/*
 * Copyright (c) 2010, 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 jdk.nashorn.internal.codegen;

import static jdk.internal.org.objectweb.asm.Opcodes.ATHROW;
import static jdk.internal.org.objectweb.asm.Opcodes.CHECKCAST;
import static jdk.internal.org.objectweb.asm.Opcodes.DUP2;
import static jdk.internal.org.objectweb.asm.Opcodes.GETFIELD;
import static jdk.internal.org.objectweb.asm.Opcodes.GETSTATIC;
import static jdk.internal.org.objectweb.asm.Opcodes.GOTO;
import static jdk.internal.org.objectweb.asm.Opcodes.H_INVOKESTATIC;
import static jdk.internal.org.objectweb.asm.Opcodes.H_INVOKEINTERFACE;
import static jdk.internal.org.objectweb.asm.Opcodes.IFEQ;
import static jdk.internal.org.objectweb.asm.Opcodes.IFGE;
import static jdk.internal.org.objectweb.asm.Opcodes.IFGT;
import static jdk.internal.org.objectweb.asm.Opcodes.IFLE;
import static jdk.internal.org.objectweb.asm.Opcodes.IFLT;
import static jdk.internal.org.objectweb.asm.Opcodes.IFNE;
import static jdk.internal.org.objectweb.asm.Opcodes.IFNONNULL;
import static jdk.internal.org.objectweb.asm.Opcodes.IFNULL;
import static jdk.internal.org.objectweb.asm.Opcodes.IF_ACMPEQ;
import static jdk.internal.org.objectweb.asm.Opcodes.IF_ACMPNE;
import static jdk.internal.org.objectweb.asm.Opcodes.IF_ICMPEQ;
import static jdk.internal.org.objectweb.asm.Opcodes.IF_ICMPGE;
import static jdk.internal.org.objectweb.asm.Opcodes.IF_ICMPGT;
import static jdk.internal.org.objectweb.asm.Opcodes.IF_ICMPLE;
import static jdk.internal.org.objectweb.asm.Opcodes.IF_ICMPLT;
import static jdk.internal.org.objectweb.asm.Opcodes.IF_ICMPNE;
import static jdk.internal.org.objectweb.asm.Opcodes.INSTANCEOF;
import static jdk.internal.org.objectweb.asm.Opcodes.INVOKEINTERFACE;
import static jdk.internal.org.objectweb.asm.Opcodes.INVOKESPECIAL;
import static jdk.internal.org.objectweb.asm.Opcodes.INVOKESTATIC;
import static jdk.internal.org.objectweb.asm.Opcodes.INVOKEVIRTUAL;
import static jdk.internal.org.objectweb.asm.Opcodes.NEW;
import static jdk.internal.org.objectweb.asm.Opcodes.PUTFIELD;
import static jdk.internal.org.objectweb.asm.Opcodes.PUTSTATIC;
import static jdk.internal.org.objectweb.asm.Opcodes.RETURN;
import static jdk.nashorn.internal.codegen.CompilerConstants.ARGUMENTS;
import static jdk.nashorn.internal.codegen.CompilerConstants.CONSTANTS;
import static jdk.nashorn.internal.codegen.CompilerConstants.SCOPE;
import static jdk.nashorn.internal.codegen.CompilerConstants.THIS;
import static jdk.nashorn.internal.codegen.CompilerConstants.THIS_DEBUGGER;
import static jdk.nashorn.internal.codegen.CompilerConstants.VARARGS;
import static jdk.nashorn.internal.codegen.CompilerConstants.className;
import static jdk.nashorn.internal.codegen.CompilerConstants.constructorNoLookup;
import static jdk.nashorn.internal.codegen.CompilerConstants.methodDescriptor;
import static jdk.nashorn.internal.codegen.CompilerConstants.staticField;
import static jdk.nashorn.internal.codegen.CompilerConstants.virtualCallNoLookup;
import static jdk.nashorn.internal.codegen.ObjectClassGenerator.PRIMITIVE_FIELD_TYPE;
import static jdk.nashorn.internal.runtime.linker.NameCodec.EMPTY_NAME;
import static jdk.nashorn.internal.runtime.linker.NashornCallSiteDescriptor.CALLSITE_OPTIMISTIC;
import static jdk.nashorn.internal.runtime.linker.NashornCallSiteDescriptor.CALLSITE_PROGRAM_POINT_SHIFT;

import java.io.PrintStream;
import java.lang.reflect.Array;
import java.util.Collection;
import java.util.EnumSet;
import java.util.IdentityHashMap;
import java.util.List;
import java.util.Map;
import jdk.internal.org.objectweb.asm.Handle;
import jdk.internal.org.objectweb.asm.MethodVisitor;
import jdk.nashorn.internal.codegen.ClassEmitter.Flag;
import jdk.nashorn.internal.codegen.CompilerConstants.Call;
import jdk.nashorn.internal.codegen.CompilerConstants.FieldAccess;
import jdk.nashorn.internal.codegen.types.ArrayType;
import jdk.nashorn.internal.codegen.types.BitwiseType;
import jdk.nashorn.internal.codegen.types.NumericType;
import jdk.nashorn.internal.codegen.types.Type;
import jdk.nashorn.internal.ir.FunctionNode;
import jdk.nashorn.internal.ir.IdentNode;
import jdk.nashorn.internal.ir.JoinPredecessor;
import jdk.nashorn.internal.ir.LiteralNode;
import jdk.nashorn.internal.ir.LocalVariableConversion;
import jdk.nashorn.internal.ir.Symbol;
import jdk.nashorn.internal.ir.TryNode;
import jdk.nashorn.internal.objects.NativeArray;
import jdk.nashorn.internal.runtime.ArgumentSetter;
import jdk.nashorn.internal.runtime.Context;
import jdk.nashorn.internal.runtime.Debug;
import jdk.nashorn.internal.runtime.JSType;
import jdk.nashorn.internal.runtime.RewriteException;
import jdk.nashorn.internal.runtime.Scope;
import jdk.nashorn.internal.runtime.ScriptObject;
import jdk.nashorn.internal.runtime.ScriptRuntime;
import jdk.nashorn.internal.runtime.UnwarrantedOptimismException;
import jdk.nashorn.internal.runtime.linker.Bootstrap;
import jdk.nashorn.internal.runtime.linker.NameCodec;
import jdk.nashorn.internal.runtime.linker.NashornCallSiteDescriptor;
import jdk.nashorn.internal.runtime.logging.DebugLogger;
import jdk.nashorn.internal.runtime.options.Options;

This is the main function responsible for emitting method code
in a class. It maintains a type stack and keeps track of control
flow to make sure that the registered instructions don't violate
byte code verification.
Running Nashorn with -ea will assert as soon as a type stack
becomes corrupt, for easier debugging
Running Nashorn with -Dnashorn.codegen.debug=true will print
all generated bytecode and labels to stderr, for easier debugging,
including bytecode stack contents
/**
 * This is the main function responsible for emitting method code
 * in a class. It maintains a type stack and keeps track of control
 * flow to make sure that the registered instructions don't violate
 * byte code verification.
 *
 * Running Nashorn with -ea will assert as soon as a type stack
 * becomes corrupt, for easier debugging
 *
 * Running Nashorn with -Dnashorn.codegen.debug=true will print
 * all generated bytecode and labels to stderr, for easier debugging,
 * including bytecode stack contents
 */
public class MethodEmitter {
    
The ASM MethodVisitor we are plugged into /** The ASM MethodVisitor we are plugged into */
    private final MethodVisitor method;

    
Parent classEmitter representing the class of this method /** Parent classEmitter representing the class of this method */
    private final ClassEmitter classEmitter;

    
FunctionNode representing this method, or null if none exists /** FunctionNode representing this method, or null if none exists */
    protected FunctionNode functionNode;

    
Current type stack for current evaluation /** Current type stack for current evaluation */
    private Label.Stack stack;

    private boolean preventUndefinedLoad;

    
Map of live local variable definitions.
/**
     * Map of live local variable definitions.
     */
    private final Map<Symbol, LocalVariableDef> localVariableDefs = new IdentityHashMap<>();

    
The context /** The context */
    private final Context context;

    
Threshold in chars for when string constants should be split /** Threshold in chars for when string constants should be split */
    static final int LARGE_STRING_THRESHOLD = 32 * 1024;

    
Debug flag, should we dump all generated bytecode along with stacks? /** Debug flag, should we dump all generated bytecode along with stacks? */
    private final DebugLogger log;
    private final boolean     debug;

    
dump stack on a particular line, or -1 if disabled /** dump stack on a particular line, or -1 if disabled */
    private static final int DEBUG_TRACE_LINE;

    static {
        final String tl = Options.getStringProperty("nashorn.codegen.debug.trace", "-1");
        int line = -1;
        try {
            line = Integer.parseInt(tl);
        } catch (final NumberFormatException e) {
            //fallthru
        }
        DEBUG_TRACE_LINE = line;
    }

    
Bootstrap for normal indy:s /** Bootstrap for normal indy:s */
    private static final Handle LINKERBOOTSTRAP  = new Handle(H_INVOKESTATIC, Bootstrap.BOOTSTRAP.className(), Bootstrap.BOOTSTRAP.name(), Bootstrap.BOOTSTRAP.descriptor(), false);

    
Bootstrap for array populators /** Bootstrap for array populators */
    private static final Handle POPULATE_ARRAY_BOOTSTRAP = new Handle(H_INVOKESTATIC, RewriteException.BOOTSTRAP.className(), RewriteException.BOOTSTRAP.name(), RewriteException.BOOTSTRAP.descriptor(), false);

    
Constructor - internal use from ClassEmitter only
Params:
classEmitter – the class emitter weaving the class this method is in
method –       a method visitor
See Also:
method.method/**
     * Constructor - internal use from ClassEmitter only
     * @see ClassEmitter#method
     *
     * @param classEmitter the class emitter weaving the class this method is in
     * @param method       a method visitor
     */
    MethodEmitter(final ClassEmitter classEmitter, final MethodVisitor method) {
        this(classEmitter, method, null);
    }

    
Constructor - internal use from ClassEmitter only
Params:
classEmitter – the class emitter weaving the class this method is in
method –       a method visitor
functionNode – a function node representing this method
See Also:
method.method/**
     * Constructor - internal use from ClassEmitter only
     * @see ClassEmitter#method
     *
     * @param classEmitter the class emitter weaving the class this method is in
     * @param method       a method visitor
     * @param functionNode a function node representing this method
     */
    MethodEmitter(final ClassEmitter classEmitter, final MethodVisitor method, final FunctionNode functionNode) {
        this.context      = classEmitter.getContext();
        this.classEmitter = classEmitter;
        this.method       = method;
        this.functionNode = functionNode;
        this.stack        = null;
        this.log          = context.getLogger(CodeGenerator.class);
        this.debug        = log.isEnabled();
    }

    
Begin a method
/**
     * Begin a method
     */
    public void begin() {
        classEmitter.beginMethod(this);
        newStack();
        method.visitCode();
    }

    
End a method
/**
     * End a method
     */
    public void end() {
        method.visitMaxs(0, 0);
        method.visitEnd();

        classEmitter.endMethod(this);
    }

    boolean isReachable() {
        return stack != null;
    }

    private void doesNotContinueSequentially() {
        stack = null;
    }

    private void newStack() {
        stack = new Label.Stack();
    }

    @Override
    public String toString() {
        return "methodEmitter: " + (functionNode == null ? method : functionNode.getName()).toString() + ' ' + Debug.id(this);
    }

    
Push a type to the existing stack
Params:
type – the type/**
     * Push a type to the existing stack
     * @param type the type
     */
    void pushType(final Type type) {
        if (type != null) {
            stack.push(type);
        }
    }

    
Pop a type from the existing stack
Params:
expected – expected type - will assert if wrong
Returns:
the type that was retrieved/**
     * Pop a type from the existing stack
     *
     * @param expected expected type - will assert if wrong
     *
     * @return the type that was retrieved
     */
    private Type popType(final Type expected) {
        final Type type = popType();
        assert type.isEquivalentTo(expected) : type + " is not compatible with " + expected;
        return type;
    }

    
Pop a type from the existing stack, no matter what it is.
Returns:
the type/**
     * Pop a type from the existing stack, no matter what it is.
     *
     * @return the type
     */
    private Type popType() {
        return stack.pop();
    }

    
Pop a type from the existing stack, ensuring that it is numeric. Boolean type is popped as int type.
Returns:
the type/**
     * Pop a type from the existing stack, ensuring that it is numeric. Boolean type is popped as int type.
     *
     * @return the type
     */
    private NumericType popNumeric() {
        final Type type = popType();
        if(type.isBoolean()) {
            // Booleans are treated as int for purposes of arithmetic operations
            return Type.INT;
        }
        assert type.isNumeric();
        return (NumericType)type;
    }

