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/*
* Copyright (c) 2010, 2013, 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).
*
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* 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
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package jdk.nashorn.internal.runtime.linker;
import static jdk.nashorn.internal.codegen.CompilerConstants.staticCallNoLookup;
import static jdk.nashorn.internal.runtime.ECMAErrors.typeError;
import java.lang.invoke.CallSite;
import java.lang.invoke.ConstantCallSite;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodHandles.Lookup;
import java.lang.invoke.MethodType;
import jdk.internal.dynalink.CallSiteDescriptor;
import jdk.internal.dynalink.DynamicLinker;
import jdk.internal.dynalink.DynamicLinkerFactory;
import jdk.internal.dynalink.GuardedInvocationFilter;
import jdk.internal.dynalink.beans.BeansLinker;
import jdk.internal.dynalink.beans.StaticClass;
import jdk.internal.dynalink.linker.GuardedInvocation;
import jdk.internal.dynalink.linker.LinkRequest;
import jdk.internal.dynalink.linker.LinkerServices;
import jdk.internal.dynalink.linker.MethodTypeConversionStrategy;
import jdk.internal.dynalink.support.TypeUtilities;
import jdk.nashorn.api.scripting.JSObject;
import jdk.nashorn.internal.codegen.CompilerConstants.Call;
import jdk.nashorn.internal.codegen.ObjectClassGenerator;
import jdk.nashorn.internal.lookup.MethodHandleFactory;
import jdk.nashorn.internal.lookup.MethodHandleFunctionality;
import jdk.nashorn.internal.runtime.ECMAException;
import jdk.nashorn.internal.runtime.JSType;
import jdk.nashorn.internal.runtime.OptimisticReturnFilters;
import jdk.nashorn.internal.runtime.ScriptFunction;
import jdk.nashorn.internal.runtime.ScriptRuntime;
import jdk.nashorn.internal.runtime.options.Options;
/**
* This class houses bootstrap method for invokedynamic instructions generated by compiler.
*/
public final class Bootstrap {
/** Reference to the seed boostrap function */
public static final Call BOOTSTRAP = staticCallNoLookup(Bootstrap.class, "bootstrap", CallSite.class, Lookup.class, String.class, MethodType.class, int.class);
private static final MethodHandleFunctionality MH = MethodHandleFactory.getFunctionality();
private static final MethodHandle VOID_TO_OBJECT = MH.constant(Object.class, ScriptRuntime.UNDEFINED);
/**
* The default dynalink relink threshold for megamorphism is 8. In the case
* of object fields only, it is fine. However, with dual fields, in order to get
* performance on benchmarks with a lot of object instantiation and then field
* reassignment, it can take slightly more relinks to become stable with type
* changes swapping out an entire property map and making a map guard fail.
* Since we need to set this value statically it must work with possibly changing
* optimistic types and dual fields settings. A higher value does not seem to have
* any other negative performance implication when running with object-only fields,
* so we choose a higher value here.
*
* See for example octane.gbemu, run with --log=fields:warning to study
* megamorphic behavior
*/
private static final int NASHORN_DEFAULT_UNSTABLE_RELINK_THRESHOLD = 16;
// do not create me!!
private Bootstrap() {
}
private static final DynamicLinker dynamicLinker;
static {
final DynamicLinkerFactory factory = new DynamicLinkerFactory();
final NashornBeansLinker nashornBeansLinker = new NashornBeansLinker();
factory.setPrioritizedLinkers(
new NashornLinker(),
new NashornPrimitiveLinker(),
new NashornStaticClassLinker(),
new BoundCallableLinker(),
new JavaSuperAdapterLinker(),
new JSObjectLinker(nashornBeansLinker),
new BrowserJSObjectLinker(nashornBeansLinker),
new ReflectionCheckLinker());
factory.setFallbackLinkers(nashornBeansLinker, new NashornBottomLinker());
factory.setSyncOnRelink(true);
factory.setPrelinkFilter(new GuardedInvocationFilter() {
@Override
public GuardedInvocation filter(final GuardedInvocation inv, final LinkRequest request, final LinkerServices linkerServices) {
final CallSiteDescriptor desc = request.getCallSiteDescriptor();
return OptimisticReturnFilters.filterOptimisticReturnValue(inv, desc).asType(linkerServices, desc.getMethodType());
}
});
factory.setAutoConversionStrategy(new MethodTypeConversionStrategy() {
@Override
public MethodHandle asType(final MethodHandle target, final MethodType newType) {
return unboxReturnType(target, newType);
}
});
factory.setInternalObjectsFilter(NashornBeansLinker.createHiddenObjectFilter());
final int relinkThreshold = Options.getIntProperty("nashorn.unstable.relink.threshold", NASHORN_DEFAULT_UNSTABLE_RELINK_THRESHOLD);
if (relinkThreshold > -1) {
factory.setUnstableRelinkThreshold(relinkThreshold);
}
// Linkers for any additional language runtimes deployed alongside Nashorn will be picked up by the factory.
