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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;

	/**
	* Information about the input and output stack map frames of a basic block.
	*
	* @author Eric Bruneton
	*/
	final class Frame {

	/*
	* Frames are computed in a two steps process: during the visit of each
	* instruction, the state of the frame at the end of current basic block is
	* updated by simulating the action of the instruction on the previous state
	* of this so called "output frame". In visitMaxs, a fix point algorithm is
	* used to compute the "input frame" of each basic block, i.e. the stack map
	* frame at the beginning of the basic block, starting from the input frame
	* of the first basic block (which is computed from the method descriptor),
	* and by using the previously computed output frames to compute the input
	* state of the other blocks.
	*
	* All output and input frames are stored as arrays of integers. Reference
	* and array types are represented by an index into a type table (which is
	* not the same as the constant pool of the class, in order to avoid adding
	* unnecessary constants in the pool - not all computed frames will end up
	* being stored in the stack map table). This allows very fast type
	* comparisons.
	*
	* Output stack map frames are computed relatively to the input frame of the
	* basic block, which is not yet known when output frames are computed. It
	* is therefore necessary to be able to represent abstract types such as
	* "the type at position x in the input frame locals" or "the type at
	* position x from the top of the input frame stack" or even "the type at
	* position x in the input frame, with y more (or less) array dimensions".
	* This explains the rather complicated type format used in output frames.
	*
	* This format is the following: DIM KIND VALUE (4, 4 and 24 bits). DIM is a
	* signed number of array dimensions (from -8 to 7). KIND is either BASE,
	* LOCAL or STACK. BASE is used for types that are not relative to the input
	* frame. LOCAL is used for types that are relative to the input local
	* variable types. STACK is used for types that are relative to the input
	* stack types. VALUE depends on KIND. For LOCAL types, it is an index in
	* the input local variable types. For STACK types, it is a position
	* relatively to the top of input frame stack. For BASE types, it is either
	* one of the constants defined below, or for OBJECT and UNINITIALIZED
	* types, a tag and an index in the type table.
	*
	* Output frames can contain types of any kind and with a positive or
	* negative dimension (and even unassigned types, represented by 0 - which
	* does not correspond to any valid type value). Input frames can only
	* contain BASE types of positive or null dimension. In all cases the type
	* table contains only internal type names (array type descriptors are
	* forbidden - dimensions must be represented through the DIM field).
	*
	* The LONG and DOUBLE types are always represented by using two slots (LONG
	* + TOP or DOUBLE + TOP), for local variable types as well as in the
	* operand stack. This is necessary to be able to simulate DUPx_y
	* instructions, whose effect would be dependent on the actual type values
	* if types were always represented by a single slot in the stack (and this
	* is not possible, since actual type values are not always known - cf LOCAL
	* and STACK type kinds).
	*/

	/**
	* Mask to get the dimension of a frame type. This dimension is a signed
	* integer between -8 and 7.
	*/
	static final int DIM = 0xF0000000;

	/**
	* Constant to be added to a type to get a type with one more dimension.
	*/
	static final int ARRAY_OF = 0x10000000;

	/**
	* Constant to be added to a type to get a type with one less dimension.
	*/
	static final int ELEMENT_OF = 0xF0000000;

	/**
	* Mask to get the kind of a frame type.
	*
	* @see #BASE
	* @see #LOCAL
	* @see #STACK
	*/
	static final int KIND = 0xF000000;

	/**
	* Flag used for LOCAL and STACK types. Indicates that if this type happens
	* to be a long or double type (during the computations of input frames),
	* then it must be set to TOP because the second word of this value has been
	* reused to store other data in the basic block. Hence the first word no
	* longer stores a valid long or double value.
	*/
	static final int TOP_IF_LONG_OR_DOUBLE = 0x800000;

	/**
	* Mask to get the value of a frame type.
	*/
	static final int VALUE = 0x7FFFFF;

	/**
	* Mask to get the kind of base types.
	*/
	static final int BASE_KIND = 0xFF00000;

	/**
	* Mask to get the value of base types.
	*/
	static final int BASE_VALUE = 0xFFFFF;

	/**
	* Kind of the types that are not relative to an input stack map frame.
	*/
	static final int BASE = 0x1000000;

	/**
	* Base kind of the base reference types. The BASE_VALUE of such types is an
	* index into the type table.
	*/
	static final int OBJECT = BASE \| 0x700000;

	/**
	* Base kind of the uninitialized base types. The BASE_VALUE of such types
	* in an index into the type table (the Item at that index contains both an
	* instruction offset and an internal class name).
	*/
	static final int UNINITIALIZED = BASE \| 0x800000;

	/**
	* Kind of the types that are relative to the local variable types of an
	* input stack map frame. The value of such types is a local variable index.
	*/
	private static final int LOCAL = 0x2000000;

	/**
	* Kind of the the types that are relative to the stack of an input stack
	* map frame. The value of such types is a position relatively to the top of
	* this stack.
	*/
	private static final int STACK = 0x3000000;

	/**
	* The TOP type. This is a BASE type.
	*/
	static final int TOP = BASE \| 0;

	/**
	* The BOOLEAN type. This is a BASE type mainly used for array types.
	*/
	static final int BOOLEAN = BASE \| 9;

	/**
	* The BYTE type. This is a BASE type mainly used for array types.
	*/
	static final int BYTE = BASE \| 10;

	/**
	* The CHAR type. This is a BASE type mainly used for array types.
	*/
	static final int CHAR = BASE \| 11;

	/**
	* The SHORT type. This is a BASE type mainly used for array types.
	*/
	static final int SHORT = BASE \| 12;

