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	/*
	* 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 java.lang.invoke.MethodHandles.Lookup;
	import java.lang.reflect.Field;
	import static java.lang.invoke.MethodHandleNatives.Constants.*;
	import static java.lang.invoke.MethodHandleStatics.*;
	import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;

	/**
	* The JVM interface for the method handles package is all here.
	* This is an interface internal and private to an implementation of JSR 292.
	* <em>This class is not part of the JSR 292 standard.</em>
	* @author jrose
	*/
	class MethodHandleNatives {

	private MethodHandleNatives() { } // static only

	/// MemberName support

	static native void init(MemberName self, Object ref);
	static native void expand(MemberName self);
	static native MemberName resolve(MemberName self, Class<?> caller) throws LinkageError, ClassNotFoundException;
	static native int getMembers(Class<?> defc, String matchName, String matchSig,
	int matchFlags, Class<?> caller, int skip, MemberName[] results);

	/// Field layout queries parallel to sun.misc.Unsafe:
	static native long objectFieldOffset(MemberName self); // e.g., returns vmindex
	static native long staticFieldOffset(MemberName self); // e.g., returns vmindex
	static native Object staticFieldBase(MemberName self); // e.g., returns clazz
	static native Object getMemberVMInfo(MemberName self); // returns {vmindex,vmtarget}

	/// MethodHandle support

	/** Fetch MH-related JVM parameter.
	* which=0 retrieves MethodHandlePushLimit
	* which=1 retrieves stack slot push size (in address units)
	*/
	static native int getConstant(int which);

	static final boolean COUNT_GWT;

	/// CallSite support

	/** Tell the JVM that we need to change the target of a CallSite. */
	static native void setCallSiteTargetNormal(CallSite site, MethodHandle target);
	static native void setCallSiteTargetVolatile(CallSite site, MethodHandle target);

	private static native void registerNatives();
	static {
	registerNatives();
	COUNT_GWT = getConstant(Constants.GC_COUNT_GWT) != 0;

	// The JVM calls MethodHandleNatives.<clinit>. Cascade the <clinit> calls as needed:
	MethodHandleImpl.initStatics();
	}

	// All compile-time constants go here.
	// There is an opportunity to check them against the JVM's idea of them.
	static class Constants {
	Constants() { } // static only
	// MethodHandleImpl
	static final int // for getConstant
	GC_COUNT_GWT = 4,
	GC_LAMBDA_SUPPORT = 5;

	// MemberName
	// The JVM uses values of -2 and above for vtable indexes.
	// Field values are simple positive offsets.
	// Ref: src/share/vm/oops/methodOop.hpp
	// This value is negative enough to avoid such numbers,
	// but not too negative.
	static final int
	MN_IS_METHOD = 0x00010000, // method (not constructor)
	MN_IS_CONSTRUCTOR = 0x00020000, // constructor
	MN_IS_FIELD = 0x00040000, // field
	MN_IS_TYPE = 0x00080000, // nested type
	MN_CALLER_SENSITIVE = 0x00100000, // @CallerSensitive annotation detected
	MN_REFERENCE_KIND_SHIFT = 24, // refKind
	MN_REFERENCE_KIND_MASK = 0x0F000000 >> MN_REFERENCE_KIND_SHIFT,
	// The SEARCH_* bits are not for MN.flags but for the matchFlags argument of MHN.getMembers:
	MN_SEARCH_SUPERCLASSES = 0x00100000,
	MN_SEARCH_INTERFACES = 0x00200000;

	/**
	* Basic types as encoded in the JVM. These code values are not
	* intended for use outside this class. They are used as part of
	* a private interface between the JVM and this class.
	*/
	static final int
	T_BOOLEAN = 4,
	T_CHAR = 5,
	T_FLOAT = 6,
	T_DOUBLE = 7,
	T_BYTE = 8,
	T_SHORT = 9,
	T_INT = 10,
	T_LONG = 11,
	T_OBJECT = 12,
	//T_ARRAY = 13
	T_VOID = 14,
	//T_ADDRESS = 15
	T_ILLEGAL = 99;