factory.setClassLoader(Bootstrap.class.getClassLoader());
dynamicLinker = factory.createLinker();
}
/**
* Returns if the given object is a "callable"
* @param obj object to be checked for callability
* @return true if the obj is callable
*/
public static boolean isCallable(final Object obj) {
if (obj == ScriptRuntime.UNDEFINED || obj == null) {
return false;
}
return obj instanceof ScriptFunction ||
isJSObjectFunction(obj) ||
BeansLinker.isDynamicMethod(obj) ||
obj instanceof BoundCallable ||
isFunctionalInterfaceObject(obj) ||
obj instanceof StaticClass;
}
/**
* Returns true if the given object is a strict callable
* @param callable the callable object to be checked for strictness
* @return true if the obj is a strict callable, false if it is a non-strict callable.
* @throws ECMAException with {@code TypeError} if the object is not a callable.
*/
public static boolean isStrictCallable(final Object callable) {
if (callable instanceof ScriptFunction) {
return ((ScriptFunction)callable).isStrict();
} else if (isJSObjectFunction(callable)) {
return ((JSObject)callable).isStrictFunction();
} else if (callable instanceof BoundCallable) {
return isStrictCallable(((BoundCallable)callable).getCallable());
} else if (BeansLinker.isDynamicMethod(callable) || callable instanceof StaticClass) {
return false;
}
throw notFunction(callable);
}
private static ECMAException notFunction(final Object obj) {
return typeError("not.a.function", ScriptRuntime.safeToString(obj));
}
private static boolean isJSObjectFunction(final Object obj) {
return obj instanceof JSObject && ((JSObject)obj).isFunction();
}
/**
* Returns if the given object is a dynalink Dynamic method
* @param obj object to be checked
* @return true if the obj is a dynamic method
*/
public static boolean isDynamicMethod(final Object obj) {
return BeansLinker.isDynamicMethod(obj instanceof BoundCallable ? ((BoundCallable)obj).getCallable() : obj);
}
/**
* Returns if the given object is an instance of an interface annotated with
* java.lang.FunctionalInterface
* @param obj object to be checked
* @return true if the obj is an instance of @FunctionalInterface interface
*/
public static boolean isFunctionalInterfaceObject(final Object obj) {
return !JSType.isPrimitive(obj) && (NashornBeansLinker.getFunctionalInterfaceMethodName(obj.getClass()) != null);
}
/**
* Create a call site and link it for Nashorn. This version of the method conforms to the invokedynamic bootstrap
* method expected signature and is referenced from Nashorn generated bytecode as the bootstrap method for all
* invokedynamic instructions.
* @param lookup MethodHandle lookup. Ignored as Nashorn only uses public lookup.
* @param opDesc Dynalink dynamic operation descriptor.
* @param type Method type.
* @param flags flags for call type, trace/profile etc.
* @return CallSite with MethodHandle to appropriate method or null if not found.