    
Pop a type from the existing stack, ensuring that it is an integer type
(integer or long). Boolean type is popped as int type.
Returns:
the type/**
     * Pop a type from the existing stack, ensuring that it is an integer type
     * (integer or long). Boolean type is popped as int type.
     *
     * @return the type
     */
    private BitwiseType popBitwise() {
        final Type type = popType();
        if(type == Type.BOOLEAN) {
            return Type.INT;
        }
        return (BitwiseType)type;
    }

    private BitwiseType popInteger() {
        final Type type = popType();
        if(type == Type.BOOLEAN) {
            return Type.INT;
        }
        assert type == Type.INT;
        return (BitwiseType)type;
    }

    
Pop a type from the existing stack, ensuring that it is an array type,
assert if not
Returns:
the type/**
     * Pop a type from the existing stack, ensuring that it is an array type,
     * assert if not
     *
     * @return the type
     */
    private ArrayType popArray() {
        final Type type = popType();
        assert type.isArray() : type;
        return (ArrayType)type;
    }

    
Peek a given number of slots from the top of the stack and return the
type in that slot
Params:
pos – the number of positions from the top, 0 is the top element
Returns:
the type at position "pos" on the stack/**
     * Peek a given number of slots from the top of the stack and return the
     * type in that slot
     *
     * @param pos the number of positions from the top, 0 is the top element
     *
     * @return the type at position "pos" on the stack
     */
    final Type peekType(final int pos) {
        return stack.peek(pos);
    }

    
Peek at the type at the top of the stack
Returns:
the type at the top of the stack/**
     * Peek at the type at the top of the stack
     *
     * @return the type at the top of the stack
     */
    final Type peekType() {
        return stack.peek();
    }

    
Generate code a for instantiating a new object and push the
object type on the stack
Params:
classDescriptor – class descriptor for the object type
type – the type of the new object
Returns:
the method emitter/**
     * Generate code a for instantiating a new object and push the
     * object type on the stack
     *
     * @param classDescriptor class descriptor for the object type
     * @param type the type of the new object
     *
     * @return the method emitter
     */
    MethodEmitter _new(final String classDescriptor, final Type type) {
        debug("new", classDescriptor);
        method.visitTypeInsn(NEW, classDescriptor);
        pushType(type);
        return this;
    }

    
Generate code a for instantiating a new object and push the
object type on the stack
Params:
clazz – class type to instatiate
Returns:
the method emitter/**
     * Generate code a for instantiating a new object and push the
     * object type on the stack
     *
     * @param clazz class type to instatiate
     *
     * @return the method emitter
     */
    MethodEmitter _new(final Class<?> clazz) {
        return _new(className(clazz), Type.typeFor(clazz));
    }

    
Generate code to call the empty constructor for a class
Params:
clazz – class type to instatiate
Returns:
the method emitter/**
     * Generate code to call the empty constructor for a class
     *
     * @param clazz class type to instatiate
     *
     * @return the method emitter
     */
    MethodEmitter newInstance(final Class<?> clazz) {
        return invoke(constructorNoLookup(clazz));
    }

    
Perform a dup, that is, duplicate the top element and
push the duplicate down a given number of positions
on the stack. This is totally type agnostic.
Params:
depth – the depth on which to put the copy
Returns:
the method emitter, or null if depth is illegal and
 has no instruction equivalent./**
     * Perform a dup, that is, duplicate the top element and
     * push the duplicate down a given number of positions
     * on the stack. This is totally type agnostic.
     *
     * @param depth the depth on which to put the copy
     *
     * @return the method emitter, or null if depth is illegal and
     *  has no instruction equivalent.
     */
    MethodEmitter dup(final int depth) {
        if (peekType().dup(method, depth) == null) {
            return null;
        }

        debug("dup", depth);

        switch (depth) {
        case 0: {
            final int l0 = stack.getTopLocalLoad();
            pushType(peekType());
            stack.markLocalLoad(l0);
            break;
        }
        case 1: {
            final int l0 = stack.getTopLocalLoad();
            final Type p0 = popType();
            final int l1 = stack.getTopLocalLoad();
            final Type p1 = popType();
            pushType(p0);
            stack.markLocalLoad(l0);
            pushType(p1);
            stack.markLocalLoad(l1);
            pushType(p0);
            stack.markLocalLoad(l0);
            break;
        }
        case 2: {
            final int l0 = stack.getTopLocalLoad();
            final Type p0 = popType();
            final int l1 = stack.getTopLocalLoad();
            final Type p1 = popType();
            final int l2 = stack.getTopLocalLoad();
            final Type p2 = popType();
            pushType(p0);
            stack.markLocalLoad(l0);
            pushType(p2);
            stack.markLocalLoad(l2);
            pushType(p1);
            stack.markLocalLoad(l1);
            pushType(p0);
            stack.markLocalLoad(l0);
            break;
        }
        default:
            assert false : "illegal dup depth = " + depth;
            return null;
        }

        return this;
    }

    
Perform a dup2, that is, duplicate the top element if it
is a category 2 type, or two top elements if they are category
1 types, and push them on top of the stack
Returns:
the method emitter/**
     * Perform a dup2, that is, duplicate the top element if it
     * is a category 2 type, or two top elements if they are category
     * 1 types, and push them on top of the stack
     *
     * @return the method emitter
     */
    MethodEmitter dup2() {
        debug("dup2");

        if (peekType().isCategory2()) {
            final int l0 = stack.getTopLocalLoad();
            pushType(peekType());
            stack.markLocalLoad(l0);
        } else {
            final int l0 = stack.getTopLocalLoad();
            final Type p0 = popType();
            final int l1 = stack.getTopLocalLoad();
            final Type p1 = popType();
            pushType(p0);
            stack.markLocalLoad(l0);
            pushType(p1);
            stack.markLocalLoad(l1);
            pushType(p0);
            stack.markLocalLoad(l0);
            pushType(p1);
            stack.markLocalLoad(l1);
        }
        method.visitInsn(DUP2);
        return this;
    }

    
Duplicate the top element on the stack and push it
Returns:
the method emitter/**
     * Duplicate the top element on the stack and push it
     *
     * @return the method emitter
     */
    MethodEmitter dup() {
        return dup(0);
    }

    
Pop the top element of the stack and throw it away
Returns:
the method emitter/**
     * Pop the top element of the stack and throw it away
     *
     * @return the method emitter
     */
    MethodEmitter pop() {
        debug("pop", peekType());
        popType().pop(method);
        return this;
    }

    
Pop the top element of the stack if category 2 type, or the two
top elements of the stack if category 1 types
Returns:
the method emitter/**
     * Pop the top element of the stack if category 2 type, or the two
     * top elements of the stack if category 1 types
     *
     * @return the method emitter
     */
    MethodEmitter pop2() {
        if (peekType().isCategory2()) {
            popType();
        } else {
            get2n();
        }
        return this;
    }

    
Swap the top two elements of the stack. This is totally
type agnostic and works for all types
Returns:
the method emitter/**
     * Swap the top two elements of the stack. This is totally
     * type agnostic and works for all types
     *
     * @return the method emitter
     */
    MethodEmitter swap() {
        debug("swap");

        final int l0 = stack.getTopLocalLoad();
        final Type p0 = popType();
        final int l1 = stack.getTopLocalLoad();
        final Type p1 = popType();
        p0.swap(method, p1);

        pushType(p0);
        stack.markLocalLoad(l0);
        pushType(p1);
        stack.markLocalLoad(l1);
        return this;
    }

    void pack() {
        final Type type = peekType();
        if (type.isInteger()) {
            convert(PRIMITIVE_FIELD_TYPE);
        } else if (type.isLong()) {
            //nop
        } else if (type.isNumber()) {
            invokestatic("java/lang/Double", "doubleToRawLongBits", "(D)J");
        } else {
            assert false : type + " cannot be packed!";
        }
    }

    
Initializes a bytecode method parameter
Params:
symbol – the symbol for the parameter
type – the type of the parameter
start – the label for the start of the method/**
     * Initializes a bytecode method parameter
     * @param symbol the symbol for the parameter
     * @param type the type of the parameter
     * @param start the label for the start of the method
     */
    void initializeMethodParameter(final Symbol symbol, final Type type, final Label start) {
        assert symbol.isBytecodeLocal();
        localVariableDefs.put(symbol, new LocalVariableDef(start.getLabel(), type));
    }

    
Create a new string builder, call the constructor and push the instance to the stack.
Returns:
the method emitter/**
     * Create a new string builder, call the constructor and push the instance to the stack.
     *
     * @return the method emitter
     */
    MethodEmitter newStringBuilder() {
        return invoke(constructorNoLookup(StringBuilder.class)).dup();
    }

    
Pop a string and a StringBuilder from the top of the stack and call the append
function of the StringBuilder, appending the string. Pushes the StringBuilder to
the stack when finished.
Returns:
the method emitter/**
     * Pop a string and a StringBuilder from the top of the stack and call the append
     * function of the StringBuilder, appending the string. Pushes the StringBuilder to
     * the stack when finished.
     *
     * @return the method emitter
     */
    MethodEmitter stringBuilderAppend() {
        convert(Type.STRING);
        return invoke(virtualCallNoLookup(StringBuilder.class, "append", StringBuilder.class, String.class));
    }

    
Pops two integer types from the stack, performs a bitwise and and pushes
the result
Returns:
the method emitter/**
     * Pops two integer types from the stack, performs a bitwise and and pushes
     * the result
     *
     * @return the method emitter
     */
    MethodEmitter and() {
        debug("and");
        pushType(get2i().and(method));
        return this;
    }

    
Pops two integer types from the stack, performs a bitwise or and pushes
the result
Returns:
the method emitter/**
     * Pops two integer types from the stack, performs a bitwise or and pushes
     * the result
     *
     * @return the method emitter
     */
    MethodEmitter or() {
        debug("or");
        pushType(get2i().or(method));
        return this;
    }

    
Pops two integer types from the stack, performs a bitwise xor and pushes
the result
Returns:
the method emitter/**
     * Pops two integer types from the stack, performs a bitwise xor and pushes
     * the result
     *
     * @return the method emitter
     */
    MethodEmitter xor() {
        debug("xor");
        pushType(get2i().xor(method));
        return this;
    }

    
Pops two integer types from the stack, performs a bitwise logic shift right and pushes
the result. The shift count, the first element, must be INT.
Returns:
the method emitter/**
     * Pops two integer types from the stack, performs a bitwise logic shift right and pushes
     * the result. The shift count, the first element, must be INT.
     *
     * @return the method emitter
     */
    MethodEmitter shr() {
        debug("shr");
        popInteger();
        pushType(popBitwise().shr(method));
        return this;
    }

    
Pops two integer types from the stack, performs a bitwise shift left and and pushes
the result. The shift count, the first element, must be INT.
Returns:
the method emitter/**
     * Pops two integer types from the stack, performs a bitwise shift left and and pushes
     * the result. The shift count, the first element, must be INT.
     *
     * @return the method emitter
     */
    MethodEmitter shl() {
        debug("shl");
        popInteger();
        pushType(popBitwise().shl(method));
        return this;
    }

    
Pops two integer types from the stack, performs a bitwise arithmetic shift right and pushes
the result. The shift count, the first element, must be INT.
Returns:
the method emitter/**
     * Pops two integer types from the stack, performs a bitwise arithmetic shift right and pushes
     * the result. The shift count, the first element, must be INT.
     *
     * @return the method emitter
     */
    MethodEmitter sar() {
        debug("sar");
        popInteger();
        pushType(popBitwise().sar(method));
        return this;
    }

    
Pops a numeric type from the stack, negates it and pushes the result
Returns:
the method emitter/**
     * Pops a numeric type from the stack, negates it and pushes the result
     *
     * @return the method emitter
     */
    MethodEmitter neg(final int programPoint) {
        debug("neg");
        pushType(popNumeric().neg(method, programPoint));
        return this;
    }

    
Add label for the start of a catch block and push the exception to the
stack
Params:
recovery – label pointing to start of catch block/**
     * Add label for the start of a catch block and push the exception to the
     * stack
     *
     * @param recovery label pointing to start of catch block
     */
    void _catch(final Label recovery) {
        // While in JVM a catch block can be reached through normal control flow, our code generator never does this,
        // so we might as well presume there's no stack on entry.
        assert stack == null;
        recovery.onCatch();
        label(recovery);
        beginCatchBlock();
    }

    
Add any number of labels for the start of a catch block and push the exception to the
stack
Params:
recoveries – labels pointing to start of catch block/**
     * Add any number of labels for the start of a catch block and push the exception to the
     * stack
     *
     * @param recoveries labels pointing to start of catch block
     */
    void _catch(final Collection<Label> recoveries) {
        assert stack == null;
        for(final Label l: recoveries) {
            label(l);
        }
        beginCatchBlock();
    }

    private void beginCatchBlock() {
        // It can happen that the catch label wasn't marked as reachable. They are marked as reachable if there's an
        // assignment in the try block, but it's possible that there was none.
        if(!isReachable()) {
            newStack();
        }
        pushType(Type.typeFor(Throwable.class));
    }

