Code (jdk.compiler 1.8.132 API)

java.lang.Object
- com.sun.tools.javac.jvm.Code

```
public class Code
extends Object
```
An internal structure that corresponds to the code attribute of methods in a classfile. The class also provides some utility operations to generate bytecode instructions.
This is NOT part of any supported API. If you write code that depends on this, you do so at your own risk. This code and its internal interfaces are subject to change or deletion without notice.

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class Code.Chain
A chain represents a list of unresolved jumps.

static class Code.StackMapFormat

Nested Classes
Modifier and Type	Class and Description
`static class`	`Code.Chain` A chain represents a list of unresolved jumps.
`static class`	`Code.StackMapFormat`

Field Summary

Fields
Modifier and Type	Field and Description
`byte[]`	`code` The code buffer.
`int`	`cp` the current code pointer.
`CRTable`	`crt` The CharacterRangeTable
`boolean`	`debugCode`
`boolean`	`fatcode` Are we generating code with jumps ≥ 32K?
`int`	`max_locals` The maximum number of local variable slots.
`int`	`max_stack` The maximum stack size.
`boolean`	`needStackMap`
`int`	`nextreg` The next available register.

Constructor Summary

Constructors
Constructor and Description
`Code(Symbol.MethodSymbol meth, boolean fatcode, Position.LineMap lineMap, boolean varDebugInfo, Code.StackMapFormat stackMap, boolean debugCode, CRTable crt, Symtab syms, Types types, Pool pool, LVTRanges lvtRanges)` Construct a code object, given the settings of the fatcode, debugging info switches and the CharacterRangeTable.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`addCatch(char startPc, char endPc, char handlerPc, char catchType)` Add a catch clause to code.
`void`	`addLineNumber(char startPc, char lineNumber)` Add a line number entry.
`void`	`align(int incr)` Align code pointer to next `incr' boundary.
`static int`	`arraycode(Type type)` Given a type, return its code for allocating arrays of that type.
`Code.Chain`	`branch(int opcode)` Emit a branch with given opcode; return its chain.
`boolean`	`checkLimits(JCDiagnostic.DiagnosticPosition pos, Log log)` Check the code against VM spec limits; if problems report them and return true.
`void`	`closeAliveRanges(JCTree tree)`
`void`	`closeAliveRanges(JCTree tree, int closingCP)`
`void`	`compressCatchTable()`
`int`	`curCP()` The current output code pointer.
`void`	`emit4(int od)` Emit four bytes of code.
`void`	`emitAnewarray(int od, Type arrayType)` Emit anewarray.
`void`	`emitInvokedynamic(int desc, Type mtype)` Emit an invokedynamic instruction.
`void`	`emitInvokeinterface(int meth, Type mtype)` Emit an invokeinterface instruction.
`void`	`emitInvokespecial(int meth, Type mtype)` Emit an invokespecial instruction.
`void`	`emitInvokestatic(int meth, Type mtype)` Emit an invokestatic instruction.
`void`	`emitInvokevirtual(int meth, Type mtype)` Emit an invokevirtual instruction.
`int`	`emitJump(int opcode)` Emit a jump instruction.
`void`	`emitLdc(int od)` Emit a ldc (or ldc_w) instruction, taking into account operand size
`void`	`emitMultianewarray(int ndims, int type, Type arrayType)` Emit a multinewarray instruction.
`void`	`emitNewarray(int elemcode, Type arrayType)` Emit newarray.
`void`	`emitop0(int op)` Emit an opcode with no operand field.
`void`	`emitop1(int op, int od)` Emit an opcode with a one-byte operand field.
`void`	`emitop1w(int op, int od)` Emit an opcode with a one-byte operand field; widen if field does not fit in a byte.
`void`	`emitop1w(int op, int od1, int od2)` Emit an opcode with two one-byte operand fields; widen if either field does not fit in a byte.
`void`	`emitop2(int op, int od)` Emit an opcode with a two-byte operand field.
`void`	`emitop4(int op, int od)` Emit an opcode with a four-byte operand field.
`void`	`emitStackMap()` Emit a stack map entry.
`void`	`endScopes(int first)` End scopes of all variables with registers ≥ first.
`int`	`entryPoint()` Declare an entry point; return current code pointer
`int`	`entryPoint(com.sun.tools.javac.jvm.Code.State state)` Declare an entry point with initial state; return current code pointer
`int`	`entryPoint(com.sun.tools.javac.jvm.Code.State state, Type pushed)` Declare an entry point with initial state plus a pushed value; return current code pointer
`void`	`fillExceptionParameterPositions()`
`int`	`get4(int pc)` Return four code bytes at position pc as an int.
`int`	`getLVTSize()` Calculates the size of the LocalVariableTable.
`boolean`	`isAlive()` Is code generation currently enabled?
`void`	`markDead()` Switch code generation on/off.
`void`	`markStatBegin()` Force stat begin eagerly
`static Code.Chain`	`mergeChains(Code.Chain chain1, Code.Chain chain2)` Merge the jumps in of two chains into one.
`static String`	`mnem(int opcode)` static tables
`static int`	`negate(int opcode)` Negate a branch opcode.
`int`	`newLocal(Symbol.VarSymbol v)`
`void`	`newRegSegment()` Start a set of fresh registers.
`void`	`put4(int pc, int od)` Place four bytes into code at address pc.
`void`	`resolve(Code.Chain chain)` Resolve chain to point to current code pointer.
`void`	`resolve(Code.Chain chain, int target)` Resolve chain to point to given target.
`void`	`resolvePending()` Resolve any pending jumps.
`void`	`setDefined(Bits newDefined)` Set the current variable defined state.
`void`	`setDefined(int adr)` Mark a register as being (possibly) defined.
`void`	`setUndefined(int adr)` Mark a register as being undefined.
`void`	`statBegin(int pos)` Mark beginning of statement.
`static int`	`truncate(int tc)` Collapse type code for subtypes of int to INTcode.
`static int`	`typecode(Type type)` Given a type, return its type code (used implicitly in the JVM architecture).
`static int`	`width(int typecode)` The width in bytes of objects of the type.
`static int`	`width(List<Type> types)` The total width taken up by a vector of objects.
`static int`	`width(Type type)`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail
- debugCode
```
public final boolean debugCode
```
- needStackMap
```
public final boolean needStackMap
```
- max_stack
```
public int max_stack
```
  The maximum stack size.
- max_locals
```
public int max_locals
```
  The maximum number of local variable slots.
- code
```
public byte[] code
```
  The code buffer.
- cp
```
public int cp
```
  the current code pointer.
- crt
```
public CRTable crt
```
  The CharacterRangeTable
- fatcode
```
public boolean fatcode
```
  Are we generating code with jumps ≥ 32K?
- nextreg
```
public int nextreg
```
  The next available register.

