Apps ART doesn't entirely replace Dalvik?

[bburd]

I keep reading articles about ART replacing Dalvik but, as far as I can determine, the ART Runtime is replacing the Dalvik Runtime, but that Dalvik bytecode (namely dex files) are still being used in ART. It looks as if, at the Dalvik bytecode level, nothing has changed. (There's no such thing as a specific ART bytecode.) Am I correct in my understanding?

 

[scary alien]

I keep reading articles about ART replacing Dalvik but, as far as I can determine, the ART Runtime is replacing the Dalvik Runtime, but that Dalvik bytecode (namely dex files) are still being used in ART. It looks as if, at the Dalvik bytecode level, nothing has changed. (There's no such thing as a specific ART bytecode.) Am I correct in my understanding?

Hmm, not sure if they (the .dex files) are really still used... The snippet of text from the below article implies that they're only needed by the dex2ota tool:

https://source.android.com/devices/tech/dalvik/art.html

Ahead-of-time (AOT) compilation

ART introduces ahead-of-time (AOT) compilation, which can improve app performance. ART also has tighter install-time verification than Dalvik.

At install time, ART compiles apps using the on-device dex2oat tool. This utility accepts DEX files as input and generates a compiled app executable for the target device. The utility should be able to compile all valid DEX files without difficulty. However, some post-processing tools produce invalid files that may be tolerated by Dalvik but cannot be compiled by ART. For more information, see Addressing Garbage Collection Issues.

I'm guessing we're just in a transitory phase where Android is simply keeping the .dex files around for the ability and ease of flipping back and forth between Davlik and ART--but not 100% sure about that :dontknow:.