changeset 3690:c86c60ad8822

7012650: implement JSR 292 EG adjustments through January 2010 Summary: misc. EG changes and polishes (excluding 7013417) Reviewed-by: twisti
author jrose
date Fri, 11 Feb 2011 01:26:28 -0800
parents d7de46ec011b
children a2241b109aa1
files src/share/classes/java/dyn/CallSite.java src/share/classes/java/dyn/ClassValue.java src/share/classes/java/dyn/ConstantCallSite.java src/share/classes/java/dyn/InvokeDynamicBootstrapError.java src/share/classes/java/dyn/Linkage.java src/share/classes/java/dyn/MethodHandle.java src/share/classes/java/dyn/MethodHandles.java src/share/classes/java/dyn/MethodType.java src/share/classes/java/dyn/MutableCallSite.java src/share/classes/java/dyn/SwitchPoint.java src/share/classes/java/dyn/Switcher.java src/share/classes/java/dyn/VolatileCallSite.java src/share/classes/java/dyn/WrongMethodTypeException.java src/share/classes/java/dyn/package-info.java src/share/classes/sun/dyn/AdapterMethodHandle.java src/share/classes/sun/dyn/FromGeneric.java src/share/classes/sun/dyn/InvokeGeneric.java src/share/classes/sun/dyn/Invokers.java src/share/classes/sun/dyn/MethodHandleImpl.java src/share/classes/sun/dyn/ToGeneric.java src/share/classes/sun/dyn/WrapperInstance.java test/java/dyn/InvokeGenericTest.java test/java/dyn/JavaDocExamplesTest.java test/java/dyn/MethodHandlesTest.java
diffstat 24 files changed, 1657 insertions(+), 877 deletions(-) [+]
line wrap: on
line diff
--- a/src/share/classes/java/dyn/CallSite.java	Fri Feb 11 01:26:24 2011 -0800
+++ b/src/share/classes/java/dyn/CallSite.java	Fri Feb 11 01:26:28 2011 -0800
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2011, 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
@@ -78,7 +78,7 @@
 }
 private static CallSite bootstrapDynamic(MethodHandles.Lookup caller, String name, MethodType type) {
   // ignore caller and name, but match the type:
-  return new ConstantCallSite(MethodHandles.collectArguments(printArgs, type));
+  return new ConstantCallSite(printArgs.asType(type));
 }
 </pre></blockquote>
  * @author John Rose, JSR 292 EG
@@ -86,6 +86,7 @@
 abstract
 public class CallSite {
     private static final Access IMPL_TOKEN = Access.getToken();
+    static { MethodHandleImpl.initStatics(); }
 
     // Fields used only by the JVM.  Do not use or change.
     private MemberName vmmethod; // supplied by the JVM (ref. to calling method)
@@ -125,8 +126,8 @@
     }
 
     /**
-     * Report the type of this call site's target.
-     * Although targets may change, the call site's type can never change.
+     * Returns the type of this call site's target.
+     * Although targets may change, any call site's type is permanent, and can never change to an unequal type.
      * The {@code setTarget} method enforces this invariant by refusing any new target that does
      * not have the previous target's type.
      * @return the type of the current target, which is also the type of any future target
@@ -154,73 +155,40 @@
     }
 
     /**
-     * Report the current linkage state of the call site, a value which may change over time.
-     * <p>
-     * If a {@code CallSite} object is returned
-     * from the bootstrap method of the {@code invokedynamic} instruction,
-     * the {@code CallSite} is permanently bound to that instruction.
-     * When the {@code invokedynamic} instruction is executed, the target method
-     * of its associated call site object is invoked directly.
-     * It is as if the instruction calls {@code getTarget} and then
-     * calls {@link MethodHandle#invokeExact invokeExact} on the result.
-     * <p>
-     * Unless specified differently by a subclass,
-     * the interactions of {@code getTarget} with memory are the same
-     * as of a read from an ordinary variable, such as an array element or a
-     * non-volatile, non-final field.
-     * <p>
-     * In particular, the current thread may choose to reuse the result
-     * of a previous read of the target from memory, and may fail to see
-     * a recent update to the target by another thread.
-     * <p>
-     * In a {@linkplain ConstantCallSite constant call site}, the {@code getTarget} method behaves
-     * like a read from a {@code final} field of the {@code CallSite}.
-     * <p>
-     * In a {@linkplain VolatileCallSite volatile call site}, the {@code getTarget} method behaves
-     * like a read from a {@code volatile} field of the {@code CallSite}.
-     * <p>
-     * This method may not be overridden by application code.
+     * Returns the target method of the call site, according to the
+     * behavior defined by this call site's specific class.
+     * The immediate subclasses of {@code CallSite} document the
+     * class-specific behaviors of this method.
+     *
      * @return the current linkage state of the call site, its target method handle
      * @see ConstantCallSite
      * @see VolatileCallSite
      * @see #setTarget
+     * @see ConstantCallSite#getTarget
+     * @see MutableCallSite#getTarget
+     * @see VolatileCallSite#getTarget
      */
-    public final MethodHandle getTarget() {
-        return getTarget0();
-    }
+    public abstract MethodHandle getTarget();
 
     /**
-     * Privileged implementations can override this to force final or volatile semantics on getTarget.
-     */
-    /*package-private*/
-    MethodHandle getTarget0() {
-        return target;
-    }
-
-    /**
-     * Set the target method of this call site.
+     * Updates the target method of this call site, according to the
+     * behavior defined by this call site's specific class.
+     * The immediate subclasses of {@code CallSite} document the
+     * class-specific behaviors of this method.
      * <p>
-     * Unless a subclass of CallSite documents otherwise,
-     * the interactions of {@code setTarget} with memory are the same
-     * as of a write to an ordinary variable, such as an array element or a
-     * non-volatile, non-final field.
-     * <p>
-     * In particular, unrelated threads may fail to see the updated target
-     * until they perform a read from memory.
-     * Stronger guarantees can be created by putting appropriate operations
-     * into the bootstrap method and/or the target methods used
-     * at any given call site.
+     * The type of the new target must be {@linkplain MethodType#equals equal to}
+     * the type of the old target.
+     *
      * @param newTarget the new target
      * @throws NullPointerException if the proposed new target is null
      * @throws WrongMethodTypeException if the proposed new target
      *         has a method type that differs from the previous target
-     * @throws UnsupportedOperationException if the call site is
-     *         in fact a {@link ConstantCallSite}
+     * @see CallSite#getTarget
+     * @see ConstantCallSite#setTarget
+     * @see MutableCallSite#setTarget
+     * @see VolatileCallSite#setTarget
      */
-    public void setTarget(MethodHandle newTarget) {
-        checkTargetChange(this.target, newTarget);
-        setTargetNormal(newTarget);
-    }
+    public abstract void setTarget(MethodHandle newTarget);
 
     void checkTargetChange(MethodHandle oldTarget, MethodHandle newTarget) {
         MethodType oldType = oldTarget.type();
@@ -236,25 +204,25 @@
     /**
      * Produce a method handle equivalent to an invokedynamic instruction
      * which has been linked to this call site.
-     * <p>If this call site is a {@linkplain ConstantCallSite constant call site},
-     * this method simply returns the call site's target, since that will never change.
-     * <p>Otherwise, this method is equivalent to the following code:
-     * <p><blockquote><pre>
+     * <p>
+     * This method is equivalent to the following code:
+     * <blockquote><pre>
      * MethodHandle getTarget, invoker, result;
-     * getTarget = MethodHandles.lookup().bind(this, "getTarget", MethodType.methodType(MethodHandle.class));
+     * getTarget = MethodHandles.publicLookup().bind(this, "getTarget", MethodType.methodType(MethodHandle.class));
      * invoker = MethodHandles.exactInvoker(this.type());
      * result = MethodHandles.foldArguments(invoker, getTarget)
      * </pre></blockquote>
+     *
      * @return a method handle which always invokes this call site's current target
      */
-    public final MethodHandle dynamicInvoker() {
-        if (this instanceof ConstantCallSite) {
-            return getTarget0();  // will not change dynamically
-        }
+    public abstract MethodHandle dynamicInvoker();
+
+    /*non-public*/ MethodHandle makeDynamicInvoker() {
         MethodHandle getTarget = MethodHandleImpl.bindReceiver(IMPL_TOKEN, GET_TARGET, this);
         MethodHandle invoker = MethodHandles.exactInvoker(this.type());
         return MethodHandles.foldArguments(invoker, getTarget);
     }
+
     private static final MethodHandle GET_TARGET;
     static {
         try {
--- a/src/share/classes/java/dyn/ClassValue.java	Fri Feb 11 01:26:24 2011 -0800
+++ b/src/share/classes/java/dyn/ClassValue.java	Fri Feb 11 01:26:28 2011 -0800
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2010, 2011, 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
@@ -31,10 +31,14 @@
 import java.lang.reflect.UndeclaredThrowableException;
 
 /**
- * Lazily associate a computed value with (potentially) every class.
+ * Lazily associate a computed value with (potentially) every type.
+ * For example, if a dynamic language needs to construct a message dispatch
+ * table for each class encountered at a message send call site,
+ * it can use a {@code ClassValue} to cache information needed to
+ * perform the message send quickly, for each class encountered.
  * @author John Rose, JSR 292 EG
  */
-public class ClassValue<T> {
+public abstract class ClassValue<T> {
     /**
      * Compute the given class's derived value for this {@code ClassValue}.
      * <p>
@@ -45,61 +49,41 @@
      * but it may be invoked again if there has been a call to
      * {@link #remove remove}.
      * <p>
-     * If there is no override from a subclass, this method returns
-     * the result of applying the {@code ClassValue}'s {@code computeValue}
-     * method handle, which was supplied at construction time.
+     * If this method throws an exception, the corresponding call to {@code get}
+     * will terminate abnormally with that exception, and no class value will be recorded.
      *
+     * @param type the type whose class value must be computed
      * @return the newly computed value associated with this {@code ClassValue}, for the given class or interface
-     * @throws UndeclaredThrowableException if the {@code computeValue} method handle invocation throws something other than a {@code RuntimeException} or {@code Error}
-     * @throws UnsupportedOperationException if the {@code computeValue} method handle is null (subclasses must override)
+     * @see #get
+     * @see #remove
      */
-    protected T computeValue(Class<?> type) {
-        if (computeValue == null)
-            return null;
-        try {
-            return (T) (Object) computeValue.invokeGeneric(type);
-        } catch (Throwable ex) {
-            if (ex instanceof Error)             throw (Error) ex;
-            if (ex instanceof RuntimeException)  throw (RuntimeException) ex;
-            throw new UndeclaredThrowableException(ex);
-        }
-    }
-
-    private final MethodHandle computeValue;
-
-    /**
-     * Creates a new class value.
-     * Subclasses which use this constructor must override
-     * the {@link #computeValue computeValue} method,
-     * since the default {@code computeValue} method requires a method handle,
-     * which this constructor does not provide.
-     */
-    protected ClassValue() {
-        this.computeValue = null;
-    }
-
-    /**
-     * Creates a new class value, whose {@link #computeValue computeValue} method
-     * will return the result of {@code computeValue.invokeGeneric(type)}.
-     * @throws NullPointerException  if the method handle parameter is null
-     */
-    public ClassValue(MethodHandle computeValue) {
-        computeValue.getClass();  // trigger NPE if null
-        this.computeValue = computeValue;
-    }
+    protected abstract T computeValue(Class<?> type);
 
     /**
      * Returns the value for the given class.
      * If no value has yet been computed, it is obtained by
-     * by an invocation of the {@link #computeValue computeValue} method.
+     * an invocation of the {@link #computeValue computeValue} method.
      * <p>
      * The actual installation of the value on the class
      * is performed atomically.
-     * At that point, if racing threads have
+     * At that point, if several racing threads have
      * computed values, one is chosen, and returned to
      * all the racing threads.
+     * <p>
+     * The {@code type} parameter is typically a class, but it may be any type,
+     * such as an interface, a primitive type (like {@code int.class}), or {@code void.class}.
+     * <p>
+     * In the absence of {@code remove} calls, a class value has a simple
+     * state diagram:  uninitialized and initialized.
+     * When {@code remove} calls are made,
+     * the rules for value observation are more complex.
+     * See the documentation for {@link #remove remove} for more information.
      *
+     * @param type the type whose class value must be computed or retrieved
      * @return the current value associated with this {@code ClassValue}, for the given class or interface
+     * @throws NullPointerException if the argument is null
+     * @see #remove
+     * @see #computeValue
      */
     public T get(Class<?> type) {
         ClassValueMap map = getMap(type);
@@ -119,12 +103,51 @@
      * This may result in an additional invocation of the
      * {@code computeValue computeValue} method for the given class.
      * <p>
-     * If racing threads perform a combination of {@code get} and {@code remove} calls,
-     * the calls are serialized.
-     * A value produced by a call to {@code computeValue} will be discarded, if
-     * the corresponding {@code get} call was followed by a {@code remove} call
-     * before the {@code computeValue} could complete.
-     * In such a case, the {@code get} call will re-invoke {@code computeValue}.
+     * In order to explain the interaction between {@code get} and {@code remove} calls,
+     * we must model the state transitions of a class value to take into account
+     * the alternation between uninitialized and initialized states.
+     * To do this, number these states sequentially from zero, and note that
+     * uninitialized (or removed) states are numbered with even numbers,
+     * while initialized (or re-initialized) states have odd numbers.
+     * <p>
+     * When a thread {@code T} removes a class value in state {@code 2N},
+     * nothing happens, since the class value is already uninitialized.
+     * Otherwise, the state is advanced atomically to {@code 2N+1}.
+     * <p>
+     * When a thread {@code T} queries a class value in state {@code 2N},
+     * the thread first attempts to initialize the class value to state {@code 2N+1}
+     * by invoking {@code computeValue} and installing the resulting value.
+     * <p>
+     * When {@code T} attempts to install the newly computed value,
+     * if the state is still at {@code 2N}, the class value will be initialized
+     * with the computed value, advancing it to state {@code 2N+1}.
+     * <p>
+     * Otherwise, whether the new state is even or odd,
+     * {@code T} will discard the newly computed value
+     * and retry the {@code get} operation.
+     * <p>
+     * Discarding and retrying is an important proviso,
+     * since otherwise {@code T} could potentially install
+     * a disastrously stale value.  For example:
+     * <ul>
+     * <li>{@code T} calls {@code CV.get(C)} and sees state {@code 2N}
+     * <li>{@code T} quickly computes a time-dependent value {@code V0} and gets ready to install it
+     * <li>{@code T} is hit by an unlucky paging or scheduling event, and goes to sleep for a long time
+     * <li>...meanwhile, {@code T2} also calls {@code CV.get(C)} and sees state {@code 2N}
+     * <li>{@code T2} quickly computes a similar time-dependent value {@code V1} and installs it on {@code CV.get(C)}
+     * <li>{@code T2} (or a third thread) then calls {@code CV.remove(C)}, undoing {@code T2}'s work
+     * <li> the previous actions of {@code T2} are repeated several times
+     * <li> also, the relevant computed values change over time: {@code V1}, {@code V2}, ...
+     * <li>...meanwhile, {@code T} wakes up and attempts to install {@code V0}; <em>this must fail</em>
+     * </ul>
+     * We can assume in the above scenario that {@code CV.computeValue} uses locks to properly
+     * observe the time-dependent states as it computes {@code V1}, etc.
+     * This does not remove the threat of a stale value, since there is a window of time
+     * between the return of {@code computeValue} in {@code T} and the installation
+     * of the the new value.  No user synchronization is possible during this time.
+     *
+     * @param type the type whose class value must be removed
+     * @throws NullPointerException if the argument is null
      */
     public void remove(Class<?> type) {
         ClassValueMap map = getMap(type);
@@ -137,9 +160,9 @@
 
     /// Implementation...
 
-    /** The hash code for this type is based on the identity of the object,
-     *  and is well-dispersed for power-of-two tables.
-     */
+    // The hash code for this type is based on the identity of the object,
+    // and is well-dispersed for power-of-two tables.
+    /** @deprecated This override, which is implementation-specific, will be removed for PFD. */
     public final int hashCode() { return hashCode; }
     private final int hashCode = HASH_CODES.getAndAdd(0x61c88647);
     private static final AtomicInteger HASH_CODES = new AtomicInteger();
--- a/src/share/classes/java/dyn/ConstantCallSite.java	Fri Feb 11 01:26:24 2011 -0800
+++ b/src/share/classes/java/dyn/ConstantCallSite.java	Fri Feb 11 01:26:28 2011 -0800
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2010, 2011, 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
@@ -32,16 +32,46 @@
  * @author John Rose, JSR 292 EG
  */
 public class ConstantCallSite extends CallSite {
-    /** Create a call site with a permanent target.
+    /**
+     * Creates a call site with a permanent target.
+     * @param target the target to be permanently associated with this call site
      * @throws NullPointerException if the proposed target is null
      */
     public ConstantCallSite(MethodHandle target) {
         super(target);
     }
+
     /**
-     * Throw an {@link UnsupportedOperationException}, because this kind of call site cannot change its target.
+     * Returns the target method of the call site, which behaves
+     * like a {@code final} field of the {@code ConstantCallSite}.
+     * That is, the the target is always the original value passed
+     * to the constructor call which created this instance.
+     *
+     * @return the immutable linkage state of this call site, a constant method handle
+     * @throws UnsupportedOperationException because this kind of call site cannot change its target
+     */
+    @Override public final MethodHandle getTarget() {
+        return target;
+    }
+
+    /**
+     * Always throws an {@link UnsupportedOperationException}.
+     * This kind of call site cannot change its target.
+     * @param ignore a new target proposed for the call site, which is ignored
+     * @throws UnsupportedOperationException because this kind of call site cannot change its target
      */
     @Override public final void setTarget(MethodHandle ignore) {
         throw new UnsupportedOperationException("ConstantCallSite");
     }
+
+    /**
+     * Returns this call site's permanent target.
+     * Since that target will never change, this is a correct implementation
+     * of {@link CallSite#dynamicInvoker CallSite.dynamicInvoker}.
+     * @return the immutable linkage state of this call site, a constant method handle
+     */
+    @Override
+    public final MethodHandle dynamicInvoker() {
+        return getTarget();
+    }
 }
--- a/src/share/classes/java/dyn/InvokeDynamicBootstrapError.java	Fri Feb 11 01:26:24 2011 -0800
+++ b/src/share/classes/java/dyn/InvokeDynamicBootstrapError.java	Fri Feb 11 01:26:28 2011 -0800
@@ -31,8 +31,8 @@
  * {@linkplain BootstrapMethod bootstrap method},
  * or the bootstrap method has
  * failed to provide a
- * {@linkplain CallSite} call site with a non-null {@linkplain MethodHandle target}
- * of the correct {@linkplain MethodType method type}.
+ * {@linkplain CallSite call site} with a {@linkplain CallSite#getTarget target}
+ * of the correct {@linkplain MethodHandle#type method type}.
  *
  * @author John Rose, JSR 292 EG
  * @since 1.7
--- a/src/share/classes/java/dyn/Linkage.java	Fri Feb 11 01:26:24 2011 -0800
+++ b/src/share/classes/java/dyn/Linkage.java	Fri Feb 11 01:26:28 2011 -0800
@@ -101,8 +101,9 @@
     /**
      * <em>METHOD WILL BE REMOVED FOR PFD:</em>
      * Invalidate all <code>invokedynamic</code> call sites everywhere.
-     * @deprecated Use {@linkplain CallSite#setTarget call site target setting}
-     * and {@link VolatileCallSite#invalidateAll call site invalidation} instead.
+     * @deprecated Use {@linkplain MutableCallSite#setTarget call site target setting},
+     * {@link MutableCallSite#syncAll call site update pushing},
+     * and {@link SwitchPoint#guardWithTest target switching} instead.
      */
     public static
     Object invalidateAll() {
@@ -113,8 +114,9 @@
      * <em>METHOD WILL BE REMOVED FOR PFD:</em>
      * Invalidate all {@code invokedynamic} call sites in the bytecodes
      * of any methods of the given class.
-     * @deprecated Use {@linkplain CallSite#setTarget call site target setting}
-     * and {@link VolatileCallSite#invalidateAll call site invalidation} instead.
+     * @deprecated Use {@linkplain MutableCallSite#setTarget call site target setting},
+     * {@link MutableCallSite#syncAll call site update pushing},
+     * and {@link SwitchPoint#guardWithTest target switching} instead.
      */
     public static
     Object invalidateCallerClass(Class<?> callerClass) {
--- a/src/share/classes/java/dyn/MethodHandle.java	Fri Feb 11 01:26:24 2011 -0800
+++ b/src/share/classes/java/dyn/MethodHandle.java	Fri Feb 11 01:26:28 2011 -0800
@@ -34,7 +34,7 @@
 import static sun.dyn.MemberName.newIllegalArgumentException;  // utility
 