	/**
	* Constant pool entry types.
	*/
	static final byte
	CONSTANT_Utf8 = 1,
	CONSTANT_Integer = 3,
	CONSTANT_Float = 4,
	CONSTANT_Long = 5,
	CONSTANT_Double = 6,
	CONSTANT_Class = 7,
	CONSTANT_String = 8,
	CONSTANT_Fieldref = 9,
	CONSTANT_Methodref = 10,
	CONSTANT_InterfaceMethodref = 11,
	CONSTANT_NameAndType = 12,
	CONSTANT_MethodHandle = 15, // JSR 292
	CONSTANT_MethodType = 16, // JSR 292
	CONSTANT_InvokeDynamic = 18,
	CONSTANT_LIMIT = 19; // Limit to tags found in classfiles

	/**
	* Access modifier flags.
	*/
	static final char
	ACC_PUBLIC = 0x0001,
	ACC_PRIVATE = 0x0002,
	ACC_PROTECTED = 0x0004,
	ACC_STATIC = 0x0008,
	ACC_FINAL = 0x0010,
	ACC_SYNCHRONIZED = 0x0020,
	ACC_VOLATILE = 0x0040,
	ACC_TRANSIENT = 0x0080,
	ACC_NATIVE = 0x0100,
	ACC_INTERFACE = 0x0200,
	ACC_ABSTRACT = 0x0400,
	ACC_STRICT = 0x0800,
	ACC_SYNTHETIC = 0x1000,
	ACC_ANNOTATION = 0x2000,
	ACC_ENUM = 0x4000,
	// aliases:
	ACC_SUPER = ACC_SYNCHRONIZED,
	ACC_BRIDGE = ACC_VOLATILE,
	ACC_VARARGS = ACC_TRANSIENT;

	/**
	* Constant pool reference-kind codes, as used by CONSTANT_MethodHandle CP entries.
	*/
	static final byte
	REF_NONE = 0, // null value
	REF_getField = 1,
	REF_getStatic = 2,
	REF_putField = 3,
	REF_putStatic = 4,
	REF_invokeVirtual = 5,
	REF_invokeStatic = 6,
	REF_invokeSpecial = 7,
	REF_newInvokeSpecial = 8,
	REF_invokeInterface = 9,
	REF_LIMIT = 10;
	}

	static boolean refKindIsValid(int refKind) {
	return (refKind > REF_NONE && refKind < REF_LIMIT);
	}
	static boolean refKindIsField(byte refKind) {
	assert(refKindIsValid(refKind));
	return (refKind <= REF_putStatic);
	}
	static boolean refKindIsGetter(byte refKind) {
	assert(refKindIsValid(refKind));
	return (refKind <= REF_getStatic);
	}
	static boolean refKindIsSetter(byte refKind) {
	return refKindIsField(refKind) && !refKindIsGetter(refKind);
	}
	static boolean refKindIsMethod(byte refKind) {
	return !refKindIsField(refKind) && (refKind != REF_newInvokeSpecial);
	}
	static boolean refKindIsConstructor(byte refKind) {
	return (refKind == REF_newInvokeSpecial);
	}
	static boolean refKindHasReceiver(byte refKind) {
	assert(refKindIsValid(refKind));
	return (refKind & 1) != 0;
	}
	static boolean refKindIsStatic(byte refKind) {
	return !refKindHasReceiver(refKind) && (refKind != REF_newInvokeSpecial);
	}
	static boolean refKindDoesDispatch(byte refKind) {
	assert(refKindIsValid(refKind));
	return (refKind == REF_invokeVirtual \|\|
	refKind == REF_invokeInterface);
	}
	static {
	final int HR_MASK = ((1 << REF_getField) \|
	(1 << REF_putField) \|
	(1 << REF_invokeVirtual) \|
	(1 << REF_invokeSpecial) \|
	(1 << REF_invokeInterface)
	);
	for (byte refKind = REF_NONE+1; refKind < REF_LIMIT; refKind++) {
	assert(refKindHasReceiver(refKind) == (((1<<refKind) & HR_MASK) != 0)) : refKind;
	}
	}
	static String refKindName(byte refKind) {
	assert(refKindIsValid(refKind));
	switch (refKind) {
	case REF_getField: return "getField";
	case REF_getStatic: return "getStatic";
	case REF_putField: return "putField";
	case REF_putStatic: return "putStatic";
	case REF_invokeVirtual: return "invokeVirtual";
	case REF_invokeStatic: return "invokeStatic";
	case REF_invokeSpecial: return "invokeSpecial";
	case REF_newInvokeSpecial: return "newInvokeSpecial";
	case REF_invokeInterface: return "invokeInterface";
	default: return "REF_???";
	}
	}

