avrora.stack
Class Analyzer.ContextSensitivePolicy

java.lang.Object
  avrora.stack.Analyzer.ContextSensitivePolicy

All Implemented Interfaces:

AnalyzerPolicy

Enclosing class:

Analyzer

public class Analyzer.ContextSensitivePolicy

extends java.lang.Object

implements AnalyzerPolicy

The ContextSensitive class implements the context-sensitive analysis similar to 1-CFA. It is an implementation of the Analyzer.Policy interface that determines what should be done in the case of a call, return, push, pop, indirect call, etc. The context-sensitive analysis does not model the contents of the stack, so pushes and pops essentially only modify the height of the stack.

Field Summary

protected int	edgeType
StateCache.State	frontierState

Constructor Summary

Analyzer.ContextSensitivePolicy()

Method Summary

MutableState	call(MutableState s, int target_address) The call() method is called by the abstract interpreter when it encounters a call instruction within the program.
MutableState	indirectCall(MutableState s, char addr_low, char addr_hi) The indirectCall() method is called by the abstract interpreter when it encounters an indirect call within the program.
MutableState	indirectCall(MutableState s, char addr_low, char addr_hi, char ext) The indirectCall() method is called by the abstract interpreter when it encounters an indirect call within the program.
MutableState	indirectJump(MutableState s, char addr_low, char addr_hi) The indirectJump() method is called by the abstract interpreter when it encounters an indirect jump within the program.
MutableState	indirectJump(MutableState s, char addr_low, char addr_hi, char ext) The indirectJump() method is called by the abstract interpreter when it encounters an indirect jump within the program.
MutableState	interrupt(MutableState s, int num) The interrupt() is called by the abstract interrupt when it encounters a place in the program when an interrupt might occur.
char	pop(MutableState s) The pop() method is called by the abstract interpreter when a pop from the stack is ecountered in the program.
void	push(MutableState s, char val) The push() method is called by the abstract interpreter when a push to the stack is encountered in the program.
void	pushState(MutableState newState) The pushState method is called by the abstract interpreter when a state is forked by the abstract interpreter (for example when a branch condition is not known and both branches must be taken.
MutableState	ret(MutableState s) The ret() method is called by the abstract interpreter when it encounters a return within the program.
MutableState	reti(MutableState s) The reti() method is called by the abstract interpreter when it encounters a return from an interrupt within the program.

Methods inherited from class java.lang.Object

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

Field Detail

frontierState

public StateCache.State frontierState

edgeType

protected int edgeType

Constructor Detail

Analyzer.ContextSensitivePolicy

public Analyzer.ContextSensitivePolicy()

Method Detail

call

public MutableState call(MutableState s,
                         int target_address)

The call() method is called by the abstract interpreter when it encounters a call instruction within the program. Different policies may handle calls differently. This context-sensitive analysis keeps track of the call site every time a new method is entered. Thus the states coming into a method call are merged according to the call site, instead of all merged together.

Specified by:

call in interface AnalyzerPolicy

Parameters:

s - the current abstract state

target_address - the concrete target address of the call

Returns:

null because the correct state transitions are inserted by the policy, and the abstract interpreter should not be concerned.

interrupt

public MutableState interrupt(MutableState s,
                              int num)

The interrupt() is called by the abstract interrupt when it encounters a place in the program when an interrupt might occur.

Specified by:

interrupt in interface AnalyzerPolicy

Parameters:

s - the abstract state just before interrupt

num - the interrupt number that might occur

Returns:

the state of the program after the interrupt, null if there is no next state

ret

public MutableState ret(MutableState s)

The ret() method is called by the abstract interpreter when it encounters a return within the program. In the context-sensitive analysis, the return state must be connected with the call site. This is done by accessing the call site list which is stored in this frontier state and inserting edges for each call site.

