The presentation slides for my talk at the 11th International Workshop on Software Clones 2017 in Klagenfurt, Austria.

1. IWSC ‘17
CREST, University College London, UK
Using Compilation/Decompilation
to Enhance Clone Detection
Chaiyong Ragkhitwetsagul, Jens Krinke

2. Clone
det.
Plag
det.
Comp.
Others
ccfx
deckard
iclones
nicad
simian
jplag-java
jplag-text
plaggie
sherlock
simjava
simtext
7zncd-BZip2
7zncd-LZMA
7zncd-LZMA2
7zncd-Deflate
7zncd-Deflate64
7zncd-PPMd
bzip2ncd
gzipncd
icd
ncd-bzlib
ncd-zlib
xz-ncd
bsdiff
diff
py-difflib
py-fuzzywuzzy
py-jellyfish
py-ngram
py-sklearn
0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 F1
Orig.
Dec.
Ragkhitwetsagul et al., 2016

3. Clone
det.
Plag
det.
Comp.
Others
ccfx
deckard
iclones
nicad
simian
jplag-java
jplag-text
plaggie
sherlock
simjava
simtext
7zncd-BZip2
7zncd-LZMA
7zncd-LZMA2
7zncd-Deflate
7zncd-Deflate64
7zncd-PPMd
bzip2ncd
gzipncd
icd
ncd-bzlib
ncd-zlib
xz-ncd
bsdiff
diff
py-difflib
py-fuzzywuzzy
py-jellyfish
py-ngram
py-sklearn
0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 F1
Orig.
Dec.

4. 4
O. Kononenko, C. Zhang, and M. W. Godfrey, ICSME ‘14
What Happens?
Compiling Clones:

5. and Decompiling
4
What Happens?
Compiling Clones:

6. Source
Code
and Decompiling
4
What Happens?
Compiling Clones:

7. Existing
tools
Source
Code
and Decompiling
4
What Happens?
Compiling Clones:

8. Missing
Source
Existing
tools
Source
Code
and Decompiling
4
What Happens?
Compiling Clones:

9. C. Ragkhitwetsagul J. Krinke CREST, UCL, UK
decomp.
clones
clone
mapper
decomp. &
mapped clones
compiler
decompiler
decompiled software
clone
detector
original
clones
5
software
common
clones
disjoint
clones
manual investigation
Experimental Framework

10. C. Ragkhitwetsagul J. Krinke CREST, UCL, UK 6
System Ver.
Original Decompiled
Files SLOC Files SLOC
4.1.3 203 9,777 311 11,233
1.5.0 644 96,711 669 85,251
9.0 1,688 241,924 2603 256,974
Apache Tomcat®
Software Systems

11. 7
Tool Config. Parameters
NiCad Type-1 UPI=0.0, renaming=none
Type-2 UPI=0.0, renaming=consistent
Type-3 UPI=0.3, renaming=consistent
Tools
javac Procyon NiCad
Compiler Decompiler Clone Detector

12. 8
Clone Mapper
decompiled
clone report
DCP1(dm1, dm2)
decompiled clone
pairs
software
m1
m2
m4
m3
mn
…
DCP2(dm1, dm3)
DCP3(dm2, dm4)
…
DCPn(dmm, dmo)
set of methods (M)
mo
decompiled-and-mapped
clone report
DCP*1((dm1,dm2),(m1,m2))
DCP*2((dm1,dm3),(m1,m3))
DCP*3((dm2,dm4),(m2,m4))
DCP*n((dmm,dmo),(mm,mo))
…
decompiled-and-mapped
clone pairs
…

13. C. Ragkhitwetsagul J. Krinke CREST, UCL, UK 9
Common & Disjoint Clone Pairs
Ccommon
Corig-only Cdecomp-only
Original Decompiled

14. C. Ragkhitwetsagul J. Krinke CREST, UCL, UK 10
Results

15. 11
JUnit
Original Decompiled
Type-1
Type-2
Type-3
6
3

16. 12
JFreeChart
Original Decompiled
Type-1
Type-2
Type-3
159
155
33
15
48
1
17
27
3

17. 13
Tomcat
Original Decompiled
Type-1
Type-2
Type-3
217
608
20
25
141
22
3
23
1

