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	/*
	* 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.
	*/

	/*
	* This file is available under and governed by the GNU General Public
	* License version 2 only, as published by the Free Software Foundation.
	* However, the following notice accompanied the original version of this
	* file:
	*
	* ASM: a very small and fast Java bytecode manipulation framework
	* Copyright (c) 2000-2011 INRIA, France Telecom
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	* 3. Neither the name of the copyright holders nor the names of its
	* contributors may be used to endorse or promote products derived from
	* this software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
	* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
	* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
	* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
	* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
	* THE POSSIBILITY OF SUCH DAMAGE.
	*/
	package jdk.internal.org.objectweb.asm.commons;

	import java.util.ArrayList;
	import java.util.HashMap;
	import java.util.List;
	import java.util.Map;
	import jdk.internal.org.objectweb.asm.ConstantDynamic;
	import jdk.internal.org.objectweb.asm.Handle;
	import jdk.internal.org.objectweb.asm.Label;
	import jdk.internal.org.objectweb.asm.MethodVisitor;
	import jdk.internal.org.objectweb.asm.Opcodes;
	import jdk.internal.org.objectweb.asm.Type;

	/**
	* A {@link MethodVisitor} to insert before, after and around advices in methods and constructors.
	* For constructors, the code keeps track of the elements on the stack in order to detect when the
	* super class constructor is called (note that there can be multiple such calls in different
	* branches). {@code onMethodEnter} is called after each super class constructor call, because the
	* object cannot be used before it is properly initialized.
	*
	* @author Eugene Kuleshov
	* @author Eric Bruneton
	*/
	public abstract class AdviceAdapter extends GeneratorAdapter implements Opcodes {

	/** The "uninitialized this" value. */
	private static final Object UNINITIALIZED_THIS = new Object();

	/** Any value other than "uninitialized this". */
	private static final Object OTHER = new Object();

	/** Prefix of the error message when invalid opcodes are found. */
	private static final String INVALID_OPCODE = "Invalid opcode ";

	/** The access flags of the visited method. */
	protected int methodAccess;

	/** The descriptor of the visited method. */
	protected String methodDesc;

	/** Whether the visited method is a constructor. */
	private final boolean isConstructor;

	/**
	* Whether the super class constructor has been called (if the visited method is a constructor),
	* at the current instruction. There can be multiple call sites to the super constructor (e.g. for
	* Java code such as {@code super(expr ? value1 : value2);}), in different branches. When scanning
	* the bytecode linearly, we can move from one branch where the super constructor has been called
	* to another where it has not been called yet. Therefore, this value can change from false to
	* true, and vice-versa.
	*/
	private boolean superClassConstructorCalled;

	/**
	* The values on the current execution stack frame (long and double are represented by two
	* elements). Each value is either {@link #UNINITIALIZED_THIS} (for the uninitialized this value),
	* or {@link #OTHER} (for any other value). This field is only maintained for constructors, in
	* branches where the super class constructor has not been called yet.
	*/
	private List<Object> stackFrame;

	/**
	* The stack map frames corresponding to the labels of the forward jumps made before the super
	* class constructor has been called (note that the Java Virtual Machine forbids backward jumps
	* before the super class constructor is called). Note that by definition (cf. the 'before'), when
	* we reach a label from this map, {@link #superClassConstructorCalled} must be reset to false.
	* This field is only maintained for constructors.
	*/
	private Map<Label, List<Object>> forwardJumpStackFrames;

	/**
	* Constructs a new {@link AdviceAdapter}.
	*
	* @param api the ASM API version implemented by this visitor. Must be one of {@link
	* Opcodes#ASM4}, {@link Opcodes#ASM5}, {@link Opcodes#ASM6} or {@link Opcodes#ASM7}.
	* @param methodVisitor the method visitor to which this adapter delegates calls.
	* @param access the method's access flags (see {@link Opcodes}).
	* @param name the method's name.
	* @param descriptor the method's descriptor (see {@link Type Type}).
	*/
	protected AdviceAdapter(
	final int api,
	final MethodVisitor methodVisitor,
	final int access,
	final String name,
	final String descriptor) {
	super(api, methodVisitor, access, name, descriptor);
	methodAccess = access;
	methodDesc = descriptor;
	isConstructor = "<init>".equals(name);
	}

