avrora.core
Class ControlFlowGraph.Block

java.lang.Object
  avrora.core.ControlFlowGraph.Block

Enclosing class:

ControlFlowGraph

public class ControlFlowGraph.Block

extends java.lang.Object

The Block class represents a basic block of code within the program. A basic block contains a straight-line piece of code that ends with a control instruction (e.g. a skip, a jump, a branch, or a call) or an implicit fall-through to the next basic block. It contains at most two references to successor basic blocks.

For fallthroughs (no ending control instruction), the next field refers to the block immediately following this block, and the other field is null.

For jumps, the other field refers to the block that is the target of the jump, and the next field is null.

For skips, branches, and calls, the next field refers to the block immediately following this block (i.e. not-taken for branches, the return address for calls). The other field refers to the target address of the branch if it is taken or the address to be called.

For indirect jumps both the next and other fields are null.

For indirect calls the next field refers to the block immediately following this block (i.e. the return address). The other field is null because the target of the call cannot be known.

Method Summary

void	addInstr(Instr i) The addInstr() method adds an instruction to the end of this basic block.
boolean	equals(java.lang.Object o) The equals() method computes object equality for basic blocks.
int	getAddress() The getAddress() method gets the starting byte address of this basic block.
java.util.Iterator	getEdgeIterator()
java.util.Iterator	getInstrIterator() The getInstrIterator() method returns an iterator over the instructions in this basic block.
int	getLastAddress() The getLastAddress() gets the last address that this block covers.
int	getLength() The getLength() returns the length of this basic block in terms of the number of instructions
int	getSize() The getSize() method returns the size of the basic block in bytes.
int	hashCode() The hashCode() method computes the hash code of this block.

Methods inherited from class java.lang.Object

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

Method Detail

addInstr

public void addInstr(Instr i)

The addInstr() method adds an instruction to the end of this basic block. It is not recommended for general use: it is generally used by the CFGBuilder class. No enforcement of invariants is made: this method does not check whether the instruction being added changes the control flow or branches to another block, etc.

Parameters:

i - the instruction to add to this basic block

hashCode

public int hashCode()

The hashCode() method computes the hash code of this block. In the initial implementation, the hash code is simply the byte address of the block

Returns:

an integer value that is the hash code of this object

equals

public boolean equals(java.lang.Object o)

The equals() method computes object equality for basic blocks. It simply compares the addresses of the basic blocks and returns true if they match.

Parameters:

o - the other object to compare to

Returns:

true if these two basic blocks are equivalent; false otherwise

getAddress

public int getAddress()

The getAddress() method gets the starting byte address of this basic block.

Returns:

the starting address of this basic block

getLastAddress

public int getLastAddress()

The getLastAddress() gets the last address that this block covers.

Returns:

the last address that this block covers

getSize

public int getSize()

The getSize() method returns the size of the basic block in bytes.

Returns:

the number of bytes in this basic block

getLength

public int getLength()

The getLength() returns the length of this basic block in terms of the number of instructions

Returns:

the number of instructions in this basic block

getInstrIterator

public java.util.Iterator getInstrIterator()

The getInstrIterator() method returns an iterator over the instructions in this basic block. The resulting iterator can be used to iterate over the instructions in the basic block in order.

Returns:

an iterator over the instructions in this block.

getEdgeIterator

public java.util.Iterator getEdgeIterator()