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	/*
	* Copyright (c) 2014, 2017, 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 static java.lang.invoke.MethodHandleStatics.UNSAFE;

	final class VarHandles {

	static VarHandle makeFieldHandle(MemberName f, Class<?> refc, Class<?> type, boolean isWriteAllowedOnFinalFields) {
	if (!f.isStatic()) {
	long foffset = MethodHandleNatives.objectFieldOffset(f);
	if (!type.isPrimitive()) {
	return f.isFinal() && !isWriteAllowedOnFinalFields
	? new VarHandleObjects.FieldInstanceReadOnly(refc, foffset, type)
	: new VarHandleObjects.FieldInstanceReadWrite(refc, foffset, type);
	}
	else if (type == boolean.class) {
	return f.isFinal() && !isWriteAllowedOnFinalFields
	? new VarHandleBooleans.FieldInstanceReadOnly(refc, foffset)
	: new VarHandleBooleans.FieldInstanceReadWrite(refc, foffset);
	}
	else if (type == byte.class) {
	return f.isFinal() && !isWriteAllowedOnFinalFields
	? new VarHandleBytes.FieldInstanceReadOnly(refc, foffset)
	: new VarHandleBytes.FieldInstanceReadWrite(refc, foffset);
	}
	else if (type == short.class) {
	return f.isFinal() && !isWriteAllowedOnFinalFields
	? new VarHandleShorts.FieldInstanceReadOnly(refc, foffset)
	: new VarHandleShorts.FieldInstanceReadWrite(refc, foffset);
	}
	else if (type == char.class) {
	return f.isFinal() && !isWriteAllowedOnFinalFields
	? new VarHandleChars.FieldInstanceReadOnly(refc, foffset)
	: new VarHandleChars.FieldInstanceReadWrite(refc, foffset);
	}
	else if (type == int.class) {
	return f.isFinal() && !isWriteAllowedOnFinalFields
	? new VarHandleInts.FieldInstanceReadOnly(refc, foffset)
	: new VarHandleInts.FieldInstanceReadWrite(refc, foffset);
	}
	else if (type == long.class) {
	return f.isFinal() && !isWriteAllowedOnFinalFields
	? new VarHandleLongs.FieldInstanceReadOnly(refc, foffset)
	: new VarHandleLongs.FieldInstanceReadWrite(refc, foffset);
	}
	else if (type == float.class) {
	return f.isFinal() && !isWriteAllowedOnFinalFields
	? new VarHandleFloats.FieldInstanceReadOnly(refc, foffset)
	: new VarHandleFloats.FieldInstanceReadWrite(refc, foffset);
	}
	else if (type == double.class) {
	return f.isFinal() && !isWriteAllowedOnFinalFields
	? new VarHandleDoubles.FieldInstanceReadOnly(refc, foffset)
	: new VarHandleDoubles.FieldInstanceReadWrite(refc, foffset);
	}
	else {
	throw new UnsupportedOperationException();
	}
	}
	else {
	// TODO This is not lazy on first invocation
	// and might cause some circular initialization issues

	// Replace with something similar to direct method handles
	// where a barrier is used then elided after use

	if (UNSAFE.shouldBeInitialized(refc))
	UNSAFE.ensureClassInitialized(refc);

