A Selective Ahead-Of-Time Compiler on Android Device

The runtime environment of Android is based on its own Java Virtual Machine(JVM) called Dalvik Virtual Machine (DVM) which is said to be having overhead of interpreting every bytecode to machine code during runtime just like other JVMs. There are already well known techniques to overcome runtime overhead of interpreting and Google has adapted one of them which is Just-In-Time Compiler (JITC) since Android 2.2, Froyo. Google chose trace based JITC to JIT compile only the hottest of hot code by using lazy fashion with counting strategy to minimize memory usage, thus applying various optimization techniques during JIT compilation to generate more efficient machine code is limited. In order to minimize runtime interpreting and compiling overhead, here a selective Ahead-Of-Time Compiler (AOTC) which generates machine code at static compile time with abundant optimization techniques for the selected hot methods by profiling will be introduced. The experimented results show that AOT compiling hot methods at static compile time and letting the others to aim the benefit of runtime JITC gives 5% of performance upgrade in average on ARM11 600MHz target environment.