	/**
	* The INTEGER type. This is a BASE type.
	*/
	static final int INTEGER = BASE \| 1;

	/**
	* The FLOAT type. This is a BASE type.
	*/
	static final int FLOAT = BASE \| 2;

	/**
	* The DOUBLE type. This is a BASE type.
	*/
	static final int DOUBLE = BASE \| 3;

	/**
	* The LONG type. This is a BASE type.
	*/
	static final int LONG = BASE \| 4;

	/**
	* The NULL type. This is a BASE type.
	*/
	static final int NULL = BASE \| 5;

	/**
	* The UNINITIALIZED_THIS type. This is a BASE type.
	*/
	static final int UNINITIALIZED_THIS = BASE \| 6;

	/**
	* The stack size variation corresponding to each JVM instruction. This
	* stack variation is equal to the size of the values produced by an
	* instruction, minus the size of the values consumed by this instruction.
	*/
	static final int[] SIZE;

	/**
	* Computes the stack size variation corresponding to each JVM instruction.
	*/
	static {
	int i;
	int[] b = new int[202];
	String s = "EFFFFFFFFGGFFFGGFFFEEFGFGFEEEEEEEEEEEEEEEEEEEEDEDEDDDDD"
	+ "CDCDEEEEEEEEEEEEEEEEEEEEBABABBBBDCFFFGGGEDCDCDCDCDCDCDCDCD"
	+ "CDCEEEEDDDDDDDCDCDCEFEFDDEEFFDEDEEEBDDBBDDDDDDCCCCCCCCEFED"
	+ "DDCDCDEEEEEEEEEEFEEEEEEDDEEDDEE";
	for (i = 0; i < b.length; ++i) {
	b[i] = s.charAt(i) - 'E';
	}
	SIZE = b;