	@Override
	public void visitCode() {
	super.visitCode();
	if (isConstructor) {
	stackFrame = new ArrayList<>();
	forwardJumpStackFrames = new HashMap<>();
	} else {
	onMethodEnter();
	}
	}

	@Override
	public void visitLabel(final Label label) {
	super.visitLabel(label);
	if (isConstructor && forwardJumpStackFrames != null) {
	List<Object> labelStackFrame = forwardJumpStackFrames.get(label);
	if (labelStackFrame != null) {
	stackFrame = labelStackFrame;
	superClassConstructorCalled = false;
	forwardJumpStackFrames.remove(label);
	}
	}
	}

	@Override
	public void visitInsn(final int opcode) {
	if (isConstructor && !superClassConstructorCalled) {
	int stackSize;
	switch (opcode) {
	case IRETURN:
	case FRETURN:
	case ARETURN:
	case LRETURN:
	case DRETURN:
	throw new IllegalArgumentException("Invalid return in constructor");
	case RETURN: // empty stack
	onMethodExit(opcode);
	break;
	case ATHROW: // 1 before n/a after
	popValue();
	onMethodExit(opcode);
	break;
	case NOP:
	case LALOAD: // remove 2 add 2
	case DALOAD: // remove 2 add 2
	case LNEG:
	case DNEG:
	case FNEG:
	case INEG:
	case L2D:
	case D2L:
	case F2I:
	case I2B:
	case I2C:
	case I2S:
	case I2F:
	case ARRAYLENGTH:
	break;
	case ACONST_NULL:
	case ICONST_M1:
	case ICONST_0:
	case ICONST_1:
	case ICONST_2:
	case ICONST_3:
	case ICONST_4:
	case ICONST_5:
	case FCONST_0:
	case FCONST_1:
	case FCONST_2:
	case F2L: // 1 before 2 after
	case F2D:
	case I2L:
	case I2D:
	pushValue(OTHER);
	break;
	case LCONST_0:
	case LCONST_1:
	case DCONST_0:
	case DCONST_1:
	pushValue(OTHER);
	pushValue(OTHER);
	break;
	case IALOAD: // remove 2 add 1
	case FALOAD: // remove 2 add 1
	case AALOAD: // remove 2 add 1
	case BALOAD: // remove 2 add 1
	case CALOAD: // remove 2 add 1
	case SALOAD: // remove 2 add 1
	case POP:
	case IADD:
	case FADD:
	case ISUB:
	case LSHL: // 3 before 2 after
	case LSHR: // 3 before 2 after
	case LUSHR: // 3 before 2 after
	case L2I: // 2 before 1 after
	case L2F: // 2 before 1 after
	case D2I: // 2 before 1 after
	case D2F: // 2 before 1 after
	case FSUB:
	case FMUL:
	case FDIV:
	case FREM:
	case FCMPL: // 2 before 1 after
	case FCMPG: // 2 before 1 after
	case IMUL:
	case IDIV:
	case IREM:
	case ISHL:
	case ISHR:
	case IUSHR:
	case IAND:
	case IOR:
	case IXOR:
	case MONITORENTER:
	case MONITOREXIT:
	popValue();
	break;
	case POP2:
	case LSUB:
	case LMUL:
	case LDIV:
	case LREM:
	case LADD:
	case LAND:
	case LOR:
	case LXOR:
	case DADD:
	case DMUL:
	case DSUB:
	case DDIV:
	case DREM:
	popValue();
	popValue();
	break;
	case IASTORE:
	case FASTORE:
	case AASTORE:
	case BASTORE:
	case CASTORE:
	case SASTORE:
	case LCMP: // 4 before 1 after
	case DCMPL:
	case DCMPG:
	popValue();
	popValue();
	popValue();
	break;
	case LASTORE:
	case DASTORE:
	popValue();
	popValue();
	popValue();
	popValue();
	break;
	case DUP:
	pushValue(peekValue());
	break;
	case DUP_X1:
	stackSize = stackFrame.size();
	stackFrame.add(stackSize - 2, stackFrame.get(stackSize - 1));
	break;
	case DUP_X2:
	stackSize = stackFrame.size();
	stackFrame.add(stackSize - 3, stackFrame.get(stackSize - 1));
	break;
	case DUP2:
	stackSize = stackFrame.size();
	stackFrame.add(stackSize - 2, stackFrame.get(stackSize - 1));
	stackFrame.add(stackSize - 2, stackFrame.get(stackSize - 1));
	break;
	case DUP2_X1:
	stackSize = stackFrame.size();
	stackFrame.add(stackSize - 3, stackFrame.get(stackSize - 1));
	stackFrame.add(stackSize - 3, stackFrame.get(stackSize - 1));
	break;
	case DUP2_X2:
	stackSize = stackFrame.size();
	stackFrame.add(stackSize - 4, stackFrame.get(stackSize - 1));
	stackFrame.add(stackSize - 4, stackFrame.get(stackSize - 1));
	break;
	case SWAP:
	stackSize = stackFrame.size();
	stackFrame.add(stackSize - 2, stackFrame.get(stackSize - 1));
	stackFrame.remove(stackSize);
	break;
	default:
	throw new IllegalArgumentException(INVALID_OPCODE + opcode);
	}
	} else {
	switch (opcode) {
	case RETURN:
	case IRETURN:
	case FRETURN:
	case ARETURN:
	case LRETURN:
	case DRETURN:
	case ATHROW:
	onMethodExit(opcode);
	break;
	default:
	break;
	}
	}
	super.visitInsn(opcode);
	}

