Slicing Java Programs that Throw and Catch Exceptions Matthew Allen Susan Horwitz University of Wisconsin-Madison PEPM 2003 San Diego, CA June 7, 2003
Slicing Java Programs that Throw and Catch Exceptions
Jan 13, 2016
Slicing Java Programs that Throw and Catch Exceptions. Matthew Allen Susan Horwitz University of Wisconsin-Madison PEPM 2003 San Diego, CA June 7, 2003. Motivation. Exceptions: Important error-handling technique BUT: Current program-slicing algorithms don’t handle exceptions Goal: - PowerPoint PPT Presentation
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Slicing Java Programs thatThrow and Catch Exceptions
Matthew Allen
Susan Horwitz
University of Wisconsin-Madison
PEPM 2003
San Diego, CA
June 7, 2003
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 2
MotivationExceptions:
Important error-handling technique
BUT: Current program-slicing algorithms don’t handle
exceptions
Goal: Extend System Dependence Graph (SDG) based
slicing to support exceptions
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 3
OutlineMotivation
Program Slicing
Slicing with the SDG
Extending SDG-Based Slicing to Handle Exceptions
Related Work
Conclusions
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 4
Program Slicing
A slice from a component S is the set of
components that might affect:
Whether or how often S executes
The value of a variable used at S
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 5
Slicing Exampleint x, y;
void foo() { fact(); print(x); print(y);}
void fact() { x = 1; while (y > 0) { x = x * y; y--; }}
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 6
Slicing Exampleint x, y;
void foo() { fact(); print(x); print(y); slice from here}
void fact() { x = 1; while (y > 0) { x = x * y; y--; }}
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 7
Slicing Exampleint x, y;
void foo() { fact(); print(x); print(y); slice from here}
void fact() { x = 1; while (y > 0) { x = x * y; y--; }}
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 8
Slicing Programs with Exceptions
Exceptions can affect:
Whether or how often a statement executes
Value of a variable used at a statement
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 9
Example: when/how often stmt executes
void foo() {
try {
fact();
print(“no error”);
}
catch (NegEx e) {
print(“error”);
}
}
void fact() throws NegEx {
x = 1;
if (y < 0)
throw new NegEx();
while (y > 0) {
x = x * y;
y--;
}
}
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 10
void foo() {
try {
fact();
print(“no error”);
}
catch (NegEx e) {
print(“error”); Slice from here
}
}
void fact() throws NegEx {
x = 1;
if (y < 0)
throw new NegEx();
while (y > 0) {
x = x * y;
y--;
}
}
Example: when/how often stmt executes
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 11
void foo() {
try {
fact();
print(“no error”);
}
catch (NegEx e) {
print(“error”); Slice from here
}
}
void fact() throws NegEx {
x = 1;
if (y < 0)
throw new NegEx();
while (y > 0) {
x = x * y;
y--;
}
}
Example: when/how often stmt executes
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 12
Exception affects value of variable
void foo() {
try {
fact();
print(x);
}
catch (NegEx e) {
print(x);
}
}
void fact() throws NegEx {
x = 1;
if (y < 0)
throw new NegEx();
while (y > 0) {
x = x * y;
y--;
}
}
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 13
Exception affects value of variable
void foo() {
try {
