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Diffstat (limited to 'src/jdk/nashorn/internal/codegen/TypeEvaluator.java')
| -rw-r--r-- | src/jdk/nashorn/internal/codegen/TypeEvaluator.java | 250 |
1 files changed, 250 insertions, 0 deletions
diff --git a/src/jdk/nashorn/internal/codegen/TypeEvaluator.java b/src/jdk/nashorn/internal/codegen/TypeEvaluator.java new file mode 100644 index 00000000..d5282a8b --- /dev/null +++ b/src/jdk/nashorn/internal/codegen/TypeEvaluator.java @@ -0,0 +1,250 @@ +/* + * 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(); + if (fnExpr instanceof FunctionNode) { + 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.LONG || returnType == Type.NUMBER || returnType == Type.OBJECT; + return returnType; + } + } + } + } + + return null; + } +} |