/*

  * Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.  Oracle designates this

  * particular file as subject to the "Classpath" exception as provided

  * by Oracle in the LICENSE file that accompanied this code.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * 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.lang.invoke;

 import sun.misc.Unsafe;

 import java.lang.reflect.Method;

 import java.util.Arrays;

 import sun.invoke.util.VerifyAccess;

 import static java.lang.invoke.MethodHandleNatives.Constants.*;

 import static java.lang.invoke.LambdaForm.*;

 import static java.lang.invoke.MethodTypeForm.*;

 import static java.lang.invoke.MethodHandleStatics.*;

 import java.lang.ref.WeakReference;

 import java.lang.reflect.Field;

 import sun.invoke.util.ValueConversions;

 import sun.invoke.util.VerifyType;

 import sun.invoke.util.Wrapper;

 /**

  * The flavor of method handle which implements a constant reference

  * to a class member.

  * @author jrose

  */

 class DirectMethodHandle extends MethodHandle {

     final MemberName member;

     // Constructors and factory methods in this class *must* be package scoped or private.

     private DirectMethodHandle(MethodType mtype, LambdaForm form, MemberName member) {

         super(mtype, form);

         if (!member.isResolved())  throw new InternalError();

         if (member.getDeclaringClass().isInterface() &&

                 member.isMethod() && !member.isAbstract()) {

             // Check for corner case: invokeinterface of Object method

             MemberName m = new MemberName(Object.class, member.getName(), member.getMethodType(), member.getReferenceKind());

             m = MemberName.getFactory().resolveOrNull(m.getReferenceKind(), m, null);

             if (m != null && m.isPublic()) {

                 member = m;

             }

         }

         this.member = member;

     }

     // Factory methods:

     static DirectMethodHandle make(byte refKind, Class<?> receiver, MemberName member) {

         MethodType mtype = member.getMethodOrFieldType();

         if (!member.isStatic()) {

             if (!member.getDeclaringClass().isAssignableFrom(receiver) || member.isConstructor())

                 throw new InternalError(member.toString());

             mtype = mtype.insertParameterTypes(0, receiver);

         }

         if (!member.isField()) {

             if (refKind == REF_invokeSpecial) {

                 member = member.asSpecial();

                 LambdaForm lform = preparedLambdaForm(member);

                 return new Special(mtype, lform, member);

             } else {

                 LambdaForm lform = preparedLambdaForm(member);

                 return new DirectMethodHandle(mtype, lform, member);

             }

         } else {

             LambdaForm lform = preparedFieldLambdaForm(member);

             if (member.isStatic()) {

                 long offset = MethodHandleNatives.staticFieldOffset(member);

                 Object base = MethodHandleNatives.staticFieldBase(member);

                 return new StaticAccessor(mtype, lform, member, base, offset);

             } else {

                 long offset = MethodHandleNatives.objectFieldOffset(member);

                 assert(offset == (int)offset);

                 return new Accessor(mtype, lform, member, (int)offset);

             }

         }

     }

     static DirectMethodHandle make(Class<?> receiver, MemberName member) {

         byte refKind = member.getReferenceKind();

         if (refKind == REF_invokeSpecial)

             refKind =  REF_invokeVirtual;

         return make(refKind, receiver, member);

     }

     static DirectMethodHandle make(MemberName member) {

         if (member.isConstructor())

             return makeAllocator(member);

         return make(member.getDeclaringClass(), member);

     }

     static DirectMethodHandle make(Method method) {

         return make(method.getDeclaringClass(), new MemberName(method));

     }

     static DirectMethodHandle make(Field field) {

         return make(field.getDeclaringClass(), new MemberName(field));

     }

     private static DirectMethodHandle makeAllocator(MemberName ctor) {

         assert(ctor.isConstructor() && ctor.getName().equals("<init>"));

         Class<?> instanceClass = ctor.getDeclaringClass();

         ctor = ctor.asConstructor();

         assert(ctor.isConstructor() && ctor.getReferenceKind() == REF_newInvokeSpecial) : ctor;

         MethodType mtype = ctor.getMethodType().changeReturnType(instanceClass);

         LambdaForm lform = preparedLambdaForm(ctor);

         MemberName init = ctor.asSpecial();

         assert(init.getMethodType().returnType() == void.class);

         return new Constructor(mtype, lform, ctor, init, instanceClass);

     }

     @Override

     MethodHandle copyWith(MethodType mt, LambdaForm lf) {

         return new DirectMethodHandle(mt, lf, member);

     }

     @Override

     String internalProperties() {

         return "/DMH="+member.toString();

     }

     //// Implementation methods.

