Presentation Droidcon London 2015

1. The Jack and Jill
build system
Eric Lafortune
Developer of ProGuard and DexGuard
CTO at GuardSquare
www.guardsquare.com

2. The Jack and Jill build system
Inside the build system
Practical implications and results

3. Jack and Jill
Java Android Compiler Kit
Jack Intermediate Library Linker

4. Jack and Jill
●
Now default in build process of AOSP
●
Optional in Gradle build process:
android {
defaultConfig {
useJack true
...
}
...
}
android {
defaultConfig {
useJack true
...
}
...
}

5. Why?
Technical
Legal ?
Strategical ?

6. Android build process
Java bytecode
(.class)
Libraries
(.class)
Dx
Javac
Source code
(.java)
Libraries
(.class)
XML resources
(.xml)
Assets Assets
Compiled
XML resources
(.xml)
Aapt
Dalvik bytecode
(classes.dex)
Runtime
(.class)

7. ProGuard
Java bytecode
(.class)
ProGuard
Libraries
(.class)
Optimized
Java bytecode
(.class)
Dx
Javac
Assets
Compiled
XML resources
(.xml)
Aapt
Dalvik bytecode
(classes.dex)
ProGuard
config
(.txt)
ProGuard
mapping
(.txt)
Source code
(.java)
Libraries
(.class)
XML resources
(.xml)
Assets
Runtime
(.class)

8. ProGuard
Java bytecode
(.class)
ProGuard
Libraries
(.class)
Optimized
Java bytecode
(.class)
Dx
Javac
Assets
Compiled
XML resources
(.xml)
Aapt
Dalvik bytecode
(classes.dex)
ProGuard
config
(.txt)
ProGuard
mapping
(.txt)
Source code
(.java)
Libraries
(.class)
XML resources
(.xml)
Assets
Runtime
(.class)

9. Jack and Jill
Libraries
(.jayce)
Jack
Assets
Compiled
XML resources
(.xml)
Aapt
Dalvik bytecode
(classes.dex)
ProGuard
config
(.txt)
ProGuard
mapping
(.txt)
Source code
(.java)
Libraries
(.class)
XML resources
(.xml)
Assets
Runtime
(.class)
Jill
Jill Runtime
(.jayce)

10. Code representations
for (int i = 0; i < 8; i++) ...for (int i = 0; i < 8; i++) ...
iconst 0
istore v0
iload v0
bipush 8
ificmpge +12
...
iinc v0, 1
goto -12
iconst 0
istore v0
iload v0
bipush 8
ificmpge +12
...
iinc v0, 1
goto -12
const/4 v0, #0
const/16 v1, #8
if-ge v0, v1, 8
...
add-int/lit8 v0, v0, #1
goto -9
const/4 v0, #0
const/16 v1, #8
if-ge v0, v1, 8
...
add-int/lit8 v0, v0, #1
goto -9
.class .dex
.java

11. Code representations
for (int i = 0; i < 8; i++) ...for (int i = 0; i < 8; i++) ...
iconst 0
istore v0
iload v0
bipush 8
ificmpge +12
...
iinc v0, 1
goto -12
iconst 0
istore v0
iload v0
bipush 8
ificmpge +12
...
iinc v0, 1
goto -12
const/4 v0, #0
const/16 v1, #8
if-ge v0, v1, 8
...
add-int/lit8 v0, v0, #1
goto -9
const/4 v0, #0
const/16 v1, #8
if-ge v0, v1, 8
...
add-int/lit8 v0, v0, #1
goto -9
.class .dex
.java
Efficient to store and execute
Inconvenient to process

12. Code representations
for (int i = 0; i < 8; i++) ...for (int i = 0; i < 8; i++) ...
iconst 0
istore v0
iload v0
bipush 8
ificmpge +12
...
iinc v0, 1
goto -12
iconst 0
istore v0
iload v0
bipush 8
ificmpge +12
...
iinc v0, 1
goto -12
const/4 v0, #0
const/16 v1, #8
if-ge v0, v1, 8
...
add-int/lit8 v0, v0, #1
goto -9
const/4 v0, #0
const/16 v1, #8
if-ge v0, v1, 8
...
add-int/lit8 v0, v0, #1
goto -9
LOCAL int n
FOR_STATEMENT:
- EXPRESSION_STATEMENT:
- ASG_OPERATION:
- LOCAL_REF i
- INT_LITERAL 1
- LT_OPERATION:
- LOCAL_REF i
- INT_LITERAL 8
- POSTFIX_INC_OPERATION:
- LOCAL_REF i
- ...
LOCAL int n
FOR_STATEMENT:
- EXPRESSION_STATEMENT:
- ASG_OPERATION:
- LOCAL_REF i
- INT_LITERAL 1
- LT_OPERATION:
- LOCAL_REF i
- INT_LITERAL 8
- POSTFIX_INC_OPERATION:
- LOCAL_REF i
- ...
.jayce.class .dex
.java