	// code to generate the above string
	//
	// int NA = 0; // not applicable (unused opcode or variable size opcode)
	//
	// b = new int[] {
	// 0, //NOP, // visitInsn
	// 1, //ACONST_NULL, // -
	// 1, //ICONST_M1, // -
	// 1, //ICONST_0, // -
	// 1, //ICONST_1, // -
	// 1, //ICONST_2, // -
	// 1, //ICONST_3, // -
	// 1, //ICONST_4, // -
	// 1, //ICONST_5, // -
	// 2, //LCONST_0, // -
	// 2, //LCONST_1, // -
	// 1, //FCONST_0, // -
	// 1, //FCONST_1, // -
	// 1, //FCONST_2, // -
	// 2, //DCONST_0, // -
	// 2, //DCONST_1, // -
	// 1, //BIPUSH, // visitIntInsn
	// 1, //SIPUSH, // -
	// 1, //LDC, // visitLdcInsn
	// NA, //LDC_W, // -
	// NA, //LDC2_W, // -
	// 1, //ILOAD, // visitVarInsn
	// 2, //LLOAD, // -
	// 1, //FLOAD, // -
	// 2, //DLOAD, // -
	// 1, //ALOAD, // -
	// NA, //ILOAD_0, // -
	// NA, //ILOAD_1, // -
	// NA, //ILOAD_2, // -
	// NA, //ILOAD_3, // -
	// NA, //LLOAD_0, // -
	// NA, //LLOAD_1, // -
	// NA, //LLOAD_2, // -
	// NA, //LLOAD_3, // -
	// NA, //FLOAD_0, // -
	// NA, //FLOAD_1, // -
	// NA, //FLOAD_2, // -
	// NA, //FLOAD_3, // -
	// NA, //DLOAD_0, // -
	// NA, //DLOAD_1, // -
	// NA, //DLOAD_2, // -
	// NA, //DLOAD_3, // -
	// NA, //ALOAD_0, // -
	// NA, //ALOAD_1, // -
	// NA, //ALOAD_2, // -
	// NA, //ALOAD_3, // -
	// -1, //IALOAD, // visitInsn
	// 0, //LALOAD, // -
	// -1, //FALOAD, // -
	// 0, //DALOAD, // -
	// -1, //AALOAD, // -
	// -1, //BALOAD, // -
	// -1, //CALOAD, // -
	// -1, //SALOAD, // -
	// -1, //ISTORE, // visitVarInsn
	// -2, //LSTORE, // -
	// -1, //FSTORE, // -
	// -2, //DSTORE, // -
	// -1, //ASTORE, // -
	// NA, //ISTORE_0, // -
	// NA, //ISTORE_1, // -
	// NA, //ISTORE_2, // -
	// NA, //ISTORE_3, // -
	// NA, //LSTORE_0, // -
	// NA, //LSTORE_1, // -
	// NA, //LSTORE_2, // -
	// NA, //LSTORE_3, // -
	// NA, //FSTORE_0, // -
	// NA, //FSTORE_1, // -
	// NA, //FSTORE_2, // -
	// NA, //FSTORE_3, // -
	// NA, //DSTORE_0, // -
	// NA, //DSTORE_1, // -
	// NA, //DSTORE_2, // -
	// NA, //DSTORE_3, // -
	// NA, //ASTORE_0, // -
	// NA, //ASTORE_1, // -
	// NA, //ASTORE_2, // -
	// NA, //ASTORE_3, // -
	// -3, //IASTORE, // visitInsn
	// -4, //LASTORE, // -
	// -3, //FASTORE, // -
	// -4, //DASTORE, // -
	// -3, //AASTORE, // -
	// -3, //BASTORE, // -
	// -3, //CASTORE, // -
	// -3, //SASTORE, // -
	// -1, //POP, // -
	// -2, //POP2, // -
	// 1, //DUP, // -
	// 1, //DUP_X1, // -
	// 1, //DUP_X2, // -
	// 2, //DUP2, // -
	// 2, //DUP2_X1, // -
	// 2, //DUP2_X2, // -
	// 0, //SWAP, // -
	// -1, //IADD, // -
	// -2, //LADD, // -
	// -1, //FADD, // -
	// -2, //DADD, // -
	// -1, //ISUB, // -
	// -2, //LSUB, // -
	// -1, //FSUB, // -
	// -2, //DSUB, // -
	// -1, //IMUL, // -
	// -2, //LMUL, // -
	// -1, //FMUL, // -
	// -2, //DMUL, // -
	// -1, //IDIV, // -
	// -2, //LDIV, // -
	// -1, //FDIV, // -
	// -2, //DDIV, // -
	// -1, //IREM, // -
	// -2, //LREM, // -
	// -1, //FREM, // -
	// -2, //DREM, // -
	// 0, //INEG, // -
	// 0, //LNEG, // -
	// 0, //FNEG, // -
	// 0, //DNEG, // -
	// -1, //ISHL, // -
	// -1, //LSHL, // -
	// -1, //ISHR, // -
	// -1, //LSHR, // -
	// -1, //IUSHR, // -
	// -1, //LUSHR, // -
	// -1, //IAND, // -
	// -2, //LAND, // -
	// -1, //IOR, // -
	// -2, //LOR, // -
	// -1, //IXOR, // -
	// -2, //LXOR, // -
	// 0, //IINC, // visitIincInsn
	// 1, //I2L, // visitInsn
	// 0, //I2F, // -
	// 1, //I2D, // -
	// -1, //L2I, // -
	// -1, //L2F, // -
	// 0, //L2D, // -
	// 0, //F2I, // -
	// 1, //F2L, // -
	// 1, //F2D, // -
	// -1, //D2I, // -
	// 0, //D2L, // -
	// -1, //D2F, // -
	// 0, //I2B, // -
	// 0, //I2C, // -
	// 0, //I2S, // -
	// -3, //LCMP, // -
	// -1, //FCMPL, // -
	// -1, //FCMPG, // -
	// -3, //DCMPL, // -
	// -3, //DCMPG, // -
	// -1, //IFEQ, // visitJumpInsn
	// -1, //IFNE, // -
	// -1, //IFLT, // -
	// -1, //IFGE, // -
	// -1, //IFGT, // -
	// -1, //IFLE, // -
	// -2, //IF_ICMPEQ, // -
	// -2, //IF_ICMPNE, // -
	// -2, //IF_ICMPLT, // -
	// -2, //IF_ICMPGE, // -
	// -2, //IF_ICMPGT, // -
	// -2, //IF_ICMPLE, // -
	// -2, //IF_ACMPEQ, // -
	// -2, //IF_ACMPNE, // -
	// 0, //GOTO, // -
	// 1, //JSR, // -
	// 0, //RET, // visitVarInsn
	// -1, //TABLESWITCH, // visiTableSwitchInsn
	// -1, //LOOKUPSWITCH, // visitLookupSwitch
	// -1, //IRETURN, // visitInsn
	// -2, //LRETURN, // -
	// -1, //FRETURN, // -
	// -2, //DRETURN, // -
	// -1, //ARETURN, // -
	// 0, //RETURN, // -
	// NA, //GETSTATIC, // visitFieldInsn
	// NA, //PUTSTATIC, // -
	// NA, //GETFIELD, // -
	// NA, //PUTFIELD, // -
	// NA, //INVOKEVIRTUAL, // visitMethodInsn
	// NA, //INVOKESPECIAL, // -
	// NA, //INVOKESTATIC, // -
	// NA, //INVOKEINTERFACE, // -
	// NA, //INVOKEDYNAMIC, // visitInvokeDynamicInsn
	// 1, //NEW, // visitTypeInsn
	// 0, //NEWARRAY, // visitIntInsn
	// 0, //ANEWARRAY, // visitTypeInsn
	// 0, //ARRAYLENGTH, // visitInsn
	// NA, //ATHROW, // -
	// 0, //CHECKCAST, // visitTypeInsn
	// 0, //INSTANCEOF, // -
	// -1, //MONITORENTER, // visitInsn
	// -1, //MONITOREXIT, // -
	// NA, //WIDE, // NOT VISITED
	// NA, //MULTIANEWARRAY, // visitMultiANewArrayInsn
	// -1, //IFNULL, // visitJumpInsn
	// -1, //IFNONNULL, // -
	// NA, //GOTO_W, // -
	// NA, //JSR_W, // -
	// };
	// for (i = 0; i < b.length; ++i) {
	// System.err.print((char)('E' + b[i]));
	// }
	// System.err.println();
	}

	/**
	* The label (i.e. basic block) to which these input and output stack map
	* frames correspond.
	*/
	Label owner;

	/**
	* The input stack map frame locals.
	*/
	int[] inputLocals;

	/**
	* The input stack map frame stack.
	*/
	int[] inputStack;

	/**
	* The output stack map frame locals.
	*/
	private int[] outputLocals;

	/**
	* The output stack map frame stack.
	*/
	private int[] outputStack;

	/**
	* Relative size of the output stack. The exact semantics of this field
	* depends on the algorithm that is used.
	*
	* When only the maximum stack size is computed, this field is the size of
	* the output stack relatively to the top of the input stack.
	*
	* When the stack map frames are completely computed, this field is the
	* actual number of types in {@link #outputStack}.
	*/
	private int outputStackTop;

	/**
	* Number of types that are initialized in the basic block.
	*
	* @see #initializations
	*/
	private int initializationCount;

