1 /* 2 * Copyright (c) 2010, 2014, 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.codegen; 27 28 import static jdk.nashorn.internal.runtime.Property.NOT_CONFIGURABLE; 29 import static jdk.nashorn.internal.runtime.Property.NOT_ENUMERABLE; 30 import static jdk.nashorn.internal.runtime.Property.NOT_WRITABLE; 31 32 import java.lang.invoke.MethodType; 33 import jdk.nashorn.internal.codegen.types.Type; 34 import jdk.nashorn.internal.ir.AccessNode; 35 import jdk.nashorn.internal.ir.CallNode; 36 import jdk.nashorn.internal.ir.Expression; 37 import jdk.nashorn.internal.ir.FunctionNode; 38 import jdk.nashorn.internal.ir.IdentNode; 39 import jdk.nashorn.internal.ir.IndexNode; 40 import jdk.nashorn.internal.ir.Optimistic; 41 import jdk.nashorn.internal.objects.ArrayBufferView; 42 import jdk.nashorn.internal.objects.NativeArray; 43 import jdk.nashorn.internal.runtime.FindProperty; 44 import jdk.nashorn.internal.runtime.JSType; 45 import jdk.nashorn.internal.runtime.Property; 46 import jdk.nashorn.internal.runtime.RecompilableScriptFunctionData; 47 import jdk.nashorn.internal.runtime.ScriptFunction; 48 import jdk.nashorn.internal.runtime.ScriptObject; 49 import jdk.nashorn.internal.runtime.ScriptRuntime; 50 51 /** 52 * Functionality for using a runtime scope to look up value types. 53 * Used during recompilation. 54 */ 55 final class TypeEvaluator { 56 /** 57 * Type signature for invocation of functions without parameters: we must pass (callee, this) of type 58 * (ScriptFunction, Object) respectively. We also use Object as the return type (we must pass something, 59 * but it'll be ignored; it can't be void, though). 60 */ 61 private static final MethodType EMPTY_INVOCATION_TYPE = MethodType.methodType(Object.class, ScriptFunction.class, Object.class); 62 63 private final Compiler compiler; 64 private final ScriptObject runtimeScope; 65 TypeEvaluator(final Compiler compiler, final ScriptObject runtimeScope)66 TypeEvaluator(final Compiler compiler, final ScriptObject runtimeScope) { 67 this.compiler = compiler; 68 this.runtimeScope = runtimeScope; 69 } 70 71 /** 72 * Returns true if the expression can be safely evaluated, and its value is an object known to always use 73 * String as the type of its property names retrieved through 74 * {@link ScriptRuntime#toPropertyIterator(Object)}. It is used to avoid optimistic assumptions about its 75 * property name types. 76 * @param expr the expression to test 77 * @return true if the expression can be safely evaluated, and its value is an object known to always use 78 * String as the type of its property iterators. 79 */ hasStringPropertyIterator(final Expression expr)80 boolean hasStringPropertyIterator(final Expression expr) { 81 return evaluateSafely(expr) instanceof ScriptObject; 82 } 83 getOptimisticType(final Optimistic node)84 Type getOptimisticType(final Optimistic node) { 85 assert compiler.useOptimisticTypes(); 86 87 final int programPoint = node.getProgramPoint(); 88 final Type validType = compiler.getInvalidatedProgramPointType(programPoint); 89 90 if (validType != null) { 91 return validType; 92 } 93 94 final Type mostOptimisticType = node.getMostOptimisticType(); 95 final Type evaluatedType = getEvaluatedType(node); 96 97 if (evaluatedType != null) { 98 if (evaluatedType.widerThan(mostOptimisticType)) { 99 final Type newValidType = evaluatedType.isObject() || evaluatedType.isBoolean() ? Type.OBJECT : evaluatedType; 100 // Update invalidatedProgramPoints so we don't re-evaluate the expression next time. This is a heuristic 101 // as we're doing a tradeoff. Re-evaluating expressions on each recompile takes time, but it might 102 // notice a widening in the type of the expression and thus prevent an unnecessary deoptimization later. 103 // We'll presume though that the types of expressions are mostly stable, so if we evaluated it in one 104 // compilation, we'll keep to that and risk a low-probability deoptimization if its type gets widened 105 // in the future. 106 compiler.addInvalidatedProgramPoint(node.getProgramPoint(), newValidType); 107 } 108 return evaluatedType; 109 } 110 return mostOptimisticType; 111 } 112 getPropertyType(final ScriptObject sobj, final String name)113 private static Type getPropertyType(final ScriptObject sobj, final String name) { 114 final FindProperty find = sobj.findProperty(name, true); 115 if (find == null) { 116 return null; 117 } 118 119 final Property property = find.getProperty(); 120 final Class<?> propertyClass = property.getType(); 121 if (propertyClass == null) { 122 // propertyClass == null means its value is Undefined. It is probably not initialized yet, so we won't make 123 // a type assumption yet. 124 return null; 125 } else if (propertyClass.isPrimitive()) { 126 return Type.typeFor(propertyClass); 127 } 128 129 final ScriptObject owner = find.getOwner(); 130 if (property.hasGetterFunction(owner)) { 131 // Can have side effects, so we can't safely evaluate it; since !propertyClass.isPrimitive(), it's Object. 132 return Type.OBJECT; 133 } 134 135 // Safely evaluate the property, and return the narrowest type for the actual value (e.g. Type.INT for a boxed 136 // integer). 