How can they toss away a fundamental part of the OS? Steve just presented it back in Tiger. This and tossing 32 bit apps to the wind. Crazy Apple.
Similarly, someday MS will remove live tiles from the start menu. It’s inevitable, but clearly internal politics are keeping the feature around. Guaranteed that 99% of humanity will rejoice when it happens, but equally guaranteed that someone on HN will express how appalled they are that a company as big as MS didn’t choose to keep the feature alive for the sake of the handful of people who liked it.
(And I'm sure a 3rd party replacement will pop up, if there are enough frustrated users).
A good example was usage of LLVM on the PPC->Intel transition which then helped when they ported OSX to ARM (ie, iOS, nee iPhoneOS).
Another is Safari (which was useful/needed on Mac at the time) but more importantly was critical in making the iPhone successful - mobile browsing sucked before the iPhone.
I’m not an Apple insider, but I don’t believe LLVM played a substantial role in either the PPC-to-x86 or x86-to-ARM-for-iOS ports — the former was accomplished with Rosetta and a lot of bugs.
The current rumor, OTOH, is that Apple’s collection of LLVM bitcode for apps is intended to allow painless migration for applications when macOS is switched over to ARM.
Has anyone been able to execute built-for-x86_64 bitcode on aarch64 ever?
I will say, however, that executing LLVM bitcode on different targets than the compilation machine is a subject of active research. It's one of the things that I work on in my day job.
Bitcode is not [12:30] a magic solution, though. You can't take a 32-bit app, for example, and run it on a 64-bit device. That kind of portability isn’t something that Bitcode can give you, notably because that is something that's visible in C. As you're writing C code, you can write #ifdef pointer size equals 32, and that’s something that Bitcode can't abstract over. It's useful for very specific, low-level kinds of enhancements, but it isn't a panacea that makes everything [13:00] magically portable.
What’s funny, is later on after Apple shipped a 64 bit chip for the Apple Watch. He admitted that forcing developers to ship watch apps as bitcode allowed Apple to recompile all of the third party Watch apps on the fly to support it, he knew that was coming, but couldn’t say anything at the time.
https://twitter.com/clattner_llvm/status/1046960724646465541