com.sun.tools.javac.jvm
Class Code

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

public class Code
extends java.lang.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 API supported by Sun Microsystems. 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

static class	Code.Chain A chain represents a list of unresolved jumps.
(package private) static class	Code.LocalVar A live range of a local variable.
private static class	Code.Mneumonics
static class	Code.StackMapFormat
(package private) static class	Code.StackMapFrame An entry in the stack map.
(package private) class	Code.State

Field Summary

private boolean	alive Code generation enabled?
(package private) ListBuffer<char[]>	catchInfo A buffer for expression catch data.
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?
private boolean	fixedPc Is it forbidden to compactify code, because something is pointing to current location?
(package private) Code.StackMapFrame	frameBeforeLast The stack map frame before the last one.
(package private) static Type	jsrReturnValue
(package private) Code.StackMapFrame	lastFrame The last stack map frame in StackMapTable.
(package private) int	lastStackMapPC The last PC at which we generated a stack map.
(package private) boolean	lineDebugInfo Switch: emit line number info.
(package private) List<char[]>	lineInfo A buffer for line number information.
(package private) Position.LineMap	lineMap Emit line number info if map supplied
(package private) Code.LocalVar[]	lvar Local variables, indexed by register.
int	max_locals The maximum number of local variable slots.
int	max_stack The maximum stack size.
(package private) Symbol.MethodSymbol	meth
boolean	needStackMap
int	nextreg The next available register.
(package private) Code.Chain	pendingJumps A chain for jumps to be resolved before the next opcode is emitted.
(package private) boolean	pendingStackMap Set true when a stackMap is needed at the current PC.
(package private) int	pendingStatPos The position of the currently statement, if we are at the start of this statement, NOPOS otherwise.
(package private) Pool	pool The constant pool of the current class.
(package private) Code.StackMapFormat	stackMap The stack map format to be generated.
(package private) Code.StackMapFrame[]	stackMapBuffer A buffer of cldc stack map entries.
(package private) int	stackMapBufferSize
(package private) ClassWriter.StackMapTableFrame[]	stackMapTableBuffer A buffer of compressed StackMapTable entries.
(package private) Code.State	state The current machine state (registers and stack).
(package private) Symtab	syms
(package private) Types	types
(package private) Code.LocalVar[]	varBuffer Previously live local variables, to be put into the variable table.
(package private) int	varBufferSize
(package private) boolean	varDebugInfo Switch: emit variable debug info.

Constructor Summary

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

Method Summary

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.
private void	addLocalVar(Symbol.VarSymbol v) Add a new local variable.
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.
int	curPc() The current output code pointer.
private void	emit1(int od) Emit a byte of code.
private void	emit2(int od) Emit two bytes of code.
void	emit4(int od) Emit four bytes of code.
void	emitAnewarray(int od, Type arrayType) Emit anewarray.
(package private) void	emitCLDCStackMap(int pc, int localsSize) Emit a CLDC stack map frame.
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	emitMultianewarray(int ndims, int type, Type arrayType) Emit a multinewarray instruction.
void	emitNewarray(int elemcode, Type arrayType) Emit newarray.
private void	emitop(int op) Emit an opcode.
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.
(package private) void	emitStackMapFrame(int pc, int localsSize)
private void	endScope(int adr) End the scope of a variable.
void	endScopes(int first) End scopes of all variables with registers >= first.
int	entryPoint() Declare an entry point; return current code pointer
int	entryPoint(Code.State state) Declare an entry point with initial state; return current code pointer
int	entryPoint(Code.State state, Type pushed) Declare an entry point with initial state plus a pushed value; return current code pointer
private int	get1(int pc) Return code byte at position pc as an unsigned int.
private int	get2(int pc) Return two code bytes at position pc as an unsigned int.
int	get4(int pc) Return four code bytes at position pc as an int.
(package private) Code.StackMapFrame	getInitialFrame()
private int	getLocalsSize()
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 java.lang.String	mnem(int opcode) static tables
static int	negate(int opcode) Negate a branch opcode.
private int	newLocal(int typecode) Create a new local variable address and return it.
int	newLocal(Symbol.VarSymbol v)
private int	newLocal(Type type)
void	newRegSegment() Start a set of fresh registers.
(package private) void	postop()
private void	put1(int pc, int op) Place a byte into code at address pc.
private void	put2(int pc, int od) Place two bytes into code at address pc.
void	put4(int pc, int od) Place four bytes into code at address pc.
(package private) void	putVar(Code.LocalVar var) Put a live variable range into the buffer to be output to the class file.
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).
private Type	typeForPool(java.lang.Object o) The type of a constant pool entry.
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

types

final Types types

syms

final Symtab syms

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.