*/
public static CallSite bootstrap(final Lookup lookup, final String opDesc, final MethodType type, final int flags) {
return dynamicLinker.link(LinkerCallSite.newLinkerCallSite(lookup, opDesc, type, flags));
}
/**
* Boostrapper for math calls that may overflow
* @param lookup lookup
* @param name name of operation
* @param type method type
* @param programPoint program point to bind to callsite
*
* @return callsite for a math intrinsic node
*/
public static CallSite mathBootstrap(final Lookup lookup, final String name, final MethodType type, final int programPoint) {
final MethodHandle mh;
switch (name) {
case "iadd":
mh = JSType.ADD_EXACT.methodHandle();
break;
case "isub":
mh = JSType.SUB_EXACT.methodHandle();
break;
case "imul":
mh = JSType.MUL_EXACT.methodHandle();
break;
case "idiv":
mh = JSType.DIV_EXACT.methodHandle();
break;
case "irem":
mh = JSType.REM_EXACT.methodHandle();
break;
case "ineg":
mh = JSType.NEGATE_EXACT.methodHandle();
break;
default:
throw new AssertionError("unsupported math intrinsic");
}
return new ConstantCallSite(MH.insertArguments(mh, mh.type().parameterCount() - 1, programPoint));
}
/**
* Returns a dynamic invoker for a specified dynamic operation using the public lookup. You can use this method to
* create a method handle that when invoked acts completely as if it were a Nashorn-linked call site. An overview of
* available dynamic operations can be found in the
* <a href="https://github.com/szegedi/dynalink/wiki/User-Guide-0.6">Dynalink User Guide</a>, but we'll show few
* examples here:
* <ul>
* <li>Get a named property with fixed name:
* <pre>
* MethodHandle getColor = Boostrap.createDynamicInvoker("dyn:getProp:color", Object.class, Object.class);
* Object obj = ...; // somehow obtain the object
* Object color = getColor.invokeExact(obj);
* </pre>
* </li>
* <li>Get a named property with variable name:
* <pre>
* MethodHandle getProperty = Boostrap.createDynamicInvoker("dyn:getElem", Object.class, Object.class, String.class);
* Object obj = ...; // somehow obtain the object
* Object color = getProperty.invokeExact(obj, "color");
* Object shape = getProperty.invokeExact(obj, "shape");
* MethodHandle getNumProperty = Boostrap.createDynamicInvoker("dyn:getElem", Object.class, Object.class, int.class);
* Object elem42 = getNumProperty.invokeExact(obj, 42);
* </pre>
* </li>
* <li>Set a named property with fixed name:
* <pre>
* MethodHandle setColor = Boostrap.createDynamicInvoker("dyn:setProp:color", void.class, Object.class, Object.class);
* Object obj = ...; // somehow obtain the object
* setColor.invokeExact(obj, Color.BLUE);
* </pre>
* </li>
* <li>Set a property with variable name:
* <pre>
* MethodHandle setProperty = Boostrap.createDynamicInvoker("dyn:setElem", void.class, Object.class, String.class, Object.class);
* Object obj = ...; // somehow obtain the object
* setProperty.invokeExact(obj, "color", Color.BLUE);
* setProperty.invokeExact(obj, "shape", Shape.CIRCLE);
* </pre>
* </li>
* <li>Call a function on an object; two-step variant. This is the actual variant used by Nashorn-generated code:
* <pre>
* MethodHandle findFooFunction = Boostrap.createDynamicInvoker("dyn:getMethod:foo", Object.class, Object.class);
* Object obj = ...; // somehow obtain the object
* Object foo_fn = findFooFunction.invokeExact(obj);
* MethodHandle callFunctionWithTwoArgs = Boostrap.createDynamicInvoker("dyn:call", Object.class, Object.class, Object.class, Object.class, Object.class);
* // Note: "call" operation takes a function, then a "this" value, then the arguments:
* Object foo_retval = callFunctionWithTwoArgs.invokeExact(foo_fn, obj, arg1, arg2);
* </pre>
* </li>
* <li>Call a function on an object; single-step variant. Although Nashorn doesn't use this variant and never
* emits any INVOKEDYNAMIC instructions with {@code dyn:getMethod}, it still supports this standard Dynalink
* operation:
* <pre>
* MethodHandle callFunctionFooWithTwoArgs = Boostrap.createDynamicInvoker("dyn:callMethod:foo", Object.class, Object.class, Object.class, Object.class);
* Object obj = ...; // somehow obtain the object
* Object foo_retval = callFunctionFooWithTwoArgs.invokeExact(obj, arg1, arg2);
* </pre>
* </li>
* </ul>
* Few additional remarks:
* <ul>
* <li>Just as Nashorn works with any Java object, the invokers returned from this method can also be applied to
* arbitrary Java objects in addition to Nashorn JavaScript objects.</li>
* <li>For invoking a named function on an object, you can also use the {@link InvokeByName} convenience class.</li>
* <li>For Nashorn objects {@code getElem}, {@code getProp}, and {@code getMethod} are handled almost identically,
* since JavaScript doesn't distinguish between different kinds of properties on an object. Either can be used with