 /**
- * A method handle is a typed, directly executable reference to a method,
+ * A method handle is a typed, directly executable reference to an underlying method,
  * constructor, field, or similar low-level operation, with optional
  * transformations of arguments or return values.
  * These transformations are quite general, and include such patterns as
@@ -48,105 +48,183 @@
  *     will be removed before the Proposed Final Draft.
  *     Also, the final version will not include any public or
  *     protected constructors.</em>
- * <p>
- * Method handles are strongly typed according to signature.
- * They are not distinguished by method name or enclosing class.
- * A method handle must be invoked under a signature which matches
- * the method handle's own {@linkplain MethodType method type}.
+ *
+ * <h3>Method handle contents</h3>
+ * Method handles are dynamically and strongly typed according to type descriptor.
+ * They are not distinguished by the name or defining class of their underlying methods.
+ * A method handle must be invoked using type descriptor which matches
+ * the method handle's own {@linkplain #type method type}.
  * <p>
  * Every method handle reports its type via the {@link #type type} accessor.
- * The structure of this type is a series of classes, one of which is
+ * This type descriptor is a {@link java.dyn.MethodType MethodType} object,
+ * whose structure is a series of classes, one of which is
  * the return type of the method (or {@code void.class} if none).
  * <p>
- * Every method handle appears as an object containing a method named
- * {@link #invokeExact invokeExact}, whose signature exactly matches
- * the method handle's type.
- * A Java method call expression, which compiles to an
- * {@code invokevirtual} instruction,
- * can invoke this method from Java source code.
+ * A method handle's type controls the types of invocations it accepts,
+ * and the kinds of transformations that apply to it.
  * <p>
- * Every call to a method handle specifies an intended method type,
- * which must exactly match the type of the method handle.
- * (The type is specified in the {@code invokevirtual} instruction,
- * via a {@code CONSTANT_NameAndType} constant pool entry.)
- * The call looks within the receiver object for a method
- * named {@code invokeExact} of the intended method type.
- * The call fails with a {@link WrongMethodTypeException}
- * if the method does not exist, even if there is an {@code invokeExact}
- * method of a closely similar signature.
- * As with other kinds
- * of methods in the JVM, signature matching during method linkage
- * is exact, and does not allow for language-level implicit conversions
- * such as {@code String} to {@code Object} or {@code short} to {@code int}.
+ * A method handle contains a pair of special invoker methods
+ * called {@link #invokeExact invokeExact} and {@link #invokeGeneric invokeGeneric}.
+ * Both invoker methods provide direct access to the method handle's
+ * underlying method, constructor, field, or other operation,
+ * as modified by transformations of arguments and return values.
+ * Both invokers accept calls which exactly match the method handle's own type.
+ * The {@code invokeGeneric} invoker also accepts a range of other call types.
  * <p>
- * Each individual method handle also contains a method named
- * {@link #invokeGeneric invokeGeneric}, whose type is the same
- * as {@code invokeExact}, and is therefore also reported by
- * the {@link #type type} accessor.
+ * Method handles are immutable and have no visible state.
+ * Of course, they can be bound to underlying methods or data which exhibit state.
+ * With respect to the Java Memory Model, any method handle will behave
+ * as if all of its (internal) fields are final variables.  This means that any method
+ * handle made visible to the application will always be fully formed.
+ * This is true even if the method handle is published through a shared
+ * variable in a data race.
+ * <p>
+ * Method handles cannot be subclassed by the user.
+ * Implementations may (or may not) create internal subclasses of {@code MethodHandle}
+ * which may be visible via the {@link java.lang.Object#getClass Object.getClass}
+ * operation.  The programmer should not draw conclusions about a method handle
+ * from its specific class, as the method handle class hierarchy (if any)
+ * may change from time to time or across implementations from different vendors.
+ *
+ * <h3>Method handle compilation</h3>
+ * A Java method call expression naming {@code invokeExact} or {@code invokeGeneric}
+ * can invoke a method handle from Java source code.
+ * From the viewpoint of source code, these methods can take any arguments
+ * and their result can be cast to any return type.
+ * Formally this is accomplished by giving the invoker methods
+ * {@code Object} return types and variable-arity {@code Object} arguments,
+ * but they have an additional quality called "signature polymorphism"
+ * which connects this freedom of invocation directly to the JVM execution stack.
+ * <p>
+ * As is usual with virtual methods, source-level calls to {@code invokeExact}
+ * and {@code invokeGeneric} compile to an {@code invokevirtual} instruction.
+ * More unusually, the compiler must record the actual argument types,
+ * and may not perform method invocation conversions on the arguments.
+ * Instead, it must push them on the stack according to their own unconverted types.
+ * The method handle object itself is pushed on the stack before the arguments.
+ * The compiler then calls the method handle with a type descriptor which
+ * describes the argument and return types.
+ * <p>
+ * To issue a complete type descriptor, the compiler must also determine
+ * the return type.  This is based on a cast on the method invocation expression,
+ * if there is one, or else {@code Object} if the invocation is an expression
+ * or else {@code void} if the invocation is a statement.
+ * The cast may be to a primitive type (but not {@code void}).
+ * <p>
+ * As a corner case, an uncasted {@code null} argument is given
+ * a type descriptor of {@code java.lang.Void}.
+ * The ambiguity with the type {@code Void} is harmless, since there are no references of type
+ * {@code Void} except the null reference.
+ *
+ * <h3>Method handle invocation</h3>
+ * The first time a {@code invokevirtual} instruction is executed
+ * it is linked, by symbolically resolving the names in the instruction
+ * and verifying that the method call is statically legal.
+ * This is true of calls to {@code invokeExact} and {@code invokeGeneric}.
+ * In this case, the type descriptor emitted by the compiler is checked for
+ * correct syntax and names it contains are resolved.
+ * Thus, an {@code invokevirtual} instruction which invokes
+ * a method handle will always link, as long
+ * as the type descriptor is syntactically well-formed
+ * and the types exist.
+ * <p>
+ * When the {@code invokevirtual} is executed after linking,
+ * the receiving method handle's type is first checked by the JVM
+ * to ensure that it matches the descriptor.
+ * If the type match fails, it means that the method which the
+ * caller is invoking is not present on the individual
+ * method handle being invoked.
+ * <p>
+ * In the case of {@code invokeExact}, the type descriptor of the invocation
+ * (after resolving symbolic type names) must exactly match the method type
+ * of the receiving method handle.
+ * In the case of {@code invokeGeneric}, the resolved type descriptor
+ * must be a valid argument to the receiver's {@link #asType asType} method.
+ * Thus, {@code invokeGeneric} is more permissive than {@code invokeExact}.
+ * <p>
+ * After type matching, a call to {@code invokeExact} directly
+ * and immediately invoke the method handle's underlying method
+ * (or other behavior, as the case may be).
+ * <p>
  * A call to {@code invokeGeneric} works the same as a call to
- * {@code invokeExact}, if the signature specified by the caller
+ * {@code invokeExact}, if the type descriptor specified by the caller
  * exactly matches the method handle's own type.
  * If there is a type mismatch, {@code invokeGeneric} attempts
- * to adjust the type of the target method handle
- * (as if by a call to {@link #asType asType})
- * to obtain an exactly invokable target.
+ * to adjust the type of the receiving method handle,
+ * as if by a call to {@link #asType asType},
+ * to obtain an exactly invokable method handle {@code M2}.
  * This allows a more powerful negotiation of method type
  * between caller and callee.
  * <p>
- * A method handle is an unrestricted capability to call a method.
- * A method handle can be formed on a non-public method by a class
- * that has access to that method; the resulting handle can be used
- * in any place by any caller who receives a reference to it.  Thus, access
- * checking is performed when the method handle is created, not
- * (as in reflection) every time it is called.  Handles to non-public
- * methods, or in non-public classes, should generally be kept secret.
+ * (Note: The adjusted method handle {@code M2} is not directly observable,
+ * and implementations are therefore not required to materialize it.)
+ *
+ * <h3>Invocation checking</h3>
+ * In typical programs, method handle type matching will usually succeed.
+ * But if a match fails, the JVM will throw a {@link WrongMethodTypeException},
+ * either directly (in the case of {@code invokeExact}) or indirectly as if
+ * by a failed call to {@code asType} (in the case of {@code invokeGeneric}).
+ * <p>
+ * Thus, a method type mismatch which might show up as a linkage error
+ * in a statically typed program can show up as
+ * a dynamic {@code WrongMethodTypeException}
+ * in a program which uses method handles.
+ * <p>
+ * Because method types contain "live" {@code Class} objects,
+ * method type matching takes into account both types names and class loaders.
+ * Thus, even if a method handle {@code M} is created in one
+ * class loader {@code L1} and used in another {@code L2},
+ * method handle calls are type-safe, because the caller's type
+ * descriptor, as resolved in {@code L2},
+ * is matched against the original callee method's type descriptor,
+ * as resolved in {@code L1}.
+ * The resolution in {@code L1} happens when {@code M} is created
+ * and its type is assigned, while the resolution in {@code L2} happens
+ * when the {@code invokevirtual} instruction is linked.
+ * <p>
+ * Apart from the checking of type descriptors,
+ * a method handle's capability to call its underlying method is unrestricted.
+ * If a method handle is formed on a non-public method by a class
+ * that has access to that method, the resulting handle can be used
+ * in any place by any caller who receives a reference to it.
+ * <p>
+ * Unlike with the Core Reflection API, where access is checked every time
+ * a reflective method is invoked,
+ * method handle access checking is performed
+ * <a href="MethodHandles.Lookup.html#access">when the method handle is created</a>.
+ * In the case of {@code ldc} (see below), access checking is performed as part of linking
+ * the constant pool entry underlying the constant method handle.
+ * <p>
+ * Thus, handles to non-public methods, or to methods in non-public classes,
+ * should generally be kept secret.
  * They should not be passed to untrusted code unless their use from
  * the untrusted code would be harmless.
+ *
+ * <h3>Method handle creation</h3>
+ * Java code can create a method handle that directly accesses
+ * any method, constructor, or field that is accessible to that code.
+ * This is done via a reflective, capability-based API called
+ * {@link java.dyn.MethodHandles.Lookup MethodHandles.Lookup}
+ * For example, a static method handle can be obtained
+ * from {@link java.dyn.MethodHandles.Lookup#findStatic Lookup.findStatic}.
+ * There are also conversion methods from Core Reflection API objects,
+ * such as {@link java.dyn.MethodHandles.Lookup#unreflect Lookup.unreflect}.
  * <p>
- * Bytecode in the JVM can directly call a method handle's
- * {@code invokeExact} method from an {@code invokevirtual} instruction.
- * The receiver class type must be {@code MethodHandle} and the method name
- * must be {@code invokeExact}.  The signature of the invocation
- * (after resolving symbolic type names) must exactly match the method type
- * of the target method.
- * Similarly, bytecode can directly call a method handle's {@code invokeGeneric}
- * method.  The signature of the invocation (after resolving symbolic type names)
- * must either exactly match the method type or be a valid argument to
- * the target's {@link #asType asType} method.
- * <p>
- * Every {@code invokeExact} and {@code invokeGeneric} method always
- * throws {@link java.lang.Throwable Throwable},
- * which is to say that there is no static restriction on what a method handle
- * can throw.  Since the JVM does not distinguish between checked
- * and unchecked exceptions (other than by their class, of course),
- * there is no particular effect on bytecode shape from ascribing
- * checked exceptions to method handle invocations.  But in Java source
- * code, methods which perform method handle calls must either explicitly
- * throw {@code java.lang.Throwable Throwable}, or else must catch all
- * throwables locally, rethrowing only those which are legal in the context,
- * and wrapping ones which are illegal.
- * <p>
- * Bytecode in the JVM can directly obtain a method handle
- * for any accessible method from a {@code ldc} instruction
- * which refers to a {@code CONSTANT_MethodHandle} constant pool entry.
- * (Each such entry refers directly to a {@code CONSTANT_Methodref},
+ * Like classes and strings, method handles that correspond to accessible
+ * fields, methods, and constructors can also be represented directly
+ * in a class file's constant pool as constants to be loaded by {@code ldc} bytecodes.
+ * A new type of constant pool entry, {@code CONSTANT_MethodHandle},
+ * refers directly to an associated {@code CONSTANT_Methodref},
  * {@code CONSTANT_InterfaceMethodref}, or {@code CONSTANT_Fieldref}
  * constant pool entry.
- * For more details, see the <a href="package-summary.html#mhcon">package summary</a>.)
+ * (For more details on method handle constants,
+ * see the <a href="package-summary.html#mhcon">package summary</a>.)
  * <p>
  * Method handles produced by lookups or constant loads from methods or
  * constructors with the variable arity modifier bit ({@code 0x0080})
  * have a corresponding variable arity, as if they were defined with
  * the help of {@link #asVarargsCollector asVarargsCollector}.
  * <p>
- * Java code can also use a reflective API called
- * {@link java.dyn.MethodHandles.Lookup MethodHandles.Lookup}
- * for creating and calling method handles.
- * For example, a static method handle can be obtained
- * from {@link java.dyn.MethodHandles.Lookup#findStatic Lookup.findStatic}.
- * There are also bridge methods from Core Reflection API objects,
- * such as {@link java.dyn.MethodHandles.Lookup#unreflect Lookup.ureflect}.
- * <p>
  * A method reference may refer either to a static or non-static method.
  * In the non-static case, the method handle type includes an explicit
  * receiver argument, prepended before any other arguments.
@@ -158,64 +236,141 @@
  * When a method handle to a virtual method is invoked, the method is
  * always looked up in the receiver (that is, the first argument).
  * <p>
- * A non-virtual method handles to a specific virtual method implementation
+ * A non-virtual method handle to a specific virtual method implementation
  * can also be created.  These do not perform virtual lookup based on
  * receiver type.  Such a method handle simulates the effect of
  * an {@code invokespecial} instruction to the same method.
- * <p>
+ *
+ * <h3>Usage examples</h3>
  * Here are some examples of usage:
  * <p><blockquote><pre>
 Object x, y; String s; int i;
 MethodType mt; MethodHandle mh;
 MethodHandles.Lookup lookup = MethodHandles.lookup();
-// mt is {(char,char) =&gt; String}
+// mt is (char,char)String
 mt = MethodType.methodType(String.class, char.class, char.class);
 mh = lookup.findVirtual(String.class, "replace", mt);
-// (Ljava/lang/String;CC)Ljava/lang/String;
 s = (String) mh.invokeExact("daddy",'d','n');
+// invokeExact(Ljava/lang/String;CC)Ljava/lang/String;
 assert(s.equals("nanny"));
 // weakly typed invocation (using MHs.invoke)
 s = (String) mh.invokeWithArguments("sappy", 'p', 'v');
 assert(s.equals("savvy"));
-// mt is {Object[] =&gt; List}
+// mt is (Object[])List
 mt = MethodType.methodType(java.util.List.class, Object[].class);
 mh = lookup.findStatic(java.util.Arrays.class, "asList", mt);
 assert(mh.isVarargsCollector());
 x = mh.invokeGeneric("one", "two");
+// invokeGeneric(Ljava/lang/String;Ljava/lang/String;)Ljava/lang/Object;
 assert(x.equals(java.util.Arrays.asList("one","two")));
-// mt is {(Object,Object,Object) =&gt; Object}
+// mt is (Object,Object,Object)Object
 mt = MethodType.genericMethodType(3);
-mh = MethodHandles.collectArguments(mh, mt);
-// mt is {(Object,Object,Object) =&gt; Object}
-// (Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;
+mh = mh.asType(mt);
 x = mh.invokeExact((Object)1, (Object)2, (Object)3);
+// invokeExact(Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;
 assert(x.equals(java.util.Arrays.asList(1,2,3)));
 // mt is { =&gt; int}
 mt = MethodType.methodType(int.class);
 mh = lookup.findVirtual(java.util.List.class, "size", mt);
-// (Ljava/util/List;)I
 i = (int) mh.invokeExact(java.util.Arrays.asList(1,2,3));
+// invokeExact(Ljava/util/List;)I
 assert(i == 3);
 mt = MethodType.methodType(void.class, String.class);
 mh = lookup.findVirtual(java.io.PrintStream.class, "println", mt);
 mh.invokeExact(System.out, "Hello, world.");
-// (Ljava/io/PrintStream;Ljava/lang/String;)V
+// invokeExact(Ljava/io/PrintStream;Ljava/lang/String;)V
  * </pre></blockquote>
- * Each of the above calls generates a single invokevirtual instruction
- * with the name {@code invoke} and the type descriptors indicated in the comments.
- * The argument types are taken directly from the actual arguments,
- * while the return type is taken from the cast immediately applied to the call.
- * This cast may be to a primitive.
- * If it is missing, the type defaults to {@code Object} if the call
- * occurs in a context which uses the return value.
- * If the call occurs as a statement, a cast is impossible,
- * and there is no return type; the call is {@code void}.
+ * Each of the above calls to {@code invokeExact} or {@code invokeGeneric}
+ * generates a single invokevirtual instruction with
+ * the type descriptor indicated in the following comment.
+ *
+ * <h3>Exceptions</h3>
+ * The methods {@code invokeExact} and {@code invokeGeneric} are declared
+ * to throw {@link java.lang.Throwable Throwable},
+ * which is to say that there is no static restriction on what a method handle
+ * can throw.  Since the JVM does not distinguish between checked
+ * and unchecked exceptions (other than by their class, of course),
+ * there is no particular effect on bytecode shape from ascribing
+ * checked exceptions to method handle invocations.  But in Java source
+ * code, methods which perform method handle calls must either explicitly
+ * throw {@code java.lang.Throwable Throwable}, or else must catch all
+ * throwables locally, rethrowing only those which are legal in the context,
+ * and wrapping ones which are illegal.
+ *
+ * <h3><a name="polysig"></a>Signature polymorphism</h3>
+ * The unusual compilation and linkage behavior of
+ * {@code invokeExact} and {@code invokeGeneric}
+ * is referenced by the term <em>signature polymorphism</em>.
+ * A signature polymorphic method is one which can operate with
+ * any of a wide range of call signatures and return types.
+ * In order to make this work, both the Java compiler and the JVM must
+ * give special treatment to signature polymorphic methods.
  * <p>
- * <em>A note on generic typing:</em>  Method handles do not represent
- * their function types in terms of Java parameterized (generic) types,
- * because there are three mismatches between function types and parameterized
+ * In source code, a call to a signature polymorphic method will
+ * compile, regardless of the requested type descriptor.
+ * As usual, the Java compiler emits an {@code invokevirtual}
+ * instruction with the given type descriptor against the named method.
+ * The unusual part is that the type descriptor is derived from
+ * the actual argument and return types, not from the method declaration.
+ * <p>
+ * When the JVM processes bytecode containing signature polymorphic calls,
+ * it will successfully link any such call, regardless of its type descriptor.
+ * (In order to retain type safety, the JVM will guard such calls with suitable
+ * dynamic type checks, as described elsewhere.)
+ * <p>
+ * Bytecode generators, including the compiler back end, are required to emit
+ * untransformed type descriptors for these methods.
+ * Tools which determine symbolic linkage are required to accept such
+ * untransformed descriptors, without reporting linkage errors.
+ *
+ * <h3>Interoperation between method handles and the Core Reflection API</h3>
+ * Using factory methods in the {@link java.dyn.MethodHandles.Lookup Lookup} API,
+ * any class member represented by a Core Reflection API object
+ * can be converted to a behaviorally equivalent method handle.
+ * For example, a reflective {@link java.lang.reflect.Method Method} can
+ * be converted to a method handle using
+ * {@link java.dyn.MethodHandles.Lookup#unreflect Lookup.unreflect}.
+ * The resulting method handles generally provide more direct and efficient
+ * access to the underlying class members.
+ * <p>
+ * As a special case,
+ * when the Core Reflection API is used to view the signature polymorphic
+ * methods {@code invokeExact} or {@code invokeGeneric} in this class,
+ * they appear as single, non-polymorphic native methods.
+ * Calls to these native methods do not result in method handle invocations.
+ * Since {@code invokevirtual} instructions can natively
+ * invoke method handles under any type descriptor, this reflective view conflicts
+ * with the normal presentation via bytecodes.
+ * Thus, these two native methods, as viewed by
+ * {@link java.lang.Class#getDeclaredMethod Class.getDeclaredMethod},
+ * are placeholders only.
+ * If invoked via {@link java.lang.reflect.Method#invoke Method.invoke},
+ * they will throw {@code UnsupportedOperationException}.
+ * <p>
+ * In order to obtain an invoker method for a particular type descriptor,
+ * use {@link java.dyn.MethodHandles#exactInvoker MethodHandles.exactInvoker},
+ * or {@link java.dyn.MethodHandles#genericInvoker MethodHandles.genericInvoker}.
+ * The {@link java.dyn.MethodHandles.Lookup#findVirtual Lookup.findVirtual}
+ * API is also able to return a method handle
+ * to call {@code invokeExact} or {@code invokeGeneric},
+ * for any specified type descriptor .
+ *
+ * <h3>Interoperation between method handles and Java generics</h3>
+ * A method handle can be obtained on a method, constructor, or field
+ * which is declared with Java generic types.
+ * As with the Core Reflection API, the type of the method handle
+ * will constructed from the erasure of the source-level type.
+ * When a method handle is invoked, the types of its arguments
+ * or the return value cast type may be generic types or type instances.
+ * If this occurs, the compiler will replace those
+ * types by their erasures when when it constructs the type descriptor
+ * for the {@code invokevirtual} instruction.
+ * <p>
+ * Method handles do not represent
+ * their function-like types in terms of Java parameterized (generic) types,
+ * because there are three mismatches between function-like types and parameterized
  * Java types.
- * <ol>
+ * <ul>
  * <li>Method types range over all possible arities,
  * from no arguments to up to 255 of arguments (a limit imposed by the JVM).
  * Generics are not variadic, and so cannot represent this.</li>
@@ -225,29 +380,7 @@
  * often generic across a wide range of function types, including
  * those of multiple arities.  It is impossible to represent such
  * genericity with a Java type parameter.</li>
- * </ol>
- * Signature polymorphic methods in this class appear to be documented
- * as having type parameters for return types and a parameter, but that is
- * merely a documentation convention.  These type parameters do
- * not play a role in type-checking method handle invocations.
- * <p>
- * Like classes and strings, method handles that correspond to accessible
- * fields, methods, and constructors can be represented directly
- * in a class file's constant pool as constants to be loaded by {@code ldc} bytecodes.
- * Loading such a constant causes the component classes of its type to be loaded as necessary.
- * <p>
- * Method handles cannot be subclassed by the user.
- * Implementations may (or may not) create internal subclasses of {@code MethodHandle}
- * which may be visible via the {@code java.lang.Object#getClass Object.getClass}
- * operation.  The programmer should not draw conclusions about a method handle
- * from its specific class, as the method handle class hierarchy (if any)
- * may change from time to time or across implementations from different vendors.
- * <p>
- * With respect to the Java Memory Model, any method handle will behave
- * as if all of its fields are final variables.  This means that any method
- * handle made visible to the application will always be fully formed.
- * This is true even if the method handle is published through a shared
- * variables in a data race.
+ * </ul>
  *
  * @see MethodType
  * @see MethodHandles
@@ -259,6 +392,7 @@
         extends MethodHandleImpl
 {
     private static Access IMPL_TOKEN = Access.getToken();
+    static { MethodHandleImpl.initStatics(); }
 
     // interface MethodHandle<R throws X extends Exception,A...>
     // { MethodType<R throws X,A...> type(); public R invokeExact(A...) throws X; }
@@ -278,7 +412,7 @@
      * Every invocation of this method handle via {@code invokeExact} must exactly match this type.
      * @return the method handle type
      */
-    public final MethodType type() {
+    public MethodType type() {
         return type;
     }
 
@@ -315,20 +449,27 @@
     }
 
     /**
-     * Invoke the method handle, allowing any caller signature, but requiring an exact signature match.
-     * The signature at the call site of {@code invokeExact} must
+     * Invoke the method handle, allowing any caller type descriptor, but requiring an exact type match.
+     * The type descriptor at the call site of {@code invokeExact} must
      * exactly match this method handle's {@link #type type}.
      * No conversions are allowed on arguments or return values.
-     * @throws WrongMethodTypeException if the target's type is not identical with the caller's type signature
+     * <p>
+     * When this method is observed via the Core Reflection API,
+     * it will appear as a single native method, taking an object array and returning an object.
+     * If this native method is invoked directly via
+     * {@link java.lang.reflect.Method#invoke Method.invoke}, via JNI,
+     * or indirectly via {@link java.dyn.MethodHandles.Lookup#unreflect Lookup.unreflect},
+     * it will throw an {@code UnsupportedOperationException}.
+     * @throws WrongMethodTypeException if the target's type is not identical with the caller's type descriptor
      * @throws Throwable anything thrown by the underlying method propagates unchanged through the method handle call
      */
     public final native @PolymorphicSignature Object invokeExact(Object... args) throws Throwable;
 
     /**
-     * Invoke the method handle, allowing any caller signature,
+     * Invoke the method handle, allowing any caller type descriptor,
      * and optionally performing conversions on arguments and return values.
      * <p>
-     * If the call site signature exactly matches this method handle's {@link #type type},
+     * If the call site type descriptor exactly matches this method handle's {@link #type type},
      * the call proceeds as if by {@link #invokeExact invokeExact}.
      * <p>
      * Otherwise, the call proceeds as if this method handle were first
@@ -341,12 +482,19 @@
      * adaptations directly on the caller's arguments,
      * and call the target method handle according to its own exact type.
      * <p>
-     * The signature at the call site of {@code invokeGeneric} must
+     * The type descriptor at the call site of {@code invokeGeneric} must
      * be a valid argument to the receivers {@code asType} method.
      * In particular, the caller must specify the same argument arity
      * as the callee's type,
      * if the callee is not a {@linkplain #asVarargsCollector variable arity collector}.
-     * @throws WrongMethodTypeException if the target's type cannot be adjusted to the caller's type signature
+     * <p>
+     * When this method is observed via the Core Reflection API,
+     * it will appear as a single native method, taking an object array and returning an object.
+     * If this native method is invoked directly via
+     * {@link java.lang.reflect.Method#invoke Method.invoke}, via JNI,
+     * or indirectly via {@link java.dyn.MethodHandles.Lookup#unreflect Lookup.unreflect},
+     * it will throw an {@code UnsupportedOperationException}.
+     * @throws WrongMethodTypeException if the target's type cannot be adjusted to the caller's type descriptor
      * @throws ClassCastException if the target's type can be adjusted to the caller, but a reference cast fails
      * @throws Throwable anything thrown by the underlying method propagates unchanged through the method handle call
      */
@@ -390,13 +538,19 @@
      * MethodHandle invoker = MethodHandles.spreadInvoker(this.type(), 0);
      * Object result = invoker.invokeExact(this, arguments);
      * </pre></blockquote>
+     * <p>
+     * Unlike the signature polymorphic methods {@code invokeExact} and {@code invokeGeneric},
+     * {@code invokeWithArguments} can be accessed normally via the Core Reflection API and JNI.
+     * It can therefore be used as a bridge between native or reflective code and method handles.
+     *
      * @param arguments the arguments to pass to the target
      * @return the result returned by the target
-     * @throws WrongMethodTypeException if the target's type cannot be adjusted to take the arguments
+     * @throws ClassCastException if an argument cannot be converted by reference casting
+     * @throws WrongMethodTypeException if the target's type cannot be adjusted to take the given number of {@code Object} arguments
      * @throws Throwable anything thrown by the target method invocation
      * @see MethodHandles#spreadInvoker
      */
-    public final Object invokeWithArguments(Object... arguments) throws Throwable {
+    public Object invokeWithArguments(Object... arguments) throws Throwable {
         int argc = arguments == null ? 0 : arguments.length;
         MethodType type = type();
         if (type.parameterCount() != argc) {
@@ -404,7 +558,7 @@
             return asType(MethodType.genericMethodType(argc)).invokeWithArguments(arguments);
         }
         if (argc <= 10) {
-            MethodHandle invoker = MethodHandles.invokers(type).genericInvoker();
+            MethodHandle invoker = invokers(type).genericInvoker();
             switch (argc) {
                 case 0:  return invoker.invokeExact(this);
                 case 1:  return invoker.invokeExact(this,
@@ -447,15 +601,7 @@
         return invoker.invokeExact(this, arguments);
     }
     /** Equivalent to {@code invokeWithArguments(arguments.toArray())}. */
-    public final Object invokeWithArguments(java.util.List<?> arguments) throws Throwable {
-        return invokeWithArguments(arguments.toArray());
-    }
-    @Deprecated
-    public final Object invokeVarargs(Object... arguments) throws Throwable {
-        return invokeWithArguments(arguments);
-    }
-    @Deprecated
-    public final Object invokeVarargs(java.util.List<?> arguments) throws Throwable {
+    public Object invokeWithArguments(java.util.List<?> arguments) throws Throwable {
         return invokeWithArguments(arguments.toArray());
     }
 