	/**
	* The types that are initialized in the basic block. A constructor
	* invocation on an UNINITIALIZED or UNINITIALIZED_THIS type must replace
	* <i>every occurence</i> of this type in the local variables and in the
	* operand stack. This cannot be done during the first phase of the
	* algorithm since, during this phase, the local variables and the operand
	* stack are not completely computed. It is therefore necessary to store the
	* types on which constructors are invoked in the basic block, in order to
	* do this replacement during the second phase of the algorithm, where the
	* frames are fully computed. Note that this array can contain types that
	* are relative to input locals or to the input stack (see below for the
	* description of the algorithm).
	*/
	private int[] initializations;

	/**
	* Returns the output frame local variable type at the given index.
	*
	* @param local
	* the index of the local that must be returned.
	* @return the output frame local variable type at the given index.
	*/
	private int get(final int local) {
	if (outputLocals == null \|\| local >= outputLocals.length) {
	// this local has never been assigned in this basic block,
	// so it is still equal to its value in the input frame
	return LOCAL \| local;
	} else {
	int type = outputLocals[local];
	if (type == 0) {
	// this local has never been assigned in this basic block,
	// so it is still equal to its value in the input frame
	type = outputLocals[local] = LOCAL \| local;
	}
	return type;
	}
	}

	/**
	* Sets the output frame local variable type at the given index.
	*
	* @param local
	* the index of the local that must be set.
	* @param type
	* the value of the local that must be set.
	*/
	private void set(final int local, final int type) {
	// creates and/or resizes the output local variables array if necessary
	if (outputLocals == null) {
	outputLocals = new int[10];
	}
	int n = outputLocals.length;
	if (local >= n) {
	int[] t = new int[Math.max(local + 1, 2 * n)];
	System.arraycopy(outputLocals, 0, t, 0, n);
	outputLocals = t;
	}
	// sets the local variable
	outputLocals[local] = type;
	}

	/**
	* Pushes a new type onto the output frame stack.
	*
	* @param type
	* the type that must be pushed.
	*/
	private void push(final int type) {
	// creates and/or resizes the output stack array if necessary
	if (outputStack == null) {
	outputStack = new int[10];
	}
	int n = outputStack.length;
	if (outputStackTop >= n) {
	int[] t = new int[Math.max(outputStackTop + 1, 2 * n)];
	System.arraycopy(outputStack, 0, t, 0, n);
	outputStack = t;
	}
	// pushes the type on the output stack
	outputStack[outputStackTop++] = type;
	// updates the maximun height reached by the output stack, if needed
	int top = owner.inputStackTop + outputStackTop;
	if (top > owner.outputStackMax) {
	owner.outputStackMax = top;
	}
	}

	/**
	* Pushes a new type onto the output frame stack.
	*
	* @param cw
	* the ClassWriter to which this label belongs.
	* @param desc
	* the descriptor of the type to be pushed. Can also be a method
	* descriptor (in this case this method pushes its return type
	* onto the output frame stack).
	*/
	private void push(final ClassWriter cw, final String desc) {
	int type = type(cw, desc);
	if (type != 0) {
	push(type);
	if (type == LONG \|\| type == DOUBLE) {
	push(TOP);
	}
	}
	}

	/**
	* Returns the int encoding of the given type.
	*
	* @param cw
	* the ClassWriter to which this label belongs.
	* @param desc
	* a type descriptor.
	* @return the int encoding of the given type.
	*/
	private static int type(final ClassWriter cw, final String desc) {
	String t;
	int index = desc.charAt(0) == '(' ? desc.indexOf(')') + 1 : 0;
	switch (desc.charAt(index)) {
	case 'V':
	return 0;
	case 'Z':
	case 'C':
	case 'B':
	case 'S':
	case 'I':
	return INTEGER;
	case 'F':
	return FLOAT;
	case 'J':
	return LONG;
	case 'D':
	return DOUBLE;
	case 'L':
	// stores the internal name, not the descriptor!
	t = desc.substring(index + 1, desc.length() - 1);
	return OBJECT \| cw.addType(t);
	// case '[':
	default:
	// extracts the dimensions and the element type
	int data;
	int dims = index + 1;
	while (desc.charAt(dims) == '[') {
	++dims;
	}
	switch (desc.charAt(dims)) {
	case 'Z':
	data = BOOLEAN;
	break;
	case 'C':
	data = CHAR;
	break;
	case 'B':
	data = BYTE;
	break;
	case 'S':
	data = SHORT;
	break;
	case 'I':
	data = INTEGER;
	break;
	case 'F':
	data = FLOAT;
	break;
	case 'J':
	data = LONG;
	break;
	case 'D':
	data = DOUBLE;
	break;
	// case 'L':
	default:
	// stores the internal name, not the descriptor
	t = desc.substring(dims + 1, desc.length() - 1);
	data = OBJECT \| cw.addType(t);
	}
	return (dims - index) << 28 \| data;
	}
	}

	/**
	* Pops a type from the output frame stack and returns its value.
	*
	* @return the type that has been popped from the output frame stack.
	*/
	private int pop() {
	if (outputStackTop > 0) {
	return outputStack[--outputStackTop];
	} else {
	// if the output frame stack is empty, pops from the input stack
	return STACK \| -(--owner.inputStackTop);
	}
	}

	/**
	* Pops the given number of types from the output frame stack.
	*
	* @param elements
	* the number of types that must be popped.
	*/
	private void pop(final int elements) {
	if (outputStackTop >= elements) {
	outputStackTop -= elements;
	} else {
	// if the number of elements to be popped is greater than the number
	// of elements in the output stack, clear it, and pops the remaining
	// elements from the input stack.
	owner.inputStackTop -= elements - outputStackTop;
	outputStackTop = 0;
	}
	}