     @Override

     MethodHandle viewAsType(MethodType newType) {

         return new DirectMethodHandle(newType, form, member);

     }

     @Override

     @ForceInline

     MemberName internalMemberName() {

         return member;

     }

     @Override

     MethodHandle bindArgument(int pos, char basicType, Object value) {

         // If the member needs dispatching, do so.

         if (pos == 0 && basicType == 'L') {

             DirectMethodHandle concrete = maybeRebind(value);

             if (concrete != null)

                 return concrete.bindReceiver(value);

         }

         return super.bindArgument(pos, basicType, value);

     }

     @Override

     MethodHandle bindReceiver(Object receiver) {

         // If the member needs dispatching, do so.

         DirectMethodHandle concrete = maybeRebind(receiver);

         if (concrete != null)

             return concrete.bindReceiver(receiver);

         return super.bindReceiver(receiver);

     }

     private static final MemberName.Factory IMPL_NAMES = MemberName.getFactory();

     private DirectMethodHandle maybeRebind(Object receiver) {

         if (receiver != null) {

             switch (member.getReferenceKind()) {

             case REF_invokeInterface:

             case REF_invokeVirtual:

                 // Pre-dispatch the member.

                 Class<?> concreteClass = receiver.getClass();

                 MemberName concrete = new MemberName(concreteClass, member.getName(), member.getMethodType(), REF_invokeSpecial);

                 concrete = IMPL_NAMES.resolveOrNull(REF_invokeSpecial, concrete, concreteClass);

                 if (concrete != null)

                     return new DirectMethodHandle(type(), preparedLambdaForm(concrete), concrete);

                 break;

             }

         }

         return null;

     }

     /**

      * Create a LF which can invoke the given method.

      * Cache and share this structure among all methods with

      * the same basicType and refKind.

      */

     private static LambdaForm preparedLambdaForm(MemberName m) {

         assert(m.isInvocable()) : m;  // call preparedFieldLambdaForm instead

         MethodType mtype = m.getInvocationType().basicType();

         assert(!m.isMethodHandleInvoke() || "invokeBasic".equals(m.getName())) : m;

         int which;

         switch (m.getReferenceKind()) {

         case REF_invokeVirtual:    which = LF_INVVIRTUAL;    break;

         case REF_invokeStatic:     which = LF_INVSTATIC;     break;

         case REF_invokeSpecial:    which = LF_INVSPECIAL;    break;

         case REF_invokeInterface:  which = LF_INVINTERFACE;  break;

         case REF_newInvokeSpecial: which = LF_NEWINVSPECIAL; break;

         default:  throw new InternalError(m.toString());

         }

         if (which == LF_INVSTATIC && shouldBeInitialized(m)) {

             // precompute the barrier-free version:

             preparedLambdaForm(mtype, which);

             which = LF_INVSTATIC_INIT;

         }

         LambdaForm lform = preparedLambdaForm(mtype, which);

         maybeCompile(lform, m);

         assert(lform.methodType().dropParameterTypes(0, 1)

                 .equals(m.getInvocationType().basicType()))

                 : Arrays.asList(m, m.getInvocationType().basicType(), lform, lform.methodType());

         return lform;

     }

     private static LambdaForm preparedLambdaForm(MethodType mtype, int which) {

         LambdaForm lform = mtype.form().cachedLambdaForm(which);

         if (lform != null)  return lform;

         lform = makePreparedLambdaForm(mtype, which);

         return mtype.form().setCachedLambdaForm(which, lform);

     }

     private static LambdaForm makePreparedLambdaForm(MethodType mtype, int which) {

         boolean needsInit = (which == LF_INVSTATIC_INIT);

         boolean doesAlloc = (which == LF_NEWINVSPECIAL);

         String linkerName, lambdaName;

         switch (which) {

         case LF_INVVIRTUAL:    linkerName = "linkToVirtual";    lambdaName = "DMH.invokeVirtual";    break;

         case LF_INVSTATIC:     linkerName = "linkToStatic";     lambdaName = "DMH.invokeStatic";     break;

         case LF_INVSTATIC_INIT:linkerName = "linkToStatic";     lambdaName = "DMH.invokeStaticInit"; break;

         case LF_INVSPECIAL:    linkerName = "linkToSpecial";    lambdaName = "DMH.invokeSpecial";    break;

         case LF_INVINTERFACE:  linkerName = "linkToInterface";  lambdaName = "DMH.invokeInterface";  break;

         case LF_NEWINVSPECIAL: linkerName = "linkToSpecial";    lambdaName = "DMH.newInvokeSpecial"; break;

         default:  throw new InternalError("which="+which);

