Program slicing with exception handling Carlos S. Galindo Jim enez - - PowerPoint PPT Presentation

Introduction Problems and proposals Conclusions

Program slicing with exception handling

Carlos S. Galindo Jim´ enez

Universidad Polit´ ecnica de Valencia

Dec 18th, 2019

Introduction Problems and proposals Conclusions

Table of Contents

Introduction Program slicing The System Dependence Graph Exception handling Problems and proposals Problem 1: incorrect slices with nested unconditional jumps Problem 2: incorrect weak slices Problem 3: incomplete catch treatment Conclusions

2/21

Introduction Problems and proposals Conclusions

Overview

Introduction Program slicing The System Dependence Graph Exception handling Problems and proposals Conclusions

3/21

Introduction Problems and proposals Conclusions

Program slicing

1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x > 0) {

5

sum += x;

6

prod *= x;

7

x--;

8

}

9

log("sum: " + sum);

10

log(" prod: " + prod);

11 } 1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x > 0) {

5

sum += x;

6

prod *= x;

7

x--;

8

}

9

log("sum: " + sum);

10

log(" prod: " + prod);

11 }

Example adapted from [Tip95].

4/21

Introduction Problems and proposals Conclusions

Program slicing

1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x > 0) {

5

sum += x;

6

prod *= x;

7

x--;

8

}

9

log("sum: " + sum);

10

log(" prod: " + prod);

11 } 1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x > 0) {

5

sum += x;

6

prod *= x;

7

x--;

8

}

9

log("sum: " + sum);

10

log(" prod: " + prod);

11 }

Example adapted from [Tip95].

4/21

Introduction Problems and proposals Conclusions

Program slicing

1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x > 0) {

5

sum += x;

6

prod *= x;

7

x--;

8

}

9

log("sum: " + sum);

10

log(" prod: " + prod);

11 } 1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x > 0) {

5

sum += x;

6

prod *= x;

7

x--;

8

}

9

log("sum: " + sum);

10

log(" prod: " + prod);

11 }

Example adapted from [Tip95].

4/21

Introduction Problems and proposals Conclusions

Program slicing

1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x > 0) {

5

sum += x;

6

prod *= x;

7

x--;

8

}

9

log("sum: " + sum);

10

log(" prod: " + prod);

11 } 1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x > 0) {

5

sum += x;

6

prod *= x;

7

x--;

8

}

9

log("sum: " + sum);

10

log(" prod: " + prod);

11 }

Example adapted from [Tip95].

4/21

Introduction Problems and proposals Conclusions

Program slicing

Applications

◮ Debugging ◮ Program specialization ◮ Software maintenance ◮ Code obfuscation ◮ Dead code removal ◮ Program parallelization

1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x > 0) {

5

sum += x;

6

prod *= x;

7

x--;

8

}

9

log("sum: " + sum);

10

log(" prod: " + prod);

11 } 5/21

Introduction Problems and proposals Conclusions

Program slicing

Metrics

• Completeness. The slice includes all instructions that are necessary.
• Correctness. The statements included affect the slicing criterion.

Correct and complete: Correct and incomplete: Incorrect and complete: Incorrect and incomplete:

6/21

Introduction Problems and proposals Conclusions

Program slicing

Metrics

• Completeness. The slice includes all instructions that are necessary.
• Correctness. The statements included affect the slicing criterion.

Correct and complete: Correct and incomplete: Incorrect and complete: Incorrect and incomplete:

6/21

Introduction Problems and proposals Conclusions

Program slicing

Metrics

• Completeness. The slice includes all instructions that are necessary.
• Correctness. The statements included affect the slicing criterion.

Correct and complete: Correct and incomplete: Incorrect and complete: Incorrect and incomplete:

6/21

Introduction Problems and proposals Conclusions

Program slicing

Metrics

• Completeness. The slice includes all instructions that are necessary.
• Correctness. The statements included affect the slicing criterion.

Correct and complete: Correct and incomplete: Incorrect and complete: Incorrect and incomplete:

6/21

Introduction Problems and proposals Conclusions

Program slicing

Metrics

• Completeness. The slice includes all instructions that are necessary.
• Correctness. The statements included affect the slicing criterion.

Correct and complete: Correct and incomplete: Incorrect and complete: Incorrect and incomplete:

6/21

Introduction Problems and proposals Conclusions

Program slicing

Metrics

• Completeness. The slice includes all instructions that are necessary.
• Correctness. The statements included affect the slicing criterion.