    
Start a try/catch block.
Params:
entry –    start label for try
exit –     end label for try
recovery – start label for catch
clazz –    exception class or null for any Throwable
isOptimismHandler – true if this is a hander for UnwarrantedOptimismException. Normally joining on a catch handler kills temporary variables, but optimism handlers are an exception, as they need to capture temporaries as well, so they must remain live./**
     * Start a try/catch block.
     *
     * @param entry    start label for try
     * @param exit     end label for try
     * @param recovery start label for catch
     * @param clazz    exception class or null for any Throwable
     * @param isOptimismHandler true if this is a hander for {@code UnwarrantedOptimismException}. Normally joining on a
     * catch handler kills temporary variables, but optimism handlers are an exception, as they need to capture
     * temporaries as well, so they must remain live.
     */
    void _try(final Label entry, final Label exit, final Label recovery, final Class<?> clazz, final boolean isOptimismHandler) {
        recovery.joinFromTry(entry.getStack(), isOptimismHandler);
        final String typeDescriptor = clazz == null ? null : CompilerConstants.className(clazz);
        method.visitTryCatchBlock(entry.getLabel(), exit.getLabel(), recovery.getLabel(), typeDescriptor);
    }

    
Start a try/catch block.
Params:
entry –    start label for try
exit –     end label for try
recovery – start label for catch
clazz –    exception class/**
     * Start a try/catch block.
     *
     * @param entry    start label for try
     * @param exit     end label for try
     * @param recovery start label for catch
     * @param clazz    exception class
     */
    void _try(final Label entry, final Label exit, final Label recovery, final Class<?> clazz) {
        _try(entry, exit, recovery, clazz, clazz == UnwarrantedOptimismException.class);
    }

    
Start a try/catch block. The catch is "Throwable" - i.e. catch-all
Params:
entry –    start label for try
exit –     end label for try
recovery – start label for catch/**
     * Start a try/catch block. The catch is "Throwable" - i.e. catch-all
     *
     * @param entry    start label for try
     * @param exit     end label for try
     * @param recovery start label for catch
     */
    void _try(final Label entry, final Label exit, final Label recovery) {
        _try(entry, exit, recovery, null, false);
    }

    void markLabelAsOptimisticCatchHandler(final Label label, final int liveLocalCount) {
        label.markAsOptimisticCatchHandler(stack, liveLocalCount);
    }

    
Load the constants array
Returns:
this method emitter/**
     * Load the constants array
     * @return this method emitter
     */
    MethodEmitter loadConstants() {
        getStatic(classEmitter.getUnitClassName(), CONSTANTS.symbolName(), CONSTANTS.descriptor());
        assert peekType().isArray() : peekType();
        return this;
    }

    
Push the undefined value for the given type, i.e.
UNDEFINED or UNDEFINEDNUMBER. Currently we have no way of
representing UNDEFINED for INTs and LONGs, so they are not
allowed to be local variables (yet)
Params:
type – the type for which to push UNDEFINED
Returns:
the method emitter/**
     * Push the undefined value for the given type, i.e.
     * UNDEFINED or UNDEFINEDNUMBER. Currently we have no way of
     * representing UNDEFINED for INTs and LONGs, so they are not
     * allowed to be local variables (yet)
     *
     * @param type the type for which to push UNDEFINED
     * @return the method emitter
     */
    MethodEmitter loadUndefined(final Type type) {
        debug("load undefined ", type);
        pushType(type.loadUndefined(method));
        return this;
    }

    MethodEmitter loadForcedInitializer(final Type type) {
        debug("load forced initializer ", type);
        pushType(type.loadForcedInitializer(method));
        return this;
    }

    
Push the empty value for the given type, i.e. EMPTY.
Params:
type – the type
Returns:
the method emitter/**
     * Push the empty value for the given type, i.e. EMPTY.
     *
     * @param type the type
     * @return the method emitter
     */
    MethodEmitter loadEmpty(final Type type) {
        debug("load empty ", type);
        pushType(type.loadEmpty(method));
        return this;
    }

    
Push null to stack
Returns:
the method emitter/**
     * Push null to stack
     *
     * @return the method emitter
     */
    MethodEmitter loadNull() {
        debug("aconst_null");
        pushType(Type.OBJECT.ldc(method, null));
        return this;
    }

    
Push a handle representing this class top stack
Params:
className – name of the class
Returns:
the method emitter/**
     * Push a handle representing this class top stack
     *
     * @param className name of the class
     *
     * @return the method emitter
     */
    MethodEmitter loadType(final String className) {
        debug("load type", className);
        method.visitLdcInsn(jdk.internal.org.objectweb.asm.Type.getObjectType(className));
        pushType(Type.OBJECT);
        return this;
    }

    
Push a boolean constant to the stack.
Params:
b – value of boolean
Returns:
the method emitter/**
     * Push a boolean constant to the stack.
     *
     * @param b value of boolean
     *
     * @return the method emitter
     */
    MethodEmitter load(final boolean b) {
        debug("load boolean", b);
        pushType(Type.BOOLEAN.ldc(method, b));
        return this;
    }

    
Push an int constant to the stack
Params:
i – value of the int
Returns:
the method emitter/**
     * Push an int constant to the stack
     *
     * @param i value of the int
     *
     * @return the method emitter
     */
    MethodEmitter load(final int i) {
        debug("load int", i);
        pushType(Type.INT.ldc(method, i));
        return this;
    }

    
Push a double constant to the stack
Params:
d – value of the double
Returns:
the method emitter/**
     * Push a double constant to the stack
     *
     * @param d value of the double
     *
     * @return the method emitter
     */
    MethodEmitter load(final double d) {
        debug("load double", d);
        pushType(Type.NUMBER.ldc(method, d));
        return this;
    }

    
Push an long constant to the stack
Params:
l – value of the long
Returns:
the method emitter/**
     * Push an long constant to the stack
     *
     * @param l value of the long
     *
     * @return the method emitter
     */
    MethodEmitter load(final long l) {
        debug("load long", l);
        pushType(Type.LONG.ldc(method, l));
        return this;
    }

    
Fetch the length of an array.
Returns:
Array length./**
     * Fetch the length of an array.
     * @return Array length.
     */
    MethodEmitter arraylength() {
        debug("arraylength");
        popType(Type.OBJECT);
        pushType(Type.OBJECT_ARRAY.arraylength(method));
        return this;
    }

    
Push a String constant to the stack
Params:
s – value of the String
Returns:
the method emitter/**
     * Push a String constant to the stack
     *
     * @param s value of the String
     *
     * @return the method emitter
     */
    MethodEmitter load(final String s) {
        debug("load string", s);

        if (s == null) {
            loadNull();
            return this;
        }

        //NASHORN-142 - split too large string
        final int length = s.length();
        if (length > LARGE_STRING_THRESHOLD) {

            _new(StringBuilder.class);
            dup();
            load(length);
            invoke(constructorNoLookup(StringBuilder.class, int.class));

            for (int n = 0; n < length; n += LARGE_STRING_THRESHOLD) {
                final String part = s.substring(n, Math.min(n + LARGE_STRING_THRESHOLD, length));
                load(part);
                stringBuilderAppend();
            }

            invoke(virtualCallNoLookup(StringBuilder.class, "toString", String.class));

            return this;
        }

        pushType(Type.OBJECT.ldc(method, s));
        return this;
    }

    
Pushes the value of an identifier to the stack. If the identifier does not represent a local variable or a
parameter, this will be a no-op.
Params:
ident – the identifier for the variable being loaded.
Returns:
the method emitter/**
     * Pushes the value of an identifier to the stack. If the identifier does not represent a local variable or a
     * parameter, this will be a no-op.
     *
     * @param ident the identifier for the variable being loaded.
     *
     * @return the method emitter
     */
    MethodEmitter load(final IdentNode ident) {
        return load(ident.getSymbol(), ident.getType());
    }

    
Pushes the value of the symbol to the stack with the specified type. No type conversion is being performed, and
the type is only being used if the symbol addresses a local variable slot. The value of the symbol is loaded if
it addresses a local variable slot, or it is a parameter (in which case it can also be loaded from a vararg array
or the arguments object). If it is neither, the operation is a no-op.
Params:
symbol – the symbol addressing the value being loaded
type – the presumed type of the value when it is loaded from a local variable slot
Returns:
the method emitter/**
     * Pushes the value of the symbol to the stack with the specified type. No type conversion is being performed, and
     * the type is only being used if the symbol addresses a local variable slot. The value of the symbol is loaded if
     * it addresses a local variable slot, or it is a parameter (in which case it can also be loaded from a vararg array
     * or the arguments object). If it is neither, the operation is a no-op.
     *
     * @param symbol the symbol addressing the value being loaded
     * @param type the presumed type of the value when it is loaded from a local variable slot
     * @return the method emitter
     */
    MethodEmitter load(final Symbol symbol, final Type type) {
        assert symbol != null;
        if (symbol.hasSlot()) {
            final int slot = symbol.getSlot(type);
            debug("load symbol", symbol.getName(), " slot=", slot, "type=", type);
            load(type, slot);
           // _try(new Label("dummy"), new Label("dummy2"), recovery);
           // method.visitTryCatchBlock(new Label(), arg1, arg2, arg3);
        } else if (symbol.isParam()) {
            assert functionNode.isVarArg() : "Non-vararg functions have slotted parameters";
            final int index = symbol.getFieldIndex();
            if (functionNode.needsArguments()) {
                // ScriptObject.getArgument(int) on arguments
                debug("load symbol", symbol.getName(), " arguments index=", index);
                loadCompilerConstant(ARGUMENTS);
                load(index);
                ScriptObject.GET_ARGUMENT.invoke(this);
            } else {
                // array load from __varargs__
                debug("load symbol", symbol.getName(), " array index=", index);
                loadCompilerConstant(VARARGS);
                load(symbol.getFieldIndex());
                arrayload();
            }
        }
        return this;
    }

    
Push a local variable to the stack, given an explicit bytecode slot.
This is used e.g. for stub generation where we know where items like
"this" and "scope" reside.
Params:
type –  the type of the variable
slot –  the slot the variable is in
Returns:
the method emitter/**
     * Push a local variable to the stack, given an explicit bytecode slot.
     * This is used e.g. for stub generation where we know where items like
     * "this" and "scope" reside.
     *
     * @param type  the type of the variable
     * @param slot  the slot the variable is in
     *
     * @return the method emitter
     */
    MethodEmitter load(final Type type, final int slot) {
        debug("explicit load", type, slot);
        final Type loadType = type.load(method, slot);
        assert loadType != null;
        pushType(loadType == Type.OBJECT && isThisSlot(slot) ? Type.THIS : loadType);
        assert !preventUndefinedLoad || (slot < stack.localVariableTypes.size() && stack.localVariableTypes.get(slot) != Type.UNKNOWN)
            : "Attempted load of uninitialized slot " + slot + " (as type " + type + ")";
        stack.markLocalLoad(slot);
        return this;
    }

    private boolean isThisSlot(final int slot) {
        if (functionNode == null) {
            return slot == CompilerConstants.JAVA_THIS.slot();
        }
        final int thisSlot = getCompilerConstantSymbol(THIS).getSlot(Type.OBJECT);
        assert !functionNode.needsCallee() || thisSlot == 1; // needsCallee -> thisSlot == 1
        assert functionNode.needsCallee() || thisSlot == 0; // !needsCallee -> thisSlot == 0
        return slot == thisSlot;
    }

    
Push a method handle to the stack
Params:
className –  class name
methodName – method name
descName –   descriptor
flags –      flags that describe this handle, e.g. invokespecial new, or invoke virtual
Returns:
the method emitter/**
     * Push a method handle to the stack
     *
     * @param className  class name
     * @param methodName method name
     * @param descName   descriptor
     * @param flags      flags that describe this handle, e.g. invokespecial new, or invoke virtual
     *
     * @return the method emitter
     */
    MethodEmitter loadHandle(final String className, final String methodName, final String descName, final EnumSet<Flag> flags) {
        final int flag = Flag.getValue(flags);
        debug("load handle ");
        pushType(Type.OBJECT.ldc(method, new Handle(flag, className, methodName, descName, flag == H_INVOKEINTERFACE)));
        return this;
    }

    private Symbol getCompilerConstantSymbol(final CompilerConstants cc) {
        return functionNode.getBody().getExistingSymbol(cc.symbolName());
    }

    
True if this method has a slot allocated for the scope variable (meaning, something in the method actually needs
the scope).
Returns:
if this method has a slot allocated for the scope variable./**
     * True if this method has a slot allocated for the scope variable (meaning, something in the method actually needs
     * the scope).
     * @return if this method has a slot allocated for the scope variable.
     */
    boolean hasScope() {
        return getCompilerConstantSymbol(SCOPE).hasSlot();
    }

    MethodEmitter loadCompilerConstant(final CompilerConstants cc) {
        return loadCompilerConstant(cc, null);
    }

    MethodEmitter loadCompilerConstant(final CompilerConstants cc, final Type type) {
        if (cc == SCOPE && peekType() == Type.SCOPE) {
            dup();
            return this;
        }
        return load(getCompilerConstantSymbol(cc), type != null ? type : getCompilerConstantType(cc));
    }

