Package jminusminus

Class CLFlowControlInstruction

java.lang.Object

jminusminus.CLInstruction

jminusminus.CLFlowControlInstruction

class CLFlowControlInstruction
extends CLInstruction

Representation for FLOW_CONTROL1, FLOW_CONTROL2, FLOW_CONTROL3 and FLOW_CONTROL4 instructions.

Field Summary

Fields inherited from class jminusminus.CLInstruction

instructionInfo, localVariableIndex, mnemonic, opcode, operandCount, pc, stackUnits

Constructor Summary

Constructors

Constructor	Description
CLFlowControlInstruction(int pc, int index, boolean isWidened)	Constructs a CLFlowControlInstruction object for RET instruction.
CLFlowControlInstruction(int opcode, int pc, String jumpToLabel)	Constructs a CLFlowControlInstruction object for FLOW_CONTROL1 instructions.
CLFlowControlInstruction(int opcode, int pc, String defaultLabel, int low, int high, ArrayList<String> labels)	Constructs a CLFlowControlInstruction object for TABLESWITCH instruction.
CLFlowControlInstruction(int opcode, int pc, String defaultLabel, int numPairs, TreeMap<Integer,String> matchLabelPairs)	Constructs a CLFlowControlInstruction object for LOOKUPSWITCH instruction.

Method Summary

Modifier and Type	Method	Description
int	jumpToOffset()	Returns the pc of instruction to jump to.
boolean	resolveLabels(Hashtable<String,Integer> labelToPC)	Resolves the jump labels to the corresponding offset values using the given label to pc mapping.
ArrayList<Integer>	toBytes()	Returns the bytecode for this instruction.

Methods inherited from class jminusminus.CLInstruction

byteAt, isValid, localVariableIndex, mnemonic, opcode, operandCount, pc, stackUnits

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

CLFlowControlInstruction

public CLFlowControlInstruction(int opcode,
 int pc,
 String jumpToLabel)

Constructs a CLFlowControlInstruction object for FLOW_CONTROL1 instructions.

Parameters:

opcode - the opcode for this instruction.

pc - index of this instruction within the code array of a method.

jumpToLabel - the label to jump to.

CLFlowControlInstruction

public CLFlowControlInstruction(int pc,
 int index,
 boolean isWidened)

Constructs a CLFlowControlInstruction object for RET instruction.

Parameters:

pc - index of this instruction within the code array of a method.

index - index of the local variable containing the return address.

isWidened - whether this instruction is preceeded by the WIDE (widening) instruction.

CLFlowControlInstruction

public CLFlowControlInstruction(int opcode,
 int pc,
 String defaultLabel,
 int low,
 int high,
 ArrayList<String> labels)

Constructs a CLFlowControlInstruction object for TABLESWITCH instruction.

Parameters:

opcode - the opcode for this instruction.

pc - index of this instruction within the code array of a method.

defaultLabel - jump label for default value.

low - smallest value of index.

high - highest value of index.

labels - list of jump labels for each index value from low to high, end values included.

CLFlowControlInstruction

public CLFlowControlInstruction(int opcode,
 int pc,
 String defaultLabel,
 int numPairs,
 TreeMap<Integer,String> matchLabelPairs)

Constructs a CLFlowControlInstruction object for LOOKUPSWITCH instruction.

Parameters:

opcode - the opcode for this instruction.

pc - index of this instruction within the code array of a method.

defaultLabel - jump label for default value.

numPairs - number of pairs in the match table.

matchLabelPairs - key match table.

Method Details

resolveLabels

public boolean resolveLabels(Hashtable<String,Integer> labelToPC)

Resolves the jump labels to the corresponding offset values using the given label to pc mapping. If unable to resolve a label, the offset is set such that the next instruction will be executed.

Parameters:

labelToPC - label to pc mapping.

Returns:

true if all labels were resolved successfully, and false otherwise.

jumpToOffset

public int jumpToOffset()

Returns the pc of instruction to jump to.

Returns:

pc to jump to.

toBytes

public ArrayList<Integer> toBytes()

Returns the bytecode for this instruction.

Specified by:

toBytes in class CLInstruction

Returns:

the bytecode for this instruction.