Correct and complete: Correct and incomplete: Incorrect and complete: Incorrect and incomplete:

6/21

Introduction Problems and proposals Conclusions

The System Dependence Graph

Creation

1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x >0) {

5

sum += sum;

6

prod *= prod;

7

x--;

8

}

9

log(sum);

10

log(prod);

11 } 7/21

Introduction Problems and proposals Conclusions

The System Dependence Graph

Creation

1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x >0) {

5

sum += sum;

6

prod *= prod;

7

x--;

8

}

9

log(sum);

10

log(prod);

11 }

Enter f() 2: int sum = 0 3: int prod = 0 4: while (x > 0) 9: log("sum: " + sum) 10: log("prod: " + prod) 5: sum += sum 6: prod *= prod 7: x--

7/21

Introduction Problems and proposals Conclusions

The System Dependence Graph

Creation

1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x >0) {

5

sum += sum;

6

prod *= prod;

7

x--;

8

}

9

log(sum);

10

log(prod);

11 }

Enter f() 2: int sum = 0 3: int prod = 0 4: while (x > 0) 9: log("sum: " + sum) 10: log("prod: " + prod) 5: sum += sum 6: prod *= prod 7: x--

7/21

Introduction Problems and proposals Conclusions

The System Dependence Graph

Creation

1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x >0) {

5

sum += sum;

6

prod *= prod;

7

x--;

8

}

9

log(sum);

10

log(prod);

11 }

Enter f() 2: int sum = 0 3: int prod = 0 4: while (x > 0) 9: log("sum: " + sum) 10: log("prod: " + prod) x = x_in 5: sum += sum 6: prod *= prod 7: x--

7/21

Introduction Problems and proposals Conclusions

The System Dependence Graph

Creation

1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x >0) {

5

sum += sum;

6

prod *= prod;

7

x--;

8

}

9

log(sum);

10

log(prod);

11 }

Enter f() 2: int sum = 0 3: int prod = 0 4: while (x > 0) 9: log("sum: " + sum) 10: log("prod: " + prod) x = x_in 5: sum += sum 6: prod *= prod 7: x--

7/21

Introduction Problems and proposals Conclusions

The System Dependence Graph

Creation

1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x >0) {

5

sum += sum;

6

prod *= prod;

7

x--;

8

}

9

log(sum);

10

log(prod);

11 }

Enter f() 2: int sum = 0 3: int prod = 0 4: while (x > 0) 9: log("sum: " + sum) 10: log("prod: " + prod) x = x_in 5: sum += sum 6: prod *= prod 7: x--

7/21

Introduction Problems and proposals Conclusions

The System Dependence Graph

Creation

1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x >0) {

5

sum += sum;

6

prod *= prod;

7

x--;

8

}

9

log(sum);

10

log(prod);

11 }

Enter f() 2: int sum = 0 3: int prod = 0 4: while (x > 0) 9: log("sum: " + sum) 10: log("prod: " + prod) x = x_in 5: sum += sum 6: prod *= prod 7: x--

7/21

Introduction Problems and proposals Conclusions

The System Dependence Graph

Traversal

1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x>0) {

5

sum += sum;

6

prod*=prod;

7

x--;

8

}

9

log(sum);

10

log(prod);

11 }

Enter f() 2: int sum = 0 3: int prod = 0 4: while (x > 0) 9: log("sum: " + sum) 10: log("prod: " + prod) x = x_in 5: sum += sum 6: prod *= prod 7: x--

8/21

Introduction Problems and proposals Conclusions

The System Dependence Graph

Traversal

1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x>0) {

5

sum += sum;

6

prod*=prod;

7

x--;

8

}

9

log(sum);

10

log(prod);

11 }

Enter f() 2: int sum = 0 3: int prod = 0 4: while (x > 0) 9: log("sum: " + sum) 10: log("prod: " + prod) x = x_in 5: sum += sum 6: prod *= prod 7: x--

8/21

Introduction Problems and proposals Conclusions

The System Dependence Graph

Traversal

1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x>0) {

5

sum += sum;

6

prod*=prod;

7

x--;

8

}

9

log(sum);

10

log(prod);

11 }

Enter f() 2: int sum = 0 3: int prod = 0 4: while (x > 0) 9: log("sum: " + sum) 10: log("prod: " + prod) x = x_in 5: sum += sum 6: prod *= prod 7: x--

8/21

Introduction Problems and proposals Conclusions

The System Dependence Graph

Traversal

1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x>0) {

5

sum += sum;

6

prod*=prod;

7

x--;

8

}

9

log(sum);

10

log(prod);

11 }

Enter f() 2: int sum = 0 3: int prod = 0 4: while (x > 0) 9: log("sum: " + sum) 10: log("prod: " + prod) x = x_in 5: sum += sum 6: prod *= prod 7: x--

8/21

Introduction Problems and proposals Conclusions

The System Dependence Graph

Traversal

1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x>0) {

5

sum += sum;

6

prod*=prod;

7

x--;

8

}

9

log(sum);

10

log(prod);

11 }

Enter f() 2: int sum = 0 3: int prod = 0 4: while (x > 0) 9: log("sum: " + sum) 10: log("prod: " + prod) x = x_in 5: sum += sum 6: prod *= prod 7: x--

8/21

Introduction Problems and proposals Conclusions

The System Dependence Graph

Traversal

1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x>0) {

5

sum += sum;