Constructor Detail

Code

public Code(Symbol.MethodSymbol meth,
            boolean fatcode,
            Position.LineMap lineMap,
            boolean varDebugInfo,
            Code.StackMapFormat stackMap,
            boolean debugCode,
            CRTable crt,
            Symtab syms,
            Types types,
            Pool pool,
            LVTRanges lvtRanges)

Construct a code object, given the settings of the fatcode, debugging info switches and the CharacterRangeTable.

Method Detail

checkLimits

public boolean checkLimits(JCDiagnostic.DiagnosticPosition pos,
                           Log log)

Check the code against VM spec limits; if problems report them and return true.

typecode
```
public static int typecode(Type type)
```
Given a type, return its type code (used implicitly in the JVM architecture).

truncate
```
public static int truncate(int tc)
```
Collapse type code for subtypes of int to INTcode.

width
```
public static int width(int typecode)
```
The width in bytes of objects of the type.

width
```
public static int width(Type type)
```

width
```
public static int width(List<Type> types)
```
The total width taken up by a vector of objects.

arraycode
```
public static int arraycode(Type type)
```
Given a type, return its code for allocating arrays of that type.

curCP
```
public int curCP()
```
The current output code pointer.

emit4
```
public void emit4(int od)
```
Emit four bytes of code.

emitLdc
```
public void emitLdc(int od)
```
Emit a ldc (or ldc_w) instruction, taking into account operand size

emitMultianewarray

public void emitMultianewarray(int ndims,
                               int type,
                               Type arrayType)

Emit a multinewarray instruction.

emitNewarray

public void emitNewarray(int elemcode,
                         Type arrayType)

Emit newarray.

emitAnewarray

public void emitAnewarray(int od,
                          Type arrayType)

Emit anewarray.

emitInvokeinterface

public void emitInvokeinterface(int meth,
                                Type mtype)

Emit an invokeinterface instruction.

emitInvokespecial

public void emitInvokespecial(int meth,
                              Type mtype)

Emit an invokespecial instruction.

emitInvokestatic

public void emitInvokestatic(int meth,
                             Type mtype)

Emit an invokestatic instruction.

emitInvokevirtual

public void emitInvokevirtual(int meth,
                              Type mtype)

Emit an invokevirtual instruction.

emitInvokedynamic

public void emitInvokedynamic(int desc,
                              Type mtype)

Emit an invokedynamic instruction.

emitop0
```
public void emitop0(int op)
```
Emit an opcode with no operand field.