@@ -524,7 +670,7 @@
      * @throws WrongMethodTypeException if the implied {@code asType} call fails
      * @see #asCollector
      */
-    public final MethodHandle asSpreader(Class<?> arrayType, int arrayLength) {
+    public MethodHandle asSpreader(Class<?> arrayType, int arrayLength) {
         Class<?> arrayElement = arrayType.getComponentType();
         if (arrayElement == null)  throw newIllegalArgumentException("not an array type");
         MethodType oldType = type();
@@ -575,7 +721,7 @@
      * @see #asSpreader
      * @see #asVarargsCollector
      */
-    public final MethodHandle asCollector(Class<?> arrayType, int arrayLength) {
+    public MethodHandle asCollector(Class<?> arrayType, int arrayLength) {
         Class<?> arrayElement = arrayType.getComponentType();
         if (arrayElement == null)  throw newIllegalArgumentException("not an array type");
         MethodType oldType = type();
@@ -699,6 +845,7 @@
 assertEquals("[three, thee, tee]", Arrays.toString((Object[])ls.get(0)));
      * </pre></blockquote>
      * <p style="font-size:smaller;">
+     * <em>Discussion:</em>
      * These rules are designed as a dynamically-typed variation
      * of the Java rules for variable arity methods.
      * In both cases, callers to a variable arity method or method handle
@@ -710,7 +857,7 @@
      * array or a single element of an array to be collected.
      * Note that the dynamic type of the trailing argument has no
      * effect on this decision, only a comparison between the static
-     * type signature of the call site and the type of the method handle.)
+     * type descriptor of the call site and the type of the method handle.)
      * <p style="font-size:smaller;">
      * As a result of the previously stated rules, the variable arity behavior
      * of a method handle may be suppressed, by binding it to the exact invoker
@@ -719,9 +866,7 @@
 MethodHandle vamh = publicLookup()
   .findStatic(Arrays.class, "asList", methodType(List.class, Object[].class))
   .asVarargsCollector(Object[].class);
-MethodHandle invokeExact = publicLookup()
-  .findVirtual(MethodHandle.class, "invokeExact", vamh.type());
-MethodHandle mh = invokeExact.bindTo(vamh);
+MethodHandle mh = MethodHandles.exactInvoker(vamh.type()).bindTo(vamh);
 assert(vamh.type().equals(mh.type()));
 assertEquals("[1, 2, 3]", vamh.invokeGeneric(1,2,3).toString());
 boolean failed = false;
@@ -731,12 +876,14 @@
      * </pre></blockquote>
      * This transformation has no behavioral effect if the method handle is
      * not of variable arity.
+     *
      * @param arrayType often {@code Object[]}, the type of the array argument which will collect the arguments
      * @return a new method handle which can collect any number of trailing arguments
      *         into an array, before calling the original method handle
      * @throws IllegalArgumentException if {@code arrayType} is not an array type
      *         or {@code arrayType} is not assignable to this method handle's trailing parameter type
      * @see #asCollector
+     * @see #isVarargsCollector
      */
     public MethodHandle asVarargsCollector(Class<?> arrayType) {
         Class<?> arrayElement = arrayType.getComponentType();
@@ -756,6 +903,7 @@
      *     which resolves to a variable arity Java method or constructor
      * </ul>
      * @return true if this method handle accepts more than one arity of {@code invokeGeneric} calls
+     * @see #asVarargsCollector
      */
     public boolean isVarargsCollector() {
         return false;
@@ -785,7 +933,7 @@
      *         to the leading parameter type of the target
      * @see MethodHandles#insertArguments
      */
-    public final MethodHandle bindTo(Object x) {
+    public MethodHandle bindTo(Object x) {
         return MethodHandles.insertArguments(this, 0, x);
     }
 
--- a/src/share/classes/java/dyn/MethodHandles.java	Fri Feb 11 01:26:24 2011 -0800
+++ b/src/share/classes/java/dyn/MethodHandles.java	Fri Feb 11 01:26:28 2011 -0800
@@ -29,6 +29,7 @@
 import sun.dyn.Access;
 import sun.dyn.MemberName;
 import sun.dyn.MethodHandleImpl;
+import sun.dyn.WrapperInstance;
 import sun.dyn.util.ValueConversions;
 import sun.dyn.util.VerifyAccess;
 import sun.dyn.util.Wrapper;
@@ -45,10 +46,10 @@
  * This class consists exclusively of static methods that operate on or return
  * method handles. They fall into several categories:
  * <ul>
- * <li>Factory methods which create method handles for methods and fields.
- * <li>Invoker methods which can invoke method handles on dynamically typed arguments and/or varargs arrays.
- * <li>Combinator methods, which combine or transforming pre-existing method handles into new ones.
- * <li>Factory methods which create method handles that emulate other common JVM operations or control flow patterns.
+ * <li>Lookup methods which help create method handles for methods and fields.
+ * <li>Combinator methods, which combine or transform pre-existing method handles into new ones.
+ * <li>Other factory methods to create method handles that emulate other common JVM operations or control flow patterns.
+ * <li>Wrapper methods which can convert between method handles and other function-like "SAM types".
  * </ul>
  * <p>
  * @author John Rose, JSR 292 EG
@@ -97,34 +98,130 @@
      * when the creation requires access checking.
      * Method handles do not perform
      * access checks when they are called, but rather when they are created.
-     * (This is a major difference
-     * from reflective {@link Method}, which performs access checking
-     * against every caller, on every call.)
      * Therefore, method handle access
      * restrictions must be enforced when a method handle is created.
      * The caller class against which those restrictions are enforced
      * is known as the {@linkplain #lookupClass lookup class}.
-     * A lookup object embodies an
-     * authenticated lookup class, and can be used to create any number
+     * <p>
+     * A lookup class which needs to create method handles will call
+     * {@link MethodHandles#lookup MethodHandles.lookup} to create a factory for itself.
+     * When the {@code Lookup} factory object is created, the identity of the lookup class is
+     * determined, and securely stored in the {@code Lookup} object.
+     * The lookup class (or its delegates) may then use factory methods
+     * on the {@code Lookup} object to create method handles for access-checked members.
+     * This includes all methods, constructors, and fields which are allowed to the lookup class,
+     * even private ones.
+     * <p>
+     * The factory methods on a {@code Lookup} object correspond to all major
+     * use cases for methods, constructors, and fields.
+     * Here is a summary of the correspondence between these factory methods and
+     * the behavior the resulting method handles:
+     * <code>
+     * <table border=1 cellpadding=5 summary="lookup method behaviors">
+     * <tr><th>lookup expression</th><th>member</th><th>behavior</th></tr>
+     * <tr>
+     *     <td>{@linkplain java.dyn.MethodHandles.Lookup#findGetter lookup.findGetter(C.class,"f",FT.class)}</td>
+     *     <td>FT f;</td><td>(T) this.f;</td>
+     * </tr>
+     * <tr>
+     *     <td>{@linkplain java.dyn.MethodHandles.Lookup#findStaticGetter lookup.findStaticGetter(C.class,"f",FT.class)}</td>
+     *     <td>static<br>FT f;</td><td>(T) C.f;</td>
+     * </tr>
+     * <tr>
+     *     <td>{@linkplain java.dyn.MethodHandles.Lookup#findSetter lookup.findSetter(C.class,"f",FT.class)}</td>
+     *     <td>FT f;</td><td>this.f = x;</td>
+     * </tr>
+     * <tr>
+     *     <td>{@linkplain java.dyn.MethodHandles.Lookup#findStaticSetter lookup.findStaticSetter(C.class,"f",FT.class)}</td>
+     *     <td>static<br>FT f;</td><td>C.f = arg;</td>
+     * </tr>
+     * <tr>
+     *     <td>{@linkplain java.dyn.MethodHandles.Lookup#findVirtual lookup.findVirtual(C.class,"m",MT)}</td>
+     *     <td>T m(A*);</td><td>(T) this.m(arg*);</td>
+     * </tr>
+     * <tr>
+     *     <td>{@linkplain java.dyn.MethodHandles.Lookup#findStatic lookup.findStatic(C.class,"m",MT)}</td>
+     *     <td>static<br>T m(A*);</td><td>(T) C.m(arg*);</td>
+     * </tr>
+     * <tr>
+     *     <td>{@linkplain java.dyn.MethodHandles.Lookup#findSpecial lookup.findSpecial(C.class,"m",MT,this.class)}</td>
+     *     <td>T m(A*);</td><td>(T) super.m(arg*);</td>
+     * </tr>
+     * <tr>
+     *     <td>{@linkplain java.dyn.MethodHandles.Lookup#findConstructor lookup.findConstructor(C.class,MT)}</td>
+     *     <td>C(A*);</td><td>(T) new C(arg*);</td>
+     * </tr>
+     * <tr>
+     *     <td>{@linkplain java.dyn.MethodHandles.Lookup#unreflectGetter lookup.unreflectGetter(aField)}</td>
+     *     <td>(static)?<br>FT f;</td><td>(FT) aField.get(thisOrNull);</td>
+     * </tr>
+     * <tr>
+     *     <td>{@linkplain java.dyn.MethodHandles.Lookup#unreflectSetter lookup.unreflectSetter(aField)}</td>
+     *     <td>(static)?<br>FT f;</td><td>aField.set(thisOrNull, arg);</td>
+     * </tr>
+     * <tr>
+     *     <td>{@linkplain java.dyn.MethodHandles.Lookup#unreflect lookup.unreflect(aMethod)}</td>
+     *     <td>(static)?<br>T m(A*);</td><td>(T) aMethod.invoke(thisOrNull, arg*);</td>
+     * </tr>
+     * <tr>
+     *     <td>{@linkplain java.dyn.MethodHandles.Lookup#unreflectConstructor lookup.unreflectConstructor(aConstructor)}</td>
+     *     <td>C(A*);</td><td>(C) aConstructor.newInstance(arg*);</td>
+     * </tr>
+     * <tr>
+     *     <td>{@linkplain java.dyn.MethodHandles.Lookup#unreflect lookup.unreflect(aMethod)}</td>
+     *     <td>(static)?<br>T m(A*);</td><td>(T) aMethod.invoke(thisOrNull, arg*);</td>
+     * </tr>
+     * </table>
+     * </code>
+     * Here, the type {@code C} is the class or interface being searched for a member,
+     * documented as a parameter named {@code refc} in the lookup methods.
+     * The method or constructor type {@code MT} is composed from the return type {@code T}
+     * and the sequence of argument types {@code A*}.
+     * Both {@code MT} and the field type {@code FT} are documented as a parameter named {@code type}.
+     * The formal parameter {@code this} stands for the self-reference of type {@code C};
+     * if it is present, it is always the leading argument to the method handle invocation.
+     * The name {@code arg} stands for all the other method handle arguments.
+     * In the code examples for the Core Reflection API, the name {@code thisOrNull}
+     * stands for a null reference if the accessed method or field is static,
+     * and {@code this} otherwise.
+     * The names {@code aMethod}, {@code aField}, and {@code aConstructor} stand
+     * for reflective objects corresponding to the given members.
+     * <p>
+     * The equivalence between looked-up method handles and underlying
+     * class members can break down in a few ways:
+     * <ul>
+     * <li>If {@code C} is not symbolically accessible from the lookup class's loader,
+     * the lookup can still succeed, even when there is no equivalent
+     * Java expression or bytecoded constant.
+     * <li>Likewise, if {@code T} or {@code MT}
+     * is not symbolically accessible from the lookup class's loader,
+     * the lookup can still succeed.
+     * For example, lookups for {@code MethodHandle.invokeExact} and
+     * {@code MethodHandle.invokeGeneric} will always succeed, regardless of requested type.
+     * </ul>
+     *
+     * <h3><a name="access"></a>Access checking</h3>
+     * Access checks are applied in the factory methods of {@code Lookup},
+     * when a method handle is created.
+     * This is a key difference from the Core Reflection API, since
+     * {@link java.lang.reflect.Method#invoke Method.invoke}
+     * performs access checking against every caller, on every call.
+     * <p>
+     * All access checks start from a {@code Lookup} object, which
+     * compares its recorded lookup class against all requests to
+     * create method handles.
+     * A single {@code Lookup} object can be used to create any number
      * of access-checked method handles, all checked against a single
      * lookup class.
      * <p>
-     * A class which needs to create method handles will call
-     * {@link MethodHandles#lookup MethodHandles.lookup} to create a factory for itself.
-     * It may then use this factory to create method handles on
-     * all of its methods, including private ones.
-     * It may also delegate the lookup (e.g., to a metaobject protocol)
-     * by passing the lookup object to other code.
-     * If this other code creates method handles, they will be access
-     * checked against the original lookup class, and not with any higher
-     * privileges.
+     * A {@code Lookup} object can be shared with other trusted code,
+     * such as a metaobject protocol.
+     * A shared {@code Lookup} object delegates the capability
+     * to create method handles on private members of the lookup class.
+     * Even if privileged code uses the {@code Lookup} object,
+     * the access checking is confined to the privileges of the
+     * original lookup class.
      * <p>
-     * Access checks only apply to named and reflected methods.
-     * Other method handle creation methods, such as
-     * {@link #convertArguments MethodHandles.convertArguments},
-     * do not require any access checks, and can be done independently
-     * of any lookup class.
-     * <h3>How access errors are handled</h3>
      * A lookup can fail, because
      * the containing class is not accessible to the lookup class, or
      * because the desired class member is missing, or because the
@@ -134,13 +231,13 @@
      * thrown from the attempted lookup.
      * <p>
      * In general, the conditions under which a method handle may be
-     * created for a method {@code M} are exactly as restrictive as the conditions
-     * under which the lookup class could have compiled a call to {@code M},
-     * or could have compiled an {@code ldc} instruction loading a
-     * {@code CONSTANT_MethodHandle} of M.
+     * looked up for a method {@code M} are exactly equivalent to the conditions
+     * under which the lookup class could have compiled and resolved a call to {@code M}.
+     * And the effect of invoking the method handle resulting from the lookup
+     * is exactly equivalent to executing the compiled and resolved call to {@code M}.
      * The same point is true of fields and constructors.
      * <p>
-     * In some cases, this access is obtained by the Java compiler by creating
+     * In some cases, access between nested classes is obtained by the Java compiler by creating
      * an wrapper method to access a private method of another class
      * in the same top-level declaration.
      * For example, a nested class {@code C.D}
@@ -152,6 +249,14 @@
      * A workaround for this limitation is the {@link Lookup#in Lookup.in} method,
      * which can transform a lookup on {@code C.E} into one on any of those other
      * classes, without special elevation of privilege.
+     * <p>
+     * Access checks only apply to named and reflected methods,
+     * constructors, and fields.
+     * Other method handle creation methods, such as
+     * {@link #convertArguments MethodHandles.convertArguments},
+     * do not require any access checks, and are done
+     * with static methods of {@link MethodHandles},
+     * independently of any {@code Lookup} object.
      */
     public static final
     class Lookup {
@@ -197,12 +302,12 @@
             return (mods != 0) ? mods : PACKAGE;
         }
 
-        /** Which class is performing the lookup?  It is this class against
+        /** Tells which class is performing the lookup.  It is this class against
          *  which checks are performed for visibility and access permissions.
          *  <p>
          *  The class implies a maximum level of access permission,
          *  but the permissions may be additionally limited by the bitmask
-         *  {@link #lookupModes}, which controls whether non-public members
+         *  {@link #lookupModes lookupModes}, which controls whether non-public members
          *  can be accessed.
          */
         public Class<?> lookupClass() {
@@ -214,7 +319,7 @@
             return (allowedModes == TRUSTED) ? null : lookupClass;
         }
 
-        /** Which types of members can this lookup object produce?
+        /** Tells which access-protection classes of members this lookup object can produce.
          *  The result is a bit-mask of the bits
          *  {@linkplain #PUBLIC PUBLIC (0x01)},
          *  {@linkplain #PRIVATE PRIVATE (0x02)},
@@ -260,7 +365,7 @@
         }
 
         /**
-         * Create a lookup on the specified new lookup class.
+         * Creates a lookup on the specified new lookup class.
          * The resulting object will report the specified
          * class as its own {@link #lookupClass lookupClass}.
          * <p>
@@ -278,6 +383,10 @@
          * then no members, not even public members, will be accessible.
          * (In all other cases, public members will continue to be accessible.)
          * </ul>
+         *
+         * @param requestedLookupClass the desired lookup class for the new lookup object
+         * @return a lookup object which reports the desired lookup class
+         * @throws NullPointerException if the argument is null
          */
         public Lookup in(Class<?> requestedLookupClass) {
             requestedLookupClass.getClass();  // null check
@@ -325,11 +434,12 @@
         }
 
         /**
-         * Display the name of the class from which lookups are to be made.
+         * Displays the name of the class from which lookups are to be made.
          * (The name is the one reported by {@link java.lang.Class#getName() Class.getName}.)
          * If there are restrictions on the access permitted to this lookup,
          * this is indicated by adding a suffix to the class name, consisting
-         * of a slash and a keyword.  The keyword is chosen as follows:
+         * of a slash and a keyword.  The keyword represents the strongest
+         * allowed access, and is chosen as follows:
          * <ul>
          * <li>If no access is allowed, the suffix is "/noaccess".
          * <li>If only public access is allowed, the suffix is "/public".
@@ -340,26 +450,37 @@
          * access (public, package, private, and protected) is allowed.
          * In this case, no suffix is added.
          * This is true only of an object obtained originally from
-         * {@link java.dyn.MethodHandles#lookup() MethodHandles.lookup}.
-         * Objects created by {@link java.dyn.MethodHandles.Lookup#in() Lookup#in}
+         * {@link java.dyn.MethodHandles#lookup MethodHandles.lookup}.
+         * Objects created by {@link java.dyn.MethodHandles.Lookup#in Lookup.in}
          * always have restricted access, and will display a suffix.
+         * <p>
+         * (It may seem strange that protected access should be
+         * stronger than private access.  Viewed independently from
+         * package access, protected access is the first to be lost,
+         * because it requires a direct subclass relationship between
+         * caller and callee.)
+         * @see #in
          */
         @Override
         public String toString() {
             String cname = lookupClass.getName();
             switch (allowedModes) {
-            case TRUSTED:
-                return "/trusted";  // internal only
+            case 0:  // no privileges
+                return cname + "/noaccess";
             case PUBLIC:
                 return cname + "/public";
             case PUBLIC|PACKAGE:
                 return cname + "/package";
-            case 0:  // no privileges
-                return cname + "/noaccess";
+            case ALL_MODES & ~PROTECTED:
+                return cname + "/private";
             case ALL_MODES:
                 return cname;
-            default:
-                return cname + "/private";
+            case TRUSTED:
+                return "/trusted";  // internal only; not exported
+            default:  // Should not happen, but it's a bitfield...
+                cname = cname + "/" + Integer.toHexString(allowedModes);
+                assert(false) : cname;
+                return cname;
             }
         }
 
@@ -374,11 +495,11 @@
         }
 
         /**
-         * Produce a method handle for a static method.
+         * Produces a method handle for a static method.
          * The type of the method handle will be that of the method.
          * (Since static methods do not take receivers, there is no
          * additional receiver argument inserted into the method handle type,
-         * as there would be with {@link #findVirtual} or {@link #findSpecial}.)
+         * as there would be with {@link #findVirtual findVirtual} or {@link #findSpecial findSpecial}.)
          * The method and all its argument types must be accessible to the lookup class.
          * If the method's class has not yet been initialized, that is done
          * immediately, before the method handle is returned.
@@ -400,7 +521,7 @@
         }
 
         /**
-         * Produce a method handle for a virtual method.
+         * Produces a method handle for a virtual method.
          * The type of the method handle will be that of the method,
          * with the receiver type (usually {@code refc}) prepended.
          * The method and all its argument types must be accessible to the lookup class.
@@ -414,6 +535,16 @@
          * The returned method handle will have
          * {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if
          * the method's variable arity modifier bit ({@code 0x0080}) is set.
+         * <p>
+         * Because of the general equivalence between {@code invokevirtual}
+         * instructions and method handles produced by {@code findVirtual},
+         * if the class is {@code MethodHandle} and the name string is
+         * {@code invokeExact} or {@code invokeGeneric}, the resulting
+         * method handle is equivalent to one produced by
+         * {@link java.dyn.MethodHandles#exactInvoker MethodHandles.exactInvoker} or
+         * {@link java.dyn.MethodHandles#genericInvoker MethodHandles.genericInvoker}
+         * with the same {@code type} argument.
+         *
          * @param refc the class or interface from which the method is accessed
          * @param name the name of the method
          * @param type the type of the method, with the receiver argument omitted
@@ -428,7 +559,7 @@
         }
 
         /**
-         * Produce a method handle which creates an object and initializes it, using
+         * Produces a method handle which creates an object and initializes it, using
          * the constructor of the specified type.
          * The parameter types of the method handle will be those of the constructor,
          * while the return type will be a reference to the constructor's class.
@@ -437,7 +568,7 @@
          * immediately, before the method handle is returned.
          * <p>
          * Note:  The requested type must have a return type of {@code void}.
-         * This is consistent with the JVM's treatment of constructor signatures.
+         * This is consistent with the JVM's treatment of constructor type descriptors.
          * <p>
          * The returned method handle will have
          * {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if
@@ -473,7 +604,7 @@
         }
 
         /**
-         * Produce an early-bound method handle for a virtual method,
+         * Produces an early-bound method handle for a virtual method,
          * as if called from an {@code invokespecial}
          * instruction from {@code caller}.
          * The type of the method handle will be that of the method,
@@ -510,12 +641,13 @@
         }
 
         /**
-         * Produce a method handle giving read access to a non-static field.
+         * Produces a method handle giving read access to a non-static field.
          * The type of the method handle will have a return type of the field's
          * value type.
          * The method handle's single argument will be the instance containing
          * the field.
          * Access checking is performed immediately on behalf of the lookup class.
+         * @param refc the class or interface from which the method is accessed
          * @param name the field's name
          * @param type the field's type
          * @return a method handle which can load values from the field
@@ -526,12 +658,13 @@
         }
 
         /**
-         * Produce a method handle giving write access to a non-static field.
+         * Produces a method handle giving write access to a non-static field.
          * The type of the method handle will have a void return type.
          * The method handle will take two arguments, the instance containing
          * the field, and the value to be stored.
          * The second argument will be of the field's value type.
          * Access checking is performed immediately on behalf of the lookup class.
+         * @param refc the class or interface from which the method is accessed
          * @param name the field's name
          * @param type the field's type
          * @return a method handle which can store values into the field
@@ -542,11 +675,12 @@
         }
 
         /**
-         * Produce a method handle giving read access to a static field.
+         * Produces a method handle giving read access to a static field.
          * The type of the method handle will have a return type of the field's
          * value type.
          * The method handle will take no arguments.
          * Access checking is performed immediately on behalf of the lookup class.
+         * @param refc the class or interface from which the method is accessed
          * @param name the field's name
          * @param type the field's type
          * @return a method handle which can load values from the field
@@ -557,11 +691,12 @@
         }
 
         /**
-         * Produce a method handle giving write access to a static field.
+         * Produces a method handle giving write access to a static field.
          * The type of the method handle will have a void return type.
          * The method handle will take a single
          * argument, of the field's value type, the value to be stored.
          * Access checking is performed immediately on behalf of the lookup class.
+         * @param refc the class or interface from which the method is accessed
          * @param name the field's name
          * @param type the field's type
          * @return a method handle which can store values into the field
@@ -572,7 +707,7 @@
         }
 
         /**
-         * Produce an early-bound method handle for a non-static method.
+         * Produces an early-bound method handle for a non-static method.
          * The receiver must have a supertype {@code defc} in which a method
          * of the given name and type is accessible to the lookup class.
          * The method and all its argument types must be accessible to the lookup class.
@@ -649,7 +784,7 @@
         }
 
         /**
-         * Produce a method handle for a reflected method.
+         * Produces a method handle for a reflected method.
          * It will bypass checks for overriding methods on the receiver,
          * as if by a {@code invokespecial} instruction from within the {@code specialCaller}.
          * The type of the method handle will be that of the method,
@@ -677,7 +812,7 @@
         }
 