	/**
	* Pops a type from the output frame stack.
	*
	* @param desc
	* the descriptor of the type to be popped. Can also be a method
	* descriptor (in this case this method pops the types
	* corresponding to the method arguments).
	*/
	private void pop(final String desc) {
	char c = desc.charAt(0);
	if (c == '(') {
	pop((Type.getArgumentsAndReturnSizes(desc) >> 2) - 1);
	} else if (c == 'J' \|\| c == 'D') {
	pop(2);
	} else {
	pop(1);
	}
	}

	/**
	* Adds a new type to the list of types on which a constructor is invoked in
	* the basic block.
	*
	* @param var
	* a type on a which a constructor is invoked.
	*/
	private void init(final int var) {
	// creates and/or resizes the initializations array if necessary
	if (initializations == null) {
	initializations = new int[2];
	}
	int n = initializations.length;
	if (initializationCount >= n) {
	int[] t = new int[Math.max(initializationCount + 1, 2 * n)];
	System.arraycopy(initializations, 0, t, 0, n);
	initializations = t;
	}
	// stores the type to be initialized
	initializations[initializationCount++] = var;
	}

	/**
	* Replaces the given type with the appropriate type if it is one of the
	* types on which a constructor is invoked in the basic block.
	*
	* @param cw
	* the ClassWriter to which this label belongs.
	* @param t
	* a type
	* @return t or, if t is one of the types on which a constructor is invoked
	* in the basic block, the type corresponding to this constructor.
	*/
	private int init(final ClassWriter cw, final int t) {
	int s;
	if (t == UNINITIALIZED_THIS) {
	s = OBJECT \| cw.addType(cw.thisName);
	} else if ((t & (DIM \| BASE_KIND)) == UNINITIALIZED) {
	String type = cw.typeTable[t & BASE_VALUE].strVal1;
	s = OBJECT \| cw.addType(type);
	} else {
	return t;
	}
	for (int j = 0; j < initializationCount; ++j) {
	int u = initializations[j];
	int dim = u & DIM;
	int kind = u & KIND;
	if (kind == LOCAL) {
	u = dim + inputLocals[u & VALUE];
	} else if (kind == STACK) {
	u = dim + inputStack[inputStack.length - (u & VALUE)];
	}
	if (t == u) {
	return s;
	}
	}
	return t;
	}

	/**
	* Initializes the input frame of the first basic block from the method
	* descriptor.
	*
	* @param cw
	* the ClassWriter to which this label belongs.
	* @param access
	* the access flags of the method to which this label belongs.
	* @param args
	* the formal parameter types of this method.
	* @param maxLocals
	* the maximum number of local variables of this method.
	*/
	void initInputFrame(final ClassWriter cw, final int access,
	final Type[] args, final int maxLocals) {
	inputLocals = new int[maxLocals];
	inputStack = new int[0];
	int i = 0;
	if ((access & Opcodes.ACC_STATIC) == 0) {
	if ((access & MethodWriter.ACC_CONSTRUCTOR) == 0) {
	inputLocals[i++] = OBJECT \| cw.addType(cw.thisName);
	} else {
	inputLocals[i++] = UNINITIALIZED_THIS;
	}
	}
	for (int j = 0; j < args.length; ++j) {
	int t = type(cw, args[j].getDescriptor());
	inputLocals[i++] = t;
	if (t == LONG \|\| t == DOUBLE) {
	inputLocals[i++] = TOP;
	}
	}
	while (i < maxLocals) {
	inputLocals[i++] = TOP;
	}
	}