	Object base = MethodHandleNatives.staticFieldBase(f);
	long foffset = MethodHandleNatives.staticFieldOffset(f);
	if (!type.isPrimitive()) {
	return f.isFinal() && !isWriteAllowedOnFinalFields
	? new VarHandleObjects.FieldStaticReadOnly(base, foffset, type)
	: new VarHandleObjects.FieldStaticReadWrite(base, foffset, type);
	}
	else if (type == boolean.class) {
	return f.isFinal() && !isWriteAllowedOnFinalFields
	? new VarHandleBooleans.FieldStaticReadOnly(base, foffset)
	: new VarHandleBooleans.FieldStaticReadWrite(base, foffset);
	}
	else if (type == byte.class) {
	return f.isFinal() && !isWriteAllowedOnFinalFields
	? new VarHandleBytes.FieldStaticReadOnly(base, foffset)
	: new VarHandleBytes.FieldStaticReadWrite(base, foffset);
	}
	else if (type == short.class) {
	return f.isFinal() && !isWriteAllowedOnFinalFields
	? new VarHandleShorts.FieldStaticReadOnly(base, foffset)
	: new VarHandleShorts.FieldStaticReadWrite(base, foffset);
	}
	else if (type == char.class) {
	return f.isFinal() && !isWriteAllowedOnFinalFields
	? new VarHandleChars.FieldStaticReadOnly(base, foffset)
	: new VarHandleChars.FieldStaticReadWrite(base, foffset);
	}
	else if (type == int.class) {
	return f.isFinal() && !isWriteAllowedOnFinalFields
	? new VarHandleInts.FieldStaticReadOnly(base, foffset)
	: new VarHandleInts.FieldStaticReadWrite(base, foffset);
	}
	else if (type == long.class) {
	return f.isFinal() && !isWriteAllowedOnFinalFields
	? new VarHandleLongs.FieldStaticReadOnly(base, foffset)
	: new VarHandleLongs.FieldStaticReadWrite(base, foffset);
	}
	else if (type == float.class) {
	return f.isFinal() && !isWriteAllowedOnFinalFields
	? new VarHandleFloats.FieldStaticReadOnly(base, foffset)
	: new VarHandleFloats.FieldStaticReadWrite(base, foffset);
	}
	else if (type == double.class) {
	return f.isFinal() && !isWriteAllowedOnFinalFields
	? new VarHandleDoubles.FieldStaticReadOnly(base, foffset)
	: new VarHandleDoubles.FieldStaticReadWrite(base, foffset);
	}
	else {
	throw new UnsupportedOperationException();
	}
	}
	}

	static VarHandle makeArrayElementHandle(Class<?> arrayClass) {
	if (!arrayClass.isArray())
	throw new IllegalArgumentException("not an array: " + arrayClass);

	Class<?> componentType = arrayClass.getComponentType();

	int aoffset = UNSAFE.arrayBaseOffset(arrayClass);
	int ascale = UNSAFE.arrayIndexScale(arrayClass);
	int ashift = 31 - Integer.numberOfLeadingZeros(ascale);

	if (!componentType.isPrimitive()) {
	return new VarHandleObjects.Array(aoffset, ashift, arrayClass);
	}
	else if (componentType == boolean.class) {
	return new VarHandleBooleans.Array(aoffset, ashift);
	}
	else if (componentType == byte.class) {
	return new VarHandleBytes.Array(aoffset, ashift);
	}
	else if (componentType == short.class) {
	return new VarHandleShorts.Array(aoffset, ashift);
	}
	else if (componentType == char.class) {
	return new VarHandleChars.Array(aoffset, ashift);
	}
	else if (componentType == int.class) {
	return new VarHandleInts.Array(aoffset, ashift);
	}
	else if (componentType == long.class) {
	return new VarHandleLongs.Array(aoffset, ashift);
	}
	else if (componentType == float.class) {
	return new VarHandleFloats.Array(aoffset, ashift);
	}
	else if (componentType == double.class) {
	return new VarHandleDoubles.Array(aoffset, ashift);
	}
	else {
	throw new UnsupportedOperationException();
	}
	}

	static VarHandle byteArrayViewHandle(Class<?> viewArrayClass,
	boolean be) {
	if (!viewArrayClass.isArray())
	throw new IllegalArgumentException("not an array: " + viewArrayClass);

	Class<?> viewComponentType = viewArrayClass.getComponentType();

	if (viewComponentType == long.class) {
	return new VarHandleByteArrayAsLongs.ArrayHandle(be);
	}
	else if (viewComponentType == int.class) {
	return new VarHandleByteArrayAsInts.ArrayHandle(be);
	}
	else if (viewComponentType == short.class) {
	return new VarHandleByteArrayAsShorts.ArrayHandle(be);
	}
	else if (viewComponentType == char.class) {
	return new VarHandleByteArrayAsChars.ArrayHandle(be);
	}
	else if (viewComponentType == double.class) {
	return new VarHandleByteArrayAsDoubles.ArrayHandle(be);
	}
	else if (viewComponentType == float.class) {
	return new VarHandleByteArrayAsFloats.ArrayHandle(be);
	}

	throw new UnsupportedOperationException();
	}

	static VarHandle makeByteBufferViewHandle(Class<?> viewArrayClass,
	boolean be) {
	if (!viewArrayClass.isArray())
	throw new IllegalArgumentException("not an array: " + viewArrayClass);

