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)) {
149 assert property.needsDeclaration();
150 // This is a LET or CONST being declared. The property is already there but flagged as needing declaration.
151 // We create a new PropertyMap with the flag removed. The map is installed with a fast compare-and-set
152 // method if the pre-callsite map is stable (which should be the case for function scopes except for
153 // non-strict functions containing eval() with var). Otherwise we have to use a slow setter that creates
154 // a new PropertyMap on the fly.
155 final PropertyMap oldMap = getMap();
156 final Property newProperty = property.removeFlags(Property.NEEDS_DECLARATION);
157 final PropertyMap newMap = oldMap.replaceProperty(property, newProperty);
158 final MethodHandle fastSetter = find.replaceProperty(newProperty).getSetter(type, isStrict, request);
159 final MethodHandle slowSetter = MH.insertArguments(ScriptObject.DECLARE_AND_SET, 1, getName()).asType(fastSetter.type());
160
161 // cas map used as guard, if true that means we can do the set fast
162 MethodHandle casMap = MH.insertArguments(ScriptObject.CAS_MAP, 1, oldMap, newMap);
163 casMap = MH.dropArguments(casMap, 1, type);
164 casMap = MH.asType(casMap, casMap.type().changeParameterType(0, Object.class));
165 methodHandle = MH.guardWithTest(casMap, fastSetter, slowSetter);
166 } else {
167 methodHandle = find.getSetter(type, isStrict, request);
168 }
169
170 assert methodHandle != null;
171 assert property != null;
172
173 final MethodHandle boundHandle;
174 if (!property.isAccessorProperty() && find.isInherited()) {
175 boundHandle = ScriptObject.addProtoFilter(methodHandle, find.getProtoChainLength());
176 } else {
177 boundHandle = methodHandle;
178 }
179 return new SetMethod(boundHandle, property);
180 }
181
182 private SetMethod createGlobalPropertySetter() {
183 final ScriptObject global = Context.getGlobal();
184 return new SetMethod(MH.filterArguments(global.addSpill(type, getName()), 0, ScriptObject.GLOBALFILTER), null);
185 }
186
187 private SetMethod createNewPropertySetter(final SwitchPoint builtinSwitchPoint) {
188 final SetMethod sm = map.getFreeFieldSlot() > -1 ? createNewFieldSetter(builtinSwitchPoint) : createNewSpillPropertySetter(builtinSwitchPoint);
189 map.propertyAdded(sm.property, true);
190 return sm;
191 }
192
193 private SetMethod createNewSetter(final Property property, final SwitchPoint builtinSwitchPoint) {
194 property.setBuiltinSwitchPoint(builtinSwitchPoint);
195
196 final PropertyMap oldMap = getMap();
197 final PropertyMap newMap = getNewMap(property);
198 final boolean isStrict = NashornCallSiteDescriptor.isStrict(desc);
199 final String name = NashornCallSiteDescriptor.getOperand(desc);
200
201 //fast type specific setter
202 final MethodHandle fastSetter = property.getSetter(type, newMap); //0 sobj, 1 value, slot folded for spill property already
203
204 //slow setter, that calls ScriptObject.set with appropriate type and key name
205 MethodHandle slowSetter = ScriptObject.SET_SLOW[getAccessorTypeIndex(type)];
206 slowSetter = MH.insertArguments(slowSetter, 3, NashornCallSiteDescriptor.getFlags(desc));
207 slowSetter = MH.insertArguments(slowSetter, 1, name);
208 slowSetter = MH.asType(slowSetter, slowSetter.type().changeParameterType(0, Object.class));
209
210 assert slowSetter.type().equals(fastSetter.type()) : "slow=" + slowSetter + " != fast=" + fastSetter;
211
212 //cas map used as guard, if true that means we can do the set fast
213 MethodHandle casMap = MH.insertArguments(ScriptObject.CAS_MAP, 1, oldMap, newMap);
214 casMap = MH.dropArguments(casMap, 1, type);
215 casMap = MH.asType(casMap, casMap.type().changeParameterType(0, Object.class));
216 final MethodHandle casGuard = MH.guardWithTest(casMap, fastSetter, slowSetter);
217
218 //outermost level needs an extendable check. if object can be extended, guard is true and
219 //we can run the cas setter. The setter goes to "nop" VOID_RETURN if false or throws an
220 //exception if we are in strict mode and object is not extensible
221 MethodHandle extCheck = MH.insertArguments(ScriptObject.EXTENSION_CHECK, 1, isStrict, name);
222 extCheck = MH.asType(extCheck, extCheck.type().changeParameterType(0, Object.class));
223 extCheck = MH.dropArguments(extCheck, 1, type);
224
225 MethodHandle nop = JSType.VOID_RETURN.methodHandle();
226 nop = MH.dropArguments(nop, 0, Object.class, type);
227
228 return new SetMethod(MH.asType(MH.guardWithTest(extCheck, casGuard, nop), fastSetter.type()), property);
229 }
230
231 private SetMethod createNewFieldSetter(final SwitchPoint builtinSwitchPoint) {
232 return createNewSetter(new AccessorProperty(getName(), getFlags(sobj), sobj.getClass(), getMap().getFreeFieldSlot(), type), builtinSwitchPoint);
233 }
234
235 private SetMethod createNewSpillPropertySetter(final SwitchPoint builtinSwitchPoint) {
236 return createNewSetter(new SpillProperty(getName(), getFlags(sobj), getMap().getFreeSpillSlot(), type), builtinSwitchPoint);
237 }
238
239 private PropertyMap getNewMap(final Property property) {
240 return getMap().addProperty(property);
241 }
242
243 private static int getFlags(final ScriptObject scriptObject) {
244 return scriptObject.useDualFields() ? Property.DUAL_FIELDS : 0;
245 }
246 }