dspl.intermediate.instructions
Class LoopInstruction

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

public class LoopInstruction
extends Instruction

LoopInstruction is used to represent for and while loops.
Note that in DSPL a while loop is a subclass of for-loop internally. meaning "for(x=0; x<10; x++) { ... }" == "x=0; while(x<10) { ... x++; }"

A note on terminology:
Assume a for loop of structure "for (x=0, y=7, z=10; x<10; x++) { a = 5+x; ... } The first portion ("x=0, y=7, z=10") is referred to as the Assignment Instruction(s) The second portion ("x<10;") is referred to as the Condition Instruction(s) The third portion ("x++") is referred to as the Arithmatic Instruction(s) The fourth portion ("a = 5+x") is referred to as the Loop Instruction(s)

Author:

David

Field Summary

Instruction	arithmaticInstr Contains the instruction(s) to be evaluated directly before evaluating the conditionInstr instruction(s)
Instruction	assignmentInstr Contains the instruction(s) to be evaluated before entering the loop is allowed to be empty
Comparison	comp Contains the single comparison instruction which if false, terminates the loop
Instruction	loopInstr Contains the instructions to be evaluated wtihin the body fo the loop

Fields inherited from class dspl.intermediate.instructions.Instruction

INST_TYPE_ARITHMATIC, INST_TYPE_BRANCH, INST_TYPE_CCALL, INST_TYPE_FORLOOP, lastInstruction, nextInstruction, prevInstruction

Constructor Summary

LoopInstruction(Instruction assignmentInstr, Comparison comp, Instruction arithmaticInstr, Instruction loopInstr)

Method Summary

int	getInstType()
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 dspl.intermediate.instructions.Instruction

setNextInstruction

Methods inherited from class java.lang.Object

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

Field Detail

assignmentInstr

public Instruction assignmentInstr

Contains the instruction(s) to be evaluated before entering the loop is allowed to be empty

comp

public Comparison comp

Contains the single comparison instruction which if false, terminates the loop

arithmaticInstr

public Instruction arithmaticInstr

Contains the instruction(s) to be evaluated directly before evaluating the conditionInstr instruction(s)

loopInstr

public Instruction loopInstr

Contains the instructions to be evaluated wtihin the body fo the loop

Constructor Detail

LoopInstruction

public LoopInstruction(Instruction assignmentInstr,
                       Comparison comp,
                       Instruction arithmaticInstr,
                       Instruction loopInstr)

Parameters:

assignmentInstr - Assignment Instruction(s)

conditionInstr - Condition Instruction(s)

arithmaticInstr - Arithmatic Instruction(s)

loopInstr - Loop Instruction(s)

Method Detail

usesVariable

public boolean usesVariable(Variable v)

Description copied from class: Instruction

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.

Specified by:

usesVariable in class Instruction

Parameters:

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

Returns:

getInstType

public int getInstType()

Specified by:

getInstType in class Instruction

Returns:

the instruction type of this instruction