	Class<?> viewComponentType = viewArrayClass.getComponentType();

	if (viewComponentType == long.class) {
	return new VarHandleByteArrayAsLongs.ByteBufferHandle(be);
	}
	else if (viewComponentType == int.class) {
	return new VarHandleByteArrayAsInts.ByteBufferHandle(be);
	}
	else if (viewComponentType == short.class) {
	return new VarHandleByteArrayAsShorts.ByteBufferHandle(be);
	}
	else if (viewComponentType == char.class) {
	return new VarHandleByteArrayAsChars.ByteBufferHandle(be);
	}
	else if (viewComponentType == double.class) {
	return new VarHandleByteArrayAsDoubles.ByteBufferHandle(be);
	}
	else if (viewComponentType == float.class) {
	return new VarHandleByteArrayAsFloats.ByteBufferHandle(be);
	}

	throw new UnsupportedOperationException();
	}

	// /**
	// * A helper program to generate the VarHandleGuards class with a set of
	// * static guard methods each of which corresponds to a particular shape and
	// * performs a type check of the symbolic type descriptor with the VarHandle
	// * type descriptor before linking/invoking to the underlying operation as
	// * characterized by the operation member name on the VarForm of the
	// * VarHandle.
	// * <p>
	// * The generated class essentially encapsulates pre-compiled LambdaForms,
	// * one for each method, for the most set of common method signatures.
	// * This reduces static initialization costs, footprint costs, and circular
	// * dependencies that may arise if a class is generated per LambdaForm.
	// * <p>
	// * A maximum of LTS methods will be generated where L is the number of
	// * access modes kinds (or unique operation signatures) and T is the number
	// * of variable types and S is the number of shapes (such as instance field,
	// * static field, or array access).
	// * If there are 4 unique operation signatures, 5 basic types (Object, int,
	// * long, float, double), and 3 shapes then a maximum of 60 methods will be
	// * generated. However, the number is likely to be less since there
	// * be duplicate signatures.
	// * <p>
	// * Each method is annotated with @LambdaForm.Compiled to inform the runtime
	// * that such methods should be treated as if a method of a class that is the
	// * result of compiling a LambdaForm. Annotation of such methods is
	// * important for correct evaluation of certain assertions and method return
	// * type profiling in HotSpot.
	// */
	// public static class GuardMethodGenerator {
	//
	// static final String GUARD_METHOD_SIG_TEMPLATE = "<RETURN> <NAME>_<SIGNATURE>(<PARAMS>)";
	//
	// static final String GUARD_METHOD_TEMPLATE =
	// "@ForceInline\n" +
	// "@LambdaForm.Compiled\n" +
	// "final static <METHOD> throws Throwable {\n" +
	// " if (handle.vform.methodType_table[ad.type] == ad.symbolicMethodType) {\n" +
	// " <RESULT_ERASED>MethodHandle.linkToStatic(<LINK_TO_STATIC_ARGS>);<RETURN_ERASED>\n" +
	// " }\n" +
	// " else {\n" +
	// " MethodHandle mh = handle.getMethodHandle(ad.mode);\n" +
	// " <RETURN>mh.asType(ad.symbolicMethodTypeInvoker).invokeBasic(<LINK_TO_INVOKER_ARGS>);\n" +
	// " }\n" +
	// "}";
	//
	// static final String GUARD_METHOD_TEMPLATE_V =
	// "@ForceInline\n" +
	// "@LambdaForm.Compiled\n" +
	// "final static <METHOD> throws Throwable {\n" +
	// " if (handle.vform.methodType_table[ad.type] == ad.symbolicMethodType) {\n" +
	// " MethodHandle.linkToStatic(<LINK_TO_STATIC_ARGS>);\n" +
	// " }\n" +
	// " else if (handle.vform.getMethodType_V(ad.type) == ad.symbolicMethodType) {\n" +
	// " MethodHandle.linkToStatic(<LINK_TO_STATIC_ARGS>);\n" +
	// " }\n" +
	// " else {\n" +