    MethodEmitter loadScope() {
        return loadCompilerConstant(SCOPE).checkcast(Scope.class);
    }

    MethodEmitter setSplitState(final int state) {
        return loadScope().load(state).invoke(Scope.SET_SPLIT_STATE);
    }

    void storeCompilerConstant(final CompilerConstants cc) {
        storeCompilerConstant(cc, null);
    }

    void storeCompilerConstant(final CompilerConstants cc, final Type type) {
        final Symbol symbol = getCompilerConstantSymbol(cc);
        if(!symbol.hasSlot()) {
            return;
        }
        debug("store compiler constant ", symbol);
        store(symbol, type != null ? type : getCompilerConstantType(cc));
    }

    private static Type getCompilerConstantType(final CompilerConstants cc) {
        final Class<?> constantType = cc.type();
        assert constantType != null;
        return Type.typeFor(constantType);
    }

    
Load an element from an array, determining type automatically
Returns:
the method emitter/**
     * Load an element from an array, determining type automatically
     * @return the method emitter
     */
    MethodEmitter arrayload() {
        debug("Xaload");
        popType(Type.INT);
        pushType(popArray().aload(method));
        return this;
    }

    
Pop a value, an index and an array from the stack and store
the value at the given index in the array.
/**
     * Pop a value, an index and an array from the stack and store
     * the value at the given index in the array.
     */
    void arraystore() {
        debug("Xastore");
        final Type value = popType();
        final Type index = popType(Type.INT);
        assert index.isInteger() : "array index is not integer, but " + index;
        final ArrayType array = popArray();

        assert value.isEquivalentTo(array.getElementType()) : "Storing "+value+" into "+array;
        assert array.isObject();
        array.astore(method);
    }

    
Pop a value from the stack and store it in a local variable represented
by the given identifier. If the symbol has no slot, this is a NOP
Params:
ident – identifier to store stack to/**
     * Pop a value from the stack and store it in a local variable represented
     * by the given identifier. If the symbol has no slot, this is a NOP
     *
     * @param ident identifier to store stack to
     */
    void store(final IdentNode ident) {
        final Type type = ident.getType();
        final Symbol symbol = ident.getSymbol();
        if(type == Type.UNDEFINED) {
            assert peekType() == Type.UNDEFINED;
            store(symbol, Type.OBJECT);
        } else {
            store(symbol, type);
        }
    }

    
Represents a definition of a local variable with a type. Used for local variable table building.
/**
     * Represents a definition of a local variable with a type. Used for local variable table building.
     */
    private static class LocalVariableDef {
        // The start label from where this definition lives.
        private final jdk.internal.org.objectweb.asm.Label label;
        // The currently live type of the local variable.
        private final Type type;

        LocalVariableDef(final jdk.internal.org.objectweb.asm.Label label, final Type type) {
            this.label = label;
            this.type = type;
        }

    }

    void closeLocalVariable(final Symbol symbol, final Label label) {
        final LocalVariableDef def = localVariableDefs.get(symbol);
        if(def != null) {
            endLocalValueDef(symbol, def, label.getLabel());
        }
        if(isReachable()) {
            markDeadLocalVariable(symbol);
        }
    }

    void markDeadLocalVariable(final Symbol symbol) {
        if(!symbol.isDead()) {
            markDeadSlots(symbol.getFirstSlot(), symbol.slotCount());
        }
    }

    void markDeadSlots(final int firstSlot, final int slotCount) {
        stack.markDeadLocalVariables(firstSlot, slotCount);
    }

    private void endLocalValueDef(final Symbol symbol, final LocalVariableDef def, final jdk.internal.org.objectweb.asm.Label label) {
        String name = symbol.getName();
        if (name.equals(THIS.symbolName())) {
            name = THIS_DEBUGGER.symbolName();
        }
        method.visitLocalVariable(name, def.type.getDescriptor(), null, def.label, label, symbol.getSlot(def.type));
    }

    void store(final Symbol symbol, final Type type) {
        store(symbol, type, true);
    }

    
Pop a value from the stack and store it in a variable denoted by the given symbol. The variable should be either a local variable, or a function parameter (and not a scoped variable). For local variables, this method will also do the bookkeeping of the local variable table as well as mark values in all alternative slots for the symbol as dead. In this regard it differs from storeHidden(Type, int). 
Params:
symbol – the symbol to store into.
type – the type to store
onlySymbolLiveValue – if true, this is the sole live value for the symbol. If false, currently live values should
be kept live./**
     * Pop a value from the stack and store it in a variable denoted by the given symbol. The variable should be either
     * a local variable, or a function parameter (and not a scoped variable). For local variables, this method will also
     * do the bookkeeping of the local variable table as well as mark values in all alternative slots for the symbol as
     * dead. In this regard it differs from {@link #storeHidden(Type, int)}.
     *
     * @param symbol the symbol to store into.
     * @param type the type to store
     * @param onlySymbolLiveValue if true, this is the sole live value for the symbol. If false, currently live values should
     * be kept live.
     */
    void store(final Symbol symbol, final Type type, final boolean onlySymbolLiveValue) {
        assert symbol != null : "No symbol to store";
        if (symbol.hasSlot()) {
            final boolean isLiveType = symbol.hasSlotFor(type);
            final LocalVariableDef existingDef = localVariableDefs.get(symbol);
            if(existingDef == null || existingDef.type != type) {
                final jdk.internal.org.objectweb.asm.Label here = new jdk.internal.org.objectweb.asm.Label();
                if(isLiveType) {
                    final LocalVariableDef newDef = new LocalVariableDef(here, type);
                    localVariableDefs.put(symbol, newDef);
                }
                method.visitLabel(here);
                if(existingDef != null) {
                    endLocalValueDef(symbol, existingDef, here);
                }
            }
            if(isLiveType) {
                final int slot = symbol.getSlot(type);
                debug("store symbol", symbol.getName(), " type=", type, " slot=", slot);
                storeHidden(type, slot, onlySymbolLiveValue);
            } else {
                if(onlySymbolLiveValue) {
                    markDeadLocalVariable(symbol);
                }
                debug("dead store symbol ", symbol.getName(), " type=", type);
                pop();
            }
        } else if (symbol.isParam()) {
            assert !symbol.isScope();
            assert functionNode.isVarArg() : "Non-vararg functions have slotted parameters";
            final int index = symbol.getFieldIndex();
            if (functionNode.needsArguments()) {
                convert(Type.OBJECT);
                debug("store symbol", symbol.getName(), " arguments index=", index);
                loadCompilerConstant(ARGUMENTS);
                load(index);
                ArgumentSetter.SET_ARGUMENT.invoke(this);
            } else {
                convert(Type.OBJECT);
                // varargs without arguments object - just do array store to __varargs__
                debug("store symbol", symbol.getName(), " array index=", index);
                loadCompilerConstant(VARARGS);
                load(index);
                ArgumentSetter.SET_ARRAY_ELEMENT.invoke(this);
            }
        } else {
            debug("dead store symbol ", symbol.getName(), " type=", type);
            pop();
        }
    }

    
Pop a value from the stack and store it in a local variable slot. Note that in contrast with store(Symbol, Type), this method does not adjust the local variable table, nor marks slots for alternative value types for the symbol as being dead. For that reason, this method is usually not called directly. Notable exceptions are temporary internal locals (e.g. quick store, last-catch-condition, etc.) that are not desired to show up in the local variable table. 
Params:
type – the type to pop
slot – the slot/**
     * Pop a value from the stack and store it in a local variable slot. Note that in contrast with
     * {@link #store(Symbol, Type)}, this method does not adjust the local variable table, nor marks slots for
     * alternative value types for the symbol as being dead. For that reason, this method is usually not called
     * directly. Notable exceptions are temporary internal locals (e.g. quick store, last-catch-condition, etc.) that
     * are not desired to show up in the local variable table.
     *
     * @param type the type to pop
     * @param slot the slot
     */
    void storeHidden(final Type type, final int slot) {
        storeHidden(type, slot, true);
    }

    void storeHidden(final Type type, final int slot, final boolean onlyLiveSymbolValue) {
        explicitStore(type, slot);
        stack.onLocalStore(type, slot, onlyLiveSymbolValue);
    }

    void storeTemp(final Type type, final int slot) {
        explicitStore(type, slot);
        defineTemporaryLocalVariable(slot, slot + type.getSlots());
        onLocalStore(type, slot);
    }

    void onLocalStore(final Type type, final int slot) {
        stack.onLocalStore(type, slot, true);
    }

    private void explicitStore(final Type type, final int slot) {
        assert slot != -1;
        debug("explicit store", type, slot);
        popType(type);
        type.store(method, slot);
    }

    
Marks a range of slots as belonging to a defined local variable. The slots will start out with no live value
in them.
Params:
fromSlot – first slot, inclusive.
toSlot – last slot, exclusive./**
     * Marks a range of slots as belonging to a defined local variable. The slots will start out with no live value
     * in them.
     * @param fromSlot first slot, inclusive.
     * @param toSlot last slot, exclusive.
     */
    void defineBlockLocalVariable(final int fromSlot, final int toSlot) {
        stack.defineBlockLocalVariable(fromSlot, toSlot);
    }

    
Marks a range of slots as belonging to a defined temporary local variable. The slots will start out with no
live value in them.
Params:
fromSlot – first slot, inclusive.
toSlot – last slot, exclusive./**
     * Marks a range of slots as belonging to a defined temporary local variable. The slots will start out with no
     * live value in them.
     * @param fromSlot first slot, inclusive.
     * @param toSlot last slot, exclusive.
     */
    void defineTemporaryLocalVariable(final int fromSlot, final int toSlot) {
        stack.defineTemporaryLocalVariable(fromSlot, toSlot);
    }

    
Defines a new temporary local variable and returns its allocated index.
Params:
width – the required width (in slots) for the new variable.
Returns:
the bytecode slot index where the newly allocated local begins./**
     * Defines a new temporary local variable and returns its allocated index.
     * @param width the required width (in slots) for the new variable.
     * @return the bytecode slot index where the newly allocated local begins.
     */
    int defineTemporaryLocalVariable(final int width) {
        return stack.defineTemporaryLocalVariable(width);
    }

    void undefineLocalVariables(final int fromSlot, final boolean canTruncateSymbol) {
        if(isReachable()) {
            stack.undefineLocalVariables(fromSlot, canTruncateSymbol);
        }
    }

    List<Type> getLocalVariableTypes() {
        return stack.localVariableTypes;
    }

    List<Type> getWidestLiveLocals(final List<Type> localTypes) {
        return stack.getWidestLiveLocals(localTypes);
    }

    String markSymbolBoundariesInLvarTypesDescriptor(final String lvarDescriptor) {
        return stack.markSymbolBoundariesInLvarTypesDescriptor(lvarDescriptor);
    }

    
Increment/Decrement a local integer by the given value.
Params:
slot – the int slot
increment – the amount to increment/**
     * Increment/Decrement a local integer by the given value.
     *
     * @param slot the int slot
     * @param increment the amount to increment
     */
    void iinc(final int slot, final int increment) {
        debug("iinc");
        method.visitIincInsn(slot, increment);
    }

    
Pop an exception object from the stack and generate code
for throwing it
/**
     * Pop an exception object from the stack and generate code
     * for throwing it
     */
    public void athrow() {
        debug("athrow");
        final Type receiver = popType(Type.OBJECT);
        assert Throwable.class.isAssignableFrom(receiver.getTypeClass()) : receiver.getTypeClass();
        method.visitInsn(ATHROW);
        doesNotContinueSequentially();
    }

    
Pop an object from the stack and perform an instanceof
operation, given a classDescriptor to compare it to.
Push the boolean result 1/0 as an int to the stack
Params:
classDescriptor – descriptor of the class to type check against
Returns:
the method emitter/**
     * Pop an object from the stack and perform an instanceof
     * operation, given a classDescriptor to compare it to.
     * Push the boolean result 1/0 as an int to the stack
     *
     * @param classDescriptor descriptor of the class to type check against
     *
     * @return the method emitter
     */
    MethodEmitter _instanceof(final String classDescriptor) {
        debug("instanceof", classDescriptor);
        popType(Type.OBJECT);
        method.visitTypeInsn(INSTANCEOF, classDescriptor);
        pushType(Type.INT);
        return this;
    }

    
Pop an object from the stack and perform an instanceof
operation, given a classDescriptor to compare it to.
Push the boolean result 1/0 as an int to the stack
Params:
clazz – the type to check instanceof against
Returns:
the method emitter/**
     * Pop an object from the stack and perform an instanceof
     * operation, given a classDescriptor to compare it to.
     * Push the boolean result 1/0 as an int to the stack
     *
     * @param clazz the type to check instanceof against
     *
     * @return the method emitter
     */
    MethodEmitter _instanceof(final Class<?> clazz) {
        return _instanceof(CompilerConstants.className(clazz));
    }