         /**
-         * Produce a method handle for a reflected constructor.
+         * Produces a method handle for a reflected constructor.
          * The type of the method handle will be that of the constructor,
          * with the return type changed to the declaring class.
          * The method handle will perform a {@code newInstance} operation,
@@ -704,7 +839,7 @@
         }
 
         /**
-         * Produce a method handle giving read access to a reflected field.
+         * Produces a method handle giving read access to a reflected field.
          * The type of the method handle will have a return type of the field's
          * value type.
          * If the field is static, the method handle will take no arguments.
@@ -721,7 +856,7 @@
         }
 
         /**
-         * Produce a method handle giving write access to a reflected field.
+         * Produces a method handle giving write access to a reflected field.
          * The type of the method handle will have a void return type.
          * If the field is static, the method handle will take a single
          * argument, of the field's value type, the value to be stored.
@@ -875,12 +1010,13 @@
     }
 
     /**
-     * Produce a method handle giving read access to elements of an array.
+     * Produces a method handle giving read access to elements of an array.
      * The type of the method handle will have a return type of the array's
      * element type.  Its first argument will be the array type,
      * and the second will be {@code int}.
      * @param arrayClass an array type
      * @return a method handle which can load values from the given array type
+     * @throws NullPointerException if the argument is null
      * @throws  IllegalArgumentException if arrayClass is not an array type
      */
     public static
@@ -889,11 +1025,12 @@
     }
 
     /**
-     * Produce a method handle giving write access to elements of an array.
+     * Produces a method handle giving write access to elements of an array.
      * The type of the method handle will have a void return type.
      * Its last argument will be the array's element type.
      * The first and second arguments will be the array type and int.
      * @return a method handle which can store values into the array type
+     * @throws NullPointerException if the argument is null
      * @throws IllegalArgumentException if arrayClass is not an array type
      */
     public static
@@ -904,47 +1041,7 @@
     /// method handle invocation (reflective style)
 
     /**
-     * Produce a method handle which will invoke any method handle of the
-     * given type on a standard set of {@code Object} type arguments.
-     * The resulting invoker will be a method handle with the following
-     * arguments:
-     * <ul>
-     * <li>a single {@code MethodHandle} target
-     * <li>zero or more {@code Object} values (one for each argument in {@code type})
-     * </ul>
-     * <p>
-     * The invoker will behave like a call to {@link MethodHandle.invokeGeneric} with
-     * the indicated {@code type}.
-     * That is, if the target is exactly of the given {@code type}, it will behave
-     * like {@code invokeExact}; otherwise it behave as if {@link MethodHandle.asType}
-     * is used to convert the target to the required {@code type}.
-     * <p>
-     * The type of the returned invoker will not be the given {@code type}, but rather
-     * will have all parameter and return types replaced by {@code Object}.
-     * <p>
-     * Before invoking its target, the invoker will apply reference casts as
-     * necessary and unbox and widen primitive arguments, as if by {@link #convertArguments}.
-     * The return value of the invoker will be an {@code Object} reference,
-     * boxing a primitive value if the original type returns a primitive,
-     * and always null if the original type returns void.
-     * <p>
-     * This method is equivalent to the following code (though it may be more efficient):
-     * <p><blockquote><pre>
-     * MethodHandle invoker = lookup().findVirtual(MethodHandle.class, "invokeGeneric", type);
-     * MethodType genericType = type.generic();
-     * genericType = genericType.insertParameterType(0, MethodHandle.class);
-     * return invoker.asType(genericType);
-     * </pre></blockquote>
-     * @param type the type of target methods which the invoker will apply to
-     * @return a method handle suitable for invoking any method handle of the given type
-     */
-    static public
-    MethodHandle genericInvoker(MethodType type) {
-        return invokers(type).genericInvoker();
-    }
-
-    /**
-     * Produce a method handle which will invoke any method handle of the
+     * Produces a method handle which will invoke any method handle of the
      * given {@code type} on a standard set of {@code Object} type arguments
      * and a single trailing {@code Object[]} array.
      * The resulting invoker will be a method handle with the following
@@ -955,10 +1052,10 @@
      * <li>an {@code Object[]} array containing more arguments
      * </ul>
      * <p>
-     * The invoker will behave like a call to {@link MethodHandle.invokeGeneric} with
+     * The invoker will behave like a call to {@link MethodHandle#invokeGeneric invokeGeneric} with
      * the indicated {@code type}.
      * That is, if the target is exactly of the given {@code type}, it will behave
-     * like {@code invokeExact}; otherwise it behave as if {@link MethodHandle.asType}
+     * like {@code invokeExact}; otherwise it behave as if {@link MethodHandle#asType asType}
      * is used to convert the target to the required {@code type}.
      * <p>
      * The type of the returned invoker will not be the given {@code type}, but rather
@@ -973,12 +1070,13 @@
      * <p>
      * This method is equivalent to the following code (though it may be more efficient):
      * <p><blockquote><pre>
-MethodHandle invoker = publicLookup()
-  .findVirtual(MethodHandle.class, "invokeGeneric", type)
+MethodHandle invoker = MethodHandles.genericInvoker(type);
 int spreadArgCount = type.parameterCount - objectArgCount;
 invoker = invoker.asSpreader(Object[].class, spreadArgCount);
 return invoker;
      * </pre></blockquote>
+     * <p>
+     * This method throws no reflective or security exceptions.
      * @param type the desired target type
      * @param objectArgCount number of fixed (non-varargs) {@code Object} arguments
      * @return a method handle suitable for invoking any method handle of the given type
@@ -991,15 +1089,37 @@
     }
 
     /**
-     * Produce a method handle which will take a invoke any method handle of the
-     * given type.  The resulting invoker will have a type which is
+     * Produces a special <em>invoker method handle</em> which can be used to
+     * invoke any method handle of the given type, as if by {@code invokeExact}.
+     * The resulting invoker will have a type which is
      * exactly equal to the desired type, except that it will accept
      * an additional leading argument of type {@code MethodHandle}.
      * <p>
      * This method is equivalent to the following code (though it may be more efficient):
      * <p><blockquote><pre>
-     * lookup().findVirtual(MethodHandle.class, "invokeExact", type);
+publicLookup().findVirtual(MethodHandle.class, "invokeExact", type)
      * </pre></blockquote>
+     *
+     * <p style="font-size:smaller;">
+     * <em>Discussion:</em>
+     * Invoker method handles can be useful when working with variable method handles
+     * of unknown types.
+     * For example, to emulate an {@code invokeExact} call to a variable method
+     * handle {@code M}, extract its type {@code T},
+     * look up the invoker method {@code X} for {@code T},
+     * and call the invoker method, as {@code X.invokeGeneric(T, A...)}.
+     * (It would not work to call {@code X.invokeExact}, since the type {@code T}
+     * is unknown.)
+     * If spreading, collecting, or other argument transformations are required,
+     * they can be applied once to the invoker {@code X} and reused on many {@code M}
+     * method handle values, as long as they are compatible with the type of {@code X}.
+     * <p>
+     * <em>(Note:  The invoker method is not available via the Core Reflection API.
+     * An attempt to call {@linkplain java.lang.reflect.Method#invoke Method.invoke}
+     * on the declared {@code invokeExact} or {@code invokeGeneric} method will raise an
+     * {@link java.lang.UnsupportedOperationException UnsupportedOperationException}.)</em>
+     * <p>
+     * This method throws no reflective or security exceptions.
      * @param type the desired target type
      * @return a method handle suitable for invoking any method handle of the given type
      */
@@ -1008,12 +1128,38 @@
         return invokers(type).exactInvoker();
     }
 
+    /**
+     * Produces a special <em>invoker method handle</em> which can be used to
+     * invoke any method handle of the given type, as if by {@code invokeGeneric}.
+     * The resulting invoker will have a type which is
+     * exactly equal to the desired type, except that it will accept
+     * an additional leading argument of type {@code MethodHandle}.
+     * <p>
+     * Before invoking its target, the invoker will apply reference casts as
+     * necessary and unbox and widen primitive arguments, as if by {@link #convertArguments convertArguments}.
+     * The return value of the invoker will be an {@code Object} reference,
+     * boxing a primitive value if the original type returns a primitive,
+     * and always null if the original type returns void.
+     * <p>
+     * This method is equivalent to the following code (though it may be more efficient):
+     * <p><blockquote><pre>
+publicLookup().findVirtual(MethodHandle.class, "invokeGeneric", type)
+     * </pre></blockquote>
+     * <p>
+     * This method throws no reflective or security exceptions.
+     * @param type the desired target type
+     * @return a method handle suitable for invoking any method handle convertible to the given type
+     */
+    static public
+    MethodHandle genericInvoker(MethodType type) {
+        return invokers(type).genericInvoker();
+    }
+
     static Invokers invokers(MethodType type) {
         return MethodTypeImpl.invokers(IMPL_TOKEN, type);
     }
 
     /**
-     * <em>WORK IN PROGRESS:</em>
      * Perform value checking, exactly as if for an adapted method handle.
      * It is assumed that the given value is either null, of type T0,
      * or (if T0 is primitive) of the wrapper type corresponding to T0.
@@ -1084,7 +1230,7 @@
     /// method handle modification (creation from other method handles)
 
     /**
-     * Produce a method handle which adapts the type of the
+     * Produces a method handle which adapts the type of the
      * given method handle to a new type by pairwise argument conversion.
      * The original type and new type must have the same number of arguments.
      * The resulting method handle is guaranteed to report a type
@@ -1123,6 +1269,7 @@
      * @return a method handle which delegates to {@code target} after performing
      *           any necessary argument conversions, and arranges for any
      *           necessary return value conversions
+     * @throws NullPointerException if either argument is null
      * @throws WrongMethodTypeException if the conversion cannot be made
      * @see MethodHandle#asType
      * @see MethodHandles#explicitCastArguments
@@ -1144,7 +1291,7 @@
     }
 
     /**
-     * Produce a method handle which adapts the type of the
+     * Produces a method handle which adapts the type of the
      * given method handle to a new type by pairwise argument conversion.
      * The original type and new type must have the same number of arguments.
      * The resulting method handle is guaranteed to report a type
@@ -1176,6 +1323,7 @@
      * @return a method handle which delegates to {@code target} after performing
      *           any necessary argument conversions, and arranges for any
      *           necessary return value conversions
+     * @throws NullPointerException if either argument is null
      * @throws WrongMethodTypeException if the conversion cannot be made
      * @see MethodHandle#asType
      * @see MethodHandles#convertArguments
@@ -1223,7 +1371,7 @@
     */
 
     /**
-     * Produce a method handle which adapts the calling sequence of the
+     * Produces a method handle which adapts the calling sequence of the
      * given method handle to a new type, by reordering the arguments.
      * The resulting method handle is guaranteed to report a type
      * which is equal to the desired new type.
@@ -1271,6 +1419,7 @@
      * @param reorder a string which controls the reordering
      * @return a method handle which delegates to {@code target} after it
      *           drops unused arguments and moves and/or duplicates the other arguments
+     * @throws NullPointerException if any argument is null
      */
     public static
     MethodHandle permuteArguments(MethodHandle target, MethodType newType, int... reorder) {
@@ -1296,11 +1445,10 @@
     }
 
     /**
-     * <em>METHOD WILL BE REMOVED FOR PFD:</em>
      * Equivalent to the following code:
      * <p><blockquote><pre>
      * int spreadPos = newType.parameterCount() - 1;
-     * Class<?> spreadType = newType.parameterType(spreadPos);
+     * Class&lt;?&gt; spreadType = newType.parameterType(spreadPos);
      * int spreadCount = target.type().parameterCount() - spreadPos;
      * MethodHandle adapter = target.asSpreader(spreadType, spreadCount);
      * adapter = adapter.asType(newType);
@@ -1310,9 +1458,8 @@
      * @param newType the expected type of the new method handle
      * @return a method handle which spreads its final argument,
      *         before calling the original method handle
-     * @deprecated Use {@link MethodHandle#asSpreader}
      */
-    public static
+    /*non-public*/ static
     MethodHandle spreadArguments(MethodHandle target, MethodType newType) {
         MethodType oldType = target.type();
         int inargs  = newType.parameterCount();
@@ -1330,11 +1477,10 @@
     }
 
     /**
-     * <em>METHOD WILL BE REMOVED FOR PFD:</em>
      * Equivalent to the following code:
      * <p><blockquote><pre>
      * int collectPos = target.type().parameterCount() - 1;
-     * Class<?> collectType = target.type().parameterType(collectPos);
+     * Class&lt;?&gt; collectType = target.type().parameterType(collectPos);
      * if (!collectType.isArray())  collectType = Object[].class;
      * int collectCount = newType.parameterCount() - collectPos;
      * MethodHandle adapter = target.asCollector(collectType, collectCount);
@@ -1345,9 +1491,8 @@
      * @param newType the expected type of the new method handle
      * @return a method handle which collects some trailing argument
      *         into an array, before calling the original method handle
-     * @deprecated Use {@link MethodHandle#asCollector} instead.
      */
-    public static
+    /*non-public*/ static
     MethodHandle collectArguments(MethodHandle target, MethodType newType) {
         MethodType oldType = target.type();
         int inargs  = newType.parameterCount();
@@ -1364,7 +1509,7 @@
     }
 
     /**
-     * Produce a method handle of the requested return type which returns the given
+     * Produces a method handle of the requested return type which returns the given
      * constant value every time it is invoked.
      * <p>
      * Before the method handle is returned, the passed-in value is converted to the requested type.
@@ -1375,12 +1520,15 @@
      * @param type the return type of the desired method handle
      * @param value the value to return
      * @return a method handle of the given return type and no arguments, which always returns the given value
-     * @throws WrongMethodTypeException if the value cannot be converted to the required return type
+     * @throws NullPointerException if the {@code type} argument is null
+     * @throws ClassCastException if the value cannot be converted to the required return type
+     * @throws IllegalArgumentException if the given type is {@code void.class}
      */
     public static
     MethodHandle constant(Class<?> type, Object value) {
         if (type.isPrimitive()) {
-            if (type == void.class)  return identity(type);
+            if (type == void.class)
+                throw newIllegalArgumentException("void type");
             Wrapper w = Wrapper.forPrimitiveType(type);
             return identity(type).bindTo(w.convert(value, type));
         } else {
@@ -1389,64 +1537,22 @@
     }
 
     /**
-     * Produce a method handle of the requested type which returns the given
-     * constant value every time it is invoked.
-     * <p>
-     * Before the method handle is returned, the passed-in value is converted to the requested return type,
-     * as if by {@link #explicitCastArguments #explicitCastArguments}.
-     * That is, if the return type is primitive, the value is unboxed,
-     * and the primitive value is widened and/or narrowed.
-     * Otherwise, reference conversions are attempted.
-     * @param type the type of the desired method handle
-     * @param value the value to return
-     * @return a method handle of the given return type and no arguments, which always returns the given value
-     * @throws WrongMethodTypeException if the value cannot be converted to the required return type
+     * Produces a method handle which returns its sole argument when invoked.
+     * <p>The identity function for {@code void} takes no arguments and returns no values.
+     * @param type the type of the sole parameter and return value of the desired method handle
+     * @return a unary method handle which accepts and returns the given type
+     * @throws NullPointerException if the argument is null
+     * @throws IllegalArgumentException if the given type is {@code void.class}
      */
     public static
-    MethodHandle constant(MethodType type, Object value) {
-        MethodHandle target = constant(type.returnType(), value);
-        int len = type.parameterCount();
-        if (len == 0)
-            return target.asType(type);
-        target = target.asType(type.dropParameterTypes(0, len));
-        return dropArguments(target, 0, type.parameterList().subList(0, len));
-    }
-
-     /**
-      * Produce a method handle which returns its sole argument when invoked.
-      * <p>The identity function for {@code void} takes no arguments and returns no values.
-      * @param type the type of the sole parameter and return value of the desired method handle
-      * @return a unary method handle which accepts and returns the given type
-      */
-    public static
     MethodHandle identity(Class<?> type) {
+        if (type == void.class)
+            throw newIllegalArgumentException("void type");
         return ValueConversions.identity(type);
     }
 
-     /**
-      * Produce a method handle of the requested type which returns its argument when invoked.
-      * If the return type differs from the first argument type, the argument will be
-      * converted as if by {@link #explicitCastArguments explicitCastArguments}.
-      * If there are additional arguments beyond the first, they are discarded.
-      * <p>The identity function for {@code void} discards all its arguments.
-      * @param type the type of the desired method handle
-      * @return a method handle of the given type, which always returns its first argument
-      * @throws WrongMethodTypeException if the first argument cannot be converted to the required return type
-      */
-    public static
-    MethodHandle identity(MethodType type) {
-        MethodHandle target = identity(type.returnType());
-        int len = type.parameterCount();
-        if (len == 1)
-            return explicitCastArguments(target, type);
-        if (len == 0)
-            throw new IllegalArgumentException("not enough arguments");
-        target = explicitCastArguments(target, type.dropParameterTypes(1, len));
-        return dropArguments(target, 1, type.parameterList().subList(1, len));
-    }
-
     /**
-     * Produce a method handle which calls the original method handle {@code target},
+     * Produces a method handle which calls the original method handle {@code target},
      * after inserting the given argument(s) at the given position.
      * The formal parameters to {@code target} which will be supplied by those
      * arguments are called <em>bound parameters</em>, because the new method
@@ -1467,6 +1573,7 @@
      * @param values the series of arguments to insert
      * @return a method handle which inserts an additional argument,
      *         before calling the original method handle
+     * @throws NullPointerException if the {@code target} argument or the {@code values} array is null
      * @see MethodHandle#bindTo
      */
     public static
@@ -1501,7 +1608,7 @@
     }
 
     /**
-     * Produce a method handle which calls the original method handle,
+     * Produces a method handle which calls the original method handle,
      * after dropping the given argument(s) at the given position.
      * The type of the new method handle will insert the given argument
      * type(s), at that position, into the original handle's type.
@@ -1533,6 +1640,9 @@
      * @param pos position of first argument to drop (zero for the leftmost)
      * @return a method handle which drops arguments of the given types,
      *         before calling the original method handle
+     * @throws NullPointerException if the {@code target} argument is null,
+     *                              or if the {@code valueTypes} list or any of its elements is null
+     * @throws IllegalArgumentException if any of the {@code valueTypes} is {@code void.class}
      */
     public static
     MethodHandle dropArguments(MethodHandle target, int pos, List<Class<?>> valueTypes) {
@@ -1550,7 +1660,7 @@
     }
 
     /**
-     * Produce a method handle which calls the original method handle,
+     * Produces a method handle which calls the original method handle,
      * after dropping the given argument(s) at the given position.
      * The type of the new method handle will insert the given argument
      * type(s), at that position, into the original handle's type.
@@ -1563,6 +1673,9 @@
      * @param pos position of first argument to drop (zero for the leftmost)
      * @return a method handle which drops arguments of the given types,
      *         before calling the original method handle
+     * @throws NullPointerException if the {@code target} argument is null,
+     *                              or if the {@code valueTypes} array or any of its elements is null
+     * @throws IllegalArgumentException if any of the {@code valueTypes} is {@code void.class}
      */
     public static
     MethodHandle dropArguments(MethodHandle target, int pos, Class<?>... valueTypes) {
@@ -1577,7 +1690,8 @@
      * <p>
      * The pre-processing is performed by one or more method handles,
      * specified in the elements of the {@code filters} array.
-     * (If there are no elements in the array, the original target is returned.)
+     * Null arguments in the array are ignored, and the corresponding arguments left unchanged.
+     * (If there are no non-null elements in the array, the original target is returned.)
      * Each filter is applied to the corresponding argument of the adapter.
      * <p>
      * If a filter {@code F} applies to the {@code N}th argument of
@@ -1607,12 +1721,16 @@
 MethodHandle f2 = filterArguments(cat, 0, upcase, upcase);
 assertEquals("XY", (String) f2.invokeExact("x", "y")); // XY
      * </pre></blockquote>
+     *
      * @param target the method handle to invoke after arguments are filtered
      * @param pos the position of the first argument to filter
      * @param filters method handles to call initially on filtered arguments
      * @return method handle which incorporates the specified argument filtering logic
-     * @throws IllegalArgumentException if an element of {@code filters} is null or
-     *          does not match a corresponding argument type of {@code target} as described above
+     * @throws NullPointerException if the {@code target} argument is null
+     *                              or if the {@code filters} array is null
+     * @throws IllegalArgumentException if a non-null element of {@code filters}
+     *          does not match a corresponding argument type of {@code target} as described above,
+     *          or if the {@code pos+filters.length} is greater than {@code target.type().parameterCount()}
      */
     public static
     MethodHandle filterArguments(MethodHandle target, int pos, MethodHandle... filters) {
@@ -1620,17 +1738,18 @@
         MethodHandle adapter = target;
         MethodType adapterType = targetType;
         int maxPos = targetType.parameterCount();
-        int curPos = pos;
+        if (pos + filters.length > maxPos)
+            throw newIllegalArgumentException("too many filters");
+        int curPos = pos-1;  // pre-incremented
         for (MethodHandle filter : filters) {
-            if (curPos >= maxPos)
-                throw newIllegalArgumentException("too many filters");
+            curPos += 1;
+            if (filter == null)  continue;  // ignore null elements of filters
             MethodType filterType = filter.type();
             if (filterType.parameterCount() != 1
                 || filterType.returnType() != targetType.parameterType(curPos))
                 throw newIllegalArgumentException("target and filter types do not match");
             adapterType = adapterType.changeParameterType(curPos, filterType.parameterType(0));
             adapter = MethodHandleImpl.filterArgument(IMPL_TOKEN, adapter, curPos, filter);
-            curPos += 1;
         }
         MethodType midType = adapter.type();
         if (midType != adapterType)
@@ -1665,7 +1784,8 @@
      * @param target the method handle to invoke before filtering the return value
      * @param filter method handle to call on the return value
      * @return method handle which incorporates the specified return value filtering logic
-     * @throws IllegalArgumentException if {@code filter} is null or
+     * @throws NullPointerException if either argument is null
+     * @throws IllegalArgumentException if {@code filter}
      *          does not match the return type of {@code target} as described above
      */
     public static
@@ -1675,9 +1795,11 @@
         if (filterType.parameterCount() != 1
             || filterType.parameterType(0) != targetType.returnType())
             throw newIllegalArgumentException("target and filter types do not match");
+        // result = fold( lambda(retval, arg...) { filter(retval) },
+        //                lambda(        arg...) { target(arg...) } )
         // FIXME: Too many nodes here.
-        MethodHandle returner = dropArguments(filter, 0, targetType.parameterList());
-        return foldArguments(returner, exactInvoker(target.type()).bindTo(target));
+        MethodHandle returner = dropArguments(filter, 1, targetType.parameterList());
+        return foldArguments(returner, target);
     }
 
     /**
@@ -1700,7 +1822,7 @@
      * (Note that {@link #dropArguments(MethodHandle,int,List) dropArguments} can be used to remove any arguments
      * that either the {@code combiner} or {@code target} does not wish to receive.
      * If some of the incoming arguments are destined only for the combiner,
-     * consider using {@link MethodHandle#asCollector} instead, since those
+     * consider using {@link MethodHandle#asCollector asCollector} instead, since those
      * arguments will not need to be live on the stack on entry to the
      * target.)
      * <p>
@@ -1719,6 +1841,7 @@
      * @param target the method handle to invoke after arguments are combined
      * @param combiner method handle to call initially on the incoming arguments
      * @return method handle which incorporates the specified argument folding logic
+     * @throws NullPointerException if either argument is null
      * @throws IllegalArgumentException if the first argument type of
      *          {@code target} is not the same as {@code combiner}'s return type,
      *          or if the following argument types of {@code target}
@@ -1767,6 +1890,7 @@
      * @param target method handle to call if test passes
      * @param fallback method handle to call if test fails
      * @return method handle which incorporates the specified if/then/else logic
+     * @throws NullPointerException if any argument is null
      * @throws IllegalArgumentException if {@code test} does not return boolean,
      *          or if all three method types do not match (with the return
      *          type of {@code test} changed to match that of {@code target}).
@@ -1835,6 +1959,7 @@
      * @param exType the type of exception which the handler will catch
      * @param handler method handle to call if a matching exception is thrown
      * @return method handle which incorporates the specified try/catch logic
+     * @throws NullPointerException if any argument is null
      * @throws IllegalArgumentException if {@code handler} does not accept
      *          the given exception type, or if the method handle types do
      *          not match in their return types and their
@@ -1865,12 +1990,14 @@
     }
 
