dspl.intermediate.instructions
Class Instruction

java.lang.Object
  dspl.intermediate.instructions.Instruction

Direct Known Subclasses:

ArithmaticInstruction, BranchInstruction, CCallInstruction, LoopInstruction, RelationInstruction

public abstract class Instruction
extends java.lang.Object

Basic Abstract class for all other Abstract classes which represent the various kinds of 3-operand intermediary instructions generated from the AST

Author:

David

Field Summary

static int	INST_TYPE_ARITHMATIC type for ArithmaticInstruction
static int	INST_TYPE_BRANCH type for BranchInstruction
static int	INST_TYPE_CCALL type for CCallInstruction
static int	INST_TYPE_FORLOOP type for LoopInstruction
Instruction	lastInstruction Valid only in the first instruction (head of the list), the lastInstruction points to the Instruction at the end of the list
Instruction	nextInstruction The next instruction to be executed after this one Note in the case of branches, this is the next instruction to be executed after all of the instructions in a particular path of the branch are executed.
Instruction	prevInstruction The previous instruction executed, or in the case of the instruction following an if { } else { } block, it would refer to the BranchInstruction, rather than the previous instruction actually executed.

Constructor Summary

Instruction()

Method Summary

abstract int	getInstType()
void	setNextInstruction(Instruction next)
abstract boolean	usesVariable(Variable v) Designed to be a recursive call to see if a given variable is used anymore within a code block, after the current instruction.

Methods inherited from class java.lang.Object

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

Field Detail

nextInstruction

public Instruction nextInstruction

The next instruction to be executed after this one Note in the case of branches, this is the next instruction to be executed after all of the instructions in a particular path of the branch are executed.

prevInstruction

public Instruction prevInstruction

The previous instruction executed, or in the case of the instruction following an if { } else { } block, it would refer to the BranchInstruction, rather than the previous instruction actually executed.

lastInstruction

public Instruction lastInstruction

Valid only in the first instruction (head of the list), the lastInstruction points to the Instruction at the end of the list

INST_TYPE_BRANCH

public static final int INST_TYPE_BRANCH

type for BranchInstruction

See Also:

Constant Field Values

INST_TYPE_ARITHMATIC

public static final int INST_TYPE_ARITHMATIC

type for ArithmaticInstruction

See Also:

Constant Field Values

INST_TYPE_CCALL

public static final int INST_TYPE_CCALL

type for CCallInstruction

See Also:

Constant Field Values

INST_TYPE_FORLOOP

public static final int INST_TYPE_FORLOOP

type for LoopInstruction

See Also:

Constant Field Values

Constructor Detail

Instruction

public Instruction()

Method Detail

getInstType

public abstract int getInstType()

Returns:

the instruction type of this instruction

usesVariable

public abstract boolean usesVariable(Variable v)

Designed to be a recursive call to see if a given variable is used anymore within a code block, after the current instruction. Intention is to allow a way to parse the Instruction tree to see if a specific variable is used again. NOTE: may not be necessary, or may need to be augmented to return a value indicating how far away from the current instruction will it be used again if desire to perform better register allocation.

Parameters:

v - the variable to search for to see if it is used

Returns:

setNextInstruction

public void setNextInstruction(Instruction next)