I think the compliance tests were making sure that your add instruction or memory load instruction followed the spec.
You mention ARM ecosystem and that is precisely the point. Apple controls their ecosystems. How do you write apps for the iPhone? You use Apple's development environment with Apple's compiler. If Apple decided NOT to implement an instruction for some reason they could simply make their compiler never output that instruction.
I worked on chips that ran embedded applications with no ability for ordinary users to change the software. What is the value of meeting an external ARM controlled spec for that?
I also worked on chips that only ran Android and nothing else. If you are also the company porting Android and writing all drivers for your own platform then people may argue whether it is worth only being 99% compatible.
Later I worked on chips where people may run Android, Windows Mobile, or plain Linux on this chip using GCC, Clang, Microsoft's compiler, or whatever. For that you definitely wanted to comply with specs.
You mention ARM ecosystem and that is precisely the point. Apple controls their ecosystems. How do you write apps for the iPhone? You use Apple's development environment with Apple's compiler. If Apple decided NOT to implement an instruction for some reason they could simply make their compiler never output that instruction.
I worked on chips that ran embedded applications with no ability for ordinary users to change the software. What is the value of meeting an external ARM controlled spec for that?
I also worked on chips that only ran Android and nothing else. If you are also the company porting Android and writing all drivers for your own platform then people may argue whether it is worth only being 99% compatible.
Later I worked on chips where people may run Android, Windows Mobile, or plain Linux on this chip using GCC, Clang, Microsoft's compiler, or whatever. For that you definitely wanted to comply with specs.