         }

         MethodType mtypeWithArg = mtype.appendParameterTypes(MemberName.class);

         if (doesAlloc)

             mtypeWithArg = mtypeWithArg

                     .insertParameterTypes(0, Object.class)  // insert newly allocated obj

                     .changeReturnType(void.class);          // <init> returns void

         MemberName linker = new MemberName(MethodHandle.class, linkerName, mtypeWithArg, REF_invokeStatic);

         try {

             linker = IMPL_NAMES.resolveOrFail(REF_invokeStatic, linker, null, NoSuchMethodException.class);

         } catch (ReflectiveOperationException ex) {

             throw newInternalError(ex);

         }

         final int DMH_THIS    = 0;

         final int ARG_BASE    = 1;

         final int ARG_LIMIT   = ARG_BASE + mtype.parameterCount();

         int nameCursor = ARG_LIMIT;

         final int NEW_OBJ     = (doesAlloc ? nameCursor++ : -1);

         final int GET_MEMBER  = nameCursor++;

         final int LINKER_CALL = nameCursor++;

         Name[] names = arguments(nameCursor - ARG_LIMIT, mtype.invokerType());

         assert(names.length == nameCursor);

         if (doesAlloc) {

             // names = { argx,y,z,... new C, init method }

             names[NEW_OBJ] = new Name(Lazy.NF_allocateInstance, names[DMH_THIS]);

             names[GET_MEMBER] = new Name(Lazy.NF_constructorMethod, names[DMH_THIS]);

         } else if (needsInit) {

             names[GET_MEMBER] = new Name(Lazy.NF_internalMemberNameEnsureInit, names[DMH_THIS]);

         } else {

             names[GET_MEMBER] = new Name(Lazy.NF_internalMemberName, names[DMH_THIS]);

         }

         Object[] outArgs = Arrays.copyOfRange(names, ARG_BASE, GET_MEMBER+1, Object[].class);

         assert(outArgs[outArgs.length-1] == names[GET_MEMBER]);  // look, shifted args!

         int result = LambdaForm.LAST_RESULT;

         if (doesAlloc) {

             assert(outArgs[outArgs.length-2] == names[NEW_OBJ]);  // got to move this one

             System.arraycopy(outArgs, 0, outArgs, 1, outArgs.length-2);

             outArgs[0] = names[NEW_OBJ];

             result = NEW_OBJ;

         }

         names[LINKER_CALL] = new Name(linker, outArgs);

         lambdaName += "_" + LambdaForm.basicTypeSignature(mtype);

         LambdaForm lform = new LambdaForm(lambdaName, ARG_LIMIT, names, result);

         // This is a tricky bit of code.  Don't send it through the LF interpreter.

         lform.compileToBytecode();

         return lform;

     }

     private static void maybeCompile(LambdaForm lform, MemberName m) {

         if (VerifyAccess.isSamePackage(m.getDeclaringClass(), MethodHandle.class))

             // Help along bootstrapping...

             lform.compileToBytecode();

     }

     /** Static wrapper for DirectMethodHandle.internalMemberName. */

     @ForceInline

     /*non-public*/ static Object internalMemberName(Object mh) {

         return ((DirectMethodHandle)mh).member;

     }

     /** Static wrapper for DirectMethodHandle.internalMemberName.

      * This one also forces initialization.

      */

     /*non-public*/ static Object internalMemberNameEnsureInit(Object mh) {

         DirectMethodHandle dmh = (DirectMethodHandle)mh;

         dmh.ensureInitialized();

         return dmh.member;

     }

     /*non-public*/ static

     boolean shouldBeInitialized(MemberName member) {

         switch (member.getReferenceKind()) {

         case REF_invokeStatic:

         case REF_getStatic:

         case REF_putStatic:

         case REF_newInvokeSpecial:

             break;

         default:

             // No need to initialize the class on this kind of member.

             return false;