	/**
	* Simulates the action of the given instruction on the output stack frame.
	*
	* @param opcode
	* the opcode of the instruction.
	* @param arg
	* the operand of the instruction, if any.
	* @param cw
	* the class writer to which this label belongs.
	* @param item
	* the operand of the instructions, if any.
	*/
	void execute(final int opcode, final int arg, final ClassWriter cw,
	final Item item) {
	int t1, t2, t3, t4;
	switch (opcode) {
	case Opcodes.NOP:
	case Opcodes.INEG:
	case Opcodes.LNEG:
	case Opcodes.FNEG:
	case Opcodes.DNEG:
	case Opcodes.I2B:
	case Opcodes.I2C:
	case Opcodes.I2S:
	case Opcodes.GOTO:
	case Opcodes.RETURN:
	break;
	case Opcodes.ACONST_NULL:
	push(NULL);
	break;
	case Opcodes.ICONST_M1:
	case Opcodes.ICONST_0:
	case Opcodes.ICONST_1:
	case Opcodes.ICONST_2:
	case Opcodes.ICONST_3:
	case Opcodes.ICONST_4:
	case Opcodes.ICONST_5:
	case Opcodes.BIPUSH:
	case Opcodes.SIPUSH:
	case Opcodes.ILOAD:
	push(INTEGER);
	break;
	case Opcodes.LCONST_0:
	case Opcodes.LCONST_1:
	case Opcodes.LLOAD:
	push(LONG);
	push(TOP);
	break;
	case Opcodes.FCONST_0:
	case Opcodes.FCONST_1:
	case Opcodes.FCONST_2:
	case Opcodes.FLOAD:
	push(FLOAT);
	break;
	case Opcodes.DCONST_0:
	case Opcodes.DCONST_1:
	case Opcodes.DLOAD:
	push(DOUBLE);
	push(TOP);
	break;
	case Opcodes.LDC:
	switch (item.type) {
	case ClassWriter.INT:
	push(INTEGER);
	break;
	case ClassWriter.LONG:
	push(LONG);
	push(TOP);
	break;
	case ClassWriter.FLOAT:
	push(FLOAT);
	break;
	case ClassWriter.DOUBLE:
	push(DOUBLE);
	push(TOP);
	break;
	case ClassWriter.CLASS:
	push(OBJECT \| cw.addType("java/lang/Class"));
	break;
	case ClassWriter.STR:
	push(OBJECT \| cw.addType("java/lang/String"));
	break;
	case ClassWriter.MTYPE:
	push(OBJECT \| cw.addType("java/lang/invoke/MethodType"));
	break;
	// case ClassWriter.HANDLE_BASE + [1..9]:
	default:
	push(OBJECT \| cw.addType("java/lang/invoke/MethodHandle"));
	}
	break;
	case Opcodes.ALOAD:
	push(get(arg));
	break;
	case Opcodes.IALOAD:
	case Opcodes.BALOAD:
	case Opcodes.CALOAD:
	case Opcodes.SALOAD:
	pop(2);
	push(INTEGER);
	break;
	case Opcodes.LALOAD:
	case Opcodes.D2L:
	pop(2);
	push(LONG);
	push(TOP);
	break;
	case Opcodes.FALOAD:
	pop(2);
	push(FLOAT);
	break;
	case Opcodes.DALOAD:
	case Opcodes.L2D:
	pop(2);
	push(DOUBLE);
	push(TOP);
	break;
	case Opcodes.AALOAD:
	pop(1);
	t1 = pop();
	push(ELEMENT_OF + t1);
	break;
	case Opcodes.ISTORE:
	case Opcodes.FSTORE:
	case Opcodes.ASTORE:
	t1 = pop();
	set(arg, t1);
	if (arg > 0) {
	t2 = get(arg - 1);
	// if t2 is of kind STACK or LOCAL we cannot know its size!
	if (t2 == LONG \|\| t2 == DOUBLE) {
	set(arg - 1, TOP);
	} else if ((t2 & KIND) != BASE) {
	set(arg - 1, t2 \| TOP_IF_LONG_OR_DOUBLE);
	}
	}
	break;
	case Opcodes.LSTORE:
	case Opcodes.DSTORE:
	pop(1);
	t1 = pop();
	set(arg, t1);
	set(arg + 1, TOP);
	if (arg > 0) {
	t2 = get(arg - 1);
	// if t2 is of kind STACK or LOCAL we cannot know its size!
	if (t2 == LONG \|\| t2 == DOUBLE) {
	set(arg - 1, TOP);
	} else if ((t2 & KIND) != BASE) {
	set(arg - 1, t2 \| TOP_IF_LONG_OR_DOUBLE);
	}
	}
	break;
	case Opcodes.IASTORE:
	case Opcodes.BASTORE:
	case Opcodes.CASTORE:
	case Opcodes.SASTORE:
	case Opcodes.FASTORE:
	case Opcodes.AASTORE:
	pop(3);
	break;
	case Opcodes.LASTORE:
	case Opcodes.DASTORE:
	pop(4);
	break;
	case Opcodes.POP:
	case Opcodes.IFEQ:
	case Opcodes.IFNE:
	case Opcodes.IFLT:
	case Opcodes.IFGE:
	case Opcodes.IFGT:
	case Opcodes.IFLE:
	case Opcodes.IRETURN:
	case Opcodes.FRETURN:
	case Opcodes.ARETURN:
	case Opcodes.TABLESWITCH:
	case Opcodes.LOOKUPSWITCH:
	case Opcodes.ATHROW:
	case Opcodes.MONITORENTER:
	case Opcodes.MONITOREXIT:
	case Opcodes.IFNULL:
	case Opcodes.IFNONNULL:
	pop(1);
	break;
	case Opcodes.POP2:
	case Opcodes.IF_ICMPEQ:
	case Opcodes.IF_ICMPNE:
	case Opcodes.IF_ICMPLT:
	case Opcodes.IF_ICMPGE:
	case Opcodes.IF_ICMPGT:
	case Opcodes.IF_ICMPLE:
	case Opcodes.IF_ACMPEQ:
	case Opcodes.IF_ACMPNE:
	case Opcodes.LRETURN:
