While the keynote at Apple’s latest Worldwide Developers Conference took the lion’s share of media attention, it turns out a session the next day could have delivered quite a big piece of news, too.
In a post published to Medium on Wednesday, June 10 (and updated on June 16), by “Inertial Lemon,” Apple’s biggest announcement apparently happened on Tuesday, June 9. During a session called “Platforms Sate of the Union,” Andreas Wendker mentioned Bitcode. As outlined in the post, Bitcode will allow future compiler optimizations to be applied to already-submitted applications. More than that, though, this new implementation will allow the store to add support for new CPU architecture introduced at some point down the road. Specifically, after an app has already been submitted for release.
All of that, without having the developers to resubmit the application in direct response to new hardware being utilized by Apple.The post articulates just what Bitcode is, saying that it is an encoding of LLVM compiler’s Intermediate Representation (IR). The post notes that LLVM front-end understands programming language, the language used to write apps. On the back-end, the LLVM understands how to showcase the executable version of apps that are downloaded by the users out in the wild. Bitcode sits in the middle of those two steps:“And in between the front and back ends sits the LLVM IR, now known as Bitcode. LLVM turns an app’s source code into Bitcode, and then turns that Bitcode into an executable app. This design makes it incredibly simple to add support for new languages (front ends), and for new CPUs (back ends). While Bitcode itself can’t run on anything, it can be transformed into any supported CPU architecture, including ones that didn’t exist when the app was submitted.“
Lemon points out that, moving forward all Watch apps need to be submitted with Bitcode, while it’s not mandatory for iOS 9 apps. However, iOS 9 app submissions will default to Bitcode. OS X was not mentioned.
Lemon outlines that Apple’s inclusion of Bitcode could very well telegraph the future of Apple’s CPU choices, suggesting that Apple will continue to focus on its own chipsets moving forward, including the CPU used within the Apple Watch, called the S1. Lemon points out that the S1 isn’t the best possible CPU, but good enough to get the Watch out the door. But, more than that, that the engineers within Apple probably already know they can make the S2, or whatever it’s called, much better. But that won’t mean the applications already supported by the Watch and its platform will have to get resubmitted to support the new hardware that Apple uses in their next wearable.
Thanks to Bitcode, Apple can use whatever architecture Apple wants, whether it’s ARM or not. And, looking even beyond that, if Apple’s S3 CPU gets even “crazier,” then all the Apple compiler engineers need to do is install the new LLVM back-end into the App Store, and Bitcode will take care of the rest.
Even better news is the fact that iOS is getting this support as well, which means that the future for iPhone CPU’s and apps is even brighter for developers, with even less work needed to get those apps over to the new hardware that Apple will inevitably release down the line. However, Lemon does suggest that these major improvements won’t be seen for quite some time, especially not with the expected A9 processor this fall. Or even the A10 processor next year. This could really take effect with the A11.
Apple could very well be forecasting its CPU decisions in the future, if the post is correct in the Cupertino-based company’s plans. It certainly sounds like Bitcode will make life easier for developers in at least one area.
[via h/t: Ben Bajarin (@BenBajarin); Medium @InertialLemon]
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