         }

         Class<?> cls = member.getDeclaringClass();

         if (cls == ValueConversions.class ||

             cls == MethodHandleImpl.class ||

             cls == Invokers.class) {

             // These guys have lots of <clinit> DMH creation but we know

             // the MHs will not be used until the system is booted.

             return false;

         }

         if (VerifyAccess.isSamePackage(MethodHandle.class, cls) ||

             VerifyAccess.isSamePackage(ValueConversions.class, cls)) {

             // It is a system class.  It is probably in the process of

             // being initialized, but we will help it along just to be safe.

             if (UNSAFE.shouldBeInitialized(cls)) {

                 UNSAFE.ensureClassInitialized(cls);

             }

             return false;

         }

         return UNSAFE.shouldBeInitialized(cls);

     }

     private static class EnsureInitialized extends ClassValue<WeakReference<Thread>> {

         @Override

         protected WeakReference<Thread> computeValue(Class<?> type) {

             UNSAFE.ensureClassInitialized(type);

             if (UNSAFE.shouldBeInitialized(type))

                 // If the previous call didn't block, this can happen.

                 // We are executing inside <clinit>.

                 return new WeakReference<>(Thread.currentThread());

             return null;

         }

         static final EnsureInitialized INSTANCE = new EnsureInitialized();

     }

     private void ensureInitialized() {

         if (checkInitialized(member)) {

             // The coast is clear.  Delete the <clinit> barrier.

             if (member.isField())

                 updateForm(preparedFieldLambdaForm(member));

             else

                 updateForm(preparedLambdaForm(member));

         }

     }

     private static boolean checkInitialized(MemberName member) {

         Class<?> defc = member.getDeclaringClass();

         WeakReference<Thread> ref = EnsureInitialized.INSTANCE.get(defc);

         if (ref == null) {

             return true;  // the final state

         }

         Thread clinitThread = ref.get();

         // Somebody may still be running defc.<clinit>.

         if (clinitThread == Thread.currentThread()) {

             // If anybody is running defc.<clinit>, it is this thread.

             if (UNSAFE.shouldBeInitialized(defc))

                 // Yes, we are running it; keep the barrier for now.

                 return false;

         } else {

             // We are in a random thread.  Block.

             UNSAFE.ensureClassInitialized(defc);

         }

         assert(!UNSAFE.shouldBeInitialized(defc));

         // put it into the final state

         EnsureInitialized.INSTANCE.remove(defc);

         return true;

     }

     /*non-public*/ static void ensureInitialized(Object mh) {

         ((DirectMethodHandle)mh).ensureInitialized();

     }

     /** This subclass represents invokespecial instructions. */

     static class Special extends DirectMethodHandle {

         private Special(MethodType mtype, LambdaForm form, MemberName member) {

             super(mtype, form, member);

         }

         @Override

         boolean isInvokeSpecial() {

             return true;

         }

         @Override

         MethodHandle viewAsType(MethodType newType) {

             return new Special(newType, form, member);

         }

     }

     /** This subclass handles constructor references. */

     static class Constructor extends DirectMethodHandle {

         final MemberName initMethod;

         final Class<?>   instanceClass;

         private Constructor(MethodType mtype, LambdaForm form, MemberName constructor,

                             MemberName initMethod, Class<?> instanceClass) {

             super(mtype, form, constructor);

             this.initMethod = initMethod;

             this.instanceClass = instanceClass;

             assert(initMethod.isResolved());

         }

         @Override

         MethodHandle viewAsType(MethodType newType) {

             return new Constructor(newType, form, member, initMethod, instanceClass);

         }

     }

     /*non-public*/ static Object constructorMethod(Object mh) {

         Constructor dmh = (Constructor)mh;

         return dmh.initMethod;

     }

     /*non-public*/ static Object allocateInstance(Object mh) throws InstantiationException {

         Constructor dmh = (Constructor)mh;

         return UNSAFE.allocateInstance(dmh.instanceClass);

     }

     /** This subclass handles non-static field references. */

     static class Accessor extends DirectMethodHandle {

         final Class<?> fieldType;

         final int      fieldOffset;

         private Accessor(MethodType mtype, LambdaForm form, MemberName member,

                          int fieldOffset) {

             super(mtype, form, member);

             this.fieldType   = member.getFieldType();

             this.fieldOffset = fieldOffset;

         }

         @Override Object checkCast(Object obj) {

             return fieldType.cast(obj);

         }

         @Override

         MethodHandle viewAsType(MethodType newType) {

             return new Accessor(newType, form, member, fieldOffset);

         }

     }

     @ForceInline

     /*non-public*/ static long fieldOffset(Object accessorObj) {

         // Note: We return a long because that is what Unsafe.getObject likes.