fact();
print(x);
}
catch (NegEx e) {
print(x); Slice from here
}
}
void fact() throws NegEx {
x = 1;
if (y < 0)
throw new NegEx();
while (y > 0) {
x = x * y;
y--;
}
}
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 14
Exception affects value of variable
void foo() {
try {
fact();
print(x);
}
catch (NegEx e) {
print(x); Slice from here
}
}
void fact() throws NegEx {
x = 1;
if (y < 0)
throw new NegEx();
while (y > 0) {
x = x * y;
y--;
}
}
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 15
Exception affects value of variable
void foo() {
try {
fact();
print(x);
}
catch (NegEx e) {
print(x); Slice from here
}
}
void fact() throws NegEx {
x = 1;
if (y < 0)
throw new NegEx();
while (y > 0) {
x = x * y;
y--;
}
}
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 16
Exception affects value of variable
void foo() {
try {
fact();
print(x); Slice from here
}
catch (NegEx e) {
print(x);
}
}
void fact() throws NegEx {
x = 1;
if (y < 0)
throw new NegEx();
while (y > 0) {
x = x * y;
y--;
}
}
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 17
Exception affects value of variable
void foo() {
try {
fact();
print(x); Slice from here
}
catch (NegEx e) {
print(x);
}
}
void fact() throws NegEx {
x = 1;
if (y < 0)
throw new NegEx();
while (y > 0) {
x = x * y;
y--;
}
}
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 18
OutlineMotivation
Program Slicing
Slicing with the SDG (no exceptions)
Extending SDG-Based Slicing to Handle Exceptions
Related Work
Conclusions
CFGPDGSDG
static void foo() {
fact();
print(x);
print(y);
}
static void fact()
throws NegEx
{
x = 1;
while (y > 0) {
x = x * y;
y--;
}
}
enter foo
print(x)
print(y)
enter fact
x = 1
x = x * y
y--
call fact
exit
T
T
F
F
T
while (y > 0)
exit foo
F
CFGPDGSDG
static void foo() {
fact();
print(x);
print(y);
}
static void fact()
throws NegEx
{
x = 1;
while (y > 0) {
x = x * y;
y--;
}
}
enter fooy = y_in
print(x)
print(y)
enter facty = y_in
x = 1
x = x * y
y--
y_in = ycall factx = x_outy = y_out
x_out = xy_out = y
exit
T
T
F
F
T
while (y > 0)
exit foo
F
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 21
CFGPDGSDG
static void foo() {
fact();
print(x);
print(y);
}
static void fact()
throws NegEx
{
x = 1;
while (y > 0) {
x = x * y;
y--;
}
}
enter foo
print(x) print(y)
enter fact
x = 1 while (y > 0)
x = x * y y--
call fact
y_in = y x = x_out y = y_out
y=y_in
y = y_in
x_out=x y_out=y
T T TT
T T T
TT T T T
T T
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 22
CFGPDGSDG
static void foo() {
fact();
print(x);
print(y);
}
static void fact()
throws NegEx
{
x = 1;
while (y > 0) {
x = x * y;
y--;
}
}
enter foo
print(x) print(y)
enter fact
x = 1 while (y > 0)
x = x * y y--
call fact
y_in = y x = x_out y = y_out
y=y_in
y = y_in
x_out=x y_out=y
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 23
print(y)
CFGPDGSDG
static void foo() {
fact();
print(x);
print(y);
}
static void fact()
throws NegEx
{
x = 1;
while (y > 0) {
x = x * y;
y--;
}
}
enter foo
print(x)
enter fact
x = 1 while (y > 0)
x = x * y y--
call fact
y_in = y x = x_out y = y_out
y=y_in
y = y_in
x_out=x y_out=y
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 24
print(y)
CFGPDGSDG
static void foo() {
fact();
print(x);
print(y);
}
static void fact()
throws NegEx
{
x = 1;
while (y > 0) {
x = x * y;
y--;
}
}
enter foo
print(x)
enter fact
x = 1 while (y > 0)
x = x * y y--
call fact
y_in = y x = x_out y = y_out
y=y_in
y = y_in