    
Perform a checkcast operation on the object at the top of the
stack.
Params:
classDescriptor – descriptor of the class to type check against
Returns:
the method emitter/**
     * Perform a checkcast operation on the object at the top of the
     * stack.
     *
     * @param classDescriptor descriptor of the class to type check against
     *
     * @return the method emitter
     */
    MethodEmitter checkcast(final String classDescriptor) {
        debug("checkcast", classDescriptor);
        assert peekType().isObject();
        method.visitTypeInsn(CHECKCAST, classDescriptor);
        return this;
    }

    
Perform a checkcast operation on the object at the top of the
stack.
Params:
clazz – class to checkcast against
Returns:
the method emitter/**
     * Perform a checkcast operation on the object at the top of the
     * stack.
     *
     * @param clazz class to checkcast against
     *
     * @return the method emitter
     */
    MethodEmitter checkcast(final Class<?> clazz) {
        return checkcast(CompilerConstants.className(clazz));
    }

    
Instantiate a new array given a length that is popped
from the stack and the array type
Params:
arrayType – the type of the array
Returns:
the method emitter/**
     * Instantiate a new array given a length that is popped
     * from the stack and the array type
     *
     * @param arrayType the type of the array
     *
     * @return the method emitter
     */
    MethodEmitter newarray(final ArrayType arrayType) {
        debug("newarray ", "arrayType=", arrayType);
        popType(Type.INT); //LENGTH
        pushType(arrayType.newarray(method));
        return this;
    }

    
Instantiate a multidimensional array with a given number of dimensions.
On the stack are dim lengths of the sub arrays.
Params:
arrayType – type of the array
dims –      number of dimensions
Returns:
the method emitter/**
     * Instantiate a multidimensional array with a given number of dimensions.
     * On the stack are dim lengths of the sub arrays.
     *
     * @param arrayType type of the array
     * @param dims      number of dimensions
     *
     * @return the method emitter
     */
    MethodEmitter multinewarray(final ArrayType arrayType, final int dims) {
        debug("multianewarray ", arrayType, dims);
        for (int i = 0; i < dims; i++) {
            popType(Type.INT); //LENGTH
        }
        pushType(arrayType.newarray(method, dims));
        return this;
    }

    
Helper function to pop and type check the appropriate arguments
from the stack given a method signature
Params:
signature – method signature
Returns:
return type of method/**
     * Helper function to pop and type check the appropriate arguments
     * from the stack given a method signature
     *
     * @param signature method signature
     *
     * @return return type of method
     */
    private Type fixParamStack(final String signature) {
        final Type[] params = Type.getMethodArguments(signature);
        for (int i = params.length - 1; i >= 0; i--) {
            popType(params[i]);
        }
        final Type returnType = Type.getMethodReturnType(signature);
        return returnType;
    }

    
Generate an invocation to a Call structure
Params:
call – the call object
See Also:
CompilerConstants
Returns:
the method emitter/**
     * Generate an invocation to a Call structure
     * @see CompilerConstants
     *
     * @param call the call object
     *
     * @return the method emitter
     */
    MethodEmitter invoke(final Call call) {
        return call.invoke(this);
    }

    private MethodEmitter invoke(final int opcode, final String className, final String methodName, final String methodDescriptor, final boolean hasReceiver) {
        final Type returnType = fixParamStack(methodDescriptor);

        if (hasReceiver) {
            popType(Type.OBJECT);
        }

        method.visitMethodInsn(opcode, className, methodName, methodDescriptor, opcode == INVOKEINTERFACE);

        if (returnType != null) {
            pushType(returnType);
        }

        return this;
    }

    
Pop receiver from stack, perform an invoke special
Params:
className –        class name
methodName –       method name
methodDescriptor – descriptor
Returns:
the method emitter/**
     * Pop receiver from stack, perform an invoke special
     *
     * @param className        class name
     * @param methodName       method name
     * @param methodDescriptor descriptor
     *
     * @return the method emitter
     */
    MethodEmitter invokespecial(final String className, final String methodName, final String methodDescriptor) {
        debug("invokespecial", className, ".", methodName, methodDescriptor);
        return invoke(INVOKESPECIAL, className, methodName, methodDescriptor, true);
    }

    
Pop receiver from stack, perform an invoke virtual, push return value if any
Params:
className –        class name
methodName –       method name
methodDescriptor – descriptor
Returns:
the method emitter/**
     * Pop receiver from stack, perform an invoke virtual, push return value if any
     *
     * @param className        class name
     * @param methodName       method name
     * @param methodDescriptor descriptor
     *
     * @return the method emitter
     */
    MethodEmitter invokevirtual(final String className, final String methodName, final String methodDescriptor) {
        debug("invokevirtual", className, ".", methodName, methodDescriptor, " ", stack);
        return invoke(INVOKEVIRTUAL, className, methodName, methodDescriptor, true);
    }

    
Perform an invoke static and push the return value if any
Params:
className –        class name
methodName –       method name
methodDescriptor – descriptor
Returns:
the method emitter/**
     * Perform an invoke static and push the return value if any
     *
     * @param className        class name
     * @param methodName       method name
     * @param methodDescriptor descriptor
     *
     * @return the method emitter
     */
    MethodEmitter invokestatic(final String className, final String methodName, final String methodDescriptor) {
        debug("invokestatic", className, ".", methodName, methodDescriptor);
        invoke(INVOKESTATIC, className, methodName, methodDescriptor, false);
        return this;
    }

    
Perform an invoke static and replace the return type if we know better, e.g. Global.allocate
that allocates an array should return an ObjectArray type as a NativeArray counts as that
Params:
className –        class name
methodName –       method name
methodDescriptor – descriptor
returnType –       return type override
Returns:
the method emitter/**
     * Perform an invoke static and replace the return type if we know better, e.g. Global.allocate
     * that allocates an array should return an ObjectArray type as a NativeArray counts as that
     *
     * @param className        class name
     * @param methodName       method name
     * @param methodDescriptor descriptor
     * @param returnType       return type override
     *
     * @return the method emitter
     */
    MethodEmitter invokestatic(final String className, final String methodName, final String methodDescriptor, final Type returnType) {
        invokestatic(className, methodName, methodDescriptor);
        popType();
        pushType(returnType);
        return this;
    }

    
Pop receiver from stack, perform an invoke interface and push return value if any
Params:
className –        class name
methodName –       method name
methodDescriptor – descriptor
Returns:
the method emitter/**
     * Pop receiver from stack, perform an invoke interface and push return value if any
     *
     * @param className        class name
     * @param methodName       method name
     * @param methodDescriptor descriptor
     *
     * @return the method emitter
     */
    MethodEmitter invokeinterface(final String className, final String methodName, final String methodDescriptor) {
        debug("invokeinterface", className, ".", methodName, methodDescriptor);
        return invoke(INVOKEINTERFACE, className, methodName, methodDescriptor, true);
    }

    static jdk.internal.org.objectweb.asm.Label[] getLabels(final Label... table) {
        final jdk.internal.org.objectweb.asm.Label[] internalLabels = new jdk.internal.org.objectweb.asm.Label[table.length];
        for (int i = 0; i < table.length; i++) {
            internalLabels[i] = table[i].getLabel();
        }
        return internalLabels;
    }

    
Generate a lookup switch, popping the switch value from the stack
Params:
defaultLabel – default label
values –       case values for the table
table –        default label/**
     * Generate a lookup switch, popping the switch value from the stack
     *
     * @param defaultLabel default label
     * @param values       case values for the table
     * @param table        default label
     */
    void lookupswitch(final Label defaultLabel, final int[] values, final Label... table) {//Collection<Label> table) {
        debug("lookupswitch", peekType());
        adjustStackForSwitch(defaultLabel, table);
        method.visitLookupSwitchInsn(defaultLabel.getLabel(), values, getLabels(table));
        doesNotContinueSequentially();
    }

    
Generate a table switch
Params:
lo –            low value
hi –            high value
defaultLabel –  default label
table –         label table/**
     * Generate a table switch
     * @param lo            low value
     * @param hi            high value
     * @param defaultLabel  default label
     * @param table         label table
     */
    void tableswitch(final int lo, final int hi, final Label defaultLabel, final Label... table) {
        debug("tableswitch", peekType());
        adjustStackForSwitch(defaultLabel, table);
        method.visitTableSwitchInsn(lo, hi, defaultLabel.getLabel(), getLabels(table));
        doesNotContinueSequentially();
    }

    private void adjustStackForSwitch(final Label defaultLabel, final Label... table) {
        popType(Type.INT);
        joinTo(defaultLabel);
        for(final Label label: table) {
            joinTo(label);
        }
    }

    
Abstraction for performing a conditional jump of any type
Params:
cond –      the condition to test
trueLabel – the destination label is condition is true
See Also:
Condition/**
     * Abstraction for performing a conditional jump of any type
     *
     * @see Condition
     *
     * @param cond      the condition to test
     * @param trueLabel the destination label is condition is true
     */
    void conditionalJump(final Condition cond, final Label trueLabel) {
        conditionalJump(cond, cond != Condition.GT && cond != Condition.GE, trueLabel);
    }

    
Abstraction for performing a conditional jump of any type,
including a dcmpg/dcmpl semantic for doubles.
Params:
cond –      the condition to test
isCmpG –    is this a dcmpg for numbers, false if it's a dcmpl
trueLabel – the destination label if condition is true/**
     * Abstraction for performing a conditional jump of any type,
     * including a dcmpg/dcmpl semantic for doubles.
     *
     * @param cond      the condition to test
     * @param isCmpG    is this a dcmpg for numbers, false if it's a dcmpl
     * @param trueLabel the destination label if condition is true
     */
    void conditionalJump(final Condition cond, final boolean isCmpG, final Label trueLabel) {
        if (peekType().isCategory2()) {
            debug("[ld]cmp isCmpG=", isCmpG);
            pushType(get2n().cmp(method, isCmpG));
            jump(Condition.toUnary(cond), trueLabel, 1);
        } else {
            debug("if", cond);
            jump(Condition.toBinary(cond, peekType().isObject()), trueLabel, 2);
        }
    }

    
Perform a non void return, popping the type from the stack
Params:
type – the type for the return/**
     * Perform a non void return, popping the type from the stack
     *
     * @param type the type for the return
     */
    void _return(final Type type) {
        debug("return", type);
        assert stack.size() == 1 : "Only return value on stack allowed at return point - depth=" + stack.size() + " stack = " + stack;
        final Type stackType = peekType();
        if (!Type.areEquivalent(type, stackType)) {
            convert(type);
        }
        popType(type)._return(method);
        doesNotContinueSequentially();
    }

    
Perform a return using the stack top value as the guide for the type
/**
     * Perform a return using the stack top value as the guide for the type
     */
    void _return() {
        _return(peekType());
    }

    
Perform a void return.
/**
     * Perform a void return.
     */
    void returnVoid() {
        debug("return [void]");
        assert stack.isEmpty() : stack;
        method.visitInsn(RETURN);
        doesNotContinueSequentially();
    }

    
Perform a comparison of two number types that are popped from the stack
Params:
isCmpG – is this a dcmpg semantic, false if it's a dcmpl semantic
Returns:
the method emitter/**
     * Perform a comparison of two number types that are popped from the stack
     *
     * @param isCmpG is this a dcmpg semantic, false if it's a dcmpl semantic
     *
     * @return the method emitter
     */
    MethodEmitter cmp(final boolean isCmpG) {
        pushType(get2n().cmp(method, isCmpG));
        return this;
    }

    
Helper function for jumps, conditional or not
Params:
opcode –  opcode for jump
label –   destination
n –       elements on stack to compare, 0-2/**
     * Helper function for jumps, conditional or not
     * @param opcode  opcode for jump
     * @param label   destination
     * @param n       elements on stack to compare, 0-2
     */
    private void jump(final int opcode, final Label label, final int n) {
        for (int i = 0; i < n; i++) {
            assert peekType().isInteger() || peekType().isBoolean() || peekType().isObject() : "expecting integer type or object for jump, but found " + peekType();
            popType();
        }
        joinTo(label);
        method.visitJumpInsn(opcode, label.getLabel());
    }

    
Generate an if_acmpeq
Params:
label – label to true case/**
     * Generate an if_acmpeq
     *
     * @param label label to true case
     */
    void if_acmpeq(final Label label) {
        debug("if_acmpeq", label);
        jump(IF_ACMPEQ, label, 2);
    }

    
Generate an if_acmpne
Params:
label – label to true case/**
     * Generate an if_acmpne
     *
     * @param label label to true case
     */
    void if_acmpne(final Label label) {
        debug("if_acmpne", label);
        jump(IF_ACMPNE, label, 2);
    }

    
Generate an ifnull
Params:
label – label to true case/**
     * Generate an ifnull
     *
     * @param label label to true case
     */
    void ifnull(final Label label) {
        debug("ifnull", label);
        jump(IFNULL, label, 1);
    }

    
Generate an ifnonnull
Params:
label – label to true case/**
     * Generate an ifnonnull
     *
     * @param label label to true case
     */
    void ifnonnull(final Label label) {
        debug("ifnonnull", label);
        jump(IFNONNULL, label, 1);
    }