     /**
-     * Produce a method handle which will throw exceptions of the given {@code exType}.
+     * Produces a method handle which will throw exceptions of the given {@code exType}.
      * The method handle will accept a single argument of {@code exType},
      * and immediately throw it as an exception.
      * The method type will nominally specify a return of {@code returnType}.
      * The return type may be anything convenient:  It doesn't matter to the
      * method handle's behavior, since it will never return normally.
+     * @return method handle which can throw the given exceptions
+     * @throws NullPointerException if either argument is null
      */
     public static
     MethodHandle throwException(Class<?> returnType, Class<? extends Throwable> exType) {
@@ -1878,11 +2005,22 @@
     }
 
     /**
-     * <em>PROVISIONAL API, WORK IN PROGRESS:</em>
-     * Produce a wrapper instance of the given "SAM" interface which redirects
+     * Produces an instance of the given "SAM" interface which redirects
      * its calls to the given method handle.
+     * <p>
      * A SAM interface is an interface which declares a single abstract method.
-     * The type must be public.  (No additional access checks are performed.)
+     * When determining the unique abstract method of a SAM interface,
+     * the public {@code Object} methods ({@code toString}, {@code equals}, {@code hashCode})
+     * are disregarded.  For example, {@link java.util.Comparator} is a SAM interface,
+     * even though it re-declares the {@code Object.equals} method.
+     * Also, if the SAM interface has a supertype,
+     * the SAM interface may override an inherited method.
+     * Any such overrides are respected, and the method handle will be accessible
+     * by either the inherited method or the SAM method.
+     * In particular, a {@linkplain java.lang.reflect.Method#isBridge bridge method}
+     * may be created if the methods have different return types.
+     * <p>
+     * The type must be public.  No additional access checks are performed.
      * <p>
      * The resulting instance of the required SAM type will respond to
      * invocation of the SAM type's single abstract method by calling
@@ -1894,6 +2032,17 @@
      * instance is created, as if by a call to {@code asType},
      * which may result in a {@code WrongMethodTypeException}.
      * <p>
+     * The wrapper instance will implement the requested SAM interface
+     * and its super-types, but no other SAM types.
+     * This means that the SAM instance will not unexpectedly
+     * pass an {@code instanceof} test for any unrequested type.
+     * <p style="font-size:smaller;">
+     * <em>Implementation Note:</em>
+     * Therefore, each SAM instance must implement a unique SAM type.
+     * Implementations may not bundle together
+     * multiple SAM types onto single implementation classes
+     * in the style of {@link java.awt.AWTEventMulticaster}.
+     * <p>
      * The method handle may throw an <em>undeclared exception</em>,
      * which means any checked exception (or other checked throwable)
      * not declared by the SAM type's single abstract method.
@@ -1901,56 +2050,46 @@
      * {@link java.lang.reflect.UndeclaredThrowableException UndeclaredThrowableException}
      * and thrown in that wrapped form.
      * <p>
-     * The wrapper instance is guaranteed to be of a non-public
-     * implementation class C in a package containing no classes
-     * or methods except system-defined classes and methods.
-     * The implementation class C will have no public supertypes
-     * or public methods beyond the following:
-     * <ul>
-     * <li>the SAM type itself and any methods in the SAM type
-     * <li>the supertypes of the SAM type (if any) and their methods
-     * <li>{@link Object} and its methods
-     * <li>{@link java.dyn.AsInstanceObject AsInstanceObject} and its methods</li>
-     * </ul>
-     * <p>
-     * (Note: When determining the unique abstract method of a SAM interface,
-     * the public {@code Object} methods ({@code toString}, {@code equals}, {@code hashCode})
-     * are disregarded.  For example, {@link java.util.Comparator} is a SAM interface,
-     * even though it re-declares the {@code Object.equals} method.)
-     * <p>
-     * No stable mapping is promised between the SAM type and
-     * the implementation class C.  Over time, several implementation
-     * classes might be used for the same SAM type.
-     * <p>
-     * This method is not guaranteed to return a distinct
-     * wrapper object for each separate call.  If the implementation is able
-     * to prove that a wrapper of the required SAM type
-     * has already been created for a given
-     * method handle, or for another method handle with the
-     * same behavior, the implementation may return that wrapper in place of
-     * a new wrapper.
-     * <p>
-     * This method is designed to apply to common use cases
-     * where a single method handle must interoperate with
-     * a type (class or interface) that implements a function-like
-     * API.  Additional variations, such as SAM classes with
-     * private constructors, or interfaces with multiple but related
-     * entry points, must be covered by hand-written or automatically
-     * generated adapter classes.  In those cases, consider implementing
-     * {@link java.dyn.MethodHandles.AsInstanceObject AsInstanceObject}
-     * in the adapters, so that generic code can extract the underlying
-     * method handle without knowing where the SAM adapter came from.
+     * Like {@link java.lang.Integer#valueOf Integer.valueOf},
+     * {@code asInstance} is a factory method whose results are defined
+     * by their behavior.
+     * It is not guaranteed to return a new instance for every call.
      * <p>
      * Future versions of this API may accept additional types,
      * such as abstract classes with single abstract methods.
+     * Future versions of this API may also equip wrapper instances
+     * with one or more additional public "marker" interfaces.
+     *
      * @param target the method handle to invoke from the wrapper
      * @param samType the desired type of the wrapper, a SAM type
      * @return a correctly-typed wrapper for the given {@code target}
+     * @throws NullPointerException if either argument is null
      * @throws IllegalArgumentException if the {@code samType} is not a
      *         valid argument to this method
      * @throws WrongMethodTypeException if the {@code target} cannot
      *         be converted to the type required by the SAM type
      */
+    // Other notes to implementors:
+    // <p>
+    // No stable mapping is promised between the SAM type and
+    // the implementation class C.  Over time, several implementation
+    // classes might be used for the same SAM type.
+    // <p>
+    // If the implementation is able
+    // to prove that a wrapper of the required SAM type
+    // has already been created for a given
+    // method handle, or for another method handle with the
+    // same behavior, the implementation may return that wrapper in place of
+    // a new wrapper.
+    // <p>
+    // This method is designed to apply to common use cases
+    // where a single method handle must interoperate with
+    // an interface that implements a function-like
+    // API.  Additional variations, such as SAM classes with
+    // private constructors, or interfaces with multiple but related
+    // entry points, must be covered by hand-written or automatically
+    // generated adapter classes.
+    //
     public static
     <T> T asInstance(final MethodHandle target, final Class<T> samType) {
         // POC implementation only; violates the above contract several ways
@@ -1963,15 +2102,15 @@
         final MethodHandle vaTarget = checkTarget.asSpreader(Object[].class, samMT.parameterCount());
         return samType.cast(Proxy.newProxyInstance(
                 samType.getClassLoader(),
-                new Class[]{ samType, AsInstanceObject.class },
+                new Class[]{ samType, WrapperInstance.class },
                 new InvocationHandler() {
                     private Object getArg(String name) {
-                        if ((Object)name == "getAsInstanceTarget")  return target;
-                        if ((Object)name == "getAsInstanceType")    return samType;
+                        if ((Object)name == "getWrapperInstanceTarget")  return target;
+                        if ((Object)name == "getWrapperInstanceType")    return samType;
                         throw new AssertionError();
                     }
                     public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
-                        if (method.getDeclaringClass() == AsInstanceObject.class)
+                        if (method.getDeclaringClass() == WrapperInstance.class)
                             return getArg(method.getName());
                         if (method.equals(sam))
                             return vaTarget.invokeExact(args);
@@ -1983,21 +2122,49 @@
     }
 
     /**
-     * <em>PROVISIONAL API, WORK IN PROGRESS:</em>
-     * Interface implemented by every object which is produced by {@link #asInstance asInstance}.
-     * The methods of this interface allow a caller to recover the parameters
-     * to {@code asInstance}.
-     * This allows applications to repeatedly convert between method handles
-     * and SAM objects, without the risk of creating unbounded delegation chains.
+     * Determine if the given object was produced by a call to {@link #asInstance asInstance}.
+     * @param x any reference
+     * @return true if the reference is not null and points to an object produced by {@code asInstance}
      */
-    public interface AsInstanceObject {
-        /** Produce or recover a target method handle which is behaviorally
-         *  equivalent to the SAM method of this object.
-         */
-        public MethodHandle getAsInstanceTarget();
-        /** Recover the SAM type for which this object was created.
-         */
-        public Class<?> getAsInstanceType();
+    public static
+    boolean isWrapperInstance(Object x) {
+        return x instanceof WrapperInstance;
+    }
+
+    private static WrapperInstance asWrapperInstance(Object x) {
+        try {
+            if (x != null)
+                return (WrapperInstance) x;
+        } catch (ClassCastException ex) {
+        }
+        throw new IllegalArgumentException("not a wrapper instance");
+    }
+
+    /**
+     * Produces or recovers a target method handle which is behaviorally
+     * equivalent to the SAM method of this wrapper instance.
+     * The object {@code x} must have been produced by a call to {@link #asInstance asInstance}.
+     * This requirement may be tested via {@link #isWrapperInstance isWrapperInstance}.
+     * @param x any reference
+     * @return a method handle implementing the SAM method
+     * @throws IllegalArgumentException if the reference x is not to a wrapper instance
+     */
+    public static
+    MethodHandle wrapperInstanceTarget(Object x) {
+        return asWrapperInstance(x).getWrapperInstanceTarget();
+    }
+
+    /**
+     * Recover the SAM type for which this wrapper instance was created.
+     * The object {@code x} must have been produced by a call to {@link #asInstance asInstance}.
+     * This requirement may be tested via {@link #isWrapperInstance isWrapperInstance}.
+     * @param x any reference
+     * @return the SAM type for which the wrapper was created
+     * @throws IllegalArgumentException if the reference x is not to a wrapper instance
+     */
+    public static
+    Class<?> wrapperInstanceType(Object x) {
+        return asWrapperInstance(x).getWrapperInstanceType();
     }
 
     private static
--- a/src/share/classes/java/dyn/MethodType.java	Fri Feb 11 01:26:24 2011 -0800
+++ b/src/share/classes/java/dyn/MethodType.java	Fri Feb 11 01:26:28 2011 -0800
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2011, 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
@@ -31,6 +31,7 @@
 import java.util.List;
 import sun.dyn.Access;
 import sun.dyn.Invokers;
+import sun.dyn.MethodHandleImpl;
 import sun.dyn.MethodTypeImpl;
 import sun.dyn.util.BytecodeDescriptor;
 import static sun.dyn.MemberName.newIllegalArgumentException;
@@ -41,8 +42,8 @@
  * and expected  by a method handle caller.  Method types must be properly
  * matched between a method handle and all its callers,
  * and the JVM's operations enforce this matching at, specifically
- * during calls to {@link MethodHandle#invokeExact}
- * and {@link MethodHandle#invokeGeneric}, and during execution
+ * during calls to {@link MethodHandle#invokeExact MethodHandle.invokeExact}
+ * and {@link MethodHandle#invokeGeneric MethodHandle.invokeGeneric}, and during execution
  * of {@code invokedynamic} instructions.
  * <p>
  * The structure is a return type accompanied by any number of parameter types.
@@ -70,8 +71,9 @@
  * with the instructions in a class file's constant pool.
  * <p>
  * Like classes and strings, method types can also be represented directly
- * in a class file's constant pool as constants. The may be loaded by an {@code ldc}
- * instruction which refers to a suitable {@code CONSTANT_MethodType} constant pool entry.
+ * in a class file's constant pool as constants.
+ * A method type may be loaded by an {@code ldc} instruction which refers
+ * to a suitable {@code CONSTANT_MethodType} constant pool entry.
  * The entry refers to a {@code CONSTANT_Utf8} spelling for the descriptor string.
  * For more details, see the <a href="package-summary.html#mtcon">package summary</a>.
  * <p>
@@ -124,15 +126,32 @@
         this.ptypes = ptypes;
     }
 
-    private void checkRtype(Class<?> rtype) {
+    private static void checkRtype(Class<?> rtype) {
         rtype.equals(rtype);  // null check
     }
-    private void checkPtypes(Class<?>[] ptypes) {
+    private static int checkPtype(Class<?> ptype) {
+        ptype.getClass();  //NPE
+        if (ptype == void.class)
+            throw newIllegalArgumentException("parameter type cannot be void");
+        if (ptype == double.class || ptype == long.class)  return 1;
+        return 0;
+    }
+    /** Return number of extra slots (count of long/double args). */
+    private static int checkPtypes(Class<?>[] ptypes) {
+        int slots = 0;
         for (Class<?> ptype : ptypes) {
-            ptype.equals(ptype);  // null check
-            if (ptype == void.class)
-                throw newIllegalArgumentException("parameter type cannot be void");
+            slots += checkPtype(ptype);
         }
+        checkSlotCount(ptypes.length + slots);
+        return slots;
+    }
+    private static void checkSlotCount(int count) {
+        if ((count & 0xFF) != count)
+            throw newIllegalArgumentException("bad parameter count "+count);
+    }
+    private static IndexOutOfBoundsException newIndexOutOfBoundsException(Object num) {
+        if (num instanceof Integer)  num = "bad index: "+num;
+        return new IndexOutOfBoundsException(num.toString());
     }
 
     static final HashMap<MethodType,MethodType> internTable
@@ -140,27 +159,39 @@
 
     static final Class<?>[] NO_PTYPES = {};
 
-    /** Find or create an instance of the given method type.
+    /**
+     * Find or create an instance of the given method type.
      * @param rtype  the return type
      * @param ptypes the parameter types
-     * @return a method type with the given parts
-     * @throws NullPointerException if rtype or any ptype is null
-     * @throws IllegalArgumentException if any of the ptypes is void
+     * @return a method type with the given components
+     * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null
+     * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class}
      */
     public static
     MethodType methodType(Class<?> rtype, Class<?>[] ptypes) {
         return makeImpl(rtype, ptypes, false);
     }
 
-    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}. */
+    /**
+     * Finds or creates a method type with the given components.
+     * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
+     * @return a method type with the given components
+     * @throws NullPointerException if {@code rtype} or {@code ptypes} or any element of {@code ptypes} is null
+     * @throws IllegalArgumentException if any element of {@code ptypes} is {@code void.class}
+     */
     public static
-    MethodType methodType(Class<?> rtype, List<? extends Class<?>> ptypes) {
+    MethodType methodType(Class<?> rtype, List<Class<?>> ptypes) {
         boolean notrust = false;  // random List impl. could return evil ptypes array
         return makeImpl(rtype, ptypes.toArray(NO_PTYPES), notrust);
     }
 
-    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.
-     *  The leading parameter type is prepended to the remaining array.
+    /**
+     * Finds or creates a method type with the given components.
+     * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
+     * The leading parameter type is prepended to the remaining array.
+     * @return a method type with the given components
+     * @throws NullPointerException if {@code rtype} or {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is null
+     * @throws IllegalArgumentException if {@code ptype0} or {@code ptypes} or any element of {@code ptypes} is {@code void.class}
      */
     public static
     MethodType methodType(Class<?> rtype, Class<?> ptype0, Class<?>... ptypes) {
@@ -170,25 +201,37 @@
         return makeImpl(rtype, ptypes1, true);
     }
 
-    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.
-     *  The resulting method has no parameter types.
+    /**
+     * Finds or creates a method type with the given components.
+     * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
+     * The resulting method has no parameter types.
+     * @return a method type with the given return value
+     * @throws NullPointerException if {@code rtype} is null
      */
     public static
     MethodType methodType(Class<?> rtype) {
         return makeImpl(rtype, NO_PTYPES, true);
     }
 
-    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.
-     *  The resulting method has the single given parameter type.
+    /**
+     * Finds or creates a method type with the given components.
+     * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
+     * The resulting method has the single given parameter type.
+     * @return a method type with the given return value and parameter type
+     * @throws NullPointerException if {@code rtype} or {@code ptype0} is null
+     * @throws IllegalArgumentException if {@code ptype0} is {@code void.class}
      */
     public static
     MethodType methodType(Class<?> rtype, Class<?> ptype0) {
         return makeImpl(rtype, new Class<?>[]{ ptype0 }, true);
     }
 
-    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.
-     *  The resulting method has the same parameter types as {@code ptypes},
-     *  and the specified return type.
+    /**
+     * Finds or creates a method type with the given components.
+     * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
+     * The resulting method has the same parameter types as {@code ptypes},
+     * and the specified return type.
+     * @throws NullPointerException if {@code rtype} or {@code ptypes} is null
      */
     public static
     MethodType methodType(Class<?> rtype, MethodType ptypes) {
@@ -237,17 +280,20 @@
     private static final MethodType[] objectOnlyTypes = new MethodType[20];
 
     /**
-     * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.
+     * Finds or creates a method type whose components are {@code Object} with an optional trailing {@code Object[]} array.
+     * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
      * All parameters and the return type will be {@code Object},
      * except the final varargs parameter if any, which will be {@code Object[]}.
      * @param objectArgCount number of parameters (excluding the varargs parameter if any)
      * @param varargs whether there will be a varargs parameter, of type {@code Object[]}
      * @return a totally generic method type, given only its count of parameters and varargs
+     * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255
      * @see #genericMethodType(int)
      */
     public static
     MethodType genericMethodType(int objectArgCount, boolean varargs) {
         MethodType mt;
+        checkSlotCount(objectArgCount);
         int ivarargs = (!varargs ? 0 : 1);
         int ootIndex = objectArgCount*2 + ivarargs;
         if (ootIndex < objectOnlyTypes.length) {
@@ -265,9 +311,12 @@
     }
 
     /**
+     * Finds or creates a method type whose components are all {@code Object}.
+     * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
      * All parameters and the return type will be Object.
      * @param objectArgCount number of parameters
      * @return a totally generic method type, given only its count of parameters
+     * @throws IllegalArgumentException if {@code objectArgCount} is negative or greater than 255
      * @see #genericMethodType(int, boolean)
      */
     public static
@@ -275,27 +324,41 @@
         return genericMethodType(objectArgCount, false);
     }
 
-    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.
+    /**
+     * Finds or creates a method type with a single different parameter type.
+     * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
      * @param num    the index (zero-based) of the parameter type to change
      * @param nptype a new parameter type to replace the old one with
      * @return the same type, except with the selected parameter changed
+     * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()}
+     * @throws IllegalArgumentException if {@code nptype} is {@code void.class}
+     * @throws NullPointerException if {@code nptype} is null
      */
     public MethodType changeParameterType(int num, Class<?> nptype) {
         if (parameterType(num) == nptype)  return this;
+        checkPtype(nptype);
         Class<?>[] nptypes = ptypes.clone();
         nptypes[num] = nptype;
         return makeImpl(rtype, nptypes, true);
     }
 
-    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.
+    /**
+     * Finds or creates a method type with additional parameter types.
+     * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
      * @param num    the position (zero-based) of the inserted parameter type(s)
-     * @param ptypesToInsert zero or more a new parameter types to insert into the parameter list
+     * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
      * @return the same type, except with the selected parameter(s) inserted
+     * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()}
+     * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
+     *                                  or if the resulting method type would have more than 255 parameter slots
+     * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
      */
     public MethodType insertParameterTypes(int num, Class<?>... ptypesToInsert) {
         int len = ptypes.length;
         if (num < 0 || num > len)
-            throw newIllegalArgumentException("num="+num); //SPECME
+            throw newIndexOutOfBoundsException(num);
+        int ins = checkPtypes(ptypesToInsert);
+        checkSlotCount(parameterSlotCount() + ptypesToInsert.length + ins);
         int ilen = ptypesToInsert.length;
         if (ilen == 0)  return this;
         Class<?>[] nptypes = Arrays.copyOfRange(ptypes, 0, len+ilen);
@@ -304,40 +367,61 @@
         return makeImpl(rtype, nptypes, true);
     }
 
-    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.
-     * @param ptypesToInsert zero or more a new parameter types to insert after the end of the parameter list
+    /**
+     * Finds or creates a method type with additional parameter types.
+     * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
+     * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list
      * @return the same type, except with the selected parameter(s) appended
+     * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
+     *                                  or if the resulting method type would have more than 255 parameter slots
+     * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
      */
     public MethodType appendParameterTypes(Class<?>... ptypesToInsert) {
         return insertParameterTypes(parameterCount(), ptypesToInsert);
     }
 
-    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.
-     * @param ptypesToInsert zero or more a new parameter types to insert after the end of the parameter list
+    /**
+     * Finds or creates a method type with additional parameter types.
+     * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
+     * @param num    the position (zero-based) of the inserted parameter type(s)
+     * @param ptypesToInsert zero or more new parameter types to insert into the parameter list
+     * @return the same type, except with the selected parameter(s) inserted
+     * @throws IndexOutOfBoundsException if {@code num} is negative or greater than {@code parameterCount()}
+     * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
+     *                                  or if the resulting method type would have more than 255 parameter slots
+     * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
+     */
+    public MethodType insertParameterTypes(int num, List<Class<?>> ptypesToInsert) {
+        return insertParameterTypes(num, ptypesToInsert.toArray(NO_PTYPES));
+    }
+
+    /**
+     * Finds or creates a method type with additional parameter types.
+     * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
+     * @param ptypesToInsert zero or more new parameter types to insert after the end of the parameter list
      * @return the same type, except with the selected parameter(s) appended
+     * @throws IllegalArgumentException if any element of {@code ptypesToInsert} is {@code void.class}
+     *                                  or if the resulting method type would have more than 255 parameter slots
+     * @throws NullPointerException if {@code ptypesToInsert} or any of its elements is null
      */
     public MethodType appendParameterTypes(List<Class<?>> ptypesToInsert) {
         return insertParameterTypes(parameterCount(), ptypesToInsert);
     }
 
-    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.
-     * @param num    the position (zero-based) of the inserted parameter type(s)
-     * @param ptypesToInsert zero or more a new parameter types to insert into the parameter list
-     * @return the same type, except with the selected parameter(s) inserted
-     */
-    public MethodType insertParameterTypes(int num, List<Class<?>> ptypesToInsert) {
-        return insertParameterTypes(num, ptypesToInsert.toArray(NO_PTYPES));
-    }
-
-    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.
+    /**
+     * Finds or creates a method type with some parameter types omitted.
+     * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
      * @param start  the index (zero-based) of the first parameter type to remove
      * @param end    the index (greater than {@code start}) of the first parameter type after not to remove
      * @return the same type, except with the selected parameter(s) removed
+     * @throws IndexOutOfBoundsException if {@code start} is negative or greater than {@code parameterCount()}
+     *                                  or if {@code end} is negative or greater than {@code parameterCount()}
+     *                                  or if {@code start} is greater than {@code end}
      */
     public MethodType dropParameterTypes(int start, int end) {
         int len = ptypes.length;
         if (!(0 <= start && start <= end && end <= len))
-            throw newIllegalArgumentException("start="+start+" end="+end); //SPECME
+            throw newIndexOutOfBoundsException("start="+start+" end="+end);
         if (start == end)  return this;
         Class<?>[] nptypes;
         if (start == 0) {
@@ -361,17 +445,20 @@
         return makeImpl(rtype, nptypes, true);
     }
 
-    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.
+    /**
+     * Finds or creates a method type with a different return type.
+     * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
      * @param nrtype a return parameter type to replace the old one with
      * @return the same type, except with the return type change
+     * @throws NullPointerException if {@code nrtype} is null
      */
     public MethodType changeReturnType(Class<?> nrtype) {
         if (returnType() == nrtype)  return this;
         return makeImpl(nrtype, ptypes, true);
     }
 
-    /** Convenience method.
-     * Report if this type contains a primitive argument or return value.
+    /**
+     * Reports if this type contains a primitive argument or return value.
      * The return type {@code void} counts as a primitive.
      * @return true if any of the types are primitives
      */
@@ -379,8 +466,8 @@
         return form.hasPrimitives();
     }
 
-    /** Convenience method.
-     * Report if this type contains a wrapper argument or return value.
+    /**
+     * Reports if this type contains a wrapper argument or return value.
      * Wrappers are types which box primitive values, such as {@link Integer}.
      * The reference type {@code java.lang.Void} counts as a wrapper.
      * @return true if any of the types are wrappers
@@ -389,8 +476,9 @@
         return unwrap() != this;
     }
 
-    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.
-     * Erase all reference types to {@code Object}.
+    /**
+     * Erases all reference types to {@code Object}.
+     * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
      * All primitive types (including {@code void}) will remain unchanged.
      * @return a version of the original type with all reference types replaced
      */
@@ -398,8 +486,9 @@
         return form.erasedType();
     }
 
-    /** Convenience method for {@link #genericMethodType(int)}.
-     * Convert all types, both reference and primitive, to {@code Object}.
+    /**
+     * Converts all types, both reference and primitive, to {@code Object}.
+     * Convenience method for {@link #genericMethodType(int) genericMethodType}.
      * The expression {@code type.wrap().erase()} produces the same value
      * as {@code type.generic()}.
      * @return a version of the original type with all types replaced
@@ -408,8 +497,9 @@
         return genericMethodType(parameterCount());
     }
 