catchInfo

ListBuffer<char[]> catchInfo

A buffer for expression catch data. Each enter is a vector of four unsigned shorts.

lineInfo

List<char[]> lineInfo

A buffer for line number information. Each entry is a vector of two unsigned shorts.

crt

public CRTable crt

The CharacterRangeTable

fatcode

public boolean fatcode

Are we generating code with jumps >= 32K?

alive

private boolean alive

Code generation enabled?

state

Code.State state

The current machine state (registers and stack).

fixedPc

private boolean fixedPc

Is it forbidden to compactify code, because something is pointing to current location?

nextreg

public int nextreg

The next available register.

pendingJumps

Code.Chain pendingJumps

A chain for jumps to be resolved before the next opcode is emitted. We do this lazily to avoid jumps to jumps.

pendingStatPos

int pendingStatPos

The position of the currently statement, if we are at the start of this statement, NOPOS otherwise. We need this to emit line numbers lazily, which we need to do because of jump-to-jump optimization.

pendingStackMap

boolean pendingStackMap

Set true when a stackMap is needed at the current PC.

stackMap

Code.StackMapFormat stackMap

The stack map format to be generated.

varDebugInfo

boolean varDebugInfo

Switch: emit variable debug info.

lineDebugInfo

boolean lineDebugInfo

Switch: emit line number info.

lineMap

Position.LineMap lineMap

Emit line number info if map supplied

pool

final Pool pool

The constant pool of the current class.

meth

final Symbol.MethodSymbol meth

stackMapBuffer

Code.StackMapFrame[] stackMapBuffer

A buffer of cldc stack map entries.

stackMapTableBuffer

ClassWriter.StackMapTableFrame[] stackMapTableBuffer

A buffer of compressed StackMapTable entries.

stackMapBufferSize

int stackMapBufferSize

lastStackMapPC

int lastStackMapPC

The last PC at which we generated a stack map.

lastFrame

Code.StackMapFrame lastFrame

The last stack map frame in StackMapTable.

frameBeforeLast

Code.StackMapFrame frameBeforeLast

The stack map frame before the last one.

jsrReturnValue

static Type jsrReturnValue

lvar

Code.LocalVar[] lvar

Local variables, indexed by register.

varBuffer

Code.LocalVar[] varBuffer

Previously live local variables, to be put into the variable table.

varBufferSize

int varBufferSize

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)

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.

curPc

public int curPc()

The current output code pointer.

emit1

private void emit1(int od)

Emit a byte of code.

emit2

private void emit2(int od)

Emit two bytes of code.

emit4

public void emit4(int od)

Emit four bytes of code.

emitop

private void emitop(int op)

Emit an opcode.

postop

void postop()

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.

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.

typeForPool

private Type typeForPool(java.lang.Object o)

The type of a constant pool entry.

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.

put1

private void put1(int pc,
                  int op)

Place a byte into code at address pc. Pre: pc + 1 <= cp.

put2

private void put2(int pc,
                  int od)

Place two bytes into code at address pc. Pre: pc + 2 <= cp.

put4

public void put4(int pc,
                 int od)

Place four bytes into code at address pc. Pre: pc + 4 <= cp.

get1

private int get1(int pc)

Return code byte at position pc as an unsigned int.

get2

private int get2(int pc)

Return two code bytes at position pc as an unsigned int.

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(Code.State state)

Declare an entry point with initial state; return current code pointer

entryPoint

public int entryPoint(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.

getLocalsSize

private int getLocalsSize()

emitCLDCStackMap

void emitCLDCStackMap(int pc,
                      int localsSize)

Emit a CLDC stack map frame.

emitStackMapFrame

void emitStackMapFrame(int pc,
                       int localsSize)

getInitialFrame

Code.StackMapFrame getInitialFrame()

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.

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

addLocalVar

private void addLocalVar(Symbol.VarSymbol v)

Add a new local variable.

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.

endScope

private void endScope(int adr)

End the scope of a variable.

putVar

void putVar(Code.LocalVar var)

Put a live variable range into the buffer to be output to the class file.

newLocal

private int newLocal(int typecode)

Create a new local variable address and return it.

newLocal

private int newLocal(Type type)

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 java.lang.String mnem(int opcode)

static tables