	case Opcodes.DRETURN:
	pop(2);
	break;
	case Opcodes.DUP:
	t1 = pop();
	push(t1);
	push(t1);
	break;
	case Opcodes.DUP_X1:
	t1 = pop();
	t2 = pop();
	push(t1);
	push(t2);
	push(t1);
	break;
	case Opcodes.DUP_X2:
	t1 = pop();
	t2 = pop();
	t3 = pop();
	push(t1);
	push(t3);
	push(t2);
	push(t1);
	break;
	case Opcodes.DUP2:
	t1 = pop();
	t2 = pop();
	push(t2);
	push(t1);
	push(t2);
	push(t1);
	break;
	case Opcodes.DUP2_X1:
	t1 = pop();
	t2 = pop();
	t3 = pop();
	push(t2);
	push(t1);
	push(t3);
	push(t2);
	push(t1);
	break;
	case Opcodes.DUP2_X2:
	t1 = pop();
	t2 = pop();
	t3 = pop();
	t4 = pop();
	push(t2);
	push(t1);
	push(t4);
	push(t3);
	push(t2);
	push(t1);
	break;
	case Opcodes.SWAP:
	t1 = pop();
	t2 = pop();
	push(t1);
	push(t2);
	break;
	case Opcodes.IADD:
	case Opcodes.ISUB:
	case Opcodes.IMUL:
	case Opcodes.IDIV:
	case Opcodes.IREM:
	case Opcodes.IAND:
	case Opcodes.IOR:
	case Opcodes.IXOR:
	case Opcodes.ISHL:
	case Opcodes.ISHR:
	case Opcodes.IUSHR:
	case Opcodes.L2I:
	case Opcodes.D2I:
	case Opcodes.FCMPL:
	case Opcodes.FCMPG:
	pop(2);
	push(INTEGER);
	break;
	case Opcodes.LADD:
	case Opcodes.LSUB:
	case Opcodes.LMUL:
	case Opcodes.LDIV:
	case Opcodes.LREM:
	case Opcodes.LAND:
	case Opcodes.LOR:
	case Opcodes.LXOR:
	pop(4);
	push(LONG);
	push(TOP);
	break;
	case Opcodes.FADD:
	case Opcodes.FSUB:
	case Opcodes.FMUL:
	case Opcodes.FDIV:
	case Opcodes.FREM:
	case Opcodes.L2F:
	case Opcodes.D2F:
	pop(2);
	push(FLOAT);
	break;
	case Opcodes.DADD:
	case Opcodes.DSUB:
	case Opcodes.DMUL:
	case Opcodes.DDIV:
	case Opcodes.DREM:
	pop(4);
	push(DOUBLE);
	push(TOP);
	break;
	case Opcodes.LSHL:
	case Opcodes.LSHR:
	case Opcodes.LUSHR:
	pop(3);
	push(LONG);
	push(TOP);
	break;
	case Opcodes.IINC:
	set(arg, INTEGER);
	break;
	case Opcodes.I2L:
	case Opcodes.F2L:
	pop(1);
	push(LONG);
	push(TOP);
	break;
	case Opcodes.I2F:
	pop(1);
	push(FLOAT);
	break;
	case Opcodes.I2D:
	case Opcodes.F2D:
	pop(1);
	push(DOUBLE);
	push(TOP);
	break;
	case Opcodes.F2I:
	case Opcodes.ARRAYLENGTH:
	case Opcodes.INSTANCEOF:
	pop(1);
	push(INTEGER);
	break;
	case Opcodes.LCMP:
	case Opcodes.DCMPL:
	case Opcodes.DCMPG:
	pop(4);
	push(INTEGER);
	break;
	case Opcodes.JSR:
	case Opcodes.RET:
	throw new RuntimeException(
	"JSR/RET are not supported with computeFrames option");
	case Opcodes.GETSTATIC:
	push(cw, item.strVal3);
	break;
	case Opcodes.PUTSTATIC:
	pop(item.strVal3);
	break;
	case Opcodes.GETFIELD:
	pop(1);
	push(cw, item.strVal3);
	break;
	case Opcodes.PUTFIELD:
	pop(item.strVal3);
	pop();
	break;
	case Opcodes.INVOKEVIRTUAL:
	case Opcodes.INVOKESPECIAL:
	case Opcodes.INVOKESTATIC:
	case Opcodes.INVOKEINTERFACE:
	pop(item.strVal3);
	if (opcode != Opcodes.INVOKESTATIC) {
	t1 = pop();
	if (opcode == Opcodes.INVOKESPECIAL
	&& item.strVal2.charAt(0) == '<') {
	init(t1);
	}
	}
	push(cw, item.strVal3);
	break;
	case Opcodes.INVOKEDYNAMIC:
	pop(item.strVal2);
	push(cw, item.strVal2);
	break;
	case Opcodes.NEW:
	push(UNINITIALIZED \| cw.addUninitializedType(item.strVal1, arg));
	break;
	case Opcodes.NEWARRAY:
	pop();
	switch (arg) {
	case Opcodes.T_BOOLEAN:
	push(ARRAY_OF \| BOOLEAN);
	break;
	case Opcodes.T_CHAR:
	push(ARRAY_OF \| CHAR);
	break;
	case Opcodes.T_BYTE:
	push(ARRAY_OF \| BYTE);
	break;
	case Opcodes.T_SHORT:
	push(ARRAY_OF \| SHORT);
	break;
	case Opcodes.T_INT:
	push(ARRAY_OF \| INTEGER);
	break;
	case Opcodes.T_FLOAT:
	push(ARRAY_OF \| FLOAT);
	break;
	case Opcodes.T_DOUBLE:
	push(ARRAY_OF \| DOUBLE);
	break;
	// case Opcodes.T_LONG:
	default:
	push(ARRAY_OF \| LONG);
	break;
	}
	break;
	case Opcodes.ANEWARRAY:
	String s = item.strVal1;
	pop();
	if (s.charAt(0) == '[') {
	push(cw, '[' + s);
	} else {
	push(ARRAY_OF \| OBJECT \| cw.addType(s));
	}
	break;
	case Opcodes.CHECKCAST:
	s = item.strVal1;
	pop();
	if (s.charAt(0) == '[') {
	push(cw, s);
	} else {
	push(OBJECT \| cw.addType(s));
	}
	break;
	// case Opcodes.MULTIANEWARRAY:
	default:
	pop(arg);
	push(cw, item.strVal1);
	break;
	}
	}