	@Override
	public void visitVarInsn(final int opcode, final int var) {
	super.visitVarInsn(opcode, var);
	if (isConstructor && !superClassConstructorCalled) {
	switch (opcode) {
	case ILOAD:
	case FLOAD:
	pushValue(OTHER);
	break;
	case LLOAD:
	case DLOAD:
	pushValue(OTHER);
	pushValue(OTHER);
	break;
	case ALOAD:
	pushValue(var == 0 ? UNINITIALIZED_THIS : OTHER);
	break;
	case ASTORE:
	case ISTORE:
	case FSTORE:
	popValue();
	break;
	case LSTORE:
	case DSTORE:
	popValue();
	popValue();
	break;
	case RET:
	break;
	default:
	throw new IllegalArgumentException(INVALID_OPCODE + opcode);
	}
	}
	}

	@Override
	public void visitFieldInsn(
	final int opcode, final String owner, final String name, final String descriptor) {
	super.visitFieldInsn(opcode, owner, name, descriptor);
	if (isConstructor && !superClassConstructorCalled) {
	char firstDescriptorChar = descriptor.charAt(0);
	boolean longOrDouble = firstDescriptorChar == 'J' \|\| firstDescriptorChar == 'D';
	switch (opcode) {
	case GETSTATIC:
	pushValue(OTHER);
	if (longOrDouble) {
	pushValue(OTHER);
	}
	break;
	case PUTSTATIC:
	popValue();
	if (longOrDouble) {
	popValue();
	}
	break;
	case PUTFIELD:
	popValue();
	popValue();
	if (longOrDouble) {
	popValue();
	}
	break;
	case GETFIELD:
	if (longOrDouble) {
	pushValue(OTHER);
	}
	break;
	default:
	throw new IllegalArgumentException(INVALID_OPCODE + opcode);
	}
	}
	}

	@Override
	public void visitIntInsn(final int opcode, final int operand) {
	super.visitIntInsn(opcode, operand);
	if (isConstructor && !superClassConstructorCalled && opcode != NEWARRAY) {
	pushValue(OTHER);
	}
	}