6

prod*=prod;

7

x--;

8

}

9

log(sum);

10

log(prod);

11 }

Enter f() 2: int sum = 0 3: int prod = 0 4: while (x > 0) 9: log("sum: " + sum) 10: log("prod: " + prod) x = x_in 5: sum += sum 6: prod *= prod 7: x--

8/21

Introduction Problems and proposals Conclusions

The System Dependence Graph

Traversal

1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x>0) {

5

sum += sum;

6

prod*=prod;

7

x--;

8

}

9

log(sum);

10

log(prod);

11 }

Enter f() 2: int sum = 0 3: int prod = 0 4: while (x > 0) 9: log("sum: " + sum) 10: log("prod: " + prod) x = x_in 5: sum += sum 6: prod *= prod 7: x--

8/21

Introduction Problems and proposals Conclusions

The System Dependence Graph

Traversal

1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x>0) {

5

sum += sum;

6

prod*=prod;

7

x--;

8

}

9

log(sum);

10

log(prod);

11 }

Enter f() 2: int sum = 0 3: int prod = 0 4: while (x > 0) 9: log("sum: " + sum) 10: log("prod: " + prod) x = x_in 5: sum += sum 6: prod *= prod 7: x--

8/21

Introduction Problems and proposals Conclusions

The System Dependence Graph

Traversal

1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x>0) {

5

sum += sum;

6

prod*=prod;

7

x--;

8

}

9

log(sum);

10

log(prod);

11 }

Enter f() 2: int sum = 0 3: int prod = 0 4: while (x > 0) 9: log("sum: " + sum) 10: log("prod: " + prod) x = x_in 5: sum += sum 6: prod *= prod 7: x--

8/21

Introduction Problems and proposals Conclusions

The System Dependence Graph

Traversal

1 void f(int x) { 2

int sum = 0;

3

int prod = 0;

4

while (x>0) {

5

sum += sum;

6

prod*=prod;

7

x--;

8

}

9

log(sum);

10

log(prod);

11 }

Enter f() 2: int sum = 0 3: int prod = 0 4: while (x > 0) 9: log("sum: " + sum) 10: log("prod: " + prod) x = x_in 5: sum += sum 6: prod *= prod 7: x--

8/21

Introduction Problems and proposals Conclusions

Exception Handling Systems

Java

1 void main () { 2

try {

3

f();

4

} catch (Exception e) {

5

log(" caught exception ");

6

} catch (Throwable e) {

7

log(" caught throwable ");

8

}

9 } 10 void f() throws Throwable { 11

switch(x) {

12

case A:

13

log("no error ");

14

break;

15

case B:

16

throw new Exception();

17

default:

18

throw new Throwable();

19

}

20 } 9/21

Introduction Problems and proposals Conclusions

Exception Handling Systems

Java

1 void main () { 2

try {

3

f();

4

} catch (Exception e) {

5

log(" caught exception ");

6

} catch (Throwable e) {

7

log(" caught throwable ");

8

}

9 } 10 void f() throws Throwable { 11

switch(x) {

12

case A:

13

log("no error ");

14

break;

15

case B:

16

throw new Exception();

17

default:

18

throw new Throwable();

19

}

20 } 9/21

Introduction Problems and proposals Conclusions

Exception Handling Systems

Java

1 void main () { 2

try {

3

f();

4

} catch (Exception e) {

5

log(" caught exception ");

6

} catch (Throwable e) {

7

log(" caught throwable ");

8

}

9 } 10 void f() throws Throwable { 11

switch(x) {

12

case A:

13

log("no error ");

14

break;

15

case B:

16

throw new Exception();

17

default:

18

throw new Throwable();

19

}

20 } 9/21

Introduction Problems and proposals Conclusions

Exception Handling Systems

Java

1 void main () { 2

try {

3

f();

4

} catch (Exception e) {

5

log(" caught exception ");

6

} catch (Throwable e) {

7

log(" caught throwable ");

8

}

9 } 10 void f() throws Throwable { 11

switch(x) {

12

case A:

13

log("no error ");

14

break;

15

case B:

16

throw new Exception();

17

default:

18

throw new Throwable();

19

}

20 } 9/21

Introduction Problems and proposals Conclusions

Exception Handling Systems

Java

1 void main () { 2

try {

3

f();

4

} catch (Exception e) {

5

log(" caught exception ");

6

} catch (Throwable e) {

7

log(" caught throwable ");

8

}

9 } 10 void f() throws Throwable { 11

switch(x) {

12

case A:

13

log("no error ");

14

break;

15

case B:

16

throw new Exception();

17

default:

18

throw new Throwable();

19

}

20 } 9/21

Introduction Problems and proposals Conclusions

Exception Handling Systems

Java

1 void main () { 2

try {

3

f();

4

} catch (Exception e) {

5

log(" caught exception ");

6

} catch (Throwable e) {

7

log(" caught throwable ");

8

}

9 } 10 void f() throws Throwable { 11

switch(x) {

12

case A:

13

log("no error ");

14

break;

15

case B:

16

throw new Exception();

17

default:

18

throw new Throwable();

19

}

20 } 9/21

Introduction Problems and proposals Conclusions

Exception Handling Systems

Java

Exception RuntimeException ... Error ... ... Throwable

◮ Checked (solid): must be caught (try-catch) or declared (f() throws T). ◮ Unchecked (dashed).