    
Generate an ifeq
Params:
label – label to true case/**
     * Generate an ifeq
     *
     * @param label label to true case
     */
    void ifeq(final Label label) {
        debug("ifeq ", label);
        jump(IFEQ, label, 1);
    }

    
Generate an if_icmpeq
Params:
label – label to true case/**
     * Generate an if_icmpeq
     *
     * @param label label to true case
     */
    void if_icmpeq(final Label label) {
        debug("if_icmpeq", label);
        jump(IF_ICMPEQ, label, 2);
    }

    
Generate an if_ne
Params:
label – label to true case/**
     * Generate an if_ne
     *
     * @param label label to true case
     */
    void ifne(final Label label) {
        debug("ifne", label);
        jump(IFNE, label, 1);
    }

    
Generate an if_icmpne
Params:
label – label to true case/**
     * Generate an if_icmpne
     *
     * @param label label to true case
     */
    void if_icmpne(final Label label) {
        debug("if_icmpne", label);
        jump(IF_ICMPNE, label, 2);
    }

    
Generate an iflt
Params:
label – label to true case/**
     * Generate an iflt
     *
     * @param label label to true case
     */
    void iflt(final Label label) {
        debug("iflt", label);
        jump(IFLT, label, 1);
    }

    
Generate an if_icmplt
Params:
label – label to true case/**
     * Generate an if_icmplt
     *
     * @param label label to true case
     */
    void if_icmplt(final Label label) {
        debug("if_icmplt", label);
        jump(IF_ICMPLT, label, 2);
    }

    
Generate an ifle
Params:
label – label to true case/**
     * Generate an ifle
     *
     * @param label label to true case
     */
    void ifle(final Label label) {
        debug("ifle", label);
        jump(IFLE, label, 1);
    }

    
Generate an if_icmple
Params:
label – label to true case/**
     * Generate an if_icmple
     *
     * @param label label to true case
     */
    void if_icmple(final Label label) {
        debug("if_icmple", label);
        jump(IF_ICMPLE, label, 2);
    }

    
Generate an ifgt
Params:
label – label to true case/**
     * Generate an ifgt
     *
     * @param label label to true case
     */
    void ifgt(final Label label) {
        debug("ifgt", label);
        jump(IFGT, label, 1);
    }

    
Generate an if_icmpgt
Params:
label – label to true case/**
     * Generate an if_icmpgt
     *
     * @param label label to true case
     */
    void if_icmpgt(final Label label) {
        debug("if_icmpgt", label);
        jump(IF_ICMPGT, label, 2);
    }

    
Generate an ifge
Params:
label – label to true case/**
     * Generate an ifge
     *
     * @param label label to true case
     */
    void ifge(final Label label) {
        debug("ifge", label);
        jump(IFGE, label, 1);
    }

    
Generate an if_icmpge
Params:
label – label to true case/**
     * Generate an if_icmpge
     *
     * @param label label to true case
     */
    void if_icmpge(final Label label) {
        debug("if_icmpge", label);
        jump(IF_ICMPGE, label, 2);
    }

    
Unconditional jump to a label
Params:
label – destination label/**
     * Unconditional jump to a label
     *
     * @param label destination label
     */
    void _goto(final Label label) {
        debug("goto", label);
        jump(GOTO, label, 0);
        doesNotContinueSequentially(); //whoever reaches the point after us provides the stack, because we don't
    }

    
Unconditional jump to the start label of a loop. It differs from ordinary _goto(Label) in that it will preserve the current label stack, as the next instruction after the goto is loop body that the loop will come back to. Also used to jump at the start label of the continuation handler, as it behaves much like a loop test in the sense that after it is evaluated, it also jumps backwards. 
Params:
loopStart – start label of a loop/**
     * Unconditional jump to the start label of a loop. It differs from ordinary {@link #_goto(Label)} in that it will
     * preserve the current label stack, as the next instruction after the goto is loop body that the loop will come
     * back to. Also used to jump at the start label of the continuation handler, as it behaves much like a loop test in
     * the sense that after it is evaluated, it also jumps backwards.
     *
     * @param loopStart start label of a loop
     */
    void gotoLoopStart(final Label loopStart) {
        debug("goto (loop)", loopStart);
        jump(GOTO, loopStart, 0);
    }

    
Unconditional jump without any control flow and data flow testing. You should not normally use this method when
generating code, except if you're very sure that you know what you're doing. Normally only used for the
admittedly torturous control flow of continuation handler plumbing.
Params:
target – the target of the jump/**
     * Unconditional jump without any control flow and data flow testing. You should not normally use this method when
     * generating code, except if you're very sure that you know what you're doing. Normally only used for the
     * admittedly torturous control flow of continuation handler plumbing.
     * @param target the target of the jump
     */
    void uncheckedGoto(final Label target) {
        method.visitJumpInsn(GOTO, target.getLabel());
    }

    
Potential transfer of control to a catch block.
Params:
catchLabel – destination catch label/**
     * Potential transfer of control to a catch block.
     *
     * @param catchLabel destination catch label
     */
    void canThrow(final Label catchLabel) {
        catchLabel.joinFromTry(stack, false);
    }

    
A join in control flow - helper function that makes sure all entry stacks
discovered for the join point so far are equivalent
MergeStack: we are about to enter a label. If its stack, label.getStack() is null
we have never been here before. Then we are expected to carry a stack with us.
Params:
label – label/**
     * A join in control flow - helper function that makes sure all entry stacks
     * discovered for the join point so far are equivalent
     *
     * MergeStack: we are about to enter a label. If its stack, label.getStack() is null
     * we have never been here before. Then we are expected to carry a stack with us.
     *
     * @param label label
     */
    private void joinTo(final Label label) {
        assert isReachable();
        label.joinFrom(stack);
    }

    
Register a new label, enter it here.
Params:
label – /**
     * Register a new label, enter it here.
     * @param label
     */
    void label(final Label label) {
        breakLabel(label, -1);
    }

    
Register a new break target label, enter it here.
Params:
label – the label
liveLocals – the number of live locals at this label/**
     * Register a new break target label, enter it here.
     *
     * @param label the label
     * @param liveLocals the number of live locals at this label
     */
    void breakLabel(final Label label, final int liveLocals) {
        if (!isReachable()) {
            // If we emit a label, and the label's stack is null, it must not be reachable.
            assert (label.getStack() == null) != label.isReachable();
        } else {
            joinTo(label);
        }
        // Use label's stack as we might have no stack.
        final Label.Stack labelStack = label.getStack();
        stack = labelStack == null ? null : labelStack.clone();
        if(stack != null && label.isBreakTarget() && liveLocals != -1) {
            // This has to be done because we might not have another frame to provide us with its firstTemp if the label
            // is only reachable through a break or continue statement; also in this case, the frame can actually
            // give us a higher number of live locals, e.g. if it comes from a catch. Typical example:
            // for(;;) { try{ throw 0; } catch(e) { break; } }.
            // Since the for loop can only be exited through the break in the catch block, it'll bring with it the
            // "e" as a live local, and we need to trim it off here.
            assert stack.firstTemp >= liveLocals;
            stack.firstTemp = liveLocals;
        }
        debug_label(label);
        method.visitLabel(label.getLabel());
    }

    
Pop element from stack, convert to given type
Params:
to – type to convert to
Returns:
the method emitter/**
     * Pop element from stack, convert to given type
     *
     * @param to type to convert to
     *
     * @return the method emitter
     */
    MethodEmitter convert(final Type to) {
        final Type from = peekType();
        final Type type = from.convert(method, to);
        if (type != null) {
            if (!from.isEquivalentTo(to)) {
                debug("convert", from, "->", to);
            }
            if (type != from) {
                final int l0 = stack.getTopLocalLoad();
                popType();
                pushType(type);
                // NOTE: conversions from a primitive type are considered to preserve the "load" property of the value
                // on the stack. Otherwise we could introduce temporary locals in a deoptimized rest-of (e.g. doing an
                // "i < x.length" where "i" is int and ".length" gets deoptimized to long would end up converting i to
                // long with "ILOAD i; I2L; LSTORE tmp; LLOAD tmp;"). Such additional temporary would cause an error
                // when restoring the state of the function for rest-of execution, as the not-yet deoptimized variant
                // would have the (now invalidated) assumption that "x.length" is an int, so it wouldn't have the I2L,
                // and therefore neither the subsequent LSTORE tmp; LLOAD tmp;. By making sure conversions from a
                // primitive type don't erase the "load" information, we don't introduce temporaries in the deoptimized
                // rest-of that didn't exist in the more optimistic version that triggered the deoptimization.
                // NOTE: as a more general observation, we could theoretically track the operations required to
                // reproduce any stack value as long as they are all local loads, constant loads, and stack operations.
                // We won't go there in the current system
                if(!from.isObject()) {
                    stack.markLocalLoad(l0);
                }
            }
        }
        return this;
    }

    
Helper function - expect two types that are equivalent
Returns:
common type/**
     * Helper function - expect two types that are equivalent
     *
     * @return common type
     */
    private Type get2() {
        final Type p0 = popType();
        final Type p1 = popType();
        assert p0.isEquivalentTo(p1) : "expecting equivalent types on stack but got " + p0 + " and " + p1;
        return p0;
    }

    
Helper function - expect two types that are integer types and equivalent
Returns:
common type/**
     * Helper function - expect two types that are integer types and equivalent
     *
     * @return common type
     */
    private BitwiseType get2i() {
        final BitwiseType p0 = popBitwise();
        final BitwiseType p1 = popBitwise();
        assert p0.isEquivalentTo(p1) : "expecting equivalent types on stack but got " + p0 + " and " + p1;
        return p0;
    }

    
Helper function - expect two types that are numbers and equivalent
Returns:
common type/**
     * Helper function - expect two types that are numbers and equivalent
     *
     * @return common type
     */
    private NumericType get2n() {
        final NumericType p0 = popNumeric();
        final NumericType p1 = popNumeric();
        assert p0.isEquivalentTo(p1) : "expecting equivalent types on stack but got " + p0 + " and " + p1;
        return p0;
    }

    
Pop two numbers, perform addition and push result
Returns:
the method emitter/**
     * Pop two numbers, perform addition and push result
     *
     * @return the method emitter
     */
    MethodEmitter add(final int programPoint) {
        debug("add");
        pushType(get2().add(method, programPoint));
        return this;
    }

    
Pop two numbers, perform subtraction and push result
Returns:
the method emitter/**
     * Pop two numbers, perform subtraction and push result
     *
     * @return the method emitter
     */
    MethodEmitter sub(final int programPoint) {
        debug("sub");
        pushType(get2n().sub(method, programPoint));
        return this;
    }

    
Pop two numbers, perform multiplication and push result
Returns:
the method emitter/**
     * Pop two numbers, perform multiplication and push result
     *
     * @return the method emitter
     */
    MethodEmitter mul(final int programPoint) {
        debug("mul ");
        pushType(get2n().mul(method, programPoint));
        return this;
    }

    
Pop two numbers, perform division and push result
Returns:
the method emitter/**
     * Pop two numbers, perform division and push result
     *
     * @return the method emitter
     */
    MethodEmitter div(final int programPoint) {
        debug("div");
        pushType(get2n().div(method, programPoint));
        return this;
    }

    
Pop two numbers, calculate remainder and push result
Returns:
the method emitter/**
     * Pop two numbers, calculate remainder and push result
     *
     * @return the method emitter
     */
    MethodEmitter rem(final int programPoint) {
        debug("rem");
        pushType(get2n().rem(method, programPoint));
        return this;
    }

    
Retrieve the top count types on the stack without modifying it.
Params:
count – number of types to return
Returns:
array of Types/**
     * Retrieve the top <code>count</code> types on the stack without modifying it.
     *
     * @param count number of types to return
     * @return array of Types
     */
    protected Type[] getTypesFromStack(final int count) {
        return stack.getTopTypes(count);
    }

    int[] getLocalLoadsOnStack(final int from, final int to) {
        return stack.getLocalLoads(from, to);
    }

    int getStackSize() {
        return stack.size();
    }

    int getFirstTemp() {
        return stack.firstTemp;
    }

    int getUsedSlotsWithLiveTemporaries() {
        return stack.getUsedSlotsWithLiveTemporaries();
    }