	private static native int getNamedCon(int which, Object[] name);
	static boolean verifyConstants() {
	Object[] box = { null };
	for (int i = 0; ; i++) {
	box[0] = null;
	int vmval = getNamedCon(i, box);
	if (box[0] == null) break;
	String name = (String) box[0];
	try {
	Field con = Constants.class.getDeclaredField(name);
	int jval = con.getInt(null);
	if (jval == vmval) continue;
	String err = (name+": JVM has "+vmval+" while Java has "+jval);
	if (name.equals("CONV_OP_LIMIT")) {
	System.err.println("warning: "+err);
	continue;
	}
	throw new InternalError(err);
	} catch (NoSuchFieldException \| IllegalAccessException ex) {
	String err = (name+": JVM has "+vmval+" which Java does not define");
	// ignore exotic ops the JVM cares about; we just wont issue them
	//System.err.println("warning: "+err);
	continue;
	}
	}
	return true;
	}
	static {
	assert(verifyConstants());
	}

	// Up-calls from the JVM.
	// These must NOT be public.

	/**
	* The JVM is linking an invokedynamic instruction. Create a reified call site for it.
	*/
	static MemberName linkCallSite(Object callerObj,
	Object bootstrapMethodObj,
	Object nameObj, Object typeObj,
	Object staticArguments,
	Object[] appendixResult) {
	MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj;
	Class<?> caller = (Class<?>)callerObj;
	String name = nameObj.toString().intern();
	MethodType type = (MethodType)typeObj;
	if (!TRACE_METHOD_LINKAGE)
	return linkCallSiteImpl(caller, bootstrapMethod, name, type,
	staticArguments, appendixResult);
	return linkCallSiteTracing(caller, bootstrapMethod, name, type,
	staticArguments, appendixResult);
	}
	static MemberName linkCallSiteImpl(Class<?> caller,
	MethodHandle bootstrapMethod,
	String name, MethodType type,
	Object staticArguments,
	Object[] appendixResult) {
	CallSite callSite = CallSite.makeSite(bootstrapMethod,
	name,
	type,
	staticArguments,
	caller);
	if (callSite instanceof ConstantCallSite) {
	appendixResult[0] = callSite.dynamicInvoker();
	return Invokers.linkToTargetMethod(type);
	} else {
	appendixResult[0] = callSite;
	return Invokers.linkToCallSiteMethod(type);
	}
	}
	// Tracing logic:
	static MemberName linkCallSiteTracing(Class<?> caller,
	MethodHandle bootstrapMethod,
	String name, MethodType type,
	Object staticArguments,
	Object[] appendixResult) {
	Object bsmReference = bootstrapMethod.internalMemberName();
	if (bsmReference == null) bsmReference = bootstrapMethod;
	Object staticArglist = (staticArguments instanceof Object[] ?
	java.util.Arrays.asList((Object[]) staticArguments) :
	staticArguments);
	System.out.println("linkCallSite "+caller.getName()+" "+
	bsmReference+" "+
	name+type+"/"+staticArglist);
	try {
	MemberName res = linkCallSiteImpl(caller, bootstrapMethod, name, type,
	staticArguments, appendixResult);
	System.out.println("linkCallSite => "+res+" + "+appendixResult[0]);
	return res;
	} catch (Throwable ex) {
	System.out.println("linkCallSite => throw "+ex);
	throw ex;
	}
	}