18. C. Ragkhitwetsagul J. Krinke CREST, UCL, UK 14
Manual Investigation

19. 15
No.ofclonepairs
0
10
20
30
40
50
Type-1 Type-2 Type-3
47
15
1
48
15
1
Candidates TP
JFreeChart
Cforig-only
No.ofclonepairs
0
6
12
18
24
30
Type-1 Type-2 Type-3
27
17
3
27
17
3
Cfdecomp-only

20. 16
No.ofclonepairs
0
32
64
96
128
160
Type-1 Type-2 Type-3
141
2522
141
2522
Candidates TP
Tomcat
Cforig-only
No.ofclonepairs
0
6
12
18
24
30
Type-1 Type-2 Type-3
23
31
23
31
Cfdecomp-only

21. Clone set Reasons
Cforig-only
Too small after decomp.
Too diff. after decomp.
Smaller after decomp. higher dissimilarity
Unknown
Cfdecomp-only
Having deleted/added stmt., type cast, package
name.
Different if-else statements
Different loop statements
Inner class methods
Unknown
Characteristics of Disjoint Clones

22. Clone set Reasons
Cforig-only Too small after decomp.
Too diff. after decomp.
Smaller after decomp. higher
dissimilarity
Unknown
Cfdecomp-only
Having deleted/added stmt., type
cast, package name.
Different if-else statements
Different loop statements
Inner class methods
Unknown
JFreeChart
0 10 20 30 40 50
5
11
32
6
9
T1 T2 T3
0 2 4 6 8 10 12 14 16
12
4
3
8
12
53

23. Clone set Reasons
Cforig-only Too small after decomp.
Too diff. after decomp.
Smaller after decomp. higher
dissimilarity
Unknown
Cfdecomp-only
Having deleted/added stmt., type
cast, package name.
Different if-else statements
Different loop statements
Inner class methods
Unknown
Tomcat
0 28 56 84 112 140
16
5
120
19
6
T1 T2 T3
0 5 10 15 20 25 30
20
2
1
3
2

24. @Override
public Range findRangeBounds(XYDataset dataset) {
if (dataset != null) {
Range r = DatasetUtilities.findRangeBounds(dataset, false);
if (r == null) {
return null;
} else {
return new Range(r.getLowerBound() + this.yOffset,
r.getUpperBound() + this.blockHeight + this.yOffset);
}
} else {
return null;
}
}
@Override
public Range findDomainBounds(XYDataset dataset) {
if (dataset == null) {
return null;
}
Range r = DatasetUtilities.findDomainBounds(dataset, false);
if (r == null) {
return null;
}
return new Range(r.getLowerBound() + this.xOffset,
r.getUpperBound() + this.blockWidth + this.xOffset);
}
O
R
I
G
I
N
A
L

25. @Override
public Range findRangeBounds(XYDataset dataset) {
if (dataset != null) {
Range r = DatasetUtilities.findRangeBounds(dataset, false);
if (r == null) {
return null;
} else {
return new Range(r.getLowerBound() + this.yOffset,
r.getUpperBound() + this.blockHeight + this.yOffset);
}
} else {
return null;
}
}
@Override
public Range findDomainBounds(XYDataset dataset) {
if (dataset == null) {
return null;
}
Range r = DatasetUtilities.findDomainBounds(dataset, false);
if (r == null) {
return null;
}
return new Range(r.getLowerBound() + this.xOffset,
r.getUpperBound() + this.blockWidth + this.xOffset);
}
O
R
I
G
I
N
A
L

26. @Override
public Range findDomainBounds(final XYDataset dataset) {
if (dataset == null) {
return null;
}
final Range r = DatasetUtilities.findDomainBounds(dataset, false);
if (r == null) {
return null;
}
return new Range(r.getLowerBound() + this.xOffset,
r.getUpperBound() + this.blockWidth + this.xOffset);
}
@Override
public Range findRangeBounds(final XYDataset dataset) {
if (dataset == null) {
return null;
}
final Range r = DatasetUtilities.findRangeBounds(dataset, false);
if (r == null) {
return null;
}
return new Range(r.getLowerBound() + this.yOffset,
r.getUpperBound() + this.blockHeight + this.yOffset);
}
D
E
C
O
M
P
I
L
E
D