10/21

Introduction Problems and proposals Conclusions

Exception Handling Systems

Other programming languages

Language % usage JavaScript 69.7 HTML/CSS 63.1 SQL 56.5 Python 39.4 Java 39.2 Bash/Shell/PowerShell 37.9 C# 31.9 PHP 25.8 TypeScript 23.5 C++ 20.4 Language % usage C 17.3 Ruby 8.9 Go 8.8 Swift 6.8 Kotlin 6.6 R 5.6 VBA 5.5 Objective-C 5.2 Assembly 5.0

Table: Programming language by usage in the software industry (StackOverflow’s 2019 Developer Survey)

11/21

Introduction Problems and proposals Conclusions

Exception Handling Systems

Other programming languages

Language % usage JavaScript 69.7 HTML/CSS 63.1 SQL 56.5 Python 39.4 Java 39.2 Bash/Shell/PowerShell 37.9 C# 31.9 PHP 25.8 TypeScript 23.5 C++ 20.4 Language % usage C 17.3 Ruby 8.9 Go 8.8 Swift 6.8 Kotlin 6.6 R 5.6 VBA 5.5 Objective-C 5.2 Assembly 5.0

Table: Programming language by usage in the software industry (StackOverflow’s 2019 Developer Survey)

11/21

Introduction Problems and proposals Conclusions

Exception Handling Systems

Other programming languages

Language % usage JavaScript 69.7 HTML/CSS 63.1 SQL 56.5 Python 39.4 Java 39.2 Bash/Shell/PowerShell 37.9 C# 31.9 PHP 25.8 TypeScript 23.5 C++ 20.4 Language % usage C 17.3 Ruby 8.9 Go 8.8 Swift 6.8 Kotlin 6.6 R 5.6 VBA 5.5 Objective-C 5.2 Assembly 5.0

Table: Programming language by usage in the software industry (StackOverflow’s 2019 Developer Survey)

11/21

Introduction Problems and proposals Conclusions

Overview

Introduction Problems and proposals Problem 1: incorrect slices with nested unconditional jumps Problem 2: incorrect weak slices Problem 3: incomplete catch treatment Conclusions

12/21

Introduction Problems and proposals Conclusions

Problem 1

The subsumption correctness error

1 public

void f() {

2

while (X) {

3

if (Y) {

4

if (Z) {

5

A;

6

break;

7

}

8

B;

9

break;

10

}

11

C;

12

}

13

D;

14 } 13/21

Introduction Problems and proposals Conclusions

Problem 1

The subsumption correctness error

1 public

void f() {

2

while (X) {

3

if (Y) {

4

if (Z) {

5

A;

6

break;

7

}

8

B;

9

break;

10

}

11

C;

12

}

13

D;

14 }

enter f() while (X) D if (Y) C if (Z) break2 break1 A B

13/21

Introduction Problems and proposals Conclusions

Problem 1

The subsumption correctness error

1 public

void f() {

2

while (X) {

3

if (Y) {

4

if (Z) {

5

A;

6

break;

7

}

8

B;

9

break;

10

}

11

C;

12

}

13

D;

14 }

enter f() while (X) D if (Y) C if (Z) break2 break1 A B

13/21

Introduction Problems and proposals Conclusions

Problem 1

The subsumption correctness error

1 public

void f() {

2

while (X) {

3

if (Y) {

4

if (Z) {

5

A;

6

break;

7

}

8

B;

9

break;

10

}

11

C;

12

}

13

D;

14 }

enter f() while (X) D if (Y) C if (Z) break2 break1 A B

13/21

Introduction Problems and proposals Conclusions

Problem 1: proposed solution

The subsumption correctness error

• 1. Identify edges caused by

unconditional jumps.

• 2. Remove from Ec all (a, b) such that

(a′, b) ∈ Ec ∧ a′, b ∈ J ∧ (a′, b), (a, b) ∈ Ea′ J: unconditional jumps Ec: control edges Ea′: edges caused by a′

14/21

Introduction Problems and proposals Conclusions

Problem 1: proposed solution

The subsumption correctness error

• 1. Identify edges caused by

unconditional jumps.

• 2. Remove from Ec all (a, b) such that

(a′, b) ∈ Ec ∧ a′, b ∈ J ∧ (a′, b), (a, b) ∈ Ea′ J: unconditional jumps Ec: control edges Ea′: edges caused by a′

14/21

Introduction Problems and proposals Conclusions

Problem 1: proposed solution

The subsumption correctness error

• 1. Identify edges caused by

unconditional jumps.

