetMethod { 93 private final MethodHandle methodHandle; 94 private final Property property; 95 96 /** 97 * Creates a new lookup result. 98 * @param methodHandle the actual method handle 99 * @param property the property object. Can be null in case we're creating a new property in the global object. 100 */ 101 SetMethod(final MethodHandle methodHandle, final Property property) { 102 assert methodHandle != null; 103 this.methodHandle = methodHandle; 104 this.property = property; 105 } 106 107 /** 108 * Composes from its components an actual guarded invocation that represents the dynamic setter method for the property. 109 * @return the composed guarded invocation that represents the dynamic setter method for the property. 110 */ 111 GuardedInvocation createGuardedInvocation() { 112 // getGuard() and getException() either both return null, or neither does. The reason for that is that now 113 // getGuard returns a map guard that casts its argument to ScriptObject, and if that fails, we need to 114 // relink on ClassCastException. 115 final boolean explicitInstanceOfCheck = NashornGuards.explicitInstanceOfCheck(desc, request); 116 return new GuardedInvocation(methodHandle, NashornGuards.getGuard(sobj, property, desc, explicitInstanceOfCheck), 117 (SwitchPoint)null, explicitInstanceOfCheck ? null : ClassCastException.class); 118 } 119 } 120 121 private SetMethod createSetMethod(final SwitchPoint builtinSwitchPoint) { 122 if (find != null) { 123 return createExistingPropertySetter(); 124 } 125 126 checkStrictCreateNewVariable(); 127 128 if (sobj.isScope()) { 129 return createGlobalPropertySetter(); 130 } 131 132 return createNewPropertySetter(builtinSwitchPoint); 133 } 134 135 private void checkStrictCreateNewVariable() { 136 // In strict mode, assignment can not create a new variable. 137 // See also ECMA Annex C item 4. ReferenceError is thrown. 138 if (NashornCallSiteDescriptor.isScope(desc) && NashornCallSiteDescriptor.isStrict(desc)) { 139 throw referenceError("not.defined", getName()); 140 } 141 } 142 143 private SetMethod createExistingPropertySetter() { 144 final Property property = find.getProperty(); 145 final boolean isStrict = NashornCallSiteDescriptor.isStrict(desc); 146 final MethodHandle methodHandle; 147 148 if (NashornCallSiteDescriptor.isDeclaration(desc) && property.needsDeclaration()) { 149 // This is a LET or CONST being declared. The property is already there but flagged as needing declaration. 150 // We create a new PropertyMap with the flag removed. The map is installed with a fast compare-and-set 151 // method if the pre-callsite map is stable (which should be the case for function scopes except for 152 // non-strict functions containing eval() with var). Otherwise we have to use a slow setter that creates 153 // a new PropertyMap on the fly. 154 final PropertyMap oldMap = getMap(); 155 final Property newProperty = property.removeFlags(Property.NEEDS_DECLARATION); 156 final PropertyMap newMap = oldMap.replaceProperty(property, newProperty); 157 final MethodHandle fastSetter = find.replaceProperty(newProperty).getSetter(type, isStrict, request); 158 final MethodHandle slowSetter = MH.insertArguments(ScriptObject.DECLARE_AND_SET, 1, getName()).asType(fastSetter.type()); 159 160 // cas map used as guard, if true that means we can do the set fast 161 MethodHandle casMap = MH.insertArguments(ScriptObject.CAS_MAP, 1, oldMap, newMap); 162 casMap = MH.dropArguments(casMap, 1, type); 163 casMap = MH.asType(casMap, casMap.type().changeParameterType(0, Object.class)); 164 methodHandle = MH.guardWithTest(casMap, fastSetter, slowSetter); 165 } else { 166 methodHandle = find.getSetter(type, isStrict, request); 167 } 168 169 assert methodHandle != null; 170 assert property != null; 171 172 