emitop1

public void emitop1(int op,
                    int od)

Emit an opcode with a one-byte operand field.

emitop1w
```
public void emitop1w(int op,
                     int od)
```
Emit an opcode with a one-byte operand field; widen if field does not fit in a byte.

emitop1w
```
public void emitop1w(int op,
                     int od1,
                     int od2)
```
Emit an opcode with two one-byte operand fields; widen if either field does not fit in a byte.

emitop2

public void emitop2(int op,
                    int od)

Emit an opcode with a two-byte operand field.

emitop4

public void emitop4(int op,
                    int od)

Emit an opcode with a four-byte operand field.

align
```
public void align(int incr)
```
Align code pointer to next `incr' boundary.

put4
```
public void put4(int pc,
                 int od)
```
Place four bytes into code at address pc. Pre: pc + 4 <= cp .

get4
```
public int get4(int pc)
```
Return four code bytes at position pc as an int.

isAlive
```
public boolean isAlive()
```
Is code generation currently enabled?

markDead
```
public void markDead()
```
Switch code generation on/off.

entryPoint
```
public int entryPoint()
```
Declare an entry point; return current code pointer

entryPoint
```
public int entryPoint(com.sun.tools.javac.jvm.Code.State state)
```
Declare an entry point with initial state; return current code pointer

entryPoint

public int entryPoint(com.sun.tools.javac.jvm.Code.State state,
                      Type pushed)

Declare an entry point with initial state plus a pushed value; return current code pointer

emitStackMap
```
public void emitStackMap()
```
Emit a stack map entry.

negate
```
public static int negate(int opcode)
```
Negate a branch opcode.

emitJump
```
public int emitJump(int opcode)
```
Emit a jump instruction. Return code pointer of instruction to be patched.

branch
```
public Code.Chain branch(int opcode)
```
Emit a branch with given opcode; return its chain. branch differs from jump in that jsr is treated as no-op.

resolve

public void resolve(Code.Chain chain,
                    int target)

Resolve chain to point to given target.

resolve
```
public void resolve(Code.Chain chain)
```
Resolve chain to point to current code pointer.

resolvePending
```
public void resolvePending()
```
Resolve any pending jumps.

mergeChains

public static Code.Chain mergeChains(Code.Chain chain1,
                                     Code.Chain chain2)

Merge the jumps in of two chains into one.

addCatch

public void addCatch(char startPc,
                     char endPc,
                     char handlerPc,
                     char catchType)

Add a catch clause to code.

compressCatchTable
```
public void compressCatchTable()
```

addLineNumber

public void addLineNumber(char startPc,
                          char lineNumber)

Add a line number entry.

statBegin
```
public void statBegin(int pos)
```
Mark beginning of statement.

markStatBegin
```
public void markStatBegin()
```
Force stat begin eagerly

closeAliveRanges

public void closeAliveRanges(JCTree tree)

closeAliveRanges

public void closeAliveRanges(JCTree tree,
                             int closingCP)

getLVTSize
```
public int getLVTSize()
```
Calculates the size of the LocalVariableTable.

setDefined
```
public void setDefined(Bits newDefined)
```
Set the current variable defined state.

setDefined
```
public void setDefined(int adr)
```
Mark a register as being (possibly) defined.

setUndefined
```
public void setUndefined(int adr)
```
Mark a register as being undefined.

fillExceptionParameterPositions

public void fillExceptionParameterPositions()

newLocal

public int newLocal(Symbol.VarSymbol v)

newRegSegment
```
public void newRegSegment()
```
Start a set of fresh registers.

endScopes
```
public void endScopes(int first)
```
End scopes of all variables with registers ≥ first.

mnem

public static String mnem(int opcode)

static tables

Class Code

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

debugCode

needStackMap

max_stack

max_locals

code

cp

crt

fatcode

nextreg

Constructor Detail

Code

Method Detail

checkLimits

typecode

truncate

width

width

width

arraycode

curCP

emit4

emitLdc

emitMultianewarray

emitNewarray

emitAnewarray

emitInvokeinterface

emitInvokespecial

emitInvokestatic

emitInvokevirtual

emitInvokedynamic

emitop0

emitop1

emitop1w

emitop1w

emitop2

emitop4

align

put4

get4

isAlive

markDead

entryPoint

entryPoint

entryPoint

emitStackMap

negate

emitJump

branch

resolve

resolve

resolvePending

mergeChains

addCatch

compressCatchTable

addLineNumber

statBegin

markStatBegin

closeAliveRanges

closeAliveRanges

getLVTSize

setDefined

setDefined

setUndefined

fillExceptionParameterPositions

newLocal

newRegSegment

endScopes

mnem