• 2. Remove from Ec all (a, b) such that

(a′, b) ∈ Ec ∧ a′, b ∈ J ∧ (a′, b), (a, b) ∈ Ea′ J: unconditional jumps Ec: control edges Ea′: edges caused by a′

enter f() while (X) D if (Y) C if (Z) break2 break1 A B 14/21

Introduction Problems and proposals Conclusions

Problem 1: proposed solution

The subsumption correctness error

• 1. Identify edges caused by

unconditional jumps.

• 2. Remove from Ec all (a, b) such that

(a′, b) ∈ Ec ∧ a′, b ∈ J ∧ (a′, b), (a, b) ∈ Ea′ J: unconditional jumps Ec: control edges Ea′: edges caused by a′

enter f() while (X) D if (Y) C if (Z) break2 break1 A B 14/21

Introduction Problems and proposals Conclusions

Problem 2

Unnecessary instructions in weak slicing

1 void g() { 2

int a = 1;

3

while (a > 0) {

4

if (a > 10)

5

break;

6

a++;

7

}

8

log(a);

9 } 15/21

Introduction Problems and proposals Conclusions

Problem 2

Unnecessary instructions in weak slicing

1 void g() { 2

int a = 1;

3

while (a > 0) {

4

if (a > 10)

5

break;

6

a++;

7

}

8

log(a);

9 } f() int a = 1 while (a > 0) if (a > 10) log(a) a++ break 15/21

Introduction Problems and proposals Conclusions

Problem 2

Unnecessary instructions in weak slicing

1 void g() { 2

int a = 1;

3

while (a > 0) {

4

if (a > 10)

5

break;

6

a++;

7

}

8

log(a);

9 } f() int a = 1 while (a > 0) if (a > 10) log(a) a++ break 15/21

Introduction Problems and proposals Conclusions

Problem 2: proposed solution

Unnecessary instructions in weak slicing

• 1. Remove all forward-jumping

unconditional jump’s nodes.

• 2. Traverse the graph.
• 3. Re-add all nodes removed if there is

any statement in the slice after their destination.

• 4. If (3) changed the graph, goto (2).

f() int a = 1 while (a > 0) if (a > 10) log(a) a++ break

16/21

Introduction Problems and proposals Conclusions

Problem 2: proposed solution

Unnecessary instructions in weak slicing

• 1. Remove all forward-jumping

unconditional jump’s nodes.

• 2. Traverse the graph.
• 3. Re-add all nodes removed if there is

any statement in the slice after their destination.

• 4. If (3) changed the graph, goto (2).

f() int a = 1 while (a > 0) if (a > 10) log(a) a++

16/21

Introduction Problems and proposals Conclusions

Problem 2: proposed solution

Unnecessary instructions in weak slicing

• 1. Remove all forward-jumping

unconditional jump’s nodes.

• 2. Traverse the graph.
• 3. Re-add all nodes removed if there is

any statement in the slice after their destination.

• 4. If (3) changed the graph, goto (2).

f() int a = 1 while (a > 0) if (a > 10) log(a) a++

16/21

Introduction Problems and proposals Conclusions

Problem 2: proposed solution

Unnecessary instructions in weak slicing

• 1. Remove all forward-jumping

unconditional jump’s nodes.

• 2. Traverse the graph.
• 3. Re-add all nodes removed if there is

any statement in the slice after their destination.

• 4. If (3) changed the graph, goto (2).

f() int a = 1 while (a > 0) if (a > 10) log(a) a++

16/21

Introduction Problems and proposals Conclusions

Problem 2: proposed solution

Unnecessary instructions in weak slicing

• 1. Remove all forward-jumping

unconditional jump’s nodes.

• 2. Traverse the graph.
• 3. Re-add all nodes removed if there is

any statement in the slice after their destination.

• 4. If (3) changed the graph, goto (2).

f() int a = 1 while (a > 0) if (a > 10) log(a) a++

16/21

Introduction Problems and proposals Conclusions

Problem 2: proposed solution

Unnecessary instructions in weak slicing

• 1. Remove all forward-jumping

unconditional jump’s nodes.

• 2. Traverse the graph.
• 3. Re-add all nodes removed if there is

any statement in the slice after their destination.