final MethodHandle boundHandle; 173 if (!property.isAccessorProperty() && find.isInherited()) { 174 boundHandle = ScriptObject.addProtoFilter(methodHandle, find.getProtoChainLength()); 175 } else { 176 boundHandle = methodHandle; 177 } 178 return new SetMethod(boundHandle, property); 179 } 180 181 private SetMethod createGlobalPropertySetter() { 182 final ScriptObject global = Context.getGlobal(); 183 return new SetMethod(MH.filterArguments(global.addSpill(type, getName()), 0, ScriptObject.GLOBALFILTER), null); 184 } 185 186 private SetMethod createNewPropertySetter(final SwitchPoint builtinSwitchPoint) { 187 final SetMethod sm = map.getFreeFieldSlot() > -1 ? createNewFieldSetter(builtinSwitchPoint) : createNewSpillPropertySetter(builtinSwitchPoint); 188 map.propertyAdded(sm.property, true); 189 return sm; 190 } 191 192 private SetMethod createNewSetter(final Property property, final SwitchPoint builtinSwitchPoint) { 193 property.setBuiltinSwitchPoint(builtinSwitchPoint); 194 195 final PropertyMap oldMap = getMap(); 196 final PropertyMap newMap = getNewMap(property); 197 final boolean isStrict = NashornCallSiteDescriptor.isStrict(desc); 198 final String name = NashornCallSiteDescriptor.getOperand(desc); 199 200 //fast type specific setter 201 final MethodHandle fastSetter = property.getSetter(type, newMap); //0 sobj, 1 value, slot folded for spill property already 202 203 //slow setter, that calls ScriptObject.set with appropriate type and key name 204 MethodHandle slowSetter = ScriptObject.SET_SLOW[getAccessorTypeIndex(type)]; 205 slowSetter = MH.insertArguments(slowSetter, 3, NashornCallSiteDescriptor.getFlags(desc)); 206 slowSetter = MH.insertArguments(slowSetter, 1, name); 207 slowSetter = MH.asType(slowSetter, slowSetter.type().changeParameterType(0, Object.class)); 208 209 assert slowSetter.type().equals(fastSetter.type()) : "slow=" + slowSetter + " != fast=" + fastSetter; 210 211 //cas map used as guard, if true that means we can do the set fast 212 MethodHandle casMap = MH.insertArguments(ScriptObject.CAS_MAP, 1, oldMap, newMap); 213 casMap = MH.dropArguments(casMap, 1, type); 214 casMap = MH.asType(casMap, casMap.type().changeParameterType(0, Object.class)); 215 final MethodHandle casGuard = MH.guardWithTest(casMap, fastSetter, slowSetter); 216 217 //outermost level needs an extendable check. if object can be extended, guard is true and 218 //we can run the cas setter. The setter goes to "nop" VOID_RETURN if false or throws an 219 //exception if we are in strict mode and object is not extensible 220 MethodHandle extCheck = MH.insertArguments(ScriptObject.EXTENSION_CHECK, 1, isStrict, name); 221 extCheck = MH.asType(extCheck, extCheck.type().changeParameterType(0, Object.class)); 222 extCheck = MH.dropArguments(extCheck, 1, type); 223 224 MethodHandle nop = JSType.VOID_RETURN.methodHandle(); 225 nop = MH.dropArguments(nop, 0, Object.class, type); 226 227 return new SetMethod(MH.asType(MH.guardWithTest(extCheck, casGuard, nop), fastSetter.type()), property); 228 } 229 230 private SetMethod createNewFieldSetter(final SwitchPoint builtinSwitchPoint) { 231 return createNewSetter(new AccessorProperty(getName(), getFlags(sobj), sobj.getClass(), getMap().getFreeFieldSlot(), type), builtinSwitchPoint); 232 } 233 234 private SetMethod createNewSpillPropertySetter(final SwitchPoint builtinSwitchPoint) { 235 return createNewSetter(new SpillProperty(getName(), getFlags(sobj), getMap().getFreeSpillSlot(), type), builtinSwitchPoint); 236 } 237 238 private PropertyMap getNewMap(final Property property) { 239 return getMap().addProperty(property); 240 } 241 242 private static int getFlags(final ScriptObject scriptObject) { 243 return scriptObject.useDualFields() ? Property.DUAL_FIELDS : 0; 244 } 245 }