	/**
	* Merges the input frame of the given basic block with the input and output
	* frames of this basic block. Returns <tt>true</tt> if the input frame of
	* the given label has been changed by this operation.
	*
	* @param cw
	* the ClassWriter to which this label belongs.
	* @param frame
	* the basic block whose input frame must be updated.
	* @param edge
	* the kind of the {@link Edge} between this label and 'label'.
	* See {@link Edge#info}.
	* @return <tt>true</tt> if the input frame of the given label has been
	* changed by this operation.
	*/
	boolean merge(final ClassWriter cw, final Frame frame, final int edge) {
	boolean changed = false;
	int i, s, dim, kind, t;

	int nLocal = inputLocals.length;
	int nStack = inputStack.length;
	if (frame.inputLocals == null) {
	frame.inputLocals = new int[nLocal];
	changed = true;
	}

	for (i = 0; i < nLocal; ++i) {
	if (outputLocals != null && i < outputLocals.length) {
	s = outputLocals[i];
	if (s == 0) {
	t = inputLocals[i];
	} else {
	dim = s & DIM;
	kind = s & KIND;
	if (kind == BASE) {
	t = s;
	} else {
	if (kind == LOCAL) {
	t = dim + inputLocals[s & VALUE];
	} else {
	t = dim + inputStack[nStack - (s & VALUE)];
	}
	if ((s & TOP_IF_LONG_OR_DOUBLE) != 0
	&& (t == LONG \|\| t == DOUBLE)) {
	t = TOP;
	}
	}
	}
	} else {
	t = inputLocals[i];
	}
	if (initializations != null) {
	t = init(cw, t);
	}
	changed \|= merge(cw, t, frame.inputLocals, i);
	}

	if (edge > 0) {
	for (i = 0; i < nLocal; ++i) {
	t = inputLocals[i];
	changed \|= merge(cw, t, frame.inputLocals, i);
	}
	if (frame.inputStack == null) {
	frame.inputStack = new int[1];
	changed = true;
	}
	changed \|= merge(cw, edge, frame.inputStack, 0);
	return changed;
	}

	int nInputStack = inputStack.length + owner.inputStackTop;
	if (frame.inputStack == null) {
	frame.inputStack = new int[nInputStack + outputStackTop];
	changed = true;
	}

	for (i = 0; i < nInputStack; ++i) {
	t = inputStack[i];
	if (initializations != null) {
	t = init(cw, t);
	}
	changed \|= merge(cw, t, frame.inputStack, i);
	}
	for (i = 0; i < outputStackTop; ++i) {
	s = outputStack[i];
	dim = s & DIM;
	kind = s & KIND;
	if (kind == BASE) {
	t = s;
	} else {
	if (kind == LOCAL) {
	t = dim + inputLocals[s & VALUE];
	} else {
	t = dim + inputStack[nStack - (s & VALUE)];
	}
	if ((s & TOP_IF_LONG_OR_DOUBLE) != 0
	&& (t == LONG \|\| t == DOUBLE)) {
	t = TOP;
	}
	}
	if (initializations != null) {
	t = init(cw, t);
	}
	changed \|= merge(cw, t, frame.inputStack, nInputStack + i);
	}
	return changed;
	}

	/**
	* Merges the type at the given index in the given type array with the given
	* type. Returns <tt>true</tt> if the type array has been modified by this
	* operation.
	*
	* @param cw
	* the ClassWriter to which this label belongs.
	* @param t
	* the type with which the type array element must be merged.
	* @param types
	* an array of types.
	* @param index
	* the index of the type that must be merged in 'types'.
	* @return <tt>true</tt> if the type array has been modified by this
	* operation.
	*/
	private static boolean merge(final ClassWriter cw, int t,
	final int[] types, final int index) {
	int u = types[index];
	if (u == t) {
	// if the types are equal, merge(u,t)=u, so there is no change
	return false;
	}
	if ((t & ~DIM) == NULL) {
	if (u == NULL) {
	return false;
	}
	t = NULL;
	}
	if (u == 0) {
	// if types[index] has never been assigned, merge(u,t)=t
	types[index] = t;
	return true;
	}
	int v;
	if ((u & BASE_KIND) == OBJECT \|\| (u & DIM) != 0) {
	// if u is a reference type of any dimension
	if (t == NULL) {
	// if t is the NULL type, merge(u,t)=u, so there is no change
	return false;
	} else if ((t & (DIM \| BASE_KIND)) == (u & (DIM \| BASE_KIND))) {
	// if t and u have the same dimension and same base kind
	if ((u & BASE_KIND) == OBJECT) {
	// if t is also a reference type, and if u and t have the
	// same dimension merge(u,t) = dim(t) \| common parent of the
	// element types of u and t
	v = (t & DIM) \| OBJECT
	\| cw.getMergedType(t & BASE_VALUE, u & BASE_VALUE);
	} else {
	// if u and t are array types, but not with the same element
	// type, merge(u,t) = dim(u) - 1 \| java/lang/Object
	int vdim = ELEMENT_OF + (u & DIM);
	v = vdim \| OBJECT \| cw.addType("java/lang/Object");
	}
	} else if ((t & BASE_KIND) == OBJECT \|\| (t & DIM) != 0) {
	// if t is any other reference or array type, the merged type
	// is min(udim, tdim) \| java/lang/Object, where udim is the
	// array dimension of u, minus 1 if u is an array type with a
	// primitive element type (and similarly for tdim).
	int tdim = (((t & DIM) == 0 \|\| (t & BASE_KIND) == OBJECT) ? 0
	: ELEMENT_OF) + (t & DIM);
	int udim = (((u & DIM) == 0 \|\| (u & BASE_KIND) == OBJECT) ? 0
	: ELEMENT_OF) + (u & DIM);
	v = Math.min(tdim, udim) \| OBJECT
	\| cw.addType("java/lang/Object");
	} else {
	// if t is any other type, merge(u,t)=TOP
	v = TOP;
	}
	} else if (u == NULL) {
	// if u is the NULL type, merge(u,t)=t,
	// or TOP if t is not a reference type
	v = (t & BASE_KIND) == OBJECT \|\| (t & DIM) != 0 ? t : TOP;
	} else {
	// if u is any other type, merge(u,t)=TOP whatever t
	v = TOP;
	}
	if (u != v) {
	types[index] = v;
	return true;
	}
	return false;
	}
	}

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