• 4. If (3) changed the graph, goto (2).

f() int a = 1 while (a > 0) if (a > 10) log(a) a++ break

16/21

Introduction Problems and proposals Conclusions

Problem 3

The Lack of Dependencies of catch Statements

1 int x; 2 3 void

main () throws Exception {

4

try {

5

f();

6

} catch (Exception e) {

7

log("error");

8

}

9 10

f();

11 } 12 13 void f()

throws Exception {

14

x++;

15

if (x > 0)

16

throw new Exception ();

17

log(x);

18 } 17/21

Introduction Problems and proposals Conclusions

Problem 3

The Lack of Dependencies of catch Statements

1 int x; 2 3 void

main () throws Exception {

4

try {

5

f();

6

} catch (Exception e) {

7

log("error");

8

}

9 10

f();

11 } 12 13 void f()

throws Exception {

14

x++;

15

if (x > 0)

16

throw new Exception ();

17

log(x);

18 }

enter x = x_in try f() x_in = x f() x = x_out x = x_out normal return error return x_in = x catch (Exception e) log("error") x = x_out x = x_out normal return error return error exit

17/21

Introduction Problems and proposals Conclusions

Problem 3

The Lack of Dependencies of catch Statements

1 int x; 2 3 void

main () throws Exception {

4

try {

5

f() ;

6

} catch (Exception e) {

7

log("error");

8

}

9 10

f();

11 } 12 13 void f()

throws Exception {

14

x++;

15

if (x > 0)

16

throw new Exception ();

17

log(x);

18 }

enter x = x_in try f() x_in = x f() x = x_out x = x_out normal return error return x_in = x catch (Exception e) log("error") x = x_out x = x_out normal return error return error exit

17/21

Introduction Problems and proposals Conclusions

Problem 3

The Lack of Dependencies of catch Statements

1 int x; 2 3 void

main () throws Exception {

4

try {

5

f() ;

6

} catch (Exception e) {

7

log("error");

8

}

9 10

f();

11 } 12 13 void f()

throws Exception {

14

x++;

15

if (x > 0)

16

throw new Exception ();

17

log(x);

18 }

enter x = x_in try f() x_in = x f() x = x_out x = x_out normal return error return x_in = x catch (Exception e) log("error") x = x_out x = x_out normal return error return error exit

17/21

Introduction Problems and proposals Conclusions

Problem 3

The Lack of Dependencies of catch Statements

1 int x; 2 3 void

main () throws Exception {

4

try {

5

f();

6

} catch (Exception e) {

7

log("error");

8

}

9 10

f() ;

11 } 12 13 void f()

throws Exception {

14

x++;

15

if (x > 0)

16

throw new Exception ();

17

log(x);

18 }

enter x = x_in try f() x_in = x f() x = x_out x = x_out normal return error return x_in = x catch (Exception e) log("error") x = x_out x = x_out normal return error return error exit

17/21

Introduction Problems and proposals Conclusions

Problem 3

The Lack of Dependencies of catch Statements

1 int x; 2 3 void

main () throws Exception {

4

try {

5

f();

6

} catch (Exception e) {

7

log("error");

8

}

9 10

f() ;

11 } 12 13 void f()

throws Exception {

14

x++;

15

if (x > 0)

16

throw new Exception ();

17

log(x);

18 }

enter x = x_in try f() x_in = x f() x = x_out x = x_out normal return error return x_in = x catch (Exception e) log("error") x = x_out x = x_out normal return error return error exit

17/21

Introduction Problems and proposals Conclusions

Problem 3

The Lack of Dependencies of catch Statements

1 int x; 2 3 void

main () throws Exception {

4

try {

5

f();

6

} catch (Exception e) {

7

log("error");

8

}

9 10

f();

11 } 12 13 void f()

throws Exception {

14

x++;

15

if (x > 0)

16

throw new Exception ();

17

log(x);

18 }

enter x = x_in try f() x_in = x f() x = x_out x = x_out normal return error return x_in = x catch (Exception e) log("error") x = x_out x = x_out normal return error return error exit

17/21

Introduction Problems and proposals Conclusions

Problem 3

The Lack of Dependencies of catch Statements

1 int x; 2 3 void

main () throws Exception {

4

try {

5

f();

6

} catch (Exception e) {

7

log("error");

8

}

9 10

f();

11 } 12 13 void f()

throws Exception {

14

x++;

15

if (x > 0)

16

throw new Exception ();

17

log(x);

18 }

enter x = x_in try f() x_in = x f() x = x_out x = x_out normal return error return x_in = x catch (Exception e) log("error") x = x_out x = x_out normal return error return error exit

17/21

Introduction Problems and proposals Conclusions

Problem 3

The Lack of Dependencies of catch Statements

1 int x; 2 3 void

main () throws Exception {

4

try {

5

f();

6

} catch (Exception e) {

7

log("error");

8

}

9

x = 0;

10

f();

11 } 12 13 void f()

throws Exception {

14

x++;

15

if (x > 0)

16

throw new Exception ();

17

log(x);

18 } enter x = x_in try x = 0 f() x_in = x f() x = x_out x = x_out normal return error return catch (Exception e) log("error") x_in = x x = x_out x = x_out normal return error return error exit 17/21

Introduction Problems and proposals Conclusions

Problem 3

The Lack of Dependencies of catch Statements

1 int x; 2 3 void

main () throws Exception {

4

try {

5

f();