13. Implications of Jack and Jill
●
Java annotation processors – supported in Jack
E.g. Dagger, Butterknife
●
Bytecode processors – only supported via Jill
E.g. JaCoCo, Retrolambda
●
Other JVM languages – only supported via Jill
E.g. Scala, Groovy, Dart

14. Implications of Jack and Jill
Libraries
(.jayce)
Jack
Assets
Compiled
XML resources
(.xml)
Aapt
Dalvik bytecode
(classes.dex)
Javac annotation processors
E.g. Dagger, Butterknife
Source code
(.scala,...)
Libraries
(.class)
XML resources
(.xml)
Assets
Runtime
(.class)
Jill
Jill Runtime
(.jayce)
Bytecode processors
Java bytecode
(.class)Scalac
Application
(.jayce)Jill

15. Internals
Jack: Java frontend
Eclipse ecj library
Jill: Java frontend
ASM4 library

16. Build performance
56s – Javac + dx (clean build)
32s – Javac + ProGuard + dx (clean build)
53s – Javac + ProGuard optimize + dx (clean build)
29s – Javac + DexGuard + dx (clean build)
2m50s – Javac + DexGuard optimize + dx (clean build)
1m48s – Jack (clean build)
20s – Jack (clear all dex files)
11s – Javac + dx (clear all class files)11s – Javac + dx (clear all class files)
9s – Javac + dx (clear one class file)9s – Javac + dx (clear one class file)
8s – Javac + dx (code unchanged)8s – Javac + dx (code unchanged)
9s – Jack (clear one dex file)9s – Jack (clear one dex file)
9s – Jack (code unchanged)9s – Jack (code unchanged)
Google I/O app
(AMD A10-7800, Ubuntu 14.04, Java 8, Android Gradle 1.2.3 / 1.3.1)
11s – Jack minify (clear all dex files)11s – Jack minify (clear all dex files)

17. Application runtime performance
50,000 – Javac + dx
63,800 – Javac + ProGuard optimize + dx
82,300 – Javac + DexGuard optimize
54,500 – Jack
Caffeinemark benchmark
(Nexus 5, Android 6.0, ART)
+9%
+28%
+65%
(higher is better)

18. Application size
3.1M – Javac + dx
1.9M – Javac + ProGuard optimize + dx
1.8M – Javac + DexGuard optimize
1.9M – Jack + minify
Google I/O app
-39%
-38%
-44%
(smaller is better)

19. DexGuard
Java bytecode
(.class)
DexGuard
Libraries
(.class)
Javac
Assets
Optimized
XML resources
(.xml)
Aapt
Optimized
Dalvik bytecode
(classes.dex)
ProGuard
config
(.txt)
ProGuard
mapping
(.txt)
Source code
(.java)
Libraries
(.class)
XML resources
(.xml)
Assets
Runtime
(.class)
Compiled
XML resources
(.xml)

20. Support for Java 8 – closures
●
Under development in branch 'ub-jack-lang-dev'
●
Test cases
●
Compiled to anonymous classes
Interface lambda = i -> i + 1;Interface lambda = i -> i + 1;
$ java -jar jack.jar --help-properties
...
jack.java.source.version:
Java source version (default is '1.8')
{1.3,1.4,1.5,5.0,5,1.6,6.0,6,1.7,7.0,7,1.8,8.0,8}
...
$ java -jar jack.jar --help-properties
...
jack.java.source.version:
Java source version (default is '1.8')
{1.3,1.4,1.5,5.0,5,1.6,6.0,6,1.7,7.0,7,1.8,8.0,8}
...
Interface lambda = new Interface() {
public int m(int i) {
return i + 1;
}
}
Interface lambda = new Interface() {
public int m(int i) {
return i + 1;
}
}

21. Conclusions
More efficient builds
Jack and Jill:
●
Java 8
●
Clean implementation
●
Room for growth

22. Further reading
●
“Experimental New Android Tool Chain - Jack and Jill”
http://tools.android.com/tech-docs/jackandjill
●
“Jack (Java Android Compiler Kit)”
https://source.android.com/source/jack.html
●
AOSP repository
https://android.googlesource.com/toolchain/jack/
●
“Hello World, meet our new experimental toolchain, Jack and Jill”, Paul Rashidi
http://android-developers.blogspot.be/2014/12/hello-world-meet-our-new-experimental.html
●
“The upcoming Jack & Jill compilers in Android”, Eric Lafortune
https://www.guardsquare.com/blog/201412
●
“AO(sp)y Episode 2 - Lambdas”, Curious Techizen, Kiran Rao
http://kiranrao.in/blog/2015/09/06/ao-spy-2/

23. Questions?
Size
Java bytecode
Performance
Jayce bytecode
Dalvik bytecode
Jack & Jill
ProGuard
DexGuard