Digging into D8 and R8
summary
D8 replaces DX and folds Java 8 desugaring into dexing so command-line experiments reproduce how lambdas become generated classes, and D8 emits different Dalvik opcodes based on minSdk (example: not vs xor optimization that saves an instruction but avoids buggy phones). R8 replaces ProGuard by running shrink/optimize during dexing and proves things like class staticization for Kotlin companion objects and nullability-driven elim, plus range propagation that can remove hundreds of AndroidX API-level branches. Build-plugin flags enable each; try on a real APK to see size and opcode changes.
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chapters (11)
- 0:00Introduction to D8 and R8
- 1:09Compilation pipeline overview
- 3:15D8 replaces DX with modern techniques
- 8:09Lambda transformations in D8
- 11:58D8’s bite code optimizations
- 16:35R8 integrates minification
- 18:23Cotlin companion object optimization
- 23:40Nullability and dead code elimination
- 28:59API level conditional code removal
- 36:27Using D8 and R8 in Gradle
- 40:23Conclusion and next steps
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