6

} catch (Exception e) {

7

log("error");

8

}

9

x = 0;

10

f();

11 } 12 13 void f()

throws Exception {

14

x++;

15

if (x > 0)

16

throw new Exception ();

17

log(x);

18 } enter x = x_in try x = 0 f() x_in = x f() x = x_out x = x_out normal return error return catch (Exception e) log("error") x_in = x x = x_out x = x_out normal return error return error exit 17/21

Introduction Problems and proposals Conclusions

Problem 3

The Lack of Dependencies of catch Statements

1 int x; 2 3 void

main () throws Exception {

4

try {

5

f();

6

} catch (Exception e) {

7

log("error");

8

}

9

x = 0;

10

f();

11 } 12 13 void f()

throws Exception {

14

x++;

15

if (x > 0)

16

throw new Exception ();

17

log(x);

18 } enter x = x_in try x = 0 f() x_in = x f() x = x_out x = x_out normal return error return catch (Exception e) log("error") x_in = x x = x_out x = x_out normal return error return error exit 17/21

Introduction Problems and proposals Conclusions

Problem 3: proposed solution

The lack of dependencies of catch statements

enter x = x_in try x = 0 f() x_in = x f() x = x_out x = x_out normal return error return catch (Exception e) log("error") x_in = x x = x_out x = x_out normal return error return error exit 18/21

Introduction Problems and proposals Conclusions

Problem 3: proposed solution

The lack of dependencies of catch statements

enter x = x_in try x = 0 f() x_in = x f() x = x_out x = x_out normal return error return catch (Exception e) log("error") x_in = x x = x_out x = x_out normal return error return error exit 18/21

Introduction Problems and proposals Conclusions

Problem 3: proposed solution

The lack of dependencies of catch statements

enter x = x_in try x_in = x f() x = x_out x = x_out normal return error return catch (Exception e) log("error") x = 0 f() x_in = x x = x_out x = x_out normal return error return error exit

18/21

Introduction Problems and proposals Conclusions

Problem 3: proposed solution

The lack of dependencies of catch statements

enter x = x_in try x_in = x f() x = x_out x = x_out normal return error return catch (Exception e) log("error") x = 0 f() x_in = x x = x_out x = x_out normal return error return error exit

18/21

Introduction Problems and proposals Conclusions

Problem 3: proposed solution

The lack of dependencies of catch statements

enter x = x_in try x_in = x f() x = x_out x = x_out normal return error return catch (Exception e) log("error") x = 0 f() x_in = x x = x_out x = x_out normal return error return error exit

18/21

Introduction Problems and proposals Conclusions

Overview

Introduction Problems and proposals Conclusions

19/21

Introduction Problems and proposals Conclusions

Conclusions

◮ Program slicing: a powerful technique, not yet complete for commonly used programming languages. ◮ Efficiency vs. completeness and correctness. ◮ Results: 3 problems and proposed solutions.

20/21

Introduction Problems and proposals Conclusions

Conclusions

◮ Program slicing: a powerful technique, not yet complete for commonly used programming languages. ◮ Efficiency vs. completeness and correctness. ◮ Results: 3 problems and proposed solutions.

20/21

Introduction Problems and proposals Conclusions

Future work

◮ Improve correctness of try-catch. ◮ Implement into existing software tools, benchmark against state of the art. ◮ Adapt to other variants of program slicing. ◮ Redefine control dependence (extend Danicic’s work [Dan+11]), execution dependence vs. presence dependence.

21/21

References

Related work

Change to state of the art and move to introduction ◮ 1988: Horwitz, Reps and Ball [HRB88] present the SDG. ◮ 1993: Ball and Horwitz [BH93] present SDG with unconditional jumps ◮ 1998: Sinha and Harrold [SH98]; [SHR99] present SDG with exceptions. ◮ 2003: Allen and Horwitz [AH03] improves [SH98]. ◮ 2004: Jo and Chang [JC04] present an alternative construction of the graph (not demonstrated, not an improvement). ◮ 2006: Jiang et al. [Jia+06] propose a solution for C++, not applicable. ◮ 2011: Prabhy, Maeda and Blakrishnan [PMB11] propose another solution for C++, no notable improvement. ◮ 2011: Jie and Shu-juan [JSJ11] introduce Object-Oriented + Exception SDG, same errors as [AH03].

21/21

References

Related work

Change to state of the art and move to introduction ◮ 1988: Horwitz, Reps and Ball [HRB88] present the SDG. ◮ 1993: Ball and Horwitz [BH93] present SDG with unconditional jumps ◮ 1998: Sinha and Harrold [SH98]; [SHR99] present SDG with exceptions. ◮ 2003: Allen and Horwitz [AH03] improves [SH98]. ◮ 2004: Jo and Chang [JC04] present an alternative construction of the graph (not demonstrated, not an improvement). ◮ 2006: Jiang et al. [Jia+06] propose a solution for C++, not applicable. ◮ 2011: Prabhy, Maeda and Blakrishnan [PMB11] propose another solution for C++, no notable improvement. ◮ 2011: Jie and Shu-juan [JSJ11] introduce Object-Oriented + Exception SDG, same errors as [AH03].