27. public void clearRangeMarkers() {
if (this.backgroundRangeMarkers != null) {
Set<Integer> keys =
this.backgroundRangeMarkers.keySet();
for (Integer key : keys) {
clearRangeMarkers(key);
}
this.backgroundRangeMarkers.clear();
}
if (this.foregroundRangeMarkers != null) {
Set<Integer> keys =
this.foregroundRangeMarkers.keySet();
for (Integer key : keys) {
clearRangeMarkers(key);
}
this.foregroundRangeMarkers.clear();
}
fireChangeEvent();
}
public void clearRangeMarkers() {
if (this.backgroundRangeMarkers != null) {
Set keys =
this.backgroundRangeMarkers.keySet();
Iterator iterator = keys.iterator();
while (iterator.hasNext()) {
Integer key = (Integer) iterator.next();
clearRangeMarkers(key.intValue());
}
this.backgroundRangeMarkers.clear();
}
if (this.foregroundRangeMarkers != null) {
Set keys =
this.foregroundRangeMarkers.keySet();
Iterator iterator = keys.iterator();
while (iterator.hasNext()) {
Integer key = (Integer) iterator.next();
clearRangeMarkers(key.intValue());
}
this.foregroundRangeMarkers.clear();
}
fireChangeEvent();
}
ORIGINAL

28. public void clearRangeMarkers() {
if (this.backgroundRangeMarkers != null) {
Set<Integer> keys =
this.backgroundRangeMarkers.keySet();
for (Integer key : keys) {
clearRangeMarkers(key);
}
this.backgroundRangeMarkers.clear();
}
if (this.foregroundRangeMarkers != null) {
Set<Integer> keys =
this.foregroundRangeMarkers.keySet();
for (Integer key : keys) {
clearRangeMarkers(key);
}
this.foregroundRangeMarkers.clear();
}
fireChangeEvent();
}
public void clearRangeMarkers() {
if (this.backgroundRangeMarkers != null) {
Set keys =
this.backgroundRangeMarkers.keySet();
Iterator iterator = keys.iterator();
while (iterator.hasNext()) {
Integer key = (Integer) iterator.next();
clearRangeMarkers(key.intValue());
}
this.backgroundRangeMarkers.clear();
}
if (this.foregroundRangeMarkers != null) {
Set keys =
this.foregroundRangeMarkers.keySet();
Iterator iterator = keys.iterator();
while (iterator.hasNext()) {
Integer key = (Integer) iterator.next();
clearRangeMarkers(key.intValue());
}
this.foregroundRangeMarkers.clear();
}
fireChangeEvent();
}
ORIGINAL

29. public void clearRangeMarkers() {
if (this.backgroundDomainMarkers != null) {
final Set<Integer> keys =
this.backgroundDomainMarkers.keySet();
for (final Integer key : keys) {
this.clearDomainMarkers(key);
}
this.backgroundDomainMarkers.clear();
}
if (this.foregroundDomainMarkers != null) {
final Set<Integer> keys =
this.foregroundDomainMarkers.keySet();
for (final Integer key : keys) {
this.clearDomainMarkers(key);
}
this.foregroundDomainMarkers.clear();
}
this.fireChangeEvent();
}
public void clearRangeMarkers() {
if (this.backgroundRangeMarkers != null) {
final Set keys =
this.backgroundRangeMarkers.keySet();
for (final Integer key : keys) {
this.clearRangeMarkers(key);
}
this.backgroundRangeMarkers.clear();
}
if (this.foregroundRangeMarkers != null) {
final Set keys =
this.foregroundRangeMarkers.keySet();
for (final Integer key : keys) {
this.clearRangeMarkers(key);
}
this.foregroundRangeMarkers.clear();
}
this.fireChangeEvent();
}
DECOMPILED

30. 26
Study on 3 real-world systems: JUnit, JFreeChart, Tomcat
Using Compilation/Decompilation
to Enhance Clone Detection
1 Clone pairs before and after decompilation are mostly
similar for all three clone types.
Findings:
2 One can complement the original clone results by
incorporating clones after decompilation.
Characteristics of disjoint clones3
C. Ragkhitwetsagul, J. Krinke
cragkhit.github.io/crjk-iwsc17