-    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.
-     * Convert all primitive types to their corresponding wrapper types.
+    /**
+     * Converts all primitive types to their corresponding wrapper types.
+     * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
      * All reference types (including wrapper types) will remain unchanged.
      * A {@code void} return type is changed to the type {@code java.lang.Void}.
      * The expression {@code type.wrap().erase()} produces the same value
@@ -420,8 +510,9 @@
         return hasPrimitives() ? wrapWithPrims(this) : this;
     }
 
-    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.
+    /**
      * Convert all wrapper types to their corresponding primitive types.
+     * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
      * All primitive types (including {@code void}) will remain unchanged.
      * A return type of {@code java.lang.Void} is changed to {@code void}.
      * @return a version of the original type with all wrapper types replaced
@@ -456,23 +547,33 @@
         return uwt;
     }
 
-    /** @param num the index (zero-based) of the desired parameter type
-     *  @return the selected parameter type
+    /**
+     * Returns the parameter type at the specified index, within this method type.
+     * @param num the index (zero-based) of the desired parameter type
+     * @return the selected parameter type
+     * @throws IndexOutOfBoundsException if {@code num} is not a valid index into {@code parameterArray()}
      */
     public Class<?> parameterType(int num) {
         return ptypes[num];
     }
-    /** @return the number of parameter types */
+    /**
+     * Returns the number of parameter types in this method type.
+     * @return the number of parameter types
+     */
     public int parameterCount() {
         return ptypes.length;
     }
-    /** @return the return type */
+    /**
+     * Returns the return type of this method type.
+     * @return the return type
+     */
     public Class<?> returnType() {
         return rtype;
     }
 
     /**
-     * Convenience method to present the arguments as a list.
+     * Presents the parameter types as a list (a convenience method).
+     * The list will be immutable.
      * @return the parameter types (as an immutable list)
      */
     public List<Class<?>> parameterList() {
@@ -480,7 +581,7 @@
     }
 
     /**
-     * Convenience method to present the arguments as an array.
+     * Presents the parameter types as an array (a convenience method).
      * Changes to the array will not result in changes to the type.
      * @return the parameter types (as a fresh copy if necessary)
      */
@@ -524,14 +625,14 @@
     }
 
     /**
+     * Returns a string representation of the method type,
+     * of the form {@code "(PT0,PT1...)RT"}.
      * The string representation of a method type is a
      * parenthesis enclosed, comma separated list of type names,
      * followed immediately by the return type.
      * <p>
      * Each type is represented by its
      * {@link java.lang.Class#getSimpleName simple name}.
-     * If a type name name is array, it the base type followed
-     * by [], rather than the Class.getName of the array type.
      */
     @Override
     public String toString() {
@@ -548,21 +649,22 @@
 
     /// Queries which have to do with the bytecode architecture
 
-    /** The number of JVM stack slots required to invoke a method
+    /** Reports the number of JVM stack slots required to invoke a method
      * of this type.  Note that (for historic reasons) the JVM requires
      * a second stack slot to pass long and double arguments.
-     * So this method returns {@link #parameterCount()} plus the
+     * So this method returns {@link #parameterCount() parameterCount} plus the
      * number of long and double parameters (if any).
      * <p>
      * This method is included for the benfit of applications that must
      * generate bytecodes that process method handles and invokedynamic.
      * @return the number of JVM stack slots for this type's parameters
+     * @deprecated Will be removed for PFD.
      */
     public int parameterSlotCount() {
         return form.parameterSlotCount();
     }
 
-    /** Number of JVM stack slots which carry all parameters including and after
+    /** Reports the number of JVM stack slots which carry all parameters including and after
      * the given position, which must be in the range of 0 to
      * {@code parameterCount} inclusive.  Successive parameters are
      * more shallowly stacked, and parameters are indexed in the bytecodes
@@ -583,6 +685,8 @@
      * @param num an index (zero-based, inclusive) within the parameter types
      * @return the index of the (shallowest) JVM stack slot transmitting the
      *         given parameter
+     * @throws IllegalArgumentException if {@code num} is negative or greater than {@code parameterCount()}
+     * @deprecated Will be removed for PFD.
      */
     public int parameterSlotDepth(int num) {
         if (num < 0 || num > ptypes.length)
@@ -590,7 +694,7 @@
         return form.parameterToArgSlot(num-1);
     }
 
-    /** The number of JVM stack slots required to receive a return value
+    /** Reports the number of JVM stack slots required to receive a return value
      * from a method of this type.
      * If the {@link #returnType() return type} is void, it will be zero,
      * else if the return type is long or double, it will be two, else one.
@@ -598,13 +702,15 @@
      * This method is included for the benfit of applications that must
      * generate bytecodes that process method handles and invokedynamic.
      * @return the number of JVM stack slots (0, 1, or 2) for this type's return value
+     * @deprecated Will be removed for PFD.
      */
     public int returnSlotCount() {
         return form.returnSlotCount();
     }
 
-    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.
-     * Find or create an instance of the given method type.
+    /**
+     * Find or create an instance of a method type, given the spelling of its bytecode descriptor.
+     * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[]) methodType}.
      * Any class or interface name embedded in the descriptor string
      * will be resolved by calling {@link ClassLoader#loadClass(java.lang.String)}
      * on the given loader (or if it is null, on the system class loader).
@@ -614,10 +720,10 @@
      * not all reachable from a common class loader.
      * <p>
      * This method is included for the benfit of applications that must
-     * generate bytecodes that process method handles and invokedynamic.
-     * @param descriptor a bytecode-level signature string "(T...)T"
+     * generate bytecodes that process method handles and {@code invokedynamic}.
+     * @param descriptor a bytecode-level type descriptor string "(T...)T"
      * @param loader the class loader in which to look up the types
-     * @return a method type matching the bytecode-level signature
+     * @return a method type matching the bytecode-level type descriptor
      * @throws IllegalArgumentException if the string is not well-formed
      * @throws TypeNotPresentException if a named type cannot be found
      */
@@ -631,17 +737,17 @@
     }
 
     /**
-     * Create a bytecode descriptor representation of the method type.
+     * Produces a bytecode descriptor representation of the method type.
      * <p>
-     * Note that this is not a strict inverse of {@link #fromMethodDescriptorString}.
+     * Note that this is not a strict inverse of {@link #fromMethodDescriptorString fromMethodDescriptorString}.
      * Two distinct classes which share a common name but have different class loaders
      * will appear identical when viewed within descriptor strings.
      * <p>
      * This method is included for the benfit of applications that must
-     * generate bytecodes that process method handles and invokedynamic.
-     * {@link #fromMethodDescriptorString(java.lang.String, java.lang.ClassLoader)},
+     * generate bytecodes that process method handles and {@code invokedynamic}.
+     * {@link #fromMethodDescriptorString(java.lang.String, java.lang.ClassLoader) fromMethodDescriptorString},
      * because the latter requires a suitable class loader argument.
-     * @return the bytecode signature representation
+     * @return the bytecode type descriptor representation
      */
     public String toMethodDescriptorString() {
         return BytecodeDescriptor.unparse(this);
--- a/src/share/classes/java/dyn/MutableCallSite.java	Fri Feb 11 01:26:24 2011 -0800
+++ b/src/share/classes/java/dyn/MutableCallSite.java	Fri Feb 11 01:26:28 2011 -0800
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2011, 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
@@ -73,7 +73,7 @@
  * (This is a normal consequence of the Java Memory Model as applied
  * to object fields.)
  * <p>
- * The {@link #sync sync} operation provides a way to force threads
+ * The {@link #syncAll syncAll} operation provides a way to force threads
  * to accept a new target value, even if there is no other synchronization.
  * <p>
  * For target values which will be frequently updated, consider using
@@ -82,13 +82,17 @@
  */
 public class MutableCallSite extends CallSite {
     /**
-     * Make a blank call site object with the given method type.
-     * An initial target method is supplied which will throw
-     * an {@link IllegalStateException} if called.
+     * Creates a blank call site object with the given method type.
+     * The initial target is set to a method handle of the given type
+     * which will throw an {@link IllegalStateException} if called.
+     * <p>
+     * The type of the call site is permanently set to the given type.
      * <p>
      * Before this {@code CallSite} object is returned from a bootstrap method,
+     * or invoked in some other manner,
      * it is usually provided with a more useful target method,
      * via a call to {@link CallSite#setTarget(MethodHandle) setTarget}.
+     * @param type the method type that this call site will have
      * @throws NullPointerException if the proposed type is null
      */
     public MutableCallSite(MethodType type) {
@@ -96,8 +100,9 @@
     }
 
     /**
-     * Make a blank call site object, possibly equipped with an initial target method handle.
-     * @param target the method handle which will be the initial target of the call site
+     * Creates a call site object with an initial target method handle.
+     * The type of the call site is permanently set to the initial target's type.
+     * @param target the method handle that will be the initial target of the call site
      * @throws NullPointerException if the proposed target is null
      */
     public MutableCallSite(MethodHandle target) {
@@ -105,7 +110,59 @@
     }
 
     /**
-     * Perform a synchronization operation on each call site in the given array,
+     * Returns the target method of the call site, which behaves
+     * like a normal field of the {@code MutableCallSite}.
+     * <p>
+     * The interactions of {@code getTarget} with memory are the same
+     * as of a read from an ordinary variable, such as an array element or a
+     * non-volatile, non-final field.
+     * <p>
+     * In particular, the current thread may choose to reuse the result
+     * of a previous read of the target from memory, and may fail to see
+     * a recent update to the target by another thread.
+     *
+     * @return the linkage state of this call site, a method handle which can change over time
+     * @see #setTarget
+     */
+    @Override public final MethodHandle getTarget() {
+        return target;
+    }
+
+    /**
+     * Updates the target method of this call site, as a normal variable.
+     * The type of the new target must agree with the type of the old target.
+     * <p>
+     * The interactions with memory are the same
+     * as of a write to an ordinary variable, such as an array element or a
+     * non-volatile, non-final field.
+     * <p>
+     * In particular, unrelated threads may fail to see the updated target
+     * until they perform a read from memory.
+     * Stronger guarantees can be created by putting appropriate operations
+     * into the bootstrap method and/or the target methods used
+     * at any given call site.
+     *
+     * @param newTarget the new target
+     * @throws NullPointerException if the proposed new target is null
+     * @throws WrongMethodTypeException if the proposed new target
+     *         has a method type that differs from the previous target
+     * @see #getTarget
+     */
+    @Override public void setTarget(MethodHandle newTarget) {
+        checkTargetChange(this.target, newTarget);
+        setTargetNormal(newTarget);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public final MethodHandle dynamicInvoker() {
+        return makeDynamicInvoker();
+    }
+
+    /**
+     * Performs a synchronization operation on each call site in the given array,
      * forcing all other threads to throw away any cached values previously
      * loaded from the target of any of the call sites.
      * <p>
@@ -115,19 +172,29 @@
      * <p>
      * The overall effect is to force all future readers of each call site's target
      * to accept the most recently stored value.
-     * ("Most recently" is reckoned relative to the {@code sync} itself.)
-     * Conversely, the {@code sync} call may block until all readers have
+     * ("Most recently" is reckoned relative to the {@code syncAll} itself.)
+     * Conversely, the {@code syncAll} call may block until all readers have
      * (somehow) decached all previous versions of each call site's target.
      * <p>
-     * To avoid race conditions, calls to {@code setTarget} and {@code sync}
+     * To avoid race conditions, calls to {@code setTarget} and {@code syncAll}
      * should generally be performed under some sort of mutual exclusion.
      * Note that reader threads may observe an updated target as early
      * as the {@code setTarget} call that install the value
-     * (and before the {@code sync} that confirms the value).
+     * (and before the {@code syncAll} that confirms the value).
      * On the other hand, reader threads may observe previous versions of
-     * the target until the {@code sync} call returns
+     * the target until the {@code syncAll} call returns
      * (and after the {@code setTarget} that attempts to convey the updated version).
      * <p>
+     * This operation is likely to be expensive and should be used sparingly.
+     * If possible, it should be buffered for batch processing on sets of call sites.
+     * <p>
+     * If {@code sites} contains a null element,
+     * a {@code NullPointerException} will be raised.
+     * In this case, some non-null elements in the array may be
+     * processed before the method returns abnormally.
+     * Which elements these are (if any) is implementation-dependent.
+     *
+     * <h3>Java Memory Model details</h3>
      * In terms of the Java Memory Model, this operation performs a synchronization
      * action which is comparable in effect to the writing of a volatile variable
      * by the current thread, and an eventual volatile read by every other thread
@@ -171,18 +238,17 @@
      * thereby ensuring communication of the new target value.
      * <p>
      * As long as the constraints of the Java Memory Model are obeyed,
-     * implementations may delay the completion of a {@code sync}
+     * implementations may delay the completion of a {@code syncAll}
      * operation while other threads ({@code T} above) continue to
      * use previous values of {@code S}'s target.
      * However, implementations are (as always) encouraged to avoid
      * livelock, and to eventually require all threads to take account
      * of the updated target.
-     * <p>
-     * This operation is likely to be expensive and should be used sparingly.
-     * If possible, it should be buffered for batch processing on sets of call sites.
+     *
      * <p style="font-size:smaller;">
-     * (This is a static method on a set of call sites, not a
-     * virtual method on a single call site, for performance reasons.
+     * <em>Discussion:</em>
+     * For performance reasons, {@code syncAll} is not a virtual method
+     * on a single call site, but rather applies to a set of call sites.
      * Some implementations may incur a large fixed overhead cost
      * for processing one or more synchronization operations,
      * but a small incremental cost for each additional call site.
@@ -191,15 +257,25 @@
      * in order to make them notice the updated target value.
      * However, it may be observed that a single call to synchronize
      * several sites has the same formal effect as many calls,
-     * each on just one of the sites.)
-     * <p>
+     * each on just one of the sites.
+     *
+     * <p style="font-size:smaller;">
+     * <em>Implementation Note:</em>
      * Simple implementations of {@code MutableCallSite} may use
      * a volatile variable for the target of a mutable call site.
-     * In such an implementation, the {@code sync} method can be a no-op,
+     * In such an implementation, the {@code syncAll} method can be a no-op,
      * and yet it will conform to the JMM behavior documented above.
+     *
+     * @param sites an array of call sites to be synchronized
+     * @throws NullPointerException if the {@code sites} array reference is null
+     *                              or the array contains a null
      */
-    public static void sync(MutableCallSite[] sites) {
+    public static void syncAll(MutableCallSite[] sites) {
+        if (sites.length == 0)  return;
         STORE_BARRIER.lazySet(0);
+        for (int i = 0; i < sites.length; i++) {
+            sites[i].getClass();  // trigger NPE on first null
+        }
         // FIXME: NYI
     }
     private static final AtomicInteger STORE_BARRIER = new AtomicInteger();
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/classes/java/dyn/SwitchPoint.java	Fri Feb 11 01:26:28 2011 -0800
@@ -0,0 +1,195 @@
+/*
+ * Copyright (c) 2010, 2011, 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 java.dyn;
+
+/**
+ * <p>
+ * A {@code SwitchPoint} is an object which can publish state transitions to other threads.
+ * A switch point is initially in the <em>valid</em> state, but may at any time be
+ * changed to the <em>invalid</em> state.  Invalidation cannot be reversed.
+ * A switch point can combine a <em>guarded pair</em> of method handles into a
+ * <em>guarded delegator</em>.
+ * The guarded delegator is a method handle which delegates to one of the old method handles.
+ * The state of the switch point determines which of the two gets the delegation.
+ * <p>
+ * A single switch point may be used to control any number of method handles.
+ * (Indirectly, therefore, it can control any number of call sites.)
+ * This is done by using the single switch point as a factory for combining
+ * any number of guarded method handle pairs into guarded delegators.
+ * <p>
+ * When a guarded delegator is created from a guarded pair, the pair
+ * is wrapped in a new method handle {@code M},
+ * which is permanently associated with the switch point that created it.
+ * Each pair consists of a target {@code T} and a fallback {@code F}.
+ * While the switch point is valid, invocations to {@code M} are delegated to {@code T}.
+ * After it is invalidated, invocations are delegated to {@code F}.
+ * <p>
+ * Invalidation is global and immediate, as if the switch point contained a
+ * volatile boolean variable consulted on every call to {@code M}.
+ * The invalidation is also permanent, which means the switch point
+ * can change state only once.
+ * The switch point will always delegate to {@code F} after being invalidated.
+ * At that point {@code guardWithTest} may ignore {@code T} and return {@code F}.
+ * <p>
+ * Here is an example of a switch point in action:
+ * <blockquote><pre>
+MethodType MT_str2 = MethodType.methodType(String.class, String.class);
+MethodHandle MH_strcat = MethodHandles.lookup()
+    .findVirtual(String.class, "concat", MT_str2);
+SwitchPoint spt = new SwitchPoint();
+// the following steps may be repeated to re-use the same switch point:
+MethodHandle worker1 = strcat;
+MethodHandle worker2 = MethodHandles.permuteArguments(strcat, MT_str2, 1, 0);
+MethodHandle worker = spt.guardWithTest(worker1, worker2);
+assertEquals("method", (String) worker.invokeExact("met", "hod"));
+SwitchPoint.invalidateAll(new SwitchPoint[]{ spt });
+assertEquals("hodmet", (String) worker.invokeExact("met", "hod"));
+ * </pre></blockquote>
+ * <p style="font-size:smaller;">
+ * <em>Discussion:</em>
+ * Switch points are useful without subclassing.  They may also be subclassed.
+ * This may be useful in order to associate application-specific invalidation logic
+ * with the switch point.
+ * <p style="font-size:smaller;">
+ * <em>Implementation Note:</em>
+ * A switch point behaves as if implemented on top of {@link MutableCallSite},
+ * approximately as follows:
+ * <blockquote><pre>
+public class SwitchPoint {
+  private static final MethodHandle
+    K_true  = MethodHandles.constant(boolean.class, true),
+    K_false = MethodHandles.constant(boolean.class, false);
+  private final MutableCallSite mcs;
+  private final MethodHandle mcsInvoker;
+  public SwitchPoint() {
+    this.mcs = new MutableCallSite(K_true);
+    this.mcsInvoker = mcs.dynamicInvoker();
+  }
+  public MethodHandle guardWithTest(
+                MethodHandle target, MethodHandle fallback) {
+    // Note:  mcsInvoker is of type ()boolean.
+    // Target and fallback may take any arguments, but must have the same type.
+    return MethodHandles.guardWithTest(this.mcsInvoker, target, fallback);
+  }
+  public static void invalidateAll(SwitchPoint[] spts) {
+    List&lt;MutableCallSite&gt; mcss = new ArrayList&lt;&gt;();
+    for (SwitchPoint spt : spts)  mcss.add(spt.mcs);
+    for (MutableCallSite mcs : mcss)  mcs.setTarget(K_false);
+    MutableCallSite.syncAll(mcss.toArray(new MutableCallSite[0]));
+  }
+}
+ * </pre></blockquote>
+ * @author Remi Forax, JSR 292 EG
+ */
+public class SwitchPoint {
+    private static final MethodHandle
+        K_true  = MethodHandles.constant(boolean.class, true),
+        K_false = MethodHandles.constant(boolean.class, false);
+
+    private final MutableCallSite mcs;
+    private final MethodHandle mcsInvoker;
+
+    /**
+     * Creates a new switch point.
+     */
+    public SwitchPoint() {
+        this.mcs = new MutableCallSite(K_true);
+        this.mcsInvoker = mcs.dynamicInvoker();
+    }
+
+    /**
+     * Returns a method handle which always delegates either to the target or the fallback.
+     * The method handle will delegate to the target exactly as long as the switch point is valid.
+     * After that, it will permanently delegate to the fallback.
+     * <p>
+     * The target and fallback must be of exactly the same method type,
+     * and the resulting combined method handle will also be of this type.
+     *
+     * @param target the method handle selected by the switch point as long as it is valid
+     * @param fallback the method handle selected by the switch point after it is invalidated
+     * @return a combined method handle which always calls either the target or fallback
+     * @throws NullPointerException if either argument is null
+     * @see MethodHandles#guardWithTest
+     */
+    public MethodHandle guardWithTest(MethodHandle target, MethodHandle fallback) {
+        if (mcs.getTarget() == K_false)
+            return fallback;  // already invalid
+        return MethodHandles.guardWithTest(mcsInvoker, target, fallback);
+    }
+
+    /**
+     * Sets all of the given switch points into the invalid state.
+     * After this call executes, no thread will observe any of the
+     * switch points to be in a valid state.
+     * <p>
+     * This operation is likely to be expensive and should be used sparingly.
+     * If possible, it should be buffered for batch processing on sets of switch points.
+     * <p>
+     * If {@code switchPoints} contains a null element,
+     * a {@code NullPointerException} will be raised.
+     * In this case, some non-null elements in the array may be
+     * processed before the method returns abnormally.
+     * Which elements these are (if any) is implementation-dependent.
+     *
+     * <p style="font-size:smaller;">
+     * <em>Discussion:</em>
+     * For performance reasons, {@code invalidateAll} is not a virtual method
+     * on a single switch point, but rather applies to a set of switch points.
+     * Some implementations may incur a large fixed overhead cost
+     * for processing one or more invalidation operations,
+     * but a small incremental cost for each additional invalidation.
+     * In any case, this operation is likely to be costly, since
+     * other threads may have to be somehow interrupted
+     * in order to make them notice the updated switch point state.
+     * However, it may be observed that a single call to invalidate
+     * several switch points has the same formal effect as many calls,
+     * each on just one of the switch points.
+     *
+     * <p style="font-size:smaller;">
+     * <em>Implementation Note:</em>
+     * Simple implementations of {@code SwitchPoint} may use
+     * a private {@link MutableCallSite} to publish the state of a switch point.
+     * In such an implementation, the {@code invalidateAll} method can
+     * simply change the call site's target, and issue one call to
+     * {@linkplain MutableCallSite#syncAll synchronize} all the
+     * private call sites.
+     *
+     * @param switchPoints an array of call sites to be synchronized
+     * @throws NullPointerException if the {@code switchPoints} array reference is null
+     *                              or the array contains a null
+     */
+    public static void invalidateAll(SwitchPoint[] switchPoints) {
+        if (switchPoints.length == 0)  return;
+        MutableCallSite[] sites = new MutableCallSite[switchPoints.length];
+        for (int i = 0; i < switchPoints.length; i++) {
+            SwitchPoint spt = switchPoints[i];
+            if (spt == null)  break;  // MSC.syncAll will trigger a NPE
+            sites[i] = spt.mcs;
+            spt.mcs.setTarget(K_false);
+        }
+        MutableCallSite.syncAll(sites);
+    }
+}
--- a/src/share/classes/java/dyn/Switcher.java	Fri Feb 11 01:26:24 2011 -0800
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,130 +0,0 @@
-/*
- * Copyright (c) 2010, 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 java.dyn;
-
-/**
- * <p>
- * A {@code Switcher} is an object which can publish state transitions to other threads.
- * A switcher is initially in the <em>valid</em> state, but may at any time be
- * changed to the <em>invalid</em> state.  Invalidation cannot be reversed.
- * <p>
- * A single switcher may be used to create any number of guarded method handle pairs.
- * Each guarded pair is wrapped in a new method handle {@code M},
- * which is permanently associated with the switcher that created it.
- * Each pair consists of a target {@code T} and a fallback {@code F}.
- * While the switcher is valid, invocations to {@code M} are delegated to {@code T}.
- * After it is invalidated, invocations are delegated to {@code F}.
- * <p>
- * Invalidation is global and immediate, as if the switcher contained a
- * volatile boolean variable consulted on every call to {@code M}.
- * The invalidation is also permanent, which means the switcher
- * can change state only once.
- * <p>
- * Here is an example of a switcher in action:
- * <blockquote><pre>
-MethodType MT_str2 = MethodType.methodType(String.class, String.class);
-MethodHandle MH_strcat = MethodHandles.lookup()
-    .findVirtual(String.class, "concat", MT_str2);
-Switcher switcher = new Switcher();
-// the following steps may be repeated to re-use the same switcher:
-MethodHandle worker1 = strcat;
-MethodHandle worker2 = MethodHandles.permuteArguments(strcat, MT_str2, 1, 0);
-MethodHandle worker = switcher.guardWithTest(worker1, worker2);
-assertEquals("method", (String) worker.invokeExact("met", "hod"));
-switcher.invalidate();
-assertEquals("hodmet", (String) worker.invokeExact("met", "hod"));
- * </pre></blockquote>
- * <p>
- * <em>Implementation Note:</em>
- * A switcher behaves as if implemented on top of {@link MutableCallSite},
- * approximately as follows:
- * <blockquote><pre>
-public class Switcher {
-  private static final MethodHandle
-    K_true  = MethodHandles.constant(boolean.class, true),
-    K_false = MethodHandles.constant(boolean.class, false);
-  private final MutableCallSite mcs;
-  private final MethodHandle mcsInvoker;
-  public Switcher() {
-    this.mcs = new MutableCallSite(K_true);
-    this.mcsInvoker = mcs.dynamicInvoker();
-  }
-  public MethodHandle guardWithTest(
-                MethodHandle target, MethodHandle fallback) {
-    // Note:  mcsInvoker is of type boolean().
-    // Target and fallback may take any arguments, but must have the same type.
-    return MethodHandles.guardWithTest(this.mcsInvoker, target, fallback);
-  }
-  public static void invalidateAll(Switcher[] switchers) {
-    List<MutableCallSite> mcss = new ArrayList<>();
-    for (Switcher s : switchers)  mcss.add(s.mcs);
-    for (MutableCallSite mcs : mcss)  mcs.setTarget(K_false);
-    MutableCallSite.sync(mcss.toArray(new MutableCallSite[0]));
-  }
-}
- * </pre></blockquote>
- * @author Remi Forax, JSR 292 EG
- */
-public class Switcher {
-    private static final MethodHandle
-        K_true  = MethodHandles.constant(boolean.class, true),
-        K_false = MethodHandles.constant(boolean.class, false);
-
-    private final MutableCallSite mcs;
-    private final MethodHandle mcsInvoker;
-
-    /** Create a switcher. */
-    public Switcher() {
-        this.mcs = new MutableCallSite(K_true);
-        this.mcsInvoker = mcs.dynamicInvoker();
-    }
-
-    /**
-     * Return a method handle which always delegates either to the target or the fallback.
-     * The method handle will delegate to the target exactly as long as the switcher is valid.
-     * After that, it will permanently delegate to the fallback.
-     * <p>
-     * The target and fallback must be of exactly the same method type,
-     * and the resulting combined method handle will also be of this type.
-     * @see MethodHandles#guardWithTest
-     */
-    public MethodHandle guardWithTest(MethodHandle target, MethodHandle fallback) {
-        if (mcs.getTarget() == K_false)
-            return fallback;  // already invalid
-        return MethodHandles.guardWithTest(mcsInvoker, target, fallback);
-    }
-
-    /** Set all of the given switchers into the invalid state. */
-    public static void invalidateAll(Switcher[] switchers) {
-        MutableCallSite[] sites = new MutableCallSite[switchers.length];
-        int fillp = 0;
-        for (Switcher switcher : switchers) {
-            sites[fillp++] = switcher.mcs;
-            switcher.mcs.setTarget(K_false);
-        }
-        MutableCallSite.sync(sites);
-    }
-}
--- a/src/share/classes/java/dyn/VolatileCallSite.java	Fri Feb 11 01:26:24 2011 -0800
+++ b/src/share/classes/java/dyn/VolatileCallSite.java	Fri Feb 11 01:26:28 2011 -0800
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2010, 2011, 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
@@ -34,7 +34,7 @@
  * There may be a performance penalty for such tight coupling between threads.
  * <p>
  * Unlike {@code MutableCallSite}, there is no
- * {@linkplain MutableCallSite#sync sync operation} on volatile
+ * {@linkplain MutableCallSite#syncAll syncAll operation} on volatile
  * call sites, since every write to a volatile variable is implicitly
  * synchronized with reader threads.
  * <p>
@@ -44,36 +44,68 @@
  * @author John Rose, JSR 292 EG
  */
 public class VolatileCallSite extends CallSite {
-    /** Create a call site with a volatile target.
-     *  The initial target is set to a method handle
-     *  of the given type which will throw {@code IllegalStateException}.
+    /**
+     * Creates a call site with a volatile binding to its target.
+     * The initial target is set to a method handle
+     * of the given type which will throw an {@code IllegalStateException} if called.
+     * @param type the method type that this call site will have
      * @throws NullPointerException if the proposed type is null
      */
     public VolatileCallSite(MethodType type) {
         super(type);
     }
 