         // We store a plain int because it is more compact.

         return ((Accessor)accessorObj).fieldOffset;

     }

     @ForceInline

     /*non-public*/ static Object checkBase(Object obj) {

         // Note that the object's class has already been verified,

         // since the parameter type of the Accessor method handle

         // is either member.getDeclaringClass or a subclass.

         // This was verified in DirectMethodHandle.make.

         // Therefore, the only remaining check is for null.

         // Since this check is *not* guaranteed by Unsafe.getInt

         // and its siblings, we need to make an explicit one here.

         obj.getClass();  // maybe throw NPE

         return obj;

     }

     /** This subclass handles static field references. */

     static class StaticAccessor extends DirectMethodHandle {

         final private Class<?> fieldType;

         final private Object   staticBase;

         final private long     staticOffset;

         private StaticAccessor(MethodType mtype, LambdaForm form, MemberName member,

                                Object staticBase, long staticOffset) {

             super(mtype, form, member);

             this.fieldType    = member.getFieldType();

             this.staticBase   = staticBase;

             this.staticOffset = staticOffset;

         }

         @Override Object checkCast(Object obj) {

             return fieldType.cast(obj);

         }

         @Override

         MethodHandle viewAsType(MethodType newType) {

             return new StaticAccessor(newType, form, member, staticBase, staticOffset);

         }

     }

     @ForceInline

     /*non-public*/ static Object nullCheck(Object obj) {

         obj.getClass();

         return obj;

     }

     @ForceInline

     /*non-public*/ static Object staticBase(Object accessorObj) {

         return ((StaticAccessor)accessorObj).staticBase;

     }

     @ForceInline

     /*non-public*/ static long staticOffset(Object accessorObj) {

         return ((StaticAccessor)accessorObj).staticOffset;

     }

     @ForceInline

     /*non-public*/ static Object checkCast(Object mh, Object obj) {

         return ((DirectMethodHandle) mh).checkCast(obj);

     }

     Object checkCast(Object obj) {

         return member.getReturnType().cast(obj);

     }

     // Caching machinery for field accessors:

     private static byte

             AF_GETFIELD        = 0,

             AF_PUTFIELD        = 1,

             AF_GETSTATIC       = 2,

             AF_PUTSTATIC       = 3,

             AF_GETSTATIC_INIT  = 4,

             AF_PUTSTATIC_INIT  = 5,

             AF_LIMIT           = 6;

     // Enumerate the different field kinds using Wrapper,

     // with an extra case added for checked references.

     private static int

             FT_LAST_WRAPPER    = Wrapper.values().length-1,

             FT_UNCHECKED_REF   = Wrapper.OBJECT.ordinal(),

             FT_CHECKED_REF     = FT_LAST_WRAPPER+1,

             FT_LIMIT           = FT_LAST_WRAPPER+2;

     private static int afIndex(byte formOp, boolean isVolatile, int ftypeKind) {

         return ((formOp * FT_LIMIT * 2)

                 + (isVolatile ? FT_LIMIT : 0)

                 + ftypeKind);

     }

     private static final LambdaForm[] ACCESSOR_FORMS

             = new LambdaForm[afIndex(AF_LIMIT, false, 0)];

     private static int ftypeKind(Class<?> ftype) {

         if (ftype.isPrimitive())

             return Wrapper.forPrimitiveType(ftype).ordinal();

         else if (VerifyType.isNullReferenceConversion(Object.class, ftype))

             return FT_UNCHECKED_REF;

         else

             return FT_CHECKED_REF;

     }

     /**

      * Create a LF which can access the given field.

      * Cache and share this structure among all fields with

      * the same basicType and refKind.