	/**
	* The JVM wants a pointer to a MethodType. Oblige it by finding or creating one.
	*/
	static MethodType findMethodHandleType(Class<?> rtype, Class<?>[] ptypes) {
	return MethodType.makeImpl(rtype, ptypes, true);
	}

	/**
	* The JVM wants to link a call site that requires a dynamic type check.
	* Name is a type-checking invoker, invokeExact or invoke.
	* Return a JVM method (MemberName) to handle the invoking.
	* The method assumes the following arguments on the stack:
	* 0: the method handle being invoked
	* 1-N: the arguments to the method handle invocation
	* N+1: an optional, implicitly added argument (typically the given MethodType)
	* <p>
	* The nominal method at such a call site is an instance of
	* a signature-polymorphic method (see @PolymorphicSignature).
	* Such method instances are user-visible entities which are
	* "split" from the generic placeholder method in {@code MethodHandle}.
	* (Note that the placeholder method is not identical with any of
	* its instances. If invoked reflectively, is guaranteed to throw an
	* {@code UnsupportedOperationException}.)
	* If the signature-polymorphic method instance is ever reified,
	* it appears as a "copy" of the original placeholder
	* (a native final member of {@code MethodHandle}) except
	* that its type descriptor has shape required by the instance,
	* and the method instance is <em>not</em> varargs.
	* The method instance is also marked synthetic, since the
	* method (by definition) does not appear in Java source code.
	* <p>
	* The JVM is allowed to reify this method as instance metadata.
	* For example, {@code invokeBasic} is always reified.
	* But the JVM may instead call {@code linkMethod}.
	* If the result is an * ordered pair of a {@code (method, appendix)},
	* the method gets all the arguments (0..N inclusive)
	* plus the appendix (N+1), and uses the appendix to complete the call.
	* In this way, one reusable method (called a "linker method")
	* can perform the function of any number of polymorphic instance
	* methods.
	* <p>
	* Linker methods are allowed to be weakly typed, with any or
	* all references rewritten to {@code Object} and any primitives
	* (except {@code long}/{@code float}/{@code double})
	* rewritten to {@code int}.
	* A linker method is trusted to return a strongly typed result,
	* according to the specific method type descriptor of the
	* signature-polymorphic instance it is emulating.
	* This can involve (as necessary) a dynamic check using
	* data extracted from the appendix argument.
	* <p>
	* The JVM does not inspect the appendix, other than to pass
	* it verbatim to the linker method at every call.
	* This means that the JDK runtime has wide latitude
	* for choosing the shape of each linker method and its
	* corresponding appendix.
	* Linker methods should be generated from {@code LambdaForm}s
	* so that they do not become visible on stack traces.
	* <p>
	* The {@code linkMethod} call is free to omit the appendix
	* (returning null) and instead emulate the required function
	* completely in the linker method.
	* As a corner case, if N==255, no appendix is possible.
	* In this case, the method returned must be custom-generated to
	* to perform any needed type checking.
	* <p>
	* If the JVM does not reify a method at a call site, but instead
	* calls {@code linkMethod}, the corresponding call represented
	* in the bytecodes may mention a valid method which is not
	* representable with a {@code MemberName}.
	* Therefore, use cases for {@code linkMethod} tend to correspond to
	* special cases in reflective code such as {@code findVirtual}
	* or {@code revealDirect}.
	*/
	static MemberName linkMethod(Class<?> callerClass, int refKind,
	Class<?> defc, String name, Object type,
	Object[] appendixResult) {
	if (!TRACE_METHOD_LINKAGE)
	return linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
	return linkMethodTracing(callerClass, refKind, defc, name, type, appendixResult);
	}
	static MemberName linkMethodImpl(Class<?> callerClass, int refKind,
	Class<?> defc, String name, Object type,
	Object[] appendixResult) {
	try {
	if (defc == MethodHandle.class && refKind == REF_invokeVirtual) {
	return Invokers.methodHandleInvokeLinkerMethod(name, fixMethodType(callerClass, type), appendixResult);
	}
	} catch (Throwable ex) {
	if (ex instanceof LinkageError)
	throw (LinkageError) ex;
	else
	throw new LinkageError(ex.getMessage(), ex);
	}
	throw new LinkageError("no such method "+defc.getName()+"."+name+type);
	}
	private static MethodType fixMethodType(Class<?> callerClass, Object type) {
	if (type instanceof MethodType)
	return (MethodType) type;
	else
	return MethodType.fromMethodDescriptorString((String)type, callerClass.getClassLoader());
	}
	// Tracing logic:
	static MemberName linkMethodTracing(Class<?> callerClass, int refKind,
	Class<?> defc, String name, Object type,
	Object[] appendixResult) {
	System.out.println("linkMethod "+defc.getName()+"."+
	name+type+"/"+Integer.toHexString(refKind));
	try {
	MemberName res = linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
	System.out.println("linkMethod => "+res+" + "+appendixResult[0]);
	return res;
	} catch (Throwable ex) {
	System.out.println("linkMethod => throw "+ex);
	throw ex;
	}
	}


