Add update README.md with information on overriding R8 in AGP
Change-Id: I50c2c5d01f0e114050f6fa52fe7aeb8f397d8f10
diff --git a/README.md b/README.md
index 0a085c1..a152891 100644
--- a/README.md
+++ b/README.md
@@ -35,6 +35,9 @@
The prebuilt JARs have been processed by R8, and for each build the corresponding
mapping file is located together with the prebuild under the name `r8lib.jar.map`.
+To get prebuilds which has not been processed by R8 replace `r8lib.jar` with `r8.jar`
+in the URLs above.
+
The Google Cloud Storage bucket r8-releases can also be used as a simple
Maven repository using the following in a Gradle build file:
@@ -150,6 +153,40 @@
R8 is not command line compatible with ProGuard, for instance keep rules cannot be passed
on the command line, but have to be passed in a file using the `--pg-conf` option.
+## <a name="replacing-r8-in-agp"></a>Replacing R8 in Android Gradle plugin
+
+Android Gradle plugin (AGP) ships with R8 embedded (as part of the `builder.jar` from
+`com.android.tools.build:builder:<agp version>` on https://maven.google.com).
+
+To override the embedded version with a prebuilt R8 with version `<version>`, merge
+the following into the top level `settings.gradle` or `settings.gradle.kts`:
+```
+pluginManagement {
+ buildscript {
+ repositories {
+ mavenCentral()
+ maven {
+ url = uri("https://storage.googleapis.com/r8-releases/raw")
+ }
+ }
+ dependencies {
+ classpath("com.android.tools:r8:<version>")
+ }
+ }
+}
+```
+To override the embedded version with a downloaded or freshly built `<path>/r8.jar` merge
+the following into the top level `settings.gradle` or `settings.gradle.kts`:
+```
+pluginManagement {
+ buildscript {
+ dependencies {
+ classpath(files("<path>/r8.jar"))
+ }
+ }
+}
+```
+
## Testing
Typical steps to run tests:
