Include libraries licenses in d8.jar and r8.jar

This change is:
- Excluding META-INF from libraries when packaging the jars.
- Adding a file LIBRARY-LICENSE listing license information of all
  libraries included in the jars.
- Adding a task checkLicenses checking that LIBRARY-LICENSE is aligned
  with the jar dependencies.
- Replace the LICENSE file included in jar by a consolidated version
  containing r8/LICENSE, r8/LIBRARY-LICENSE and every file found in
  library-licensing

From there, any addition or removal of dependency will need an update of
LIBRARY-LICENSE or r8.jar/d8.jar won't package. When updating
LIBRARY-LICENSE we'll need to check that the content of
library-licensing is still accurate, there is no check on this.

Bug: 65479022
Change-Id: I1746c574744bc3d8afc0d16d5687994bc14fd5ea
6 files changed
tree: 43ab9ea4805b912c5c433fa179f6c675d480ea1e
  1. buildSrc/
  2. library-licensing/
  3. scripts/
  4. src/
  5. tests/
  6. third_party/
  7. tools/
  8. .gitignore
  9. AUTHORS
  10. build.gradle
  11. codereview.settings
  12. CONTRIBUTING.md
  13. copyAdditionalJctfCommonFiles.gradle
  14. LIBRARY-LICENSE
  15. LICENSE
  16. README.md
README.md

D8 dexer and R8 shrinker

The R8 repo contains two tools:

  • D8 is a dexer that converts java byte code to dex code.
  • R8 is a java program shrinking and minification tool that converts java byte code to optimized dex code.

D8 is a replacement for the DX dexer and R8 is a replacement for the Proguard shrinking and minification tool.

Downloading and building

The R8 project uses depot_tools from the chromium project to manage dependencies. Install depot_tools and add it to your path before proceeding.

The R8 project uses Java 8 language features and requires a Java 8 compiler and runtime system.

Typical steps to download and build:

$ git clone https://r8.googlesource.com/r8
$ cd r8
$ tools/gradle.py d8 r8

The tools/gradle.py script will bootstrap using depot_tools to download a version of gradle to use for building on the first run. This will produce two jar files: build/libs/d8.jar and build/libs/r8.jar.

Running D8

The D8 dexer has a simple command-line interface with only a few options.

The most important option is whether to build in debug or release mode. Debug is the default mode and includes debugging information in the resulting dex files. Debugging information contains information about local variables used when debugging dex code. This information is not useful when shipping final Android apps to users and therefore, final builds should use the --release flag to remove this debugging information to produce smaller dex files.

Typical invocations of D8 to produce dex file(s) in the out directoy:

Debug mode build:

$ java -jar build/libs/d8.jar --output out input.jar

Release mode build:

$ java -jar build/libs/d8.jar --release --output out input.jar

The full set of D8 options can be obtained by running the command line tool with the --help option.

Running R8

R8 is a Proguard replacement for whole-program optimization, shrinking and minification. R8 uses the Proguard keep rule format for specifying the entry points for an application.

Typical invocations of R8 to produce optimized dex file(s) in the out directory:

$ java -jar build/libs/r8.jar --release --output out --pg-conf proguard.cfg input.jar

The full set of R8 options can be obtained by running the command line tool with the --help option.

Testing

Typical steps to run tests:

$ tools/test.py --no_internal

The tools/test.py script will use depot_tools to download a lot of tests and test dependencies on the first run. This includes prebuilt version of the art runtime on which to validate the produced dex code.

Getting help

For questions, bug reports and other issues reach out to us at r8-dev@googlegroups.com.