* fixed property name or a variable property name. The only significant difference is handling of missing
* properties: {@code getMethod} for a missing member will link to a potential invocation of
* {@code __noSuchMethod__} on the object, {@code getProp} for a missing member will link to a potential invocation
* of {@code __noSuchProperty__}, while {@code getElem} for a missing member will link to an empty getter.</li>
* <li>In similar vein, {@code setElem} and {@code setProp} are handled identically on Nashorn objects.</li>
* <li>There's no rule that the variable property identifier has to be a {@code String} for {@code getProp/setProp}
* and {@code int} for {@code getElem/setElem}. You can declare their type to be {@code int}, {@code double},
* {@code Object}, and so on regardless of the kind of the operation.</li>
* <li>You can be as specific in parameter types as you want. E.g. if you know that the receiver of the operation
* will always be {@code ScriptObject}, you can pass {@code ScriptObject.class} as its parameter type. If you happen
* to link to a method that expects different types, (you can use these invokers on POJOs too, after all, and end up
* linking with their methods that have strongly-typed signatures), all necessary conversions allowed by either Java
* or JavaScript will be applied: if invoked methods specify either primitive or wrapped Java numeric types, or
* {@code String} or {@code boolean/Boolean}, then the parameters might be subjected to standard ECMAScript
* {@code ToNumber}, {@code ToString}, and {@code ToBoolean} conversion, respectively. Less obviously, if the
* expected parameter type is a SAM type, and you pass a JavaScript function, a proxy object implementing the SAM
* type and delegating to the function will be passed. Linkage can often be optimized when linkers have more
* specific type information than "everything can be an object".</li>
* <li>You can also be as specific in return types as you want. For return types any necessary type conversion
* available in either Java or JavaScript will be automatically applied, similar to the process described for
* parameters, only in reverse direction: if you specify any either primitive or wrapped Java numeric type, or
* {@code String} or {@code boolean/Boolean}, then the return values will be subjected to standard ECMAScript
* {@code ToNumber}, {@code ToString}, and {@code ToBoolean} conversion, respectively. Less obviously, if the return
* type is a SAM type, and the return value is a JavaScript function, a proxy object implementing the SAM type and
* delegating to the function will be returned.</li>
* </ul>
* @param opDesc Dynalink dynamic operation descriptor.
* @param rtype the return type for the operation
* @param ptypes the parameter types for the operation
* @return MethodHandle for invoking the operation.
*/
public static MethodHandle createDynamicInvoker(final String opDesc, final Class<?> rtype, final Class<?>... ptypes) {
return createDynamicInvoker(opDesc, MethodType.methodType(rtype, ptypes));
}
/**
* Returns a dynamic invoker for a specified dynamic operation using the public lookup. Similar to
* {@link #createDynamicInvoker(String, Class, Class...)} but with an additional parameter to
* set the call site flags of the dynamic invoker.
* @param opDesc Dynalink dynamic operation descriptor.
* @param flags the call site flags for the operation
* @param rtype the return type for the operation
* @param ptypes the parameter types for the operation
* @return MethodHandle for invoking the operation.
*/
public static MethodHandle createDynamicInvoker(final String opDesc, final int flags, final Class<?> rtype, final Class<?>... ptypes) {
return bootstrap(MethodHandles.publicLookup(), opDesc, MethodType.methodType(rtype, ptypes), flags).dynamicInvoker();
}
/**
* Returns a dynamic invoker for a specified dynamic operation using the public lookup. Similar to
* {@link #createDynamicInvoker(String, Class, Class...)} but with return and parameter types composed into a
* method type in the signature. See the discussion of that method for details.
* @param opDesc Dynalink dynamic operation descriptor.
* @param type the method type for the operation
* @return MethodHandle for invoking the operation.
*/
public static MethodHandle createDynamicInvoker(final String opDesc, final MethodType type) {
return bootstrap(MethodHandles.publicLookup(), opDesc, type, 0).dynamicInvoker();
}
/**
* Binds any object Nashorn can use as a [[Callable]] to a receiver and optionally arguments.
* @param callable the callable to bind
* @param boundThis the bound "this" value.
* @param boundArgs the bound arguments. Can be either null or empty array to signify no arguments are bound.
* @return a bound callable.
* @throws ECMAException with {@code TypeError} if the object is not a callable.