	// " MethodHandle mh = handle.getMethodHandle(ad.mode);\n" +
	// " mh.asType(ad.symbolicMethodTypeInvoker).invokeBasic(<LINK_TO_INVOKER_ARGS>);\n" +
	// " }\n" +
	// "}";
	//
	// // A template for deriving the operations
	// // could be supported by annotating VarHandle directly with the
	// // operation kind and shape
	// interface VarHandleTemplate {
	// Object get();
	//
	// void set(Object value);
	//
	// boolean compareAndSet(Object actualValue, Object expectedValue);
	//
	// Object compareAndExchange(Object actualValue, Object expectedValue);
	//
	// Object getAndUpdate(Object value);
	// }
	//
	// static class HandleType {
	// final Class<?> receiver;
	// final Class<?>[] intermediates;
	// final Class<?> value;
	//
	// HandleType(Class<?> receiver, Class<?> value, Class<?>... intermediates) {
	// this.receiver = receiver;
	// this.intermediates = intermediates;
	// this.value = value;
	// }
	// }
	//
	// /**
	// * @param args parameters
	// */
	// public static void main(String[] args) {
	// System.out.println("package java.lang.invoke;");
	// System.out.println();
	// System.out.println("import jdk.internal.vm.annotation.ForceInline;");
	// System.out.println();
	// System.out.println("// This class is auto-generated by " +
	// GuardMethodGenerator.class.getName() +
	// ". Do not edit.");
	// System.out.println("final class VarHandleGuards {");
	//
	// System.out.println();
	//
	// // Declare the stream of shapes
	// Stream<HandleType> hts = Stream.of(
	// // Object->Object
	// new HandleType(Object.class, Object.class),
	// // Object->int
	// new HandleType(Object.class, int.class),
	// // Object->long
	// new HandleType(Object.class, long.class),
	// // Object->float
	// new HandleType(Object.class, float.class),
	// // Object->double
	// new HandleType(Object.class, double.class),
	//
	// // <static>->Object
	// new HandleType(null, Object.class),
	// // <static>->int
	// new HandleType(null, int.class),
	// // <static>->long
	// new HandleType(null, long.class),
	// // <static>->float
	// new HandleType(null, float.class),
	// // <static>->double
	// new HandleType(null, double.class),
	//
	// // Array[int]->Object
	// new HandleType(Object.class, Object.class, int.class),
	// // Array[int]->int
	// new HandleType(Object.class, int.class, int.class),
	// // Array[int]->long
	// new HandleType(Object.class, long.class, int.class),
	// // Array[int]->float
	// new HandleType(Object.class, float.class, int.class),
	// // Array[int]->double
	// new HandleType(Object.class, double.class, int.class),
	//
	// // Array[long]->int
	// new HandleType(Object.class, int.class, long.class),
	// // Array[long]->long
	// new HandleType(Object.class, long.class, long.class)
	// );
	//
	// hts.flatMap(ht -> Stream.of(VarHandleTemplate.class.getMethods()).
	// map(m -> generateMethodType(m, ht.receiver, ht.value, ht.intermediates))).
	// distinct().
	// map(mt -> generateMethod(mt)).
	// forEach(s -> {
	// System.out.println(s);
	// System.out.println();
	// });
	//
	// System.out.println("}");
	// }
	//
	// static MethodType generateMethodType(Method m, Class<?> receiver, Class<?> value, Class<?>... intermediates) {
	// Class<?> returnType = m.getReturnType() == Object.class
	// ? value : m.getReturnType();
	//
	// List<Class<?>> params = new ArrayList<>();
	// if (receiver != null)
	// params.add(receiver);
	// for (int i = 0; i < intermediates.length; i++) {
	// params.add(intermediates[i]);
	// }
	// for (Parameter p : m.getParameters()) {
	// params.add(value);
	// }
	// return MethodType.methodType(returnType, params);
