edu.jmu.decaf

Class ILOCFunction

java.lang.Object

edu.jmu.decaf.ILOCFunction

public class ILOCFunction
extends Object

Decaf function in ILOC intermediate representation (IR). Eases the process of intraprocedural analysis by aggregating all information relevant to a single procedure.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	ILOCFunction.Variable Helper wrapper class for debug variable information (useful for data flow analysis)

Field Summary

Fields

Modifier and Type	Field and Description
List<ILOCBasicBlock>	allBlocks It is useful to maintain a list of all blocks for liveness analysis
ILOCBasicBlock	entryBlock Entry block (start of CFG)
Symbol	functionSymbol Function Symbol from the AST symbol tables
List<ILOCInstruction>	instructions List of ILOC instructions
int	localSize Size (in bytes) to allocate on stack for local variables

Constructor Summary

Constructors

Constructor and Description
ILOCFunction(Symbol symbol) Create a new (empty) ILOC function

Method Summary

Modifier and Type	Method and Description
void	addInstruction(ILOCInstruction insn) Append a new instruction to the function.
void	buildCFG() Builds the control flow graph for this function.
void	findBlockVars(Set<Integer> seen, ILOCBasicBlock current, Set<Integer> candidates, Map<Integer,String> varMap) This is a recursive helper function which finds the uninitialized variables in a given basic block and all successors Original code written by Steven Young, CS 480 honors student.
void	findUnitializedVars(boolean strictFlag) Finds and reports possible uninitialized variables in this ILOCFunction Original code written by Steven Young, CS 480 honors student.
void	flattenCFG() Flattens the control-flow graph into linear form (presumably after modifications have been made to the CFG).
ILOCBasicBlock	getEntryBlock() Get the entry point to the function's control flow graph.
List<ILOCInstruction>	getInstructions() Get the current instruction sequence.
void	setInstructions(List<ILOCInstruction> instructions) Replace all instructions with a new sequence.
void	temp(List<ILOCBasicBlock> allBlocks)
String	toString() Builds a standard string-based representation of an ILOC function

Methods inherited from class java.lang.Object

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

Field Detail

functionSymbol

public Symbol functionSymbol

Function Symbol from the AST symbol tables

localSize

public int localSize

Size (in bytes) to allocate on stack for local variables

instructions

public List<ILOCInstruction> instructions

List of ILOC instructions

entryBlock

public ILOCBasicBlock entryBlock

Entry block (start of CFG)

allBlocks

public List<ILOCBasicBlock> allBlocks

It is useful to maintain a list of all blocks for liveness analysis

Constructor Detail

ILOCFunction

public ILOCFunction(Symbol symbol)

Create a new (empty) ILOC function

Parameters:

symbol - Symbol object from AST

Method Detail

getInstructions

public List<ILOCInstruction> getInstructions()

Get the current instruction sequence.

Returns:

List of ILOCInstruction objects

setInstructions

public void setInstructions(List<ILOCInstruction> instructions)

Replace all instructions with a new sequence.

Parameters:

instructions - Replacement instructions

addInstruction

public void addInstruction(ILOCInstruction insn)

Append a new instruction to the function.

Parameters:

insn - New instruction

getEntryBlock

public ILOCBasicBlock getEntryBlock()

Get the entry point to the function's control flow graph. This will cause the CFG to be built the first time it is executed.

Returns:

CFG entry point

buildCFG

public void buildCFG()

Builds the control flow graph for this function. Original code written by Steven Young, CS 480 honors student.

temp

public void temp(List<ILOCBasicBlock> allBlocks)

findUnitializedVars

public void findUnitializedVars(boolean strictFlag)

Finds and reports possible uninitialized variables in this ILOCFunction Original code written by Steven Young, CS 480 honors student.

Parameters:

strictFlag - - if true will report on variables that can be defined as: "being read with no prior definition in at least one of the predecessor blocks" if passed false, will report all variables that can be described as: "being read with no prior definition in all of the previous blocks"

findBlockVars

public void findBlockVars(Set<Integer> seen,
                          ILOCBasicBlock current,
                          Set<Integer> candidates,
                          Map<Integer,String> varMap)

This is a recursive helper function which finds the uninitialized variables in a given basic block and all successors Original code written by Steven Young, CS 480 honors student.

Parameters:

seen - - the set of currently live variables

current - - the current basic block

candidates - - the set of possibly uninitialized variables

varMap - - mapping from variable offsets to variable names

flattenCFG

public void flattenCFG()

Flattens the control-flow graph into linear form (presumably after modifications have been made to the CFG).

toString

public String toString()

Builds a standard string-based representation of an ILOC function

Overrides:

toString in class Object