      */

     private static LambdaForm preparedFieldLambdaForm(MemberName m) {

         Class<?> ftype = m.getFieldType();

         boolean isVolatile = m.isVolatile();

         byte formOp;

         switch (m.getReferenceKind()) {

         case REF_getField:      formOp = AF_GETFIELD;    break;

         case REF_putField:      formOp = AF_PUTFIELD;    break;

         case REF_getStatic:     formOp = AF_GETSTATIC;   break;

         case REF_putStatic:     formOp = AF_PUTSTATIC;   break;

         default:  throw new InternalError(m.toString());

         }

         if (shouldBeInitialized(m)) {

             // precompute the barrier-free version:

             preparedFieldLambdaForm(formOp, isVolatile, ftype);

             assert((AF_GETSTATIC_INIT - AF_GETSTATIC) ==

                    (AF_PUTSTATIC_INIT - AF_PUTSTATIC));

             formOp += (AF_GETSTATIC_INIT - AF_GETSTATIC);

         }

         LambdaForm lform = preparedFieldLambdaForm(formOp, isVolatile, ftype);

         maybeCompile(lform, m);

         assert(lform.methodType().dropParameterTypes(0, 1)

                 .equals(m.getInvocationType().basicType()))

                 : Arrays.asList(m, m.getInvocationType().basicType(), lform, lform.methodType());

         return lform;

     }

     private static LambdaForm preparedFieldLambdaForm(byte formOp, boolean isVolatile, Class<?> ftype) {

         int afIndex = afIndex(formOp, isVolatile, ftypeKind(ftype));

         LambdaForm lform = ACCESSOR_FORMS[afIndex];

         if (lform != null)  return lform;

         lform = makePreparedFieldLambdaForm(formOp, isVolatile, ftypeKind(ftype));

         ACCESSOR_FORMS[afIndex] = lform;  // don't bother with a CAS

         return lform;

     }

     private static LambdaForm makePreparedFieldLambdaForm(byte formOp, boolean isVolatile, int ftypeKind) {

         boolean isGetter  = (formOp & 1) == (AF_GETFIELD & 1);

         boolean isStatic  = (formOp >= AF_GETSTATIC);

         boolean needsInit = (formOp >= AF_GETSTATIC_INIT);

         boolean needsCast = (ftypeKind == FT_CHECKED_REF);

         Wrapper fw = (needsCast ? Wrapper.OBJECT : Wrapper.values()[ftypeKind]);

         Class<?> ft = fw.primitiveType();

         assert(ftypeKind(needsCast ? String.class : ft) == ftypeKind);

         String tname  = fw.primitiveSimpleName();

         String ctname = Character.toUpperCase(tname.charAt(0)) + tname.substring(1);

         if (isVolatile)  ctname += "Volatile";

         String getOrPut = (isGetter ? "get" : "put");

         String linkerName = (getOrPut + ctname);  // getObject, putIntVolatile, etc.

         MethodType linkerType;

         if (isGetter)

             linkerType = MethodType.methodType(ft, Object.class, long.class);

         else

             linkerType = MethodType.methodType(void.class, Object.class, long.class, ft);

         MemberName linker = new MemberName(Unsafe.class, linkerName, linkerType, REF_invokeVirtual);

         try {

             linker = IMPL_NAMES.resolveOrFail(REF_invokeVirtual, linker, null, NoSuchMethodException.class);

         } catch (ReflectiveOperationException ex) {

             throw newInternalError(ex);

         }

         // What is the external type of the lambda form?

         MethodType mtype;

         if (isGetter)

             mtype = MethodType.methodType(ft);

         else

             mtype = MethodType.methodType(void.class, ft);

         mtype = mtype.basicType();  // erase short to int, etc.

         if (!isStatic)

             mtype = mtype.insertParameterTypes(0, Object.class);

         final int DMH_THIS  = 0;

         final int ARG_BASE  = 1;

         final int ARG_LIMIT = ARG_BASE + mtype.parameterCount();

         // if this is for non-static access, the base pointer is stored at this index:

         final int OBJ_BASE  = isStatic ? -1 : ARG_BASE;

         // if this is for write access, the value to be written is stored at this index:

         final int SET_VALUE  = isGetter ? -1 : ARG_LIMIT - 1;

         int nameCursor = ARG_LIMIT;

         final int F_HOLDER  = (isStatic ? nameCursor++ : -1);  // static base if any

         final int F_OFFSET  = nameCursor++;  // Either static offset or field offset.

         final int OBJ_CHECK = (OBJ_BASE >= 0 ? nameCursor++ : -1);

         final int INIT_BAR  = (needsInit ? nameCursor++ : -1);

         final int PRE_CAST  = (needsCast && !isGetter ? nameCursor++ : -1);

         final int LINKER_CALL = nameCursor++;

         final int POST_CAST = (needsCast && isGetter ? nameCursor++ : -1);

         final int RESULT    = nameCursor-1;  // either the call or the cast

         Name[] names = arguments(nameCursor - ARG_LIMIT, mtype.invokerType());

         if (needsInit)

             names[INIT_BAR] = new Name(Lazy.NF_ensureInitialized, names[DMH_THIS]);

         if (needsCast && !isGetter)

             names[PRE_CAST] = new Name(Lazy.NF_checkCast, names[DMH_THIS], names[SET_VALUE]);