x_out=x y_out=y
enter foo
call fact
y_in = y y = y_out
y = y_in
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 25
print(y)
CFGPDGSDG
static void foo() {
fact();
print(x);
print(y);
}
static void fact()
throws NegEx
{
x = 1;
while (y > 0) {
x = x * y;
y--;
}
}
enter foo
print(x)
enter fact
x = 1 while (y > 0)
x = x * y y--
call fact
y_in = y x = x_out y = y_out
y=y_in
y = y_in
x_out=x y_out=y
enter foo
call fact
y_in = y y = y_out
y = y_in
enter fact
while (y > 0)
y--
y=y_in y_out=y
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 26
OutlineMotivation
Program Slicing
Slicing with the SDG
Extending SDG-Based Slicing to Handle Exceptions
Related Work
Conclusions
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 27
Example Revisited
static void foo() {
try {
fact();
print(“no error”);
}
catch (NegEx e) {
print(“error”); Slice from here
}
}
static void fact() throws NegEx {
x = 1;
if (y < 0)
throw new NegEx ();
while (y > 0) {
x = x * y;
y--;
}
}
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 28
enter foo
y=y_in try
call fact
y_in=y x=x_out y=y_out normalreturn
catch(NegEx e)
enter factprint(“no error”)
print(“error”)
y=y_in x=1 if(y<0) x_out=x y_out=y
throw newNegEx()
while(y>0)
normalexit
NegExexit
x=x*y y--
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 29
enter foo
y=y_in try
call fact
y_in=y x=x_out y=y_out normalreturn
catch(NegEx e)
enter factprint(“no error”)
print(“error”)
y=y_in x=1 if(y<0) x_out=x y_out=y
throw newNegEx()
while(y>0)
normalexit
NegExexit
x=x*y y--
catch(NegEx e)
NegExexit
throw newNegEx()
if(y<0)
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 30
static void fact()
throws NegEx
{
x = 1;
if (y < 0)
throw new NegEx ();
while (y > 0) {
x = x * y;
y--;
}
}
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 31
static void fact()
throws NegEx
{
x = 1;
if (y < 0)
throw new NegEx ();
while (y > 0) {
x = x * y;
y--;
}
}
enter facty = y_in
x=1
if(y<0)
throw new NegEx()
while (y>0)
x_out = xy_out = y
exit
x=x*y
y--
T
T
T
F
F
F
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 32
static void fact() {
x = 1;
if (y < 0)
throw new NegEx ();
while (y > 0) {
x = x * y;
y--;
}
}
enter facty = y_in
x=1
if(y<0)
throw new NegEx()
while (y>0)
x_out = xy_out = y
exit
x=x*y
y--
T
T
T
F
F
NegEx exit
F
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 33
static void fact() {
x = 1;
if (y < 0)
throw new NegEx ();
while (y > 0) {
x = x * y;
y--;
}
}
enter facty = y_in
x=1
if(y<0)
throw new NegEx()
while (y>0)
x_out = xy_out = y
exit
x=x*y
y--
T
T
T
F
F
NegEx exit
normal exit
F
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 34
static void fact() {
x = 1;
if (y < 0)
throw new NegEx ();
while (y > 0) {
x = x * y;
y--;
}
}
enter facty = y_in
x=1
if(y<0)
throw new NegEx()
while (y>0)
x_out = xy_out = y
exit
x=x*y
y--
T
T
T
F
F
NegEx exit
F
normal exit
TF
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 35
static void fact() {
x = 1;
if (y < 0)
throw new NegEx ();
while (y > 0) {
x = x * y;
y--;
}
}
enter facty = y_in
x=1
if(y<0)
throw new NegEx()
while (y>0)
x_out = xy_out = y
exit
x=x*y
y--
T
T
T
F
F
NegEx exit
F
normal exit
TF
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 36
static void foo() {
try {
fact();
print(“no error”);
}
catch (NegEx e) {
print(“error”);
}
}
enter foo
try
y = y_incall fact
catch(NegEx e)
print(“no error”)
print(“error”)
x_out = xy_out = y
exit