	@Override
	public void visitLdcInsn(final Object value) {
	super.visitLdcInsn(value);
	if (isConstructor && !superClassConstructorCalled) {
	pushValue(OTHER);
	if (value instanceof Double
	\|\| value instanceof Long
	\|\| (value instanceof ConstantDynamic && ((ConstantDynamic) value).getSize() == 2)) {
	pushValue(OTHER);
	}
	}
	}

	@Override
	public void visitMultiANewArrayInsn(final String descriptor, final int numDimensions) {
	super.visitMultiANewArrayInsn(descriptor, numDimensions);
	if (isConstructor && !superClassConstructorCalled) {
	for (int i = 0; i < numDimensions; i++) {
	popValue();
	}
	pushValue(OTHER);
	}
	}

	@Override
	public void visitTypeInsn(final int opcode, final String type) {
	super.visitTypeInsn(opcode, type);
	// ANEWARRAY, CHECKCAST or INSTANCEOF don't change stack.
	if (isConstructor && !superClassConstructorCalled && opcode == NEW) {
	pushValue(OTHER);
	}
	}

	@Override
	public void visitMethodInsn(
	final int opcodeAndSource,
	final String owner,
	final String name,
	final String descriptor,
	final boolean isInterface) {
	if (api < Opcodes.ASM5 && (opcodeAndSource & Opcodes.SOURCE_DEPRECATED) == 0) {
	// Redirect the call to the deprecated version of this method.
	super.visitMethodInsn(opcodeAndSource, owner, name, descriptor, isInterface);
	return;
	}
	super.visitMethodInsn(opcodeAndSource, owner, name, descriptor, isInterface);
	int opcode = opcodeAndSource & ~Opcodes.SOURCE_MASK;

	doVisitMethodInsn(opcode, descriptor);
	}

	private void doVisitMethodInsn(final int opcode, final String descriptor) {
	if (isConstructor && !superClassConstructorCalled) {
	for (Type argumentType : Type.getArgumentTypes(descriptor)) {
	popValue();
	if (argumentType.getSize() == 2) {
	popValue();
	}
	}
	switch (opcode) {
	case INVOKEINTERFACE:
	case INVOKEVIRTUAL:
	popValue();
	break;
	case INVOKESPECIAL:
	Object value = popValue();
	if (value == UNINITIALIZED_THIS && !superClassConstructorCalled) {
	superClassConstructorCalled = true;
	onMethodEnter();
	}
	break;
	default:
	break;
	}

	Type returnType = Type.getReturnType(descriptor);
	if (returnType != Type.VOID_TYPE) {
	pushValue(OTHER);
	if (returnType.getSize() == 2) {
	pushValue(OTHER);
	}
	}
	}
	}

	@Override
	public void visitInvokeDynamicInsn(
	final String name,
	final String descriptor,
	final Handle bootstrapMethodHandle,
	final Object... bootstrapMethodArguments) {
	super.visitInvokeDynamicInsn(name, descriptor, bootstrapMethodHandle, bootstrapMethodArguments);
	doVisitMethodInsn(Opcodes.INVOKEDYNAMIC, descriptor);
	}

	@Override
	public void visitJumpInsn(final int opcode, final Label label) {
	super.visitJumpInsn(opcode, label);
	if (isConstructor && !superClassConstructorCalled) {
	switch (opcode) {
	case IFEQ:
	case IFNE:
	case IFLT:
	case IFGE:
	case IFGT:
	case IFLE:
	case IFNULL:
	case IFNONNULL:
	popValue();
	break;
	case IF_ICMPEQ:
	case IF_ICMPNE:
	case IF_ICMPLT:
	case IF_ICMPGE:
	case IF_ICMPGT:
	case IF_ICMPLE:
	case IF_ACMPEQ:
	case IF_ACMPNE:
	popValue();
	popValue();
	break;
	case JSR:
	pushValue(OTHER);
	break;
	default:
	break;
	}
	addForwardJump(label);
	}
	}