         Object[] outArgs = new Object[1 + linkerType.parameterCount()];

         assert(outArgs.length == (isGetter ? 3 : 4));

         outArgs[0] = UNSAFE;

         if (isStatic) {

             outArgs[1] = names[F_HOLDER]  = new Name(Lazy.NF_staticBase, names[DMH_THIS]);

             outArgs[2] = names[F_OFFSET]  = new Name(Lazy.NF_staticOffset, names[DMH_THIS]);

         } else {

             outArgs[1] = names[OBJ_CHECK] = new Name(Lazy.NF_checkBase, names[OBJ_BASE]);

             outArgs[2] = names[F_OFFSET]  = new Name(Lazy.NF_fieldOffset, names[DMH_THIS]);

         }

         if (!isGetter) {

             outArgs[3] = (needsCast ? names[PRE_CAST] : names[SET_VALUE]);

         }

         for (Object a : outArgs)  assert(a != null);

         names[LINKER_CALL] = new Name(linker, outArgs);

         if (needsCast && isGetter)

             names[POST_CAST] = new Name(Lazy.NF_checkCast, names[DMH_THIS], names[LINKER_CALL]);

         for (Name n : names)  assert(n != null);

         String fieldOrStatic = (isStatic ? "Static" : "Field");

         String lambdaName = (linkerName + fieldOrStatic);  // significant only for debugging

         if (needsCast)  lambdaName += "Cast";

         if (needsInit)  lambdaName += "Init";

         return new LambdaForm(lambdaName, ARG_LIMIT, names, RESULT);

     }

     /**

      * Pre-initialized NamedFunctions for bootstrapping purposes.

      * Factored in an inner class to delay initialization until first usage.

      */

     private static class Lazy {

         static final NamedFunction

                 NF_internalMemberName,

                 NF_internalMemberNameEnsureInit,

                 NF_ensureInitialized,

                 NF_fieldOffset,

                 NF_checkBase,

                 NF_staticBase,

                 NF_staticOffset,

                 NF_checkCast,

                 NF_allocateInstance,

                 NF_constructorMethod;

         static {

             try {

                 NamedFunction nfs[] = {

                         NF_internalMemberName = new NamedFunction(DirectMethodHandle.class

                                 .getDeclaredMethod("internalMemberName", Object.class)),

                         NF_internalMemberNameEnsureInit = new NamedFunction(DirectMethodHandle.class

                                 .getDeclaredMethod("internalMemberNameEnsureInit", Object.class)),

                         NF_ensureInitialized = new NamedFunction(DirectMethodHandle.class

                                 .getDeclaredMethod("ensureInitialized", Object.class)),

                         NF_fieldOffset = new NamedFunction(DirectMethodHandle.class

                                 .getDeclaredMethod("fieldOffset", Object.class)),

                         NF_checkBase = new NamedFunction(DirectMethodHandle.class

                                 .getDeclaredMethod("checkBase", Object.class)),

                         NF_staticBase = new NamedFunction(DirectMethodHandle.class

                                 .getDeclaredMethod("staticBase", Object.class)),

                         NF_staticOffset = new NamedFunction(DirectMethodHandle.class

                                 .getDeclaredMethod("staticOffset", Object.class)),

                         NF_checkCast = new NamedFunction(DirectMethodHandle.class

                                 .getDeclaredMethod("checkCast", Object.class, Object.class)),

                         NF_allocateInstance = new NamedFunction(DirectMethodHandle.class

                                 .getDeclaredMethod("allocateInstance", Object.class)),

                         NF_constructorMethod = new NamedFunction(DirectMethodHandle.class

                                 .getDeclaredMethod("constructorMethod", Object.class))

                 };

                 for (NamedFunction nf : nfs) {

                     // Each nf must be statically invocable or we get tied up in our bootstraps.

                     assert(InvokerBytecodeGenerator.isStaticallyInvocable(nf.member)) : nf;

                     nf.resolve();

                 }

             } catch (ReflectiveOperationException ex) {

                 throw newInternalError(ex);

             }

         }

     }

 }