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 37
static void foo() {
try {
fact();
print(“no error”);
}
catch (NegEx e) {
print(“error”);
}
}
enter foo
try
y = y_incall fact
normalreturn
catch(NegEx e)
print(“no error”)
print(“error”)
x_out = xy_out = y
exit
normal NegEx
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 38
static void foo() {
try {
fact();
print(“no error”);
}
catch (NegEx e) {
print(“error”);
}
}
enter foo
try
y = y_incall fact
normalreturn
catch(NegEx e)
print(“no error”)
print(“error”)
x_out = xy_out = y
exit
normal NegEx
T TF F
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 39
static void foo() {
try {
fact();
print(“no error”);
}
catch (NegEx e) {
print(“error”);
}
}
enter foo
try
y = y_incall fact
normalreturn
catch(NegEx e)
print(“no error”)
print(“error”)
x_out = xy_out = y
exit
normal NegEx
T TF F
TF
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 40
static void foo() {
try {
fact();
print(“no error”);
}
catch (NegEx e) {
print(“error”);
}
}
enter foo
try
y = y_incall fact
normalreturn
catch(NegEx e)
print(“no error”)
print(“error”)
x_out = xy_out = y
exit
normal NegEx
T TF F
TF
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 41
Example revisited
static void foo() {
try {
fact();
print(x);
}
catch (NegEx e) {
print(x); Slice from here
}
}
static void fact() {
x = 1;
if (y < 0)
throw new NegEx ();
while (y > 0) {
x = x * y;
y--;
}
}
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 42
print(x)
enter foo
y=y_in try
call fact
y_in=y x=x_out y=y_out normalreturn
catch(NegEx e)
enter factprint(x)
y=y_in x=1 if(y<0) x_out=x y_out=y
throw newNegEx()
while(y>0)
normalexit
NegExexit
x=x*y y--
x=x_out
x_out=xx=1
x=x*y
enter foo
y=y_in try
call fact
y_in=ynormalreturn
catch(NegEx e)
enter factprint(x)
y=y_in x=1 if(y<0)
throw newNegEx()
while(y>0)
normalexit
NegExexit x=x*y y--
x_out=xy_out=y
x_out=xy_out=y
x=x_out y=y_out print(x)x=x_out y=y_out
enter foo
y=y_in try
call fact
y_in=ynormalreturn
catch(NegEx e)
enter factprint(x)
y=y_in x=1 if(y<0)
throw newNegEx()
while(y>0)
normalexit
NegExexit x=x*y y--
x_out=xy_out=y
x_out=xy_out=y
x=x_out y=y_out print(x)x=x_out y=y_outx=x_out
x_out=x
x=1
enter foo
y=y_in try
call fact
y_in=ynormalreturn
catch(NegEx e)
enter factprint(x)
y=y_in x=1 if(y<0)
throw newNegEx()
while(y>0)
normalexit
NegExexit x=x*y y--
x_out=xy_out=y
x_out=xy_out=y
x=x_out y=y_out print(x)x=x_out y=y_out
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 46
Other Issues finally clauses Unchecked exceptions
See paper!
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 47
OutlineMotivation
Program Slicing
Slicing with the SDG
Extending SDG-Based Slicing to Handle Exceptions
Related Work
Conclusions
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 48
Related Work[Sinha / Harrold / Rothermel 1999]
Addresses slicing programs with exceptions. Some similar aspects . Problems:
Does not correctly represent interprocedural control dependences when length of call chain from try to throw is greater than 1.
Does not address data dependences.
[Sinha / Harrold 1998, 2000]
Addresses handling finally clauses. See paper.
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 49
ConclusionsSlicing is an important operation.
Slicing Java programs is an area of current interest.
Contribution:
Extend SDG-based Slicing: To correctly handle exceptions.
Changes only to CFG. Same slicing algorithm!
