Baseline Profiles and R8: Advanced Android Performance Tuning

// :baseline-profile/build.gradle.kts
plugins {
    id("com.android.test")
    id("androidx.baselineprofile")
}

android {
    namespace = "com.example.baselineprofile"
    // The module the profile is generated for
    targetProjectPath = ":app"
}

dependencies {
    implementation("androidx.benchmark:benchmark-macro-junit4:1.5.0")
}

// :app/build.gradle.kts
plugins {
    id("com.android.application")
    id("androidx.baselineprofile")
}

dependencies {
    implementation("androidx.profileinstaller:profileinstaller:1.4.1")
    baselineProfile(project(":baseline-profile"))
}

baselineProfile {
    // Regenerate the profile for each release assembly
    automaticGenerationDuringBuild = true
    // Store it under src/<variant>/generated/baselineProfiles
    saveInSrc = true
}

@RunWith(AndroidJUnit4::class)
class BaselineProfileGenerator {

    @get:Rule
    val rule = BaselineProfileRule()

    @Test
    fun startup() = rule.collect(
        packageName = "com.example.app",
        // Startup code also goes into the Startup Profile
        includeInStartupProfile = true,
    ) {
        pressHome()
        startActivityAndWait()
    }

    @Test
    fun criticalJourney() = rule.collect(
        packageName = "com.example.app",
    ) {
        startActivityAndWait()
        // Drive the journeys that matter here: open a detail
        // screen, scroll the main list, run a search.
    }
}

// Generate from the command line:
// ./gradlew :app:generateBaselineProfile

// app/build.gradle.kts, AGP 9.3 and higher
android {
    buildTypes {
        release {
            optimization {
                enable = true // Code and resource optimization
            }
        }
    }
}

# proguard-rules.pro: what to delete from an old file
#
# -optimizationpasses 5            ignored by R8
# -mergeinterfacesaggressively     ignored by R8
# -repackageclasses ''             default for apps since AGP 9.1
# -allowaccessmodification         default since AGP 8.2
# -keep class androidx.compose.runtime.** { *; }   package-wide keep
#
# What is left is specific to your own code, for example a class
# you reach by reflection:
-keepclassmembers class com.example.MyClass {
    void someSpecificMethod();
}

@RunWith(AndroidJUnit4::class)
class StartupBenchmark {

    @get:Rule
    val rule = MacrobenchmarkRule()

    @Test
    fun startupNoCompilation() = startup(CompilationMode.None())

    @Test
    fun startupWithBaselineProfile() = startup(
        CompilationMode.Partial(
            baselineProfileMode = BaselineProfileMode.Require,
            warmupIterations = 0,
        )
    )

    private fun startup(compilationMode: CompilationMode) {
        rule.measureRepeated(
            packageName = "com.example.app",
            metrics = listOf(StartupTimingMetric()),
            compilationMode = compilationMode,
            startupMode = StartupMode.COLD,
            iterations = 10,
        ) {
            pressHome()
            startActivityAndWait()
        }
    }
}