-    /** Create a call site with a volatile target.
-     *  The target is set to the given value.
+    /**
+     * Creates a call site with a volatile binding to its target.
+     * The target is set to the given value.
+     * @param target the method handle that will be the initial target of the call site
      * @throws NullPointerException if the proposed target is null
      */
     public VolatileCallSite(MethodHandle target) {
         super(target);
     }
 
-    /** Internal override to nominally final getTarget. */
-    @Override
-    MethodHandle getTarget0() {
+    /**
+     * Returns the target method of the call site, which behaves
+     * like a {@code volatile} field of the {@code VolatileCallSite}.
+     * <p>
+     * The interactions of {@code getTarget} with memory are the same
+     * as of a read from a {@code volatile} field.
+     * <p>
+     * In particular, the current thread is required to issue a fresh
+     * read of the target from memory, and must not fail to see
+     * a recent update to the target by another thread.
+     *
+     * @return the linkage state of this call site, a method handle which can change over time
+     * @see #setTarget
+     */
+    @Override public final MethodHandle getTarget() {
         return getTargetVolatile();
     }
 
     /**
-     * Set the target method of this call site, as a volatile variable.
-     * Has the same effect as {@link CallSite#setTarget CallSite.setTarget}, with the additional
-     * effects associated with volatiles, in the Java Memory Model.
+     * Updates the target method of this call site, as a volatile variable.
+     * The type of the new target must agree with the type of the old target.
+     * <p>
+     * The interactions with memory are the same as of a write to a volatile field.
+     * In particular, any threads is guaranteed to see the updated target
+     * the next time it calls {@code getTarget}.
+     * @param newTarget the new target
+     * @throws NullPointerException if the proposed new target is null
+     * @throws WrongMethodTypeException if the proposed new target
+     *         has a method type that differs from the previous target
+     * @see #getTarget
      */
     @Override public void setTarget(MethodHandle newTarget) {
         checkTargetChange(getTargetVolatile(), newTarget);
         setTargetVolatile(newTarget);
     }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public final MethodHandle dynamicInvoker() {
+        return makeDynamicInvoker();
+    }
 }
--- a/src/share/classes/java/dyn/WrongMethodTypeException.java	Fri Feb 11 01:26:24 2011 -0800
+++ b/src/share/classes/java/dyn/WrongMethodTypeException.java	Fri Feb 11 01:26:28 2011 -0800
@@ -29,7 +29,7 @@
  * Thrown to indicate that code has attempted to call a method handle
  * via the wrong method type.  As with the bytecode representation of
  * normal Java method calls, method handle calls are strongly typed
- * to a specific signature associated with a call site.
+ * to a specific type descriptor associated with a call site.
  * <p>
  * This exception may also be thrown when two method handles are
  * composed, and the system detects that their types cannot be
--- a/src/share/classes/java/dyn/package-info.java	Fri Feb 11 01:26:24 2011 -0800
+++ b/src/share/classes/java/dyn/package-info.java	Fri Feb 11 01:26:28 2011 -0800
@@ -24,21 +24,20 @@
  */
 
 /**
- * This package contains dynamic language support provided directly by
+ * The {@code java.lang.invoke} package contains dynamic language support provided directly by
  * the Java core class libraries and virtual machine.
+ *
+ * <p style="font-size:smaller;">
+ * <em>Historic Note:</em> In some early versions of Java SE 7,
+ * the name of this package is {@code java.dyn}.
  * <p>
  * Certain types in this package have special relations to dynamic
  * language support in the virtual machine:
  * <ul>
- * <li>In source code, a call to
- * {@link java.dyn.MethodHandle#invokeExact   MethodHandle.invokeExact} or
- * {@link java.dyn.MethodHandle#invokeGeneric MethodHandle.invokeGeneric}
- * will compile and link, regardless of the requested type signature.
- * As usual, the Java compiler emits an {@code invokevirtual}
- * instruction with the given signature against the named method.
- * The JVM links any such call (regardless of signature) to a dynamically
- * typed method handle invocation.  In the case of {@code invokeGeneric},
- * argument and return value conversions are applied.
+ * <li>The class {@link java.dyn.MethodHandle MethodHandle} contains
+ * <a href="MethodHandle.html#sigpoly">signature polymorphic methods</a>
+ * which can be linked regardless of their type descriptor.
+ * Normally, method linkage requires exact matching of type descriptors.
  * </li>
  *
  * <li>The JVM bytecode format supports immediate constants of
@@ -58,12 +57,11 @@
  * The final two bytes are reserved for future use and required to be zero.
  * The constant pool reference of an {@code invokedynamic} instruction is to a entry
  * with tag {@code CONSTANT_InvokeDynamic} (decimal 18).  See below for its format.
- * (The tag value 17 is also temporarily allowed.  See below.)
  * The entry specifies the following information:
  * <ul>
  * <li>a bootstrap method (a {@link java.dyn.MethodHandle MethodHandle} constant)</li>
  * <li>the dynamic invocation name (a UTF8 string)</li>
- * <li>the argument and return types of the call (encoded as a signature in a UTF8 string)</li>
+ * <li>the argument and return types of the call (encoded as a type descriptor in a UTF8 string)</li>
  * <li>optionally, a sequence of additional <em>static arguments</em> to the bootstrap method ({@code ldc}-type constants)</li>
  * </ul>
  * <p>
@@ -78,9 +76,9 @@
  * as <a href="#bsm">described below</a>.
  *
  * <p style="font-size:smaller;">
- * (Historic Note: Some older JVMs may allow the index of a {@code CONSTANT_NameAndType}
+ * <em>Historic Note:</em> Some older JVMs may allow the index of a {@code CONSTANT_NameAndType}
  * instead of a {@code CONSTANT_InvokeDynamic}.  In earlier, obsolete versions of this API, the
- * bootstrap method was specified dynamically, in a per-class basis, during class initialization.)
+ * bootstrap method was specified dynamically, in a per-class basis, during class initialization.
  *
  * <h3><a name="indycon"></a>constant pool entries for {@code invokedynamic} instructions</h3>
  * If a constant pool entry has the tag {@code CONSTANT_InvokeDynamic} (decimal 18),
@@ -90,33 +88,21 @@
  * <em>bootstrap method table</em>, which is stored in the {@code BootstrapMethods}
  * attribute as <a href="#bsmattr">described below</a>.
  * The second pair of bytes must be an index to a {@code CONSTANT_NameAndType}.
- * This table is not part of the constant pool.  Instead, it is stored
- * in a class attribute named {@code BootstrapMethods}, described below.
  * <p>
  * The first index specifies a bootstrap method used by the associated dynamic call sites.
  * The second index specifies the method name, argument types, and return type of the dynamic call site.
  * The structure of such an entry is therefore analogous to a {@code CONSTANT_Methodref},
  * except that the bootstrap method specifier reference replaces
  * the {@code CONSTANT_Class} reference of a {@code CONSTANT_Methodref} entry.
- * <p>
- * Some older JVMs may allow an older constant pool entry tag of decimal 17.
- * The format and behavior of a constant pool entry with this tag is identical to
- * an entry with a tag of decimal 18, except that the first index refers directly
- * to a {@code CONSTANT_MethodHandle} to use as the bootstrap method.
- * This format does not require the bootstrap method table.
- *
- * <p style="font-size:smaller;">
- * <em>(Note: The Proposed Final Draft of this specification is likely to support
- * only the tag 18, not the tag 17.)</em>
  *
  * <h3><a name="mtcon"></a>constant pool entries for {@linkplain java.dyn.MethodType method types}</h3>
  * If a constant pool entry has the tag {@code CONSTANT_MethodType} (decimal 16),
  * it must contain exactly two more bytes, which must be an index to a {@code CONSTANT_Utf8}
- * entry which represents a method type signature.
+ * entry which represents a method type descriptor.
  * <p>
  * The JVM will ensure that on first
  * execution of an {@code ldc} instruction for this entry, a {@link java.dyn.MethodType MethodType}
- * will be created which represents the signature.
+ * will be created which represents the type descriptor.
  * Any classes mentioned in the {@code MethodType} will be loaded if necessary,
  * but not initialized.
  * Access checking and error reporting is performed exactly as it is for
@@ -144,24 +130,58 @@
  * The method handle itself will have a type and behavior determined by the subtag as follows:
  * <code>
  * <table border=1 cellpadding=5 summary="CONSTANT_MethodHandle subtypes">
- * <tr><th>N</th><th>subtag name</th><th>member</th><th>MH type</th><th>MH behavior</th></tr>
- * <tr><td>1</td><td>REF_getField</td><td>C.f:T</td><td>(C)T</td><td>getfield C.f:T</td></tr>
- * <tr><td>2</td><td>REF_getStatic</td><td>C.f:T</td><td>(&nbsp;)T</td><td>getstatic C.f:T</td></tr>
- * <tr><td>3</td><td>REF_putField</td><td>C.f:T</td><td>(C,T)void</td><td>putfield C.f:T</td></tr>
- * <tr><td>4</td><td>REF_putStatic</td><td>C.f:T</td><td>(T)void</td><td>putstatic C.f:T</td></tr>
- * <tr><td>5</td><td>REF_invokeVirtual</td><td>C.m(A*)T</td><td>(C,A*)T</td><td>invokevirtual C.m(A*)T</td></tr>
- * <tr><td>6</td><td>REF_invokeStatic</td><td>C.m(A*)T</td><td>(C,A*)T</td><td>invokestatic C.m(A*)T</td></tr>
- * <tr><td>7</td><td>REF_invokeSpecial</td><td>C.m(A*)T</td><td>(C,A*)T</td><td>invokespecial C.m(A*)T</td></tr>
- * <tr><td>8</td><td>REF_newInvokeSpecial</td><td>C.&lt;init&gt;(A*)void</td><td>(A*)C</td><td>new C; dup; invokespecial C.&lt;init&gt;(A*)void</td></tr>
- * <tr><td>9</td><td>REF_invokeInterface</td><td>C.m(A*)T</td><td>(C,A*)T</td><td>invokeinterface C.m(A*)T</td></tr>
+ * <tr><th>N</th><th>subtag name</th><th>member</th><th>MH type</th><th>bytecode behavior</th><th>lookup expression</th></tr>
+ * <tr><td>1</td><td>REF_getField</td><td>C.f:T</td><td>(C)T</td><td>getfield C.f:T</td>
+ *               <td>{@linkplain java.dyn.MethodHandles.Lookup#findGetter findGetter(C.class,"f",T.class)}</td></tr>
+ * <tr><td>2</td><td>REF_getStatic</td><td>C.f:T</td><td>(&nbsp;)T</td><td>getstatic C.f:T</td>
+ *               <td>{@linkplain java.dyn.MethodHandles.Lookup#findStaticGetter findStaticGetter(C.class,"f",T.class)}</td></tr>
+ * <tr><td>3</td><td>REF_putField</td><td>C.f:T</td><td>(C,T)void</td><td>putfield C.f:T</td>
+ *               <td>{@linkplain java.dyn.MethodHandles.Lookup#findSetter findSetter(C.class,"f",T.class)}</td></tr>
+ * <tr><td>4</td><td>REF_putStatic</td><td>C.f:T</td><td>(T)void</td><td>putstatic C.f:T</td>
+ *               <td>{@linkplain java.dyn.MethodHandles.Lookup#findStaticSetter findStaticSetter(C.class,"f",T.class)}</td></tr>
+ * <tr><td>5</td><td>REF_invokeVirtual</td><td>C.m(A*)T</td><td>(C,A*)T</td><td>invokevirtual C.m(A*)T</td>
+ *               <td>{@linkplain java.dyn.MethodHandles.Lookup#findVirtual findVirtual(C.class,"m",MT)}</td></tr>
+ * <tr><td>6</td><td>REF_invokeStatic</td><td>C.m(A*)T</td><td>(C,A*)T</td><td>invokestatic C.m(A*)T</td>
+ *               <td>{@linkplain java.dyn.MethodHandles.Lookup#findStatic findStatic(C.class,"m",MT)}</td></tr>
+ * <tr><td>7</td><td>REF_invokeSpecial</td><td>C.m(A*)T</td><td>(C,A*)T</td><td>invokespecial C.m(A*)T</td>
+ *               <td>{@linkplain java.dyn.MethodHandles.Lookup#findSpecial findSpecial(C.class,"m",MT,this.class)}</td></tr>
+ * <tr><td>8</td><td>REF_newInvokeSpecial</td><td>C.&lt;init&gt;(A*)void</td><td>(A*)C</td><td>new C; dup; invokespecial C.&lt;init&gt;(A*)void</td>
+ *               <td>{@linkplain java.dyn.MethodHandles.Lookup#findConstructor findConstructor(C.class,MT)}</td></tr>
+ * <tr><td>9</td><td>REF_invokeInterface</td><td>C.m(A*)T</td><td>(C,A*)T</td><td>invokeinterface C.m(A*)T</td>
+ *               <td>{@linkplain java.dyn.MethodHandles.Lookup#findVirtual findVirtual(C.class,"m",MT)}</td></tr>
  * </table>
  * </code>
+ * Here, the type {@code C} is taken from the {@code CONSTANT_Class} reference associated
+ * with the {@code CONSTANT_NameAndType} descriptor.
+ * The field name {@code f} or method name {@code m} is taken from the {@code CONSTANT_NameAndType}
+ * as is the result type {@code T} and (in the case of a method or constructor) the argument type sequence
+ * {@code A*}.
+ * <p>
+ * Each method handle constant has an equivalent instruction sequence called its <em>bytecode behavior</em>.
+ * In general, creating a method handle constant can be done in exactly the same circumstances that
+ * the JVM would successfully resolve the symbolic references in the bytecode behavior.
+ * Also, the type of a method handle constant is such that a valid {@code invokeExact} call
+ * on the method handle has exactly the same JVM stack effects as the <em>bytecode behavior</em>.
+ * Finally, calling a method handle constant on a valid set of arguments has exactly the same effect
+ * and returns the same result (if any) as the corresponding <em>bytecode behavior</em>.
+ * <p>
+ * Each method handle constant also has an equivalent reflective <em>lookup expression</em>,
+ * which is a query to a method in {@link java.dyn.MethodHandles.Lookup}.
+ * In the example lookup method expression given in the table above, the name {@code MT}
+ * stands for a {@code MethodType} built from {@code T} and the sequence of argument types {@code A*}.
+ * (Note that the type {@code C} is not prepended to the query type {@code MT} even if the member is non-static.)
+ * In the case of {@code findSpecial}, the name {@code this.class} refers to the class containing
+ * the bytecodes.
  * <p>
  * The special name {@code <clinit>} is not allowed.
  * The special name {@code <init>} is not allowed except for subtag 8 as shown.
  * <p>
  * The JVM verifier and linker apply the same access checks and restrictions for these references as for the hypothetical
- * bytecode instructions specified in the last column of the table.  In particular, method handles to
+ * bytecode instructions specified in the last column of the table.
+ * A method handle constant will successfully resolve to a method handle if the symbolic references
+ * of the corresponding bytecode instruction(s) would also resolve successfully.
+ * Otherwise, an attempt to resolve the constant will throw equivalent linkage errors.
+ * In particular, method handles to
  * private and protected members can be created in exactly those classes for which the corresponding
  * normal accesses are legal.
  * <p>
@@ -186,14 +206,14 @@
  * by the execution of {@code invokedynamic} and {@code ldc} instructions.
  * (Roughly speaking, this means that every use of a constant pool entry
  * must lead to the same outcome.
- * If the resoultion succeeds, the same object reference is produced
+ * If the resolution succeeds, the same object reference is produced
  * by every subsequent execution of the same instruction.
  * If the resolution of the constant causes an error to occur,
  * the same error will be re-thrown on every subsequent attempt
  * to use this particular constant.)
  * <p>
  * Constants created by the resolution of these constant pool types are not necessarily
- * interned.  Except for {@link CONSTANT_Class} and {@link CONSTANT_String} entries,
+ * interned.  Except for {@code CONSTANT_Class} and {@code CONSTANT_String} entries,
  * two distinct constant pool entries might not resolve to the same reference
  * even if they contain the same symbolic reference.
  *
@@ -207,31 +227,31 @@
  * <p>
  * Each {@code invokedynamic} instruction statically specifies its own
  * bootstrap method as a constant pool reference.
- * The constant pool reference also specifies the call site's name and type signature,
+ * The constant pool reference also specifies the call site's name and type descriptor,
  * just like {@code invokevirtual} and the other invoke instructions.
  * <p>
  * Linking starts with resolving the constant pool entry for the
  * bootstrap method, and resolving a {@link java.dyn.MethodType MethodType} object for
- * the type signature of the dynamic call site.
+ * the type descriptor of the dynamic call site.
  * This resolution process may trigger class loading.
  * It may therefore throw an error if a class fails to load.
  * This error becomes the abnormal termination of the dynamic
  * call site execution.
  * Linkage does not trigger class initialization.
  * <p>
- * Next, the bootstrap method call is started, with four or five values being stacked:
+ * Next, the bootstrap method call is started, with at least four values being stacked:
  * <ul>
  * <li>a {@code MethodHandle}, the resolved bootstrap method itself </li>
  * <li>a {@code MethodHandles.Lookup}, a lookup object on the <em>caller class</em> in which dynamic call site occurs </li>
  * <li>a {@code String}, the method name mentioned in the call site </li>
- * <li>a {@code MethodType}, the resolved type signature of the call </li>
- * <li>optionally, a single object representing one or more <a href="#args">additional static arguments</a> </li>
+ * <li>a {@code MethodType}, the resolved type descriptor of the call </li>
+ * <li>optionally, one or more <a href="#args">additional static arguments</a> </li>
  * </ul>
  * The method handle is then applied to the other values as if by
  * {@link java.dyn.MethodHandle#invokeGeneric invokeGeneric}.
  * The returned result must be a {@link java.dyn.CallSite CallSite} (or a subclass).
  * The type of the call site's target must be exactly equal to the type
- * derived from the dynamic call site signature and passed to
+ * derived from the dynamic call site's type descriptor and passed to
  * the bootstrap method.
  * The call site then becomes permanently linked to the dynamic call site.
  * <p>
@@ -299,11 +319,11 @@
  * chosen target object.
  *
  * <p style="font-size:smaller;">
- * (Historic Note: Unlike some previous versions of this specification,
+ * <em>Historic Note:</em> Unlike some previous versions of this specification,
  * these rules do not enable the JVM to duplicate dynamic call sites,
  * or to issue &ldquo;causeless&rdquo; bootstrap method calls.
  * Every dynamic call site transitions at most once from unlinked to linked,
- * just before its first invocation.)
+ * just before its first invocation.
  *
  * <h3><a name="bsmattr">the {@code BootstrapMethods} attribute </h3>
  * Each {@code CONSTANT_InvokeDynamic} entry contains an index which references
@@ -349,7 +369,6 @@
  * Static arguments are specified constant pool indexes stored in the {@code BootstrapMethods} attribute.
  * Before the bootstrap method is invoked, each index is used to compute an {@code Object}
  * reference to the indexed value in the constant pool.
- * If the value is a primitive type, it is converted to a reference by boxing conversion.
  * The valid constant pool entries are listed in this table:
  * <code>
  * <table border=1 cellpadding=5 summary="Static argument types">
@@ -374,6 +393,9 @@
  * at most 252 extra arguments can be supplied.)
  * The bootstrap method will be invoked as if by either {@code invokeGeneric}
  * or {@code invokeWithArguments}.  (There is no way to tell the difference.)
+ * <p>
+ * The normal argument conversion rules for {@code invokeGeneric} apply to all stacked arguments.
+ * For example, if a pushed value is a primitive type, it may be converted to a reference by boxing conversion.
  * If the bootstrap method is a variable arity method (its modifier bit {@code 0x0080} is set),
  * then some or all of the arguments specified here may be collected into a trailing array parameter.
  * (This is not a special rule, but rather a useful consequence of the interaction
@@ -430,11 +452,6 @@
   u1 tag = 16;
   u2 descriptor_index;    // index to CONSTANT_Utf8, as in NameAndType
 }
-struct CONSTANT_InvokeDynamic_17_info {
-  u1 tag = 17;
-  u2 bootstrap_method_index;   // index to CONSTANT_MethodHandle
-  u2 name_and_type_index;      // same as for CONSTANT_Methodref, etc.
-}
 struct CONSTANT_InvokeDynamic_info {
   u1 tag = 18;
   u2 bootstrap_method_attr_index;  // index into BootstrapMethods_attr
@@ -451,9 +468,6 @@
  } bootstrap_methods[bootstrap_method_count];
 }
  * </pre></blockquote>
- * <p>
- * <em>Note: The Proposed Final Draft of JSR 292 may remove the constant tag 17,
- * for the sake of simplicity.</em>
  *
  * @author John Rose, JSR 292 EG
  */
--- a/src/share/classes/sun/dyn/AdapterMethodHandle.java	Fri Feb 11 01:26:24 2011 -0800
+++ b/src/share/classes/sun/dyn/AdapterMethodHandle.java	Fri Feb 11 01:26:28 2011 -0800
@@ -962,7 +962,7 @@
 