	@Override
	public void visitLookupSwitchInsn(final Label dflt, final int[] keys, final Label[] labels) {
	super.visitLookupSwitchInsn(dflt, keys, labels);
	if (isConstructor && !superClassConstructorCalled) {
	popValue();
	addForwardJumps(dflt, labels);
	}
	}

	@Override
	public void visitTableSwitchInsn(
	final int min, final int max, final Label dflt, final Label... labels) {
	super.visitTableSwitchInsn(min, max, dflt, labels);
	if (isConstructor && !superClassConstructorCalled) {
	popValue();
	addForwardJumps(dflt, labels);
	}
	}

	@Override
	public void visitTryCatchBlock(
	final Label start, final Label end, final Label handler, final String type) {
	super.visitTryCatchBlock(start, end, handler, type);
	// By definition of 'forwardJumpStackFrames', 'handler' should be pushed only if there is an
	// instruction between 'start' and 'end' at which the super class constructor is not yet
	// called. Unfortunately, try catch blocks must be visited before their labels, so we have no
	// way to know this at this point. Instead, we suppose that the super class constructor has not
	// been called at the start of any exception handler. If this is wrong, normally there should
	// not be a second super class constructor call in the exception handler (an object can't be
	// initialized twice), so this is not issue (in the sense that there is no risk to emit a wrong
	// 'onMethodEnter').
	if (isConstructor && !forwardJumpStackFrames.containsKey(handler)) {
	List<Object> handlerStackFrame = new ArrayList<>();
	handlerStackFrame.add(OTHER);
	forwardJumpStackFrames.put(handler, handlerStackFrame);
	}
	}

	private void addForwardJumps(final Label dflt, final Label[] labels) {
	addForwardJump(dflt);
	for (Label label : labels) {
	addForwardJump(label);
	}
	}

	private void addForwardJump(final Label label) {
	if (forwardJumpStackFrames.containsKey(label)) {
	return;
	}
	forwardJumpStackFrames.put(label, new ArrayList<>(stackFrame));
	}

	private Object popValue() {
	return stackFrame.remove(stackFrame.size() - 1);
	}

	private Object peekValue() {
	return stackFrame.get(stackFrame.size() - 1);
	}

	private void pushValue(final Object value) {
	stackFrame.add(value);
	}

	/**
	* Generates the "before" advice for the visited method. The default implementation of this method
	* does nothing. Subclasses can use or change all the local variables, but should not change state
	* of the stack. This method is called at the beginning of the method or after super class
	* constructor has been called (in constructors).
	*/
	protected void onMethodEnter() {}

	/**
	* Generates the "after" advice for the visited method. The default implementation of this method
	* does nothing. Subclasses can use or change all the local variables, but should not change state
	* of the stack. This method is called at the end of the method, just before return and athrow
	* instructions. The top element on the stack contains the return value or the exception instance.
	* For example:
	*
	* <pre>
	* public void onMethodExit(final int opcode) {
	* if (opcode == RETURN) {
	* visitInsn(ACONST_NULL);
	* } else if (opcode == ARETURN \|\| opcode == ATHROW) {
	* dup();
	* } else {
	* if (opcode == LRETURN \|\| opcode == DRETURN) {
	* dup2();
	* } else {
	* dup();
	* }
	* box(Type.getReturnType(this.methodDesc));
	* }
	* visitIntInsn(SIPUSH, opcode);
	* visitMethodInsn(INVOKESTATIC, owner, "onExit", "(Ljava/lang/Object;I)V");
	* }
	*
	* // An actual call back method.
	* public static void onExit(final Object exitValue, final int opcode) {
	* ...
	* }
	* </pre>
	*
	* @param opcode one of {@link Opcodes#RETURN}, {@link Opcodes#IRETURN}, {@link Opcodes#FRETURN},
	* {@link Opcodes#ARETURN}, {@link Opcodes#LRETURN}, {@link Opcodes#DRETURN} or {@link
	* Opcodes#ATHROW}.
	*/
	protected void onMethodExit(final int opcode) {}
	}

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