Name: R8 URL: https://r8.googlesource.com/r8 Version: 3.0.33 License: BSD 3-Clause License File: NOT_SHIPPED Security Critical: no

Description: lib/r8.jar

• Contains R8 (proguard replacement) as well as D8 (dexer). 3pp
• Contains code for 3pp-linux-amd64-packager to package and upload new versions of r8. desugar_jdk_libs.json
• Configuration for Java library desugaring.
• Taken from //third_party/android_deps/libs/com_android_tools_desugar_jdk_libs_configuration/ inside the jar file, in META-INF/desugar/d8/desugar.json. License is also BSD 3-Clause (the r8 version).

R8 is a proguard-like optimizer that also has the ability to dex.

Local Modifications:

• Refer to commit descriptions within "3pp/patches" directory.
• Added "playground" directory for quick "how does this optimize" tests.
• Removed references to ConcurrentHashMap and TimeZone#getTimeZone in desugar_jdk_libs.json.
• Added "java/src/org/chromium/build/CustomD8.java", custom_d8.jar, and BUILD.gn.
  • Used in "build/android/gyp/dex.py" to enable desugar dependencies.

Update Instructions:

• For the custom d8 jar:

  • This is required only when CustomD8.java changes.
  • Uncomment the flag --skip-custom-d8 in internal_rules.gni to avoid depending on the previously built custom_d8.jar. autoninja -C out/Debug third_party/r8:custom_d8_java cp out/Debug/obj/third_party/r8/custom_d8_java.javac.jar third_party/r8/custom_d8.jar

• For a new version of r8:

  • Find the latest successful run of the build bot:
    • https://ci.chromium.org/p/chromium/builders/ci/3pp-linux-amd64-packager
    • The bot autoruns every 6 hours. Ping a trooper to trigger it if you need it sooner.
      • https://luci-scheduler.appspot.com/jobs/chromium/3pp-linux-amd64-packager
  • Go to its log page and look under:
    • Expand "building chromium/third_party/r8" to see the CIPD instance ID.
  • Copy this instance ID to the r8 entry in //DEPS.
  • Update this file with the new version string and submit.

• If patching fails: git clone https://r8.googlesource.com/r8 cd r8

  • Find latest tag: git fetch origin --tags git tag -l # Often unnecessary as output from the fetch includes recent tags. git checkout $TAG # e.g. 3.0.25-dev, whichever tag failed patching.
  • Apply patches: git checkout -b my_branch git am $CHROMIUM_SRC/third_party/r8/patches/*.patch
  • Fix patch conflicts.
  • Save new patches. Change number if expecting more or fewer patches: git format-patch -3 -o $CHROMIUM_SRC/third_party/r8/3pp/patches
  • Submit these fixed patches and the bot will automatically retry.

• Local development (see above for setting up the r8 repo):

  • Build tools/gradle.py r8
  • Shrink (improves r8/d8 launch time): java -jar build/libs/r8.jar --debug --classfile --output r8.jar
    --lib $CHROMIUM_SRC/third_party/jdk/current --pg-conf src/main/keep.txt
    --no-minification --no-desugaring build/libs/r8.jar mv $CHROMIUM_SRC/third_party/r8/lib/r8.jar{,.bak} cp r8.jar $CHROMIUM_SRC/third_party/r8/lib/r8.jar

• Update backported methods list: cd $CHROMIUM_SRC java -cp third_party/r8/lib/r8.jar com.android.tools.r8.BackportedMethodList --min-api 16 > third_party/r8/backported_methods.txt

• Update instructions for desugar_jdk_libs.json: unzip -p third_party/android_deps/libs/com_android_tools_desugar_jdk_libs_configuration/*.jar META-INF/desugar/d8/desugar.json > third_party/r8/desugar_jdk_libs.json

  • Remove all mentions of ConcurrentHashMap and TimeZone#getTimeZone and remove trailing commas.
  • Update //build/config/android/internal_rules.gni to point at the new .jar files:
    • desugar_jdk_libs-1.1.1.jar
    • desugar_jdk_libs_configuration-1.1.1.jar

How to file bugs against R8:

• Copy & paste the failing ninja command (starts with proguard.py), and add --dump-inputs.
  • This also works for dex.py, it produces d8inputs.zip
• File bug at go/r8bug
• Things to include (use discretion if some are not relevant):
  • src revision bug reproduces at
  • Repro steps (gn gen & autoninja commands)
    • Prefer enable_chrome_android_internal=false
  • The r8inputs.zip from --dump-inputs
  • Any relevant dexdump analysis

How to submit CLs to R8:

• Request to be added to their allowlist in order to upload CLs.
• After CLs are submitted, check the bots for build breakage.
  • https://ci.chromium.org/p/r8/g/main_all/console