21/21

References

Program slicing

Strong and Weak Slices

Definition (Strong slice [Wei81])

Given a program P, its slice S w.r.t. a slicing criterion SC is a subset of the statements (S ⊆ P) such that the execution of S yields the same sequence of values

• n SC as the execution of P.

Definition (Weak slice [BG96])

Given a program P, its slice S w.r.t. a slicing criterion SC is a subset of the statements (S ⊆ P) such that the execution of S yields a sequence of values on SC (seqS), the execution of P yields a sequence of values on SC (seqP), and seqP is a prefix of seqS.

21/21

References

Program Slicing

Strong and Weak Slices: Example

Original program 1 2 6

• Slice A

1 2 6

• Slice B

1 2 6 24 120 Slice C 1 1 1 1 1

Table: Sequences of values produced on the slicing criterion.

21/21

References

Bibliography I

Matthew Allen and Susan Horwitz. “Slicing Java Programs That Throw and Catch Exceptions”. In: SIGPLAN Not. 38.10 (2003),

• pp. 44–54. issn: 0362-1340.

David Binkley and Keith Brian Gallagher. “Program Slicing”. In: Advances in Computers 43.2 (1996), pp. 1–50. doi: 10.1016/S0065-2458(08)60641-5. url: http://dx.doi.org/10.1016/S0065-2458(08)60641-5. Thomas Ball and Susan Horwitz. “Slicing Programs with Arbitrary Control-flow”. In: Proceedings of the First International Workshop on Automated and Algorithmic Debugging. AADEBUG ’93. London, UK, UK: Springer-Verlag, 1993, pp. 206–222. isbn: 3-540-57417-4.

21/21

References

Bibliography II

Sebastian Danicic et al. “A unifying theory of control dependence and its application to arbitrary program structures”. In: Theoretical Computer Science 412 (Nov. 2011), pp. 6809–6842. doi: 10.1016/j.tcs.2011.08.033. Susan Horwitz, Thomas Reps, and David Binkley. “Interprocedural Slicing Using Dependence Graphs”. In: Proceedings of the ACM SIGPLAN 1988 Conference on Programming Language Design and

• Implementation. PLDI ’88. Atlanta, Georgia, USA: ACM, 1988,
• pp. 35–46. isbn: 0-89791-269-1. doi: 10.1145/53990.53994. url:

http://doi.acm.org/10.1145/53990.53994. Jang-Wu Jo and Byeong-mo Chang. “Constructing Control Flow Graph for Java by Decoupling Exception Flow from Normal Flow”. In: May 2004, pp. 106–113. doi: 10.1007/978-3-540-24707-4_14.

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References

Bibliography III

• S. Jiang et al. “Improving the Preciseness of Dependence Analysis

Using Exception Analysis”. In: 2006 15th International Conference on

• Computing. IEEE, 2006, pp. 277–282. doi: 10.1109/CIC.2006.40.
• H. Jie, J. Shu-juan, and H. Jie. “An approach of slicing for

Object-Oriented language with exception handling”. In: 2011 International Conference on Mechatronic Science, Electric Engineering and Computer (MEC). 2011, pp. 883–886. doi: 10.1109/MEC.2011.6025605. Prakash Prabhu, Naoto Maeda, and Gogul Balakrishnan. “Interprocedural Exception Analysis for C++”. In: Proceedings of the 25th European Conference on Object-oriented Programming. ECOOP’11. Berlin, Heidelberg: Springer-Verlag, 2011, pp. 583–608. isbn: 978-3-642-22654-0. url: http://dl.acm.org/citation.cfm?id=2032497.2032536.

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References

Bibliography IV

• S. Sinha and M. J. Harrold. “Analysis of programs with

exception-handling constructs”. In: Proceedings. International Conference on Software Maintenance (Cat. No. 98CB36272). IEEE, 1998,

• pp. 348–357. doi: 10.1109/ICSM.1998.738526.
• S. Sinha, M. J. Harrold, and G. Rothermel.

“System-dependence-graph-based slicing of programs with arbitrary interprocedural control flow”. In: Proceedings of the 1999 International Conference on Software Engineering (IEEE Cat. No.99CB37002). IEEE, 1999, pp. 432–441. doi: 10.1145/302405.302675. Frank Tip. “A Survey of Program Slicing Techniques”. In: Journal of Programming Languages 3.3 (1995), pp. 121–189.

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References

Bibliography V

Mark Weiser. “Program Slicing”. In: Proceedings of the 5th international conference on Software engineering (ICSE ’81). San Diego, California, United States: IEEE Press, 1981, pp. 439–449. isbn: 0-89791-146-6.

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