    
Helper function to generate a function signature based on stack contents
and argument count and return type
Params:
returnType – return type
argCount –   argument count
Returns:
function signature for stack contents/**
     * Helper function to generate a function signature based on stack contents
     * and argument count and return type
     *
     * @param returnType return type
     * @param argCount   argument count
     *
     * @return function signature for stack contents
     */
    private String getDynamicSignature(final Type returnType, final int argCount) {
        final Type[]         paramTypes = new Type[argCount];

        int pos = 0;
        for (int i = argCount - 1; i >= 0; i--) {
            Type pt = stack.peek(pos++);
            // "erase" specific ScriptObject subtype info - except for NativeArray.
            // NativeArray is used for array/List/Deque conversion for Java calls.
            if (ScriptObject.class.isAssignableFrom(pt.getTypeClass()) &&
                !NativeArray.class.isAssignableFrom(pt.getTypeClass())) {
                pt = Type.SCRIPT_OBJECT;
            }
            paramTypes[i] = pt;
        }
        final String descriptor = Type.getMethodDescriptor(returnType, paramTypes);
        for (int i = 0; i < argCount; i++) {
            popType(paramTypes[argCount - i - 1]);
        }

        return descriptor;
    }

    MethodEmitter invalidateSpecialName(final String name) {
        switch (name) {
        case "apply":
        case "call":
            debug("invalidate_name", "name=", name);
            load("Function");
            invoke(ScriptRuntime.INVALIDATE_RESERVED_BUILTIN_NAME);
            break;
        default:
            break;
        }
        return this;
    }

    
Generate a dynamic new
Params:
argCount –  number of arguments
flags –     callsite flags
Returns:
the method emitter/**
     * Generate a dynamic new
     *
     * @param argCount  number of arguments
     * @param flags     callsite flags
     *
     * @return the method emitter
     */
    MethodEmitter dynamicNew(final int argCount, final int flags) {
        return dynamicNew(argCount, flags, null);
    }

    
Generate a dynamic new
Params:
argCount –  number of arguments
flags –     callsite flags
msg –        additional message to be used when reporting error
Returns:
the method emitter/**
     * Generate a dynamic new
     *
     * @param argCount  number of arguments
     * @param flags     callsite flags
     * @param msg        additional message to be used when reporting error
     *
     * @return the method emitter
     */
    MethodEmitter dynamicNew(final int argCount, final int flags, final String msg) {
        assert !isOptimistic(flags);
        debug("dynamic_new", "argcount=", argCount);
        final String signature = getDynamicSignature(Type.OBJECT, argCount);
        method.visitInvokeDynamicInsn(
                msg != null && msg.length() < LARGE_STRING_THRESHOLD? NameCodec.encode(msg) : EMPTY_NAME,
                signature, LINKERBOOTSTRAP, flags | NashornCallSiteDescriptor.NEW);
        pushType(Type.OBJECT); //TODO fix result type
        return this;
    }

    
Generate a dynamic call
Params:
returnType – return type
argCount –   number of arguments
flags –      callsite flags
Returns:
the method emitter/**
     * Generate a dynamic call
     *
     * @param returnType return type
     * @param argCount   number of arguments
     * @param flags      callsite flags
     *
     * @return the method emitter
     */
    MethodEmitter dynamicCall(final Type returnType, final int argCount, final int flags) {
        return dynamicCall(returnType, argCount, flags, null);
    }

    
Generate a dynamic call
Params:
returnType – return type
argCount –   number of arguments
flags –      callsite flags
msg –        additional message to be used when reporting error
Returns:
the method emitter/**
     * Generate a dynamic call
     *
     * @param returnType return type
     * @param argCount   number of arguments
     * @param flags      callsite flags
     * @param msg        additional message to be used when reporting error
     *
     * @return the method emitter
     */
    MethodEmitter dynamicCall(final Type returnType, final int argCount, final int flags, final String msg) {
        debug("dynamic_call", "args=", argCount, "returnType=", returnType);
        final String signature = getDynamicSignature(returnType, argCount); // +1 because the function itself is the 1st parameter for dynamic calls (what you call - call target)
        debug("   signature", signature);
        method.visitInvokeDynamicInsn(
                msg != null && msg.length() < LARGE_STRING_THRESHOLD? NameCodec.encode(msg) : EMPTY_NAME,
                signature, LINKERBOOTSTRAP, flags | NashornCallSiteDescriptor.CALL);
        pushType(returnType);

        return this;
    }

    MethodEmitter dynamicArrayPopulatorCall(final int argCount, final int startIndex) {
        debug("populate_array", "args=", argCount, "startIndex=", startIndex);
        final String signature = getDynamicSignature(Type.OBJECT_ARRAY, argCount);
        method.visitInvokeDynamicInsn("populateArray", signature, POPULATE_ARRAY_BOOTSTRAP, startIndex);
        pushType(Type.OBJECT_ARRAY);
        return this;
    }

    
Generate dynamic getter. Pop object from stack. Push result.
Params:
valueType – type of the value to set
name –      name of property
flags –     call site flags
isMethod –  should it prefer retrieving methods
isIndex –   is this an index operation?
Returns:
the method emitter/**
     * Generate dynamic getter. Pop object from stack. Push result.
     *
     * @param valueType type of the value to set
     * @param name      name of property
     * @param flags     call site flags
     * @param isMethod  should it prefer retrieving methods
     * @param isIndex   is this an index operation?
     * @return the method emitter
     */
    MethodEmitter dynamicGet(final Type valueType, final String name, final int flags, final boolean isMethod, final boolean isIndex) {
        if (name.length() > LARGE_STRING_THRESHOLD) { // use getIndex for extremely long names
            return load(name).dynamicGetIndex(valueType, flags, isMethod);
        }

        debug("dynamic_get", name, valueType, getProgramPoint(flags));

        Type type = valueType;
        if (type.isObject() || type.isBoolean()) {
            type = Type.OBJECT; //promote e.g strings to object generic setter
        }

        popType(Type.OBJECT);
        method.visitInvokeDynamicInsn(NameCodec.encode(name),
                Type.getMethodDescriptor(type, Type.OBJECT), LINKERBOOTSTRAP, flags | dynGetOperation(isMethod, isIndex));

        pushType(type);
        convert(valueType); //most probably a nop

        return this;
    }

    
Generate dynamic setter. Pop receiver and property from stack.
Params:
name –  name of property
flags – call site flags
isIndex – is this an index operation?/**
     * Generate dynamic setter. Pop receiver and property from stack.
     *
     * @param name  name of property
     * @param flags call site flags
     * @param isIndex is this an index operation?
     */
    void dynamicSet(final String name, final int flags, final boolean isIndex) {
        if (name.length() > LARGE_STRING_THRESHOLD) { // use setIndex for extremely long names
            load(name).swap().dynamicSetIndex(flags);
            return;
        }

        assert !isOptimistic(flags);
        debug("dynamic_set", name, peekType());

        Type type = peekType();
        if (type.isObject() || type.isBoolean()) { //promote strings to objects etc
            type = Type.OBJECT;
            convert(Type.OBJECT); //TODO bad- until we specialize boolean setters,
        }
        popType(type);
        popType(Type.OBJECT);

        method.visitInvokeDynamicInsn(NameCodec.encode(name),
                methodDescriptor(void.class, Object.class, type.getTypeClass()), LINKERBOOTSTRAP, flags | dynSetOperation(isIndex));
    }

    
Generate dynamic remover. Pop object from stack. Push result.
Params:
name –      name of property
flags –     call site flags
Returns:
the method emitter/**
     * Generate dynamic remover. Pop object from stack. Push result.
     *
     * @param name      name of property
     * @param flags     call site flags
     * @return the method emitter
     */
    MethodEmitter dynamicRemove(final String name, final int flags, final boolean isIndex) {
        if (name.length() > LARGE_STRING_THRESHOLD) { // use removeIndex for extremely long names
            return load(name).dynamicRemoveIndex(flags);
        }

        debug("dynamic_remove", name, Type.BOOLEAN, getProgramPoint(flags));

        popType(Type.OBJECT);
        // Type is widened to OBJECT then coerced back to BOOLEAN
        method.visitInvokeDynamicInsn(NameCodec.encode(name),
                Type.getMethodDescriptor(Type.OBJECT, Type.OBJECT), LINKERBOOTSTRAP, flags | dynRemoveOperation(isIndex));

        pushType(Type.OBJECT);
        convert(Type.BOOLEAN); //most probably a nop

        return this;
    }

    
Dynamic getter for indexed structures. Pop index and receiver from stack,
generate appropriate signatures based on types
Params:
result – result type for getter
flags – call site flags for getter
isMethod – should it prefer retrieving methods
Returns:
the method emitter/**
     * Dynamic getter for indexed structures. Pop index and receiver from stack,
     * generate appropriate signatures based on types
     *
     * @param result result type for getter
     * @param flags call site flags for getter
     * @param isMethod should it prefer retrieving methods
     *
     * @return the method emitter
     */
    MethodEmitter dynamicGetIndex(final Type result, final int flags, final boolean isMethod) {
        assert result.getTypeClass().isPrimitive() || result.getTypeClass() == Object.class;
        debug("dynamic_get_index", peekType(1), "[", peekType(), "]", getProgramPoint(flags));

        Type resultType = result;
        if (result.isBoolean()) {
            resultType = Type.OBJECT; // INT->OBJECT to avoid another dimension of cross products in the getters. TODO
        }

        Type index = peekType();
        if (index.isObject() || index.isBoolean()) {
            index = Type.OBJECT; //e.g. string->object
            convert(Type.OBJECT);
        }
        popType();

        popType(Type.OBJECT);

        final String signature = Type.getMethodDescriptor(resultType, Type.OBJECT /*e.g STRING->OBJECT*/, index);

        method.visitInvokeDynamicInsn(EMPTY_NAME, signature, LINKERBOOTSTRAP, flags | dynGetOperation(isMethod, true));
        pushType(resultType);

        if (result.isBoolean()) {
            convert(Type.BOOLEAN);
        }

        return this;
    }

    private static String getProgramPoint(final int flags) {
        if((flags & CALLSITE_OPTIMISTIC) == 0) {
            return "";
        }
        return "pp=" + String.valueOf((flags & (-1 << CALLSITE_PROGRAM_POINT_SHIFT)) >> CALLSITE_PROGRAM_POINT_SHIFT);
    }

    
Dynamic setter for indexed structures. Pop value, index and receiver from
stack, generate appropriate signature based on types
Params:
flags – call site flags for setter/**
     * Dynamic setter for indexed structures. Pop value, index and receiver from
     * stack, generate appropriate signature based on types
     *
     * @param flags call site flags for setter
     */
    void dynamicSetIndex(final int flags) {
        assert !isOptimistic(flags);
        debug("dynamic_set_index", peekType(2), "[", peekType(1), "] =", peekType());

        Type value = peekType();
        if (value.isObject() || value.isBoolean()) {
            value = Type.OBJECT; //e.g. STRING->OBJECT - one descriptor for all object types
            convert(Type.OBJECT);
        }
        popType();

        Type index = peekType();
        if (index.isObject() || index.isBoolean()) {
            index = Type.OBJECT; //e.g. string->object
            convert(Type.OBJECT);
        }
        popType(index);

        final Type receiver = popType(Type.OBJECT);
        assert receiver.isObject();

        method.visitInvokeDynamicInsn(EMPTY_NAME,
                methodDescriptor(void.class, receiver.getTypeClass(), index.getTypeClass(), value.getTypeClass()),
                LINKERBOOTSTRAP, flags | NashornCallSiteDescriptor.SET_ELEMENT);
    }

    
Dynamic remover for indexed structures. Pop index and receiver from stack,
generate appropriate signatures based on types
Params:
flags – call site flags for getter
Returns:
the method emitter/**
     * Dynamic remover for indexed structures. Pop index and receiver from stack,
     * generate appropriate signatures based on types
     *
     * @param flags call site flags for getter
     *
     * @return the method emitter
     */
    MethodEmitter dynamicRemoveIndex(final int flags) {
        debug("dynamic_remove_index", peekType(1), "[", peekType(), "]", getProgramPoint(flags));

        Type index = peekType();
        if (index.isObject() || index.isBoolean()) {
            index = Type.OBJECT; //e.g. string->object
            convert(Type.OBJECT);
        }
        popType();

        popType(Type.OBJECT);

        final String signature = Type.getMethodDescriptor(Type.OBJECT, Type.OBJECT /*e.g STRING->OBJECT*/, index);

        method.visitInvokeDynamicInsn(EMPTY_NAME, signature, LINKERBOOTSTRAP, flags | dynRemoveOperation(true));
        pushType(Type.OBJECT);
        convert(Type.BOOLEAN);

        return this;
    }

    
Load a key value in the proper form.
Params:
key – /**
     * Load a key value in the proper form.
     *
     * @param key
     */
    //TODO move this and break it apart
    MethodEmitter loadKey(final Object key) {
        if (key instanceof IdentNode) {
            method.visitLdcInsn(((IdentNode) key).getName());
        } else if (key instanceof LiteralNode) {
            method.visitLdcInsn(((LiteralNode<?>)key).getString());
        } else {
            method.visitLdcInsn(JSType.toString(key));
        }
        pushType(Type.OBJECT); //STRING
        return this;
    }

     @SuppressWarnings("fallthrough")
     private static Type fieldType(final String desc) {
         switch (desc) {
         case "Z":
         case "B":
         case "C":
         case "S":
         case "I":
             return Type.INT;
         case "F":
             assert false;
         case "D":
             return Type.NUMBER;
         case "J":
             return Type.LONG;
         default:
             assert desc.startsWith("[") || desc.startsWith("L") : desc + " is not an object type";
             switch (desc.charAt(0)) {
             case 'L':
                 return Type.OBJECT;
             case '[':
                 return Type.typeFor(Array.newInstance(fieldType(desc.substring(1)).getTypeClass(), 0).getClass());
             default:
                 assert false;
             }
             return Type.OBJECT;
         }
     }