Specified by:

ret in interface AnalyzerPolicy

Parameters:

s - the current abstract state

Returns:

null because the correct state transitions are inserted by the policy, and the abstract interpreter should not be concerned.

reti

public MutableState reti(MutableState s)

The reti() method is called by the abstract interpreter when it encounters a return from an interrupt within the program.

Specified by:

reti in interface AnalyzerPolicy

Parameters:

s - the current abstract state

Returns:

null because the correct state transitions are inserted by the policy, and the abstract interpreter should not be concerned.

indirectCall

public MutableState indirectCall(MutableState s,
                                 char addr_low,
                                 char addr_hi)

The indirectCall() method is called by the abstract interpreter when it encounters an indirect call within the program. The abstract values of the address are given as parameters, so that a policy can choose to compute possible targets or be conservative or whatever it so chooses.

Specified by:

indirectCall in interface AnalyzerPolicy

Parameters:

s - the current abstract state

addr_low - the (abstract) low byte of the address

addr_hi - the (abstract) high byte of the address

Returns:

null because the correct state transitions are inserted by the policy, and the abstract interpreter should not be concerned.

indirectJump

public MutableState indirectJump(MutableState s,
                                 char addr_low,
                                 char addr_hi)

The indirectJump() method is called by the abstract interpreter when it encounters an indirect jump within the program. The abstract values of the address are given as parameters, so that a policy can choose to compute possible targets or be conservative or whatever it so chooses.

Specified by:

indirectJump in interface AnalyzerPolicy

Parameters:

s - the current abstract state

addr_low - the (abstract) low byte of the address

addr_hi - the (abstract) high byte of the address

Returns:

null because the correct state transitions are inserted by the policy, and the abstract interpreter should not be concerned.

indirectCall

public MutableState indirectCall(MutableState s,
                                 char addr_low,
                                 char addr_hi,
                                 char ext)

The indirectCall() method is called by the abstract interpreter when it encounters an indirect call within the program. The abstract values of the address are given as parameters, so that a policy can choose to compute possible targets or be conservative or whatever it so chooses.

Specified by:

indirectCall in interface AnalyzerPolicy

Parameters:

s - the current abstract state

addr_low - the (abstract) low byte of the address

addr_hi - the (abstract) high byte of the address

ext - the (abstract) extended part of the address

Returns:

null because the correct state transitions are inserted by the policy, and the abstract interpreter should not be concerned.

indirectJump

public MutableState indirectJump(MutableState s,
                                 char addr_low,
                                 char addr_hi,
                                 char ext)

The indirectJump() method is called by the abstract interpreter when it encounters an indirect jump within the program. The abstract values of the address are given as parameters, so that a policy can choose to compute possible targets or be conservative or whatever it so chooses.

Specified by:

indirectJump in interface AnalyzerPolicy

Parameters:

s - the current abstract state

addr_low - the (abstract) low byte of the address

addr_hi - the (abstract) high byte of the address

ext - the (abstract) extended part of the address

Returns:

null because the correct state transitions are inserted by the policy, and the abstract interpreter should not be concerned.

push

public void push(MutableState s,
                 char val)

The push() method is called by the abstract interpreter when a push to the stack is encountered in the program. The policy can then choose what outgoing and/or modelling of the stack needs to be done.

Specified by:

push in interface AnalyzerPolicy

Parameters:

s - the current abstract state

val - the abstract value to push onto the stack

pop

public char pop(MutableState s)

The pop() method is called by the abstract interpreter when a pop from the stack is ecountered in the program. The policy can then choose to either return whatever information it has about the stack contents, or return an UNKNOWN value.

Specified by:

pop in interface AnalyzerPolicy

Parameters:

s - the current abstract state

Returns:

the abstract value popped from the stack

pushState

public void pushState(MutableState newState)

The pushState method is called by the abstract interpreter when a state is forked by the abstract interpreter (for example when a branch condition is not known and both branches must be taken.

Specified by:

pushState in interface AnalyzerPolicy

Parameters:

newState - the new state created