     @Override
     public String toString() {
-        return nonAdapter((MethodHandle)vmtarget).toString();
+        return MethodHandleImpl.getNameString(IMPL_TOKEN, nonAdapter((MethodHandle)vmtarget), this);
     }
 
     private static MethodHandle nonAdapter(MethodHandle mh) {
--- a/src/share/classes/sun/dyn/FromGeneric.java	Fri Feb 11 01:26:24 2011 -0800
+++ b/src/share/classes/sun/dyn/FromGeneric.java	Fri Feb 11 01:26:28 2011 -0800
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2011, 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
@@ -28,6 +28,7 @@
 import java.dyn.*;
 import java.lang.reflect.*;
 import sun.dyn.util.*;
+import static sun.dyn.MethodTypeImpl.invokers;
 
 /**
  * Adapters which mediate between incoming calls which are generic
@@ -128,7 +129,7 @@
             MethodType targetType, MethodType internalType) {
         // All the adapters we have here have reference-untyped internal calls.
         assert(internalType == internalType.erase());
-        MethodHandle invoker = MethodHandles.exactInvoker(targetType);
+        MethodHandle invoker = invokers(targetType).exactInvoker();
         // cast all narrow reference types, unbox all primitive arguments:
         MethodType fixArgsType = internalType.changeReturnType(targetType.returnType());
         MethodHandle fixArgs = AdapterMethodHandle.convertArguments(Access.TOKEN,
--- a/src/share/classes/sun/dyn/InvokeGeneric.java	Fri Feb 11 01:26:24 2011 -0800
+++ b/src/share/classes/sun/dyn/InvokeGeneric.java	Fri Feb 11 01:26:28 2011 -0800
@@ -28,6 +28,7 @@
 import java.dyn.*;
 import java.lang.reflect.*;
 import sun.dyn.util.*;
+import static sun.dyn.MethodTypeImpl.invokers;
 
 /**
  * Adapters which manage MethodHanndle.invokeGeneric calls.
@@ -87,7 +88,7 @@
     private MethodHandle makePostDispatchInvoker() {
         // Take (MH'; MT, MH; A...) and run MH'(MT, MH; A...).
         MethodType invokerType = erasedCallerType.insertParameterTypes(0, EXTRA_ARGS);
-        return MethodHandles.exactInvoker(invokerType);
+        return invokers(invokerType).exactInvoker();
     }
     private MethodHandle dropDispatchArguments(MethodHandle targetInvoker) {
         assert(targetInvoker.type().parameterType(0) == MethodHandle.class);
--- a/src/share/classes/sun/dyn/Invokers.java	Fri Feb 11 01:26:24 2011 -0800
+++ b/src/share/classes/sun/dyn/Invokers.java	Fri Feb 11 01:26:28 2011 -0800
@@ -104,8 +104,7 @@
         MethodHandle vaInvoker = spreadInvokers[objectArgCount];
         if (vaInvoker != null)  return vaInvoker;
         MethodHandle gInvoker = genericInvoker();
-        MethodType vaType = MethodType.genericMethodType(objectArgCount, true);
-        vaInvoker = MethodHandles.spreadArguments(gInvoker, invokerType(vaType));
+        vaInvoker = gInvoker.asSpreader(Object[].class, targetType.parameterCount() - objectArgCount);
         spreadInvokers[objectArgCount] = vaInvoker;
         return vaInvoker;
     }
--- a/src/share/classes/sun/dyn/MethodHandleImpl.java	Fri Feb 11 01:26:24 2011 -0800
+++ b/src/share/classes/sun/dyn/MethodHandleImpl.java	Fri Feb 11 01:26:28 2011 -0800
@@ -136,6 +136,8 @@
     }
 
     static {
+        if (!MethodHandleNatives.JVM_SUPPORT)  // force init of native API
+            throw new InternalError("No JVM support for JSR 292");
         // Force initialization of Lookup, so it calls us back as initLookup:
         MethodHandles.publicLookup();
         if (IMPL_LOOKUP_INIT == null)
@@ -1216,14 +1218,24 @@
     }
     static <T extends Throwable> Empty throwException(T t) throws T { throw t; }
 
-    public static String getNameString(Access token, MethodHandle target) {
+    public static String getNameString(Access token, MethodHandle target, Object type) {
         Access.check(token);
+        if (!(type instanceof MethodType)) {
+            if (type == null)
+                type = target.type();
+            else if (type instanceof MethodHandle)
+                type = ((MethodHandle)type).type();
+        }
         MemberName name = null;
         if (target != null)
             name = MethodHandleNatives.getMethodName(target);
         if (name == null)
-            return "invoke" + target.type();
-        return name.getName() + target.type();
+            return "invoke" + type;
+        return name.getName() + type;
+    }
+
+    public static String getNameString(Access token, MethodHandle target) {
+        return getNameString(token, target, null);
     }
 
     static String addTypeString(Object obj, MethodHandle target) {
--- a/src/share/classes/sun/dyn/ToGeneric.java	Fri Feb 11 01:26:24 2011 -0800
+++ b/src/share/classes/sun/dyn/ToGeneric.java	Fri Feb 11 01:26:28 2011 -0800
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2011, 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
@@ -31,6 +31,7 @@
 import sun.dyn.util.ValueConversions;
 import sun.dyn.util.Wrapper;
 import static sun.dyn.MemberName.newIllegalArgumentException;
+import static sun.dyn.MethodTypeImpl.invokers;
 
 /**
  * Adapters which mediate between incoming calls which are not generic
@@ -72,7 +73,7 @@
         assert(entryType.erase() == entryType); // for now
         // incoming call will first "forget" all reference types except Object
         this.entryType = entryType;
-        MethodHandle invoker0 = MethodHandles.exactInvoker(entryType.generic());
+        MethodHandle invoker0 = invokers(entryType.generic()).exactInvoker();
         MethodType rawEntryTypeInit;
         Adapter ad = findAdapter(rawEntryTypeInit = entryType);
         if (ad != null) {
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/classes/sun/dyn/WrapperInstance.java	Fri Feb 11 01:26:28 2011 -0800
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2011, 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 sun.dyn;
+
+import java.dyn.MethodHandle;
+
+/**
+ * Private API used inside of java.dyn.MethodHandles.
+ * Interface implemented by every object which is produced by
+ * {@link java.dyn.MethodHandles#asInstance MethodHandles.asInstance}.
+ * The methods of this interface allow a caller to recover the parameters
+ * to {@code asInstance}.
+ * This allows applications to repeatedly convert between method handles
+ * and SAM objects, without the risk of creating unbounded delegation chains.
+ */
+public interface WrapperInstance {
+    /** Produce or recover a target method handle which is behaviorally
+     *  equivalent to the SAM method of this object.
+     */
+    public MethodHandle getWrapperInstanceTarget();
+    /** Recover the SAM type for which this object was created.
+     */
+    public Class<?> getWrapperInstanceType();
+}
+
--- a/test/java/dyn/InvokeGenericTest.java	Fri Feb 11 01:26:24 2011 -0800
+++ b/test/java/dyn/InvokeGenericTest.java	Fri Feb 11 01:26:28 2011 -0800
@@ -320,7 +320,7 @@
     MethodHandle callable(List<Class<?>> params) {
         MethodHandle mh = CALLABLES.get(params);
         if (mh == null) {
-            mh = collectArguments(collector_MH, methodType(Object.class, params));
+            mh = collector_MH.asType(methodType(Object.class, params));
             CALLABLES.put(params, mh);
         }
         return mh;
--- a/test/java/dyn/JavaDocExamplesTest.java	Fri Feb 11 01:26:24 2011 -0800
+++ b/test/java/dyn/JavaDocExamplesTest.java	Fri Feb 11 01:26:28 2011 -0800
@@ -151,8 +151,8 @@
 // mt is (char,char)String
 mt = MethodType.methodType(String.class, char.class, char.class);
 mh = lookup.findVirtual(String.class, "replace", mt);
-// (Ljava/lang/String;CC)Ljava/lang/String;
 s = (String) mh.invokeExact("daddy",'d','n');
+// invokeExact(Ljava/lang/String;CC)Ljava/lang/String;
 assert(s.equals("nanny"));
 // weakly typed invocation (using MHs.invoke)
 s = (String) mh.invokeWithArguments("sappy", 'p', 'v');
@@ -162,23 +162,24 @@
 mh = lookup.findStatic(java.util.Arrays.class, "asList", mt);
 assert(mh.isVarargsCollector());
 x = mh.invokeGeneric("one", "two");
+// invokeGeneric(Ljava/lang/String;Ljava/lang/String;)Ljava/lang/Object;
 assert(x.equals(java.util.Arrays.asList("one","two")));
 // mt is (Object,Object,Object)Object
 mt = MethodType.genericMethodType(3);
-mh = MethodHandles.collectArguments(mh, mt);
-// mt is (Object,Object,Object)Object
-// (Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;
+mh = mh.asType(mt);
 x = mh.invokeExact((Object)1, (Object)2, (Object)3);
+// invokeExact(Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;
 assert(x.equals(java.util.Arrays.asList(1,2,3)));
 // mt is { =&gt; int}
 mt = MethodType.methodType(int.class);
 mh = lookup.findVirtual(java.util.List.class, "size", mt);
-// (Ljava/util/List;)I
 i = (int) mh.invokeExact(java.util.Arrays.asList(1,2,3));
+// invokeExact(Ljava/util/List;)I
 assert(i == 3);
 mt = MethodType.methodType(void.class, String.class);
 mh = lookup.findVirtual(java.io.PrintStream.class, "println", mt);
 mh.invokeExact(System.out, "Hello, world.");
+// invokeExact(Ljava/io/PrintStream;Ljava/lang/String;)V
 {}
             }}
     }
@@ -206,9 +207,7 @@
 MethodHandle vamh = publicLookup()
   .findStatic(Arrays.class, "asList", methodType(List.class, Object[].class))
   .asVarargsCollector(Object[].class);
-MethodHandle invokeExact = publicLookup()
-  .findVirtual(MethodHandle.class, "invokeExact", vamh.type());
-MethodHandle mh = invokeExact.bindTo(vamh);
+MethodHandle mh = MethodHandles.exactInvoker(vamh.type()).bindTo(vamh);
 assert(vamh.type().equals(mh.type()));
 assertEquals("[1, 2, 3]", vamh.invokeGeneric(1,2,3).toString());
 boolean failed = false;
--- a/test/java/dyn/MethodHandlesTest.java	Fri Feb 11 01:26:24 2011 -0800
+++ b/test/java/dyn/MethodHandlesTest.java	Fri Feb 11 01:26:28 2011 -0800
@@ -323,6 +323,44 @@
         return x.getClass().getSimpleName();
     }
 
+    /** Return lambda(arg...[arity]) { new Object[]{ arg... } } */
+    static MethodHandle varargsList(int arity) {
+        return ValueConversions.varargsList(arity);
+    }
+    /** Return lambda(arg...[arity]) { Arrays.asList(arg...) } */
+    static MethodHandle varargsArray(int arity) {
+        return ValueConversions.varargsArray(arity);
+    }
+    /** Variation of varargsList, but with the given rtype. */
+    static MethodHandle varargsList(int arity, Class<?> rtype) {
+        MethodHandle list = varargsList(arity);
+        MethodType listType = list.type().changeReturnType(rtype);
+        if (List.class.isAssignableFrom(rtype) || rtype == void.class || rtype == Object.class) {
+            // OK
+        } else if (rtype.isAssignableFrom(String.class)) {
+            if (LIST_TO_STRING == null)
+                try {
+                    LIST_TO_STRING = PRIVATE.findStatic(PRIVATE.lookupClass(), "listToString",
+                                                        MethodType.methodType(String.class, List.class));
+                } catch (Exception ex) { throw new RuntimeException(ex); }
+            list = MethodHandles.filterReturnValue(list, LIST_TO_STRING);
+        } else if (rtype.isPrimitive()) {
+            if (LIST_TO_INT == null)
+                try {
+                    LIST_TO_INT = PRIVATE.findStatic(PRIVATE.lookupClass(), "listToInt",
+                                                     MethodType.methodType(int.class, List.class));
+                } catch (Exception ex) { throw new RuntimeException(ex); }
+            list = MethodHandles.filterReturnValue(list, LIST_TO_INT);
+            list = MethodHandles.explicitCastArguments(list, listType);
+        } else {
+            throw new RuntimeException("varargsList: "+rtype);
+        }
+        return list.asType(listType);
+    }
+    private static MethodHandle LIST_TO_STRING, LIST_TO_INT;
+    private static String listToString(List x) { return x.toString(); }
+    private static int listToInt(List x) { return x.toString().hashCode(); }
+
     static MethodHandle changeArgTypes(MethodHandle target, Class<?> argType) {
         return changeArgTypes(target, 0, 999, argType);
     }
@@ -1302,7 +1340,7 @@
         }
         MethodType inType  = MethodType.methodType(Object.class, types);
         MethodType outType = MethodType.methodType(Object.class, permTypes);
-        MethodHandle target = MethodHandles.convertArguments(ValueConversions.varargsList(outargs), outType);
+        MethodHandle target = MethodHandles.convertArguments(varargsList(outargs), outType);
         MethodHandle newTarget = MethodHandles.permuteArguments(target, inType, reorder);
         Object result = newTarget.invokeWithArguments(args);
         Object expected = Arrays.asList(permArgs);
@@ -1329,7 +1367,7 @@
     }
     public void testSpreadArguments(Class<?> argType, int pos, int nargs) throws Throwable {
         countTest();
-        MethodHandle target = ValueConversions.varargsArray(nargs);
+        MethodHandle target = varargsArray(nargs);
         MethodHandle target2 = changeArgTypes(target, argType);
         if (verbosity >= 3)
             System.out.println("spread into "+target2+" ["+pos+".."+nargs+"]");
@@ -1359,7 +1397,7 @@
             spreadParams.clear(); spreadParams.add(Object[].class);
         }
         MethodType newType = MethodType.methodType(Object.class, newParams);
-        MethodHandle result = MethodHandles.spreadArguments(target2, newType);
+        MethodHandle result = target2.asSpreader(Object[].class, nargs-pos).asType(newType);
         Object[] returnValue;
         if (pos == 0) {
             // In the following line, the first cast implies
@@ -1393,7 +1431,7 @@
     public void testCollectArguments(Class<?> argType, int pos, int nargs) throws Throwable {
         countTest();
         // fake up a MH with the same type as the desired adapter:
-        MethodHandle fake = ValueConversions.varargsArray(nargs);
+        MethodHandle fake = varargsArray(nargs);
         fake = changeArgTypes(fake, argType);
         MethodType newType = fake.type();
         Object[] args = randomArgs(newType.parameterArray());
@@ -1401,12 +1439,12 @@
         Object[] collectedArgs = Arrays.copyOfRange(args, 0, pos+1);
         collectedArgs[pos] = Arrays.copyOfRange(args, pos, args.length);
         // here is the MH which will witness the collected argument tail:
-        MethodHandle target = ValueConversions.varargsArray(pos+1);
+        MethodHandle target = varargsArray(pos+1);
         target = changeArgTypes(target, 0, pos, argType);
         target = changeArgTypes(target, pos, pos+1, Object[].class);
         if (verbosity >= 3)
             System.out.println("collect from "+Arrays.asList(args)+" ["+pos+".."+nargs+"]");
-        MethodHandle result = MethodHandles.collectArguments(target, newType);
+        MethodHandle result = target.asCollector(Object[].class, nargs-pos).asType(newType);
         Object[] returnValue = (Object[]) result.invokeWithArguments(args);
 //        assertTrue(returnValue.length == pos+1 && returnValue[pos] instanceof Object[]);
 //        returnValue[pos] = Arrays.asList((Object[]) returnValue[pos]);
@@ -1430,7 +1468,7 @@
 
     void testInsertArguments(int nargs, int pos, int ins) throws Throwable {
         countTest();
-        MethodHandle target = ValueConversions.varargsArray(nargs + ins);
+        MethodHandle target = varargsArray(nargs + ins);
         Object[] args = randomArgs(target.type().parameterArray());
         List<Object> resList = Arrays.asList(args);
         List<Object> argsToPass = new ArrayList<Object>(resList);
@@ -1450,6 +1488,55 @@
     }
 
     @Test
+    public void testFilterReturnValue() throws Throwable {
+        if (CAN_SKIP_WORKING)  return;
+        startTest("filterReturnValue");
+        Class<?> classOfVCList = varargsList(1).invokeWithArguments(0).getClass();
+        assertTrue(List.class.isAssignableFrom(classOfVCList));
+        for (int nargs = 0; nargs <= 3; nargs++) {
+            for (Class<?> rtype : new Class[] { Object.class,
+                                                List.class,
+                                                int.class,
+                                                //byte.class, //FIXME: add this
+                                                //long.class, //FIXME: add this
+                                                CharSequence.class,
+                                                String.class }) {
+                testFilterReturnValue(nargs, rtype);
+            }
+        }
+    }
+
+    void testFilterReturnValue(int nargs, Class<?> rtype) throws Throwable {
+        countTest();
+        MethodHandle target = varargsList(nargs, rtype);
+        MethodHandle filter;
+        if (List.class.isAssignableFrom(rtype) || rtype.isAssignableFrom(List.class))
+            filter = varargsList(1);  // add another layer of list-ness
+        else
+            filter = MethodHandles.identity(rtype);
+        filter = filter.asType(MethodType.methodType(target.type().returnType(), rtype));
+        Object[] argsToPass = randomArgs(nargs, Object.class);
+        if (verbosity >= 3)
+            System.out.println("filter "+target+" to "+rtype.getSimpleName()+" with "+filter);
+        MethodHandle target2 = MethodHandles.filterReturnValue(target, filter);
+        if (verbosity >= 4)
+            System.out.println("filtered target: "+target2);
+        // Simulate expected effect of filter on return value:
+        Object unfiltered = target.invokeWithArguments(argsToPass);
+        Object expected = filter.invokeWithArguments(unfiltered);
+        if (verbosity >= 4)
+            System.out.println("unfiltered: "+unfiltered+" : "+unfiltered.getClass().getSimpleName());
+        if (verbosity >= 4)
+            System.out.println("expected: "+expected+" : "+expected.getClass().getSimpleName());
+        Object result = target2.invokeWithArguments(argsToPass);
+        if (verbosity >= 3)
+            System.out.println("result: "+result+" : "+result.getClass().getSimpleName());
+        if (!expected.equals(result))
+            System.out.println("*** fail at n/rt = "+nargs+"/"+rtype.getSimpleName()+": "+Arrays.asList(argsToPass)+" => "+result+" != "+expected);
+        assertEquals(expected, result);
+    }
+
+    @Test
     public void testFilterArguments() throws Throwable {
         if (CAN_SKIP_WORKING)  return;
         startTest("filterArguments");
@@ -1462,8 +1549,8 @@
 
     void testFilterArguments(int nargs, int pos) throws Throwable {
         countTest();
-        MethodHandle target = ValueConversions.varargsList(nargs);
-        MethodHandle filter = ValueConversions.varargsList(1);
+        MethodHandle target = varargsList(nargs);
+        MethodHandle filter = varargsList(1);
         filter = MethodHandles.convertArguments(filter, filter.type().generic());
         Object[] argsToPass = randomArgs(nargs, Object.class);
         if (verbosity >= 3)
@@ -1477,7 +1564,7 @@
         if (verbosity >= 3)
             System.out.println("result: "+result);
         if (!expected.equals(result))
-            System.out.println("*** fail at n/p = "+nargs+"/"+pos+": "+argsToPass+" => "+result);
+            System.out.println("*** fail at n/p = "+nargs+"/"+pos+": "+Arrays.asList(argsToPass)+" => "+result+" != "+expected);
         assertEquals(expected, result);
     }
 
@@ -1497,8 +1584,8 @@
     void testFoldArguments(int nargs, int pos, int fold) throws Throwable {
         if (pos != 0)  return;  // can fold only at pos=0 for now
         countTest();
-        MethodHandle target = ValueConversions.varargsList(1 + nargs);
-        MethodHandle combine = ValueConversions.varargsList(fold).asType(MethodType.genericMethodType(fold));
+        MethodHandle target = varargsList(1 + nargs);
+        MethodHandle combine = varargsList(fold).asType(MethodType.genericMethodType(fold));
         List<Object> argsToPass = Arrays.asList(randomArgs(nargs, Object.class));
         if (verbosity >= 3)
             System.out.println("fold "+target+" with "+combine);
@@ -1514,7 +1601,7 @@
         if (verbosity >= 3)
             System.out.println("result: "+result);
         if (!expected.equals(result))
-            System.out.println("*** fail at n/p/f = "+nargs+"/"+pos+"/"+fold+": "+argsToPass+" => "+result);
+            System.out.println("*** fail at n/p/f = "+nargs+"/"+pos+"/"+fold+": "+argsToPass+" => "+result+" != "+expected);
         assertEquals(expected, result);
     }
 
@@ -1533,7 +1620,7 @@
 
     void testDropArguments(int nargs, int pos, int drop) throws Throwable {
         countTest();
-        MethodHandle target = ValueConversions.varargsArray(nargs);
+        MethodHandle target = varargsArray(nargs);
         Object[] args = randomArgs(target.type().parameterArray());
         MethodHandle target2 = MethodHandles.dropArguments(target, pos,
                 Collections.nCopies(drop, Object.class).toArray(new Class[0]));
@@ -1584,7 +1671,8 @@
         boolean testRetCode = type.returnType() != void.class;
         MethodHandle target = PRIVATE.findStatic(MethodHandlesTest.class, "invokee",
                                 MethodType.genericMethodType(0, true));
-        target = MethodHandles.collectArguments(target, type);
+        assertTrue(target.isVarargsCollector());
+        target = target.asType(type);
         Object[] args = randomArgs(type.parameterArray());
         List<Object> targetPlusArgs = new ArrayList<Object>(Arrays.asList(args));
         targetPlusArgs.add(0, target);
@@ -1808,7 +1896,7 @@
         MethodHandle thrower = throwOrReturn.asType(MethodType.genericMethodType(2));
         while (thrower.type().parameterCount() < nargs)
             thrower = MethodHandles.dropArguments(thrower, thrower.type().parameterCount(), Object.class);
-        MethodHandle catcher = ValueConversions.varargsList(1+nargs).asType(MethodType.genericMethodType(1+nargs));
+        MethodHandle catcher = varargsList(1+nargs).asType(MethodType.genericMethodType(1+nargs));
         MethodHandle target = MethodHandles.catchException(thrower,
                 thrown.getClass(), catcher);
         assertEquals(thrower.type(), target.type());
@@ -2079,7 +2167,7 @@
                                              CharSequence.class,
                                              Example.class }) {
             try {
-                MethodHandles.asInstance(ValueConversions.varargsArray(0), nonSAM);
+                MethodHandles.asInstance(varargsArray(0), nonSAM);
                 System.out.println("Failed to throw");
                 assertTrue(false);
             } catch (IllegalArgumentException ex) {
@@ -2183,22 +2271,22 @@
                                      Object a8, Object a9)
                 { return makeList(a0, a1, a2, a3, a4, a5, a6, a7, a8, a9); }
     static MethodHandle[] makeLists() {
-        ArrayList<MethodHandle> arrays = new ArrayList<MethodHandle>();
+        ArrayList<MethodHandle> lists = new ArrayList<MethodHandle>();
         MethodHandles.Lookup lookup = IMPL_LOOKUP;
         for (;;) {
-            int nargs = arrays.size();
+            int nargs = lists.size();
             MethodType type = MethodType.genericMethodType(nargs).changeReturnType(List.class);
             String name = "list";
-            MethodHandle array = null;
+            MethodHandle list = null;
             try {
-                array = lookup.findStatic(ValueConversions.class, name, type);
+                list = lookup.findStatic(ValueConversions.class, name, type);
             } catch (NoAccessException ex) {
             }
-            if (array == null)  break;
-            arrays.add(array);
+            if (list == null)  break;
+            lists.add(list);
         }
-        assert(arrays.size() == 11);  // current number of methods
-        return arrays.toArray(new MethodHandle[0]);
+        assert(lists.size() == 11);  // current number of methods
+        return lists.toArray(new MethodHandle[0]);
     }
     static final MethodHandle[] LISTS = makeLists();