	// }
	//
	// static String generateMethod(MethodType mt) {
	// Class<?> returnType = mt.returnType();
	//
	// LinkedHashMap<String, Class<?>> params = new LinkedHashMap<>();
	// params.put("handle", VarHandle.class);
	// for (int i = 0; i < mt.parameterCount(); i++) {
	// params.put("arg" + i, mt.parameterType(i));
	// }
	// params.put("ad", VarHandle.AccessDescriptor.class);
	//
	// // Generate method signature line
	// String RETURN = className(returnType);
	// String NAME = "guard";
	// String SIGNATURE = getSignature(mt);
	// String PARAMS = params.entrySet().stream().
	// map(e -> className(e.getValue()) + " " + e.getKey()).
	// collect(joining(", "));
	// String METHOD = GUARD_METHOD_SIG_TEMPLATE.
	// replace("<RETURN>", RETURN).
	// replace("<NAME>", NAME).
	// replace("<SIGNATURE>", SIGNATURE).
	// replace("<PARAMS>", PARAMS);
	//
	// // Generate method
	// params.remove("ad");
	//
	// List<String> LINK_TO_STATIC_ARGS = params.keySet().stream().
	// collect(toList());
	// LINK_TO_STATIC_ARGS.add("handle.vform.getMemberName(ad.mode)");
	// List<String> LINK_TO_STATIC_ARGS_V = params.keySet().stream().
	// collect(toList());
	// LINK_TO_STATIC_ARGS_V.add("handle.vform.getMemberName_V(ad.mode)");
	//
	// List<String> LINK_TO_INVOKER_ARGS = params.keySet().stream().
	// collect(toList());
	//
	// RETURN = returnType == void.class
	// ? ""
	// : returnType == Object.class
	// ? "return "
	// : "return (" + returnType.getName() + ") ";
	//
	// String RESULT_ERASED = returnType == void.class
	// ? ""
	// : returnType != Object.class
	// ? "return (" + returnType.getName() + ") "
	// : "Object r = ";
	//
	// String RETURN_ERASED = returnType != Object.class
	// ? ""
	// : " return ad.returnType.cast(r);";
	//
	// String template = returnType == void.class
	// ? GUARD_METHOD_TEMPLATE_V
	// : GUARD_METHOD_TEMPLATE;
	// return template.
	// replace("<METHOD>", METHOD).
	// replace("<NAME>", NAME).
	// replaceAll("<RETURN>", RETURN).
	// replace("<RESULT_ERASED>", RESULT_ERASED).
	// replace("<RETURN_ERASED>", RETURN_ERASED).
	// replaceAll("<LINK_TO_STATIC_ARGS>", LINK_TO_STATIC_ARGS.stream().
	// collect(joining(", "))).
	// replaceAll("<LINK_TO_STATIC_ARGS_V>", LINK_TO_STATIC_ARGS_V.stream().
	// collect(joining(", "))).
	// replace("<LINK_TO_INVOKER_ARGS>", LINK_TO_INVOKER_ARGS.stream().
	// collect(joining(", ")))
	// ;
	// }
	//
	// static String className(Class<?> c) {
	// String n = c.getName();
	// if (n.startsWith("java.lang.")) {
	// n = n.replace("java.lang.", "");
	// if (n.startsWith("invoke.")) {
	// n = n.replace("invoke.", "");
	// }
	// }
	// return n.replace('$', '.');
	// }
	//
	// static String getSignature(MethodType m) {
	// StringBuilder sb = new StringBuilder(m.parameterCount() + 1);
	//
	// for (int i = 0; i < m.parameterCount(); i++) {
	// Class<?> pt = m.parameterType(i);
	// sb.append(getCharType(pt));
	// }
	//
	// sb.append('_').append(getCharType(m.returnType()));
	//
	// return sb.toString();
	// }
	//
	// static char getCharType(Class<?> pt) {
	// if (pt == void.class) {
	// return 'V';
	// }
	// else if (!pt.isPrimitive()) {
	// return 'L';
	// }
	// else if (pt == boolean.class) {
	// return 'Z';
	// }
	// else if (pt == int.class) {
	// return 'I';
	// }
	// else if (pt == long.class) {
	// return 'J';
	// }
	// else if (pt == float.class) {
	// return 'F';
	// }
	// else if (pt == double.class) {
	// return 'D';
	// }
	// else {
	// throw new IllegalStateException(pt.getName());
	// }
	// }
	// }
	}

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