/* * Copyright (c) 2010, 2014, 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.codegen; import static jdk.nashorn.internal.runtime.Property.NOT_CONFIGURABLE; import static jdk.nashorn.internal.runtime.Property.NOT_ENUMERABLE; import static jdk.nashorn.internal.runtime.Property.NOT_WRITABLE; import java.lang.invoke.MethodType; import jdk.nashorn.internal.codegen.types.Type; import jdk.nashorn.internal.ir.AccessNode; import jdk.nashorn.internal.ir.CallNode; import jdk.nashorn.internal.ir.Expression; import jdk.nashorn.internal.ir.FunctionNode; import jdk.nashorn.internal.ir.IdentNode; import jdk.nashorn.internal.ir.IndexNode; import jdk.nashorn.internal.ir.Optimistic; import jdk.nashorn.internal.objects.ArrayBufferView; import jdk.nashorn.internal.objects.NativeArray; import jdk.nashorn.internal.runtime.FindProperty; import jdk.nashorn.internal.runtime.JSType; import jdk.nashorn.internal.runtime.Property; import jdk.nashorn.internal.runtime.RecompilableScriptFunctionData; import jdk.nashorn.internal.runtime.ScriptFunction; import jdk.nashorn.internal.runtime.ScriptObject; import jdk.nashorn.internal.runtime.ScriptRuntime; /** * Functionality for using a runtime scope to look up value types. * Used during recompilation. */ final class TypeEvaluator { /** * Type signature for invocation of functions without parameters: we must pass (callee, this) of type * (ScriptFunction, Object) respectively. We also use Object as the return type (we must pass something, * but it'll be ignored; it can't be void, though). */ private static final MethodType EMPTY_INVOCATION_TYPE = MethodType.methodType(Object.class, ScriptFunction.class, Object.class); private final Compiler compiler; private final ScriptObject runtimeScope; TypeEvaluator(final Compiler compiler, final ScriptObject runtimeScope) { this.compiler = compiler; this.runtimeScope = runtimeScope; } /** * Returns true if the expression can be safely evaluated, and its value is an object known to always use * String as the type of its property names retrieved through * {@link ScriptRuntime#toPropertyIterator(Object)}. It is used to avoid optimistic assumptions about its * property name types. * @param expr the expression to test * @return true if the expression can be safely evaluated, and its value is an object known to always use * String as the type of its property iterators. */ boolean hasStringPropertyIterator(final Expression expr) { return evaluateSafely(expr) instanceof ScriptObject; } Type getOptimisticType(final Optimistic node) { assert compiler.useOptimisticTypes(); final int programPoint = node.getProgramPoint(); final Type validType = compiler.getInvalidatedProgramPointType(programPoint); if (validType != null) { return validType; } final Type mostOptimisticType = node.getMostOptimisticType(); final Type evaluatedType = getEvaluatedType(node); if (evaluatedType != null) { if (evaluatedType.widerThan(mostOptimisticType)) { final Type newValidType = evaluatedType.isObject() || evaluatedType.isBoolean() ? Type.OBJECT : evaluatedType; // Update invalidatedProgramPoints so we don't re-evaluate the expression next time. This is a heuristic // as we're doing a tradeoff. Re-evaluating expressions on each recompile takes time, but it might // notice a widening in the type of the expression and thus prevent an unnecessary deoptimization later. // We'll presume though that the types of expressions are mostly stable, so if we evaluated it in one // compilation, we'll keep to that and risk a low-probability deoptimization if its type gets widened // in the future. compiler.addInvalidatedProgramPoint(node.getProgramPoint(), newValidType); } return evaluatedType; } return mostOptimisticType; } private static Type getPropertyType(final ScriptObject sobj, final String name) { final FindProperty find = sobj.findProperty(name, true); if (find == null) { return null; } final Property property = find.getProperty(); final Class propertyClass = property.getType(); if (propertyClass == null) { // propertyClass == null means its value is Undefined. It is probably not initialized yet, so we won't make // a type assumption yet. return null; } else if (propertyClass.isPrimitive()) { return Type.typeFor(propertyClass); } final ScriptObject owner = find.getOwner(); if (property.hasGetterFunction(owner)) { // Can have side effects, so we can't safely evaluate it; since !propertyClass.isPrimitive(), it's Object. return Type.OBJECT; } // Safely evaluate the property, and return the narrowest type for the actual value (e.g. Type.INT for a boxed // integer). final Object value = property.needsDeclaration() ? ScriptRuntime.UNDEFINED : property.getObjectValue(owner, owner); if (value == ScriptRuntime.UNDEFINED) { return null; } return Type.typeFor(JSType.unboxedFieldType(value)); } /** * Declares a symbol name as belonging to a non-scoped local variable during an on-demand compilation of a single * function. This method will add an explicit Undefined binding for the local into the runtime scope if it's * otherwise implicitly undefined so that when an expression is evaluated for the name, it won't accidentally find * an unrelated value higher up the scope chain. It is only required to call this method when doing an optimistic * on-demand compilation. * @param symbolName the name of the symbol that is to be declared as being a non-scoped local variable. */ void declareLocalSymbol(final String symbolName) { assert compiler.useOptimisticTypes() && compiler.isOnDemandCompilation() && runtimeScope != null : "useOptimistic=" + compiler.useOptimisticTypes() + " isOnDemand=" + compiler.isOnDemandCompilation() + " scope="+runtimeScope; if (runtimeScope.findProperty(symbolName, false) == null) { runtimeScope.addOwnProperty(symbolName, NOT_WRITABLE | NOT_ENUMERABLE | NOT_CONFIGURABLE, ScriptRuntime.UNDEFINED); } } private Object evaluateSafely(final Expression expr) { if (expr instanceof IdentNode) { return runtimeScope == null ? null : evaluatePropertySafely(runtimeScope, ((IdentNode)expr).getName()); } if (expr instanceof AccessNode) { final AccessNode accessNode = (AccessNode)expr; final Object base = evaluateSafely(accessNode.getBase()); if (!(base instanceof ScriptObject)) { return null; } return evaluatePropertySafely((ScriptObject)base, accessNode.getProperty()); } return null; } private static Object evaluatePropertySafely(final ScriptObject sobj, final String name) { final FindProperty find = sobj.findProperty(name, true); if (find == null) { return null; } final Property property = find.getProperty(); final ScriptObject owner = find.getOwner(); if (property.hasGetterFunction(owner)) { // Possible side effects; can't evaluate safely return null; } return property.getObjectValue(owner, owner); } private Type getEvaluatedType(final Optimistic expr) { if (expr instanceof IdentNode) { if (runtimeScope == null) { return null; } return getPropertyType(runtimeScope, ((IdentNode)expr).getName()); } else if (expr instanceof AccessNode) { final AccessNode accessNode = (AccessNode)expr; final Object base = evaluateSafely(accessNode.getBase()); if (!(base instanceof ScriptObject)) { return null; } return getPropertyType((ScriptObject)base, accessNode.getProperty()); } else if (expr instanceof IndexNode) { final IndexNode indexNode = (IndexNode)expr; final Object base = evaluateSafely(indexNode.getBase()); if(base instanceof NativeArray || base instanceof ArrayBufferView) { // NOTE: optimistic array getters throw UnwarrantedOptimismException based on the type of their // underlying array storage, not based on values of individual elements. Thus, a LongArrayData will // throw UOE for every optimistic int linkage attempt, even if the long value being returned in the // first invocation would be representable as int. That way, we can presume that the array's optimistic // type is the most optimistic type for which an element getter has a chance of executing successfully. return ((ScriptObject)base).getArray().getOptimisticType(); } } else if (expr instanceof CallNode) { // Currently, we'll only try to guess the return type of immediately invoked function expressions with no // parameters, that is (function() { ... })(). We could do better, but these are all heuristics and we can // gradually introduce them as needed. An easy one would be to do the same for .call(this) idiom. final CallNode callExpr = (CallNode)expr; final Expression fnExpr = callExpr.getFunction(); // Skip evaluation if running with eager compilation as we may violate constraints in RecompilableScriptFunctionData if (fnExpr instanceof FunctionNode && compiler.getContext().getEnv()._lazy_compilation) { final FunctionNode fn = (FunctionNode)fnExpr; if (callExpr.getArgs().isEmpty()) { final RecompilableScriptFunctionData data = compiler.getScriptFunctionData(fn.getId()); if (data != null) { final Type returnType = Type.typeFor(data.getReturnType(EMPTY_INVOCATION_TYPE, runtimeScope)); if (returnType == Type.BOOLEAN) { // We don't have optimistic booleans. In fact, optimistic call sites getting back boolean // currently deoptimize all the way to Object. return Type.OBJECT; } assert returnType == Type.INT || returnType == Type.NUMBER || returnType == Type.OBJECT; return returnType; } } } } return null; } }