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 50
void foo() {
try {
fact();
print(“no error”); Slice from here
}
catch (NegEx e) {
print(“error”);
}
}
void fact() throws NegEx {
x = 1;
if (y < 0)
throw new NegEx();
while (y > 0) {
x = x * y;
y--;
}
}
Example: when/how often stmt executes
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 51
void foo() {
try {
fact();
print(“no error”); Slice from here
}
catch (NegEx e) {
print(“error”);
}
}
void fact() throws NegEx {
x = 1;
if (y < 0)
throw new NegEx();
while (y > 0) {
x = x * y;
y--;
}
}
Example: when/how often stmt executes
CFGPDGSDG
static void foo() {
fact();
print(x);
print(y);
}
static void fact() {
x = 1;
while (y > 0) {
x = x * y;
y--;
}
}
enter fooy = y_in
print(x)
print(y)
enter facty = y_in
x = 1
x = x * y
y--
y_in = ycall factx = x_outy = y_out
x_out = xy_out = y
exit
T
T
F
F
T
while (y > 0)
exit foo
F
datadependence
controldependence
TTT
T
TT
T
CFGPDGSDG
static void foo() {
fact();
print(x);
print(y);
}
static void fact() {
x = 1;
while (y > 0) {
x = x * y;
y--;
}
}
enter fooy = y_in
print(x)
print(y)
enter facty = y_in
x = 1
x = x * y
y--
y_in = ycall factx = x_outy = y_out
x_out = xy_out = y
exit
while (y > 0)
exit foo datadependence
controldependence
TTT
T
TT
T
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 54
print(y)
CFGPDGSDG
static void foo() {
fact();
print(x);
print(y);
}
static void fact() {
x = 1;
while (y > 0) {
x = x * y;
y--;
}
}
enter foo
print(x)
enter fact
x = 1 while (y > 0)
x = x * y y--
call fact
y_in = y x = x_out y = y_out
y=y_in
y = y_in
x_out=x y_out=y
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 55
print(y)
CFGPDGSDG
static void foo() {
fact();
print(x);
print(y);
}
static void fact() {
x = 1;
while (y > 0) {
x = x * y;
y--;
}
}
enter foo
print(x)
enter fact
x = 1 while (y > 0)
x = x * y y--
call fact
y_in = y x = x_out y = y_out
y=y_in
y = y_in
x_out=x y_out=y
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 56
enter foo
y=y_in try
call fact
y_in=y x=x_out y=y_out normalreturn
catch(NegEx e)
enter factprint(“no error”)
print(“error”)
y=y_in x=1 if(y<0) x_out=x y_out=y
throw newNegEx()
while(y>0)
normalexit
NegExexit
x=x*y y--
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 57
enter foo
y=y_in try
call fact
y_in=y x=x_out y=y_out normalreturn
catch(NegEx e)
enter factprint(“no error”)
print(“error”)
y=y_in x=1 if(y<0) x_out=x y_out=y
throw newNegEx()
while(y>0)
normalexit
NegExexit
x=x*y y--
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 58
enter foo
y=y_in try
call fact
y_in=y x=x_out y=y_out normalreturn
catch(NegEx e)
enter factprint(“no error”)
print(“error”)
y=y_in x=1 if(y<0) x_out=x y_out=y
throw newNegEx()
while(y>0)
normalexit
NegExexit
x=x*y y--
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 59
print(x)
enter foo
y=y_in try
call fact
y_in=y x=x_out y=y_out normalreturn
catch(NegEx e)
enter factprint(x)
y=y_in x=1 if(y<0) x_out=x y_out=y
throw newNegEx()
while(y>0)
normalexit
NegExexit
x=x*y y--
Slicing Java Programs that Throw and Catch Exceptions – Allen / HorwitzSlide 60
print(x)
enter foo
y=y_in try
call fact
y_in=y x=x_out y=y_out normalreturn
catch(NegEx e)
enter factprint(x)
y=y_in x=1 if(y<0) x_out=x y_out=y
throw newNegEx()
while(y>0)
normalexit
NegExexit
x=x*y y--
enter foo
y=y_in try
call fact
y_in=ynormalreturn
catch(NegEx e)
enter factprint(x)
y=y_in x=1 if(y<0)
throw newNegEx()
while(y>0)
normalexit
NegExexit x=x*y y--
x_out=xy_out=y
x_out=xy_out=y
x=x_out y=y_out print(x)x=x_out y=y_out
enter foo
y=y_in try
call fact
y_in=ynormalreturn
catch(NegEx e)
enter factprint(x)
y=y_in x=1 if(y<0)
throw newNegEx()
while(y>0)
normalexit
NegExexit x=x*y y--
x_out=xy_out=y
x_out=xy_out=y
x=x_out y=y_out print(x)x=x_out y=y_out
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