137 final Object value = property.needsDeclaration() ? ScriptRuntime.UNDEFINED : property.getObjectValue(owner, owner); 138 if (value == ScriptRuntime.UNDEFINED) { 139 return null; 140 } 141 return Type.typeFor(JSType.unboxedFieldType(value)); 142 } 143 144 /** 145 * Declares a symbol name as belonging to a non-scoped local variable during an on-demand compilation of a single 146 * function. This method will add an explicit Undefined binding for the local into the runtime scope if it's 147 * otherwise implicitly undefined so that when an expression is evaluated for the name, it won't accidentally find 148 * an unrelated value higher up the scope chain. It is only required to call this method when doing an optimistic 149 * on-demand compilation. 150 * @param symbolName the name of the symbol that is to be declared as being a non-scoped local variable. 151 */ declareLocalSymbol(final String symbolName)152 void declareLocalSymbol(final String symbolName) { 153 assert 154 compiler.useOptimisticTypes() && 155 compiler.isOnDemandCompilation() && 156 runtimeScope != null : 157 "useOptimistic=" + 158 compiler.useOptimisticTypes() + 159 " isOnDemand=" + 160 compiler.isOnDemandCompilation() + 161 " scope="+runtimeScope; 162 163 if (runtimeScope.findProperty(symbolName, false) == null) { 164 runtimeScope.addOwnProperty(symbolName, NOT_WRITABLE | NOT_ENUMERABLE | NOT_CONFIGURABLE, ScriptRuntime.UNDEFINED); 165 } 166 } 167 evaluateSafely(final Expression expr)168 private Object evaluateSafely(final Expression expr) { 169 if (expr instanceof IdentNode) { 170 return runtimeScope == null ? null : evaluatePropertySafely(runtimeScope, ((IdentNode)expr).getName()); 171 } 172 173 if (expr instanceof AccessNode) { 174 final AccessNode accessNode = (AccessNode)expr; 175 final Object base = evaluateSafely(accessNode.getBase()); 176 if (!(base instanceof ScriptObject)) { 177 return null; 178 } 179 return evaluatePropertySafely((ScriptObject)base, accessNode.getProperty()); 180 } 181 182 return null; 183 } 184 evaluatePropertySafely(final ScriptObject sobj, final String name)185 private static Object evaluatePropertySafely(final ScriptObject sobj, final String name) { 186 final FindProperty find = sobj.findProperty(name, true); 187 if (find == null) { 188 return null; 189 } 190 final Property property = find.getProperty(); 191 final ScriptObject owner = find.getOwner(); 192 if (property.hasGetterFunction(owner)) { 193 // Possible side effects; can't evaluate safely 194 return null; 195 } 196 return property.getObjectValue(owner, owner); 197 } 198 199 getEvaluatedType(final Optimistic expr)200 private Type getEvaluatedType(final Optimistic expr) { 201 if (expr instanceof IdentNode) { 202 if (runtimeScope == null) { 203 return null; 204 } 205 return getPropertyType(runtimeScope, ((IdentNode)expr).getName()); 206 } else if (expr instanceof AccessNode) { 207 final AccessNode accessNode = (AccessNode)expr; 208 final Object base = evaluateSafely(accessNode.getBase()); 209 if (!(base instanceof ScriptObject)) { 210 return null; 211 } 212 return getPropertyType((ScriptObject)base, accessNode.getProperty()); 213 } else if (expr instanceof IndexNode) { 214 final IndexNode indexNode = (IndexNode)expr; 215 final Object base = evaluateSafely(indexNode.getBase()); 216 if(base instanceof NativeArray || base instanceof ArrayBufferView) { 217 // NOTE: optimistic array getters throw UnwarrantedOptimismException based on the type of their 218 // underlying array storage, not based on values of individual elements. Thus, a LongArrayData will 219 // throw UOE for every optimistic int linkage attempt, even if the long value being returned in the 220 // first invocation would be representable as int. That way, we can presume that the array's optimistic 221 // type is the most optimistic type for which an element getter has a chance of executing successfully. 222 return ((ScriptObject)base).getArray().getOptimisticType(); 223 } 224 } else if (expr instanceof CallNode) { 225 // Currently, we'll only try to guess the return type of immediately invoked function expressions with no 226 // parameters, that is (function() { ... })(). We could do better, but these are all heuristics and we can 227 // gradually introduce them as needed. An easy one would be to do the same for .call(this) idiom. 228 final CallNode callExpr = (CallNode)expr; 229 final Expression fnExpr = callExpr.getFunction(); 230 // Skip evaluation if running with eager compilation as we may violate constraints in RecompilableScriptFunctionData 231 if (fnExpr instanceof FunctionNode && compiler.getContext().getEnv()._lazy_compilation) { 232 final FunctionNode fn = (FunctionNode)fnExpr; 233 if (callExpr.getArgs().isEmpty()) { 234 final RecompilableScriptFunctionData data = compiler.getScriptFunctionData(fn.getId()); 235 if (data != null) { 236 final Type returnType = Type.typeFor(data.getReturnType(EMPTY_INVOCATION_TYPE, runtimeScope)); 237 if (returnType == Type.BOOLEAN) { 238 // We don't have optimistic booleans. In fact, optimistic call sites getting back boolean 239 // currently deoptimize all the way to Object. 240 return Type.OBJECT; 241 } 242 assert returnType == Type.INT || returnType == Type.NUMBER || returnType == Type.OBJECT; 243 return returnType; 244 } 245 } 246 } 247 } 248 249 return null; 250 } 251 } 252