	/**
	* The JVM is resolving a CONSTANT_MethodHandle CP entry. And it wants our help.
	* It will make an up-call to this method. (Do not change the name or signature.)
	* The type argument is a Class for field requests and a MethodType for non-fields.
	* <p>
	* Recent versions of the JVM may also pass a resolved MemberName for the type.
	* In that case, the name is ignored and may be null.
	*/
	static MethodHandle linkMethodHandleConstant(Class<?> callerClass, int refKind,
	Class<?> defc, String name, Object type) {
	try {
	Lookup lookup = IMPL_LOOKUP.in(callerClass);
	assert(refKindIsValid(refKind));
	return lookup.linkMethodHandleConstant((byte) refKind, defc, name, type);
	} catch (IllegalAccessException ex) {
	Throwable cause = ex.getCause();
	if (cause instanceof AbstractMethodError) {
	throw (AbstractMethodError) cause;
	} else {
	Error err = new IllegalAccessError(ex.getMessage());
	throw initCauseFrom(err, ex);
	}
	} catch (NoSuchMethodException ex) {
	Error err = new NoSuchMethodError(ex.getMessage());
	throw initCauseFrom(err, ex);
	} catch (NoSuchFieldException ex) {
	Error err = new NoSuchFieldError(ex.getMessage());
	throw initCauseFrom(err, ex);
	} catch (ReflectiveOperationException ex) {
	Error err = new IncompatibleClassChangeError();
	throw initCauseFrom(err, ex);
	}
	}

	/**
	* Use best possible cause for err.initCause(), substituting the
	* cause for err itself if the cause has the same (or better) type.
	*/
	static private Error initCauseFrom(Error err, Exception ex) {
	Throwable th = ex.getCause();
	if (err.getClass().isInstance(th))
	return (Error) th;
	err.initCause(th == null ? ex : th);
	return err;
	}

	/**
	* Is this method a caller-sensitive method?
	* I.e., does it call Reflection.getCallerClass or a similer method
	* to ask about the identity of its caller?
	*/
	static boolean isCallerSensitive(MemberName mem) {
	if (!mem.isInvocable()) return false; // fields are not caller sensitive

	return mem.isCallerSensitive() \|\| canBeCalledVirtual(mem);
	}

	static boolean canBeCalledVirtual(MemberName mem) {
	assert(mem.isInvocable());
	Class<?> defc = mem.getDeclaringClass();
	switch (mem.getName()) {
	case "checkMemberAccess":
	return canBeCalledVirtual(mem, java.lang.SecurityManager.class);
	case "getContextClassLoader":
	return canBeCalledVirtual(mem, java.lang.Thread.class);
	}
	return false;
	}

	static boolean canBeCalledVirtual(MemberName symbolicRef, Class<?> definingClass) {
	Class<?> symbolicRefClass = symbolicRef.getDeclaringClass();
	if (symbolicRefClass == definingClass) return true;
	if (symbolicRef.isStatic() \|\| symbolicRef.isPrivate()) return false;
	return (definingClass.isAssignableFrom(symbolicRefClass) \|\| // Msym overrides Mdef
	symbolicRefClass.isInterface()); // Mdef implements Msym
	}
	}

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