*/
public static Object bindCallable(final Object callable, final Object boundThis, final Object[] boundArgs) {
if (callable instanceof ScriptFunction) {
return ((ScriptFunction)callable).createBound(boundThis, boundArgs);
} else if (callable instanceof BoundCallable) {
return ((BoundCallable)callable).bind(boundArgs);
} else if (isCallable(callable)) {
return new BoundCallable(callable, boundThis, boundArgs);
}
throw notFunction(callable);
}
/**
* Creates a super-adapter for an adapter, that is, an adapter to the adapter that allows invocation of superclass
* methods on it.
* @param adapter the original adapter
* @return a new adapter that can be used to invoke super methods on the original adapter.
*/
public static Object createSuperAdapter(final Object adapter) {
return new JavaSuperAdapter(adapter);
}
/**
* If the given class is a reflection-specific class (anything in {@code java.lang.reflect} and
* {@code java.lang.invoke} package, as well a {@link Class} and any subclass of {@link ClassLoader}) and there is
* a security manager in the system, then it checks the {@code nashorn.JavaReflection} {@code RuntimePermission}.
* @param clazz the class being tested
* @param isStatic is access checked for static members (or instance members)
*/
public static void checkReflectionAccess(final Class<?> clazz, final boolean isStatic) {
ReflectionCheckLinker.checkReflectionAccess(clazz, isStatic);
}
/**
* Returns the Nashorn's internally used dynamic linker's services object. Note that in code that is processing a
* linking request, you will normally use the {@code LinkerServices} object passed by whatever top-level linker
* invoked the linking (if the call site is in Nashorn-generated code, you'll get this object anyway). You should
* only resort to retrieving a linker services object using this method when you need some linker services (e.g.
* type converter method handles) outside of a code path that is linking a call site.
* @return Nashorn's internal dynamic linker's services object.
*/
public static LinkerServices getLinkerServices() {
return dynamicLinker.getLinkerServices();
}
/**
* Takes a guarded invocation, and ensures its method and guard conform to the type of the call descriptor, using
* all type conversions allowed by the linker's services. This method is used by Nashorn's linkers as a last step
* before returning guarded invocations. Most of the code used to produce the guarded invocations does not make an
* effort to coordinate types of the methods, and so a final type adjustment before a guarded invocation is returned
* to the aggregating linker is the responsibility of the linkers themselves.
* @param inv the guarded invocation that needs to be type-converted. Can be null.
* @param linkerServices the linker services object providing the type conversions.
* @param desc the call site descriptor to whose method type the invocation needs to conform.
* @return the type-converted guarded invocation. If input is null, null is returned. If the input invocation
* already conforms to the requested type, it is returned unchanged.
*/
static GuardedInvocation asTypeSafeReturn(final GuardedInvocation inv, final LinkerServices linkerServices, final CallSiteDescriptor desc) {
return inv == null ? null : inv.asTypeSafeReturn(linkerServices, desc.getMethodType());
}
/**
* Adapts the return type of the method handle with {@code explicitCastArguments} when it is an unboxing
* conversion. This will ensure that nulls are unwrapped to false or 0.
* @param target the target method handle
* @param newType the desired new type. Note that this method does not adapt the method handle completely to the
* new type, it only adapts the return type; this is allowed as per
* {@link DynamicLinkerFactory#setAutoConversionStrategy(MethodTypeConversionStrategy)}, which is what this method
* is used for.
* @return the method handle with adapted return type, if it required an unboxing conversion.
*/
private static MethodHandle unboxReturnType(final MethodHandle target, final MethodType newType) {
final MethodType targetType = target.type();
final Class<?> oldReturnType = targetType.returnType();
final Class<?> newReturnType = newType.returnType();
if (TypeUtilities.isWrapperType(oldReturnType)) {
if (newReturnType.isPrimitive()) {
// The contract of setAutoConversionStrategy is such that the difference between newType and targetType
// can only be JLS method invocation conversions.
assert TypeUtilities.isMethodInvocationConvertible(oldReturnType, newReturnType);
return MethodHandles.explicitCastArguments(target, targetType.changeReturnType(newReturnType));
}
} else if (oldReturnType == void.class && newReturnType == Object.class) {
return MethodHandles.filterReturnValue(target, VOID_TO_OBJECT);
}
return target;
}
}