     
Generate get for a field access
Params:
fa – the field access
Returns:
the method emitter/**
      * Generate get for a field access
      *
      * @param fa the field access
      *
      * @return the method emitter
      */
    MethodEmitter getField(final FieldAccess fa) {
        return fa.get(this);
    }

     
Generate set for a field access
Params:
fa – the field access/**
      * Generate set for a field access
      *
      * @param fa the field access
      */
    void putField(final FieldAccess fa) {
        fa.put(this);
    }

    
Get the value of a non-static field, pop the receiver from the stack,
push value to the stack
Params:
className –        class
fieldName –        field name
fieldDescriptor –  field descriptor
Returns:
the method emitter/**
     * Get the value of a non-static field, pop the receiver from the stack,
     * push value to the stack
     *
     * @param className        class
     * @param fieldName        field name
     * @param fieldDescriptor  field descriptor
     *
     * @return the method emitter
     */
    MethodEmitter getField(final String className, final String fieldName, final String fieldDescriptor) {
        debug("getfield", "receiver=", peekType(), className, ".", fieldName, fieldDescriptor);
        final Type receiver = popType();
        assert receiver.isObject();
        method.visitFieldInsn(GETFIELD, className, fieldName, fieldDescriptor);
        pushType(fieldType(fieldDescriptor));
        return this;
    }

    
Get the value of a static field, push it to the stack
Params:
className –        class
fieldName –        field name
fieldDescriptor –  field descriptor
Returns:
the method emitter/**
     * Get the value of a static field, push it to the stack
     *
     * @param className        class
     * @param fieldName        field name
     * @param fieldDescriptor  field descriptor
     *
     * @return the method emitter
     */
    MethodEmitter getStatic(final String className, final String fieldName, final String fieldDescriptor) {
        debug("getstatic", className, ".", fieldName, ".", fieldDescriptor);
        method.visitFieldInsn(GETSTATIC, className, fieldName, fieldDescriptor);
        pushType(fieldType(fieldDescriptor));
        return this;
    }

    
Pop value and field from stack and write to a non-static field
Params:
className –       class
fieldName –       field name
fieldDescriptor – field descriptor/**
     * Pop value and field from stack and write to a non-static field
     *
     * @param className       class
     * @param fieldName       field name
     * @param fieldDescriptor field descriptor
     */
    void putField(final String className, final String fieldName, final String fieldDescriptor) {
        debug("putfield", "receiver=", peekType(1), "value=", peekType());
        popType(fieldType(fieldDescriptor));
        popType(Type.OBJECT);
        method.visitFieldInsn(PUTFIELD, className, fieldName, fieldDescriptor);
    }

    
Pop value from stack and write to a static field
Params:
className –       class
fieldName –       field name
fieldDescriptor – field descriptor/**
     * Pop value from stack and write to a static field
     *
     * @param className       class
     * @param fieldName       field name
     * @param fieldDescriptor field descriptor
     */
    void putStatic(final String className, final String fieldName, final String fieldDescriptor) {
        debug("putfield", "value=", peekType());
        popType(fieldType(fieldDescriptor));
        method.visitFieldInsn(PUTSTATIC, className, fieldName, fieldDescriptor);
    }

    
Register line number at a label
Params:
line –  line number/**
     * Register line number at a label
     *
     * @param line  line number
     */
    void lineNumber(final int line) {
        if (context.getEnv()._debug_lines) {
            debug_label("[LINE]", line);
            final jdk.internal.org.objectweb.asm.Label l = new jdk.internal.org.objectweb.asm.Label();
            method.visitLabel(l);
            method.visitLineNumber(line, l);
        }
    }

    void beforeJoinPoint(final JoinPredecessor joinPredecessor) {
        LocalVariableConversion next = joinPredecessor.getLocalVariableConversion();
        while(next != null) {
            final Symbol symbol = next.getSymbol();
            if(next.isLive()) {
                emitLocalVariableConversion(next, true);
            } else {
                markDeadLocalVariable(symbol);
            }
            next = next.getNext();
        }
    }

    void beforeTry(final TryNode tryNode, final Label recovery) {
        LocalVariableConversion next = tryNode.getLocalVariableConversion();
        while(next != null) {
            if(next.isLive()) {
                final Type to = emitLocalVariableConversion(next, false);
                recovery.getStack().onLocalStore(to, next.getSymbol().getSlot(to), true);
            }
            next = next.getNext();
        }
    }

    private static int dynGetOperation(final boolean isMethod, final boolean isIndex) {
        if (isMethod) {
            return isIndex ? NashornCallSiteDescriptor.GET_METHOD_ELEMENT : NashornCallSiteDescriptor.GET_METHOD_PROPERTY;
        } else {
            return isIndex ? NashornCallSiteDescriptor.GET_ELEMENT : NashornCallSiteDescriptor.GET_PROPERTY;
        }
    }

    private static int dynSetOperation(final boolean isIndex) {
        return isIndex ? NashornCallSiteDescriptor.SET_ELEMENT : NashornCallSiteDescriptor.SET_PROPERTY;
    }

    private static int dynRemoveOperation(final boolean isIndex) {
        return isIndex ? NashornCallSiteDescriptor.REMOVE_ELEMENT : NashornCallSiteDescriptor.REMOVE_PROPERTY;
    }

    private Type emitLocalVariableConversion(final LocalVariableConversion conversion, final boolean onlySymbolLiveValue) {
        final Type from = conversion.getFrom();
        final Type to = conversion.getTo();
        final Symbol symbol = conversion.getSymbol();
        assert symbol.isBytecodeLocal();
        if(from == Type.UNDEFINED) {
            loadUndefined(to);
        } else {
            load(symbol, from).convert(to);
        }
        store(symbol, to, onlySymbolLiveValue);
        return to;
    }

    /*
     * Debugging below
     */

    private final FieldAccess ERR_STREAM       = staticField(System.class, "err", PrintStream.class);
    private final Call        PRINT            = virtualCallNoLookup(PrintStream.class, "print", void.class, Object.class);
    private final Call        PRINTLN          = virtualCallNoLookup(PrintStream.class, "println", void.class, Object.class);
    private final Call        PRINT_STACKTRACE = virtualCallNoLookup(Throwable.class, "printStackTrace", void.class);

    
Emit a System.err.print statement of whatever is on top of the bytecode stack
/**
     * Emit a System.err.print statement of whatever is on top of the bytecode stack
     */
     void print() {
         getField(ERR_STREAM);
         swap();
         convert(Type.OBJECT);
         invoke(PRINT);
     }

    
Emit a System.err.println statement of whatever is on top of the bytecode stack
/**
     * Emit a System.err.println statement of whatever is on top of the bytecode stack
     */
     void println() {
         getField(ERR_STREAM);
         swap();
         convert(Type.OBJECT);
         invoke(PRINTLN);
     }

     
Emit a System.err.print statement
Params:
string – string to print/**
      * Emit a System.err.print statement
      * @param string string to print
      */
     void print(final String string) {
         getField(ERR_STREAM);
         load(string);
         invoke(PRINT);
     }

     
Emit a System.err.println statement
Params:
string – string to print/**
      * Emit a System.err.println statement
      * @param string string to print
      */
     void println(final String string) {
         getField(ERR_STREAM);
         load(string);
         invoke(PRINTLN);
     }

     
Print a stacktrace to S
/**
      * Print a stacktrace to S
      */
     void stacktrace() {
         _new(Throwable.class);
         dup();
         invoke(constructorNoLookup(Throwable.class));
         invoke(PRINT_STACKTRACE);
     }

    private static int linePrefix = 0;

    
Debug function that outputs generated bytecode and stack contents
Params:
args – debug information to print/**
     * Debug function that outputs generated bytecode and stack contents
     *
     * @param args debug information to print
     */
    @SuppressWarnings("unused")
    private void debug(final Object... args) {
        if (debug) {
            debug(30, args);
        }
    }

    private void debug(final String arg) {
        if (debug) {
            debug(30, arg);
        }
    }

    private void debug(final Object arg0, final Object arg1) {
        if (debug) {
            debug(30, new Object[] { arg0, arg1 });
        }
    }

    private void debug(final Object arg0, final Object arg1, final Object arg2) {
        if (debug) {
            debug(30, new Object[] { arg0, arg1, arg2 });
        }
    }

    private void debug(final Object arg0, final Object arg1, final Object arg2, final Object arg3) {
        if (debug) {
            debug(30, new Object[] { arg0, arg1, arg2, arg3 });
        }
    }

    private void debug(final Object arg0, final Object arg1, final Object arg2, final Object arg3, final Object arg4) {
        if (debug) {
            debug(30, new Object[] { arg0, arg1, arg2, arg3, arg4 });
        }
    }

    private void debug(final Object arg0, final Object arg1, final Object arg2, final Object arg3, final Object arg4, final Object arg5) {
        if (debug) {
            debug(30, new Object[] { arg0, arg1, arg2, arg3, arg4, arg5 });
        }
    }

    private void debug(final Object arg0, final Object arg1, final Object arg2, final Object arg3, final Object arg4, final Object arg5, final Object arg6) {
        if (debug) {
            debug(30, new Object[] { arg0, arg1, arg2, arg3, arg4, arg5, arg6 });
        }
    }

    
Debug function that outputs generated bytecode and stack contents
for a label - indentation is currently the only thing that differs
Params:
args – debug information to print/**
     * Debug function that outputs generated bytecode and stack contents
     * for a label - indentation is currently the only thing that differs
     *
     * @param args debug information to print
     */
    private void debug_label(final Object... args) {
        if (debug) {
            debug(22, args);
        }
    }

    private void debug(final int padConstant, final Object... args) {
        if (debug) {
            final StringBuilder sb = new StringBuilder();
            int pad;

            sb.append('#');
            sb.append(++linePrefix);

            pad = 5 - sb.length();
            while (pad > 0) {
                sb.append(' ');
                pad--;
            }

            if (isReachable() && !stack.isEmpty()) {
                sb.append("{");
                sb.append(stack.size());
                sb.append(":");
                for (int pos = 0; pos < stack.size(); pos++) {
                    final Type t = stack.peek(pos);

                    if (t == Type.SCOPE) {
                        sb.append("scope");
                    } else if (t == Type.THIS) {
                        sb.append("this");
                    } else if (t.isObject()) {
                        String desc = t.getDescriptor();
                        int i;
                        for (i = 0; desc.charAt(i) == '[' && i < desc.length(); i++) {
                            sb.append('[');
                        }
                        desc = desc.substring(i);
                        final int slash = desc.lastIndexOf('/');
                        if (slash != -1) {
                            desc = desc.substring(slash + 1, desc.length() - 1);
                        }
                        if ("Object".equals(desc)) {
                            sb.append('O');
                        } else {
                            sb.append(desc);
                        }
                    } else {
                        sb.append(t.getDescriptor());
                    }
                    final int loadIndex = stack.localLoads[stack.sp - 1 - pos];
                    if(loadIndex != Label.Stack.NON_LOAD) {
                        sb.append('(').append(loadIndex).append(')');
                    }
                    if (pos + 1 < stack.size()) {
                        sb.append(' ');
                    }
                }
                sb.append('}');
                sb.append(' ');
            }

            pad = padConstant - sb.length();
            while (pad > 0) {
                sb.append(' ');
                pad--;
            }

            for (final Object arg : args) {
                sb.append(arg);
                sb.append(' ');
            }

            if (context.getEnv() != null) { //early bootstrap code doesn't have inited context yet
                log.info(sb);
                if (DEBUG_TRACE_LINE == linePrefix) {
                    new Throwable().printStackTrace(log.getOutputStream());
                }
            }
        }
    }

    
Set the current function node being emitted
Params:
functionNode – the function node/**
     * Set the current function node being emitted
     * @param functionNode the function node
     */
    void setFunctionNode(final FunctionNode functionNode) {
        this.functionNode = functionNode;
    }

    
Invoke to enforce assertions preventing load from a local variable slot that's known to not have been written to.
Used by CodeGenerator, as it strictly enforces tracking of stores. Simpler uses of MethodEmitter, e.g. those
for creating initializers for structure  classes, array getters, etc. don't have strict tracking of stores,
therefore they would fail if they had this assertion turned on.
/**
     * Invoke to enforce assertions preventing load from a local variable slot that's known to not have been written to.
     * Used by CodeGenerator, as it strictly enforces tracking of stores. Simpler uses of MethodEmitter, e.g. those
     * for creating initializers for structure  classes, array getters, etc. don't have strict tracking of stores,
     * therefore they would fail if they had this assertion turned on.
     */
    void setPreventUndefinedLoad() {
        this.preventUndefinedLoad = true;
    }

    private static boolean isOptimistic(final int flags) {
        return (flags & CALLSITE_OPTIMISTIC) != 0;
    }
}