[llvm] r363039 - [ARM] Add the non-MVE instructions in Arm v8.1-M.

[Simon Tatham via llvm-commits]

> From: Mikael Holmén <mikael.holmen at ericsson.com>
> Sent: 12 June 2019 06:58
> 
> Are all possible cases handled in the if/else if/else if branches?
> 
> Perhaps we should add an else branch containing an llvm_unreachable to
> make sure? Or change the last else if to else and then assert that we
> indeed get an MI->getOperand(1).isSymbol() there?

I wasn't the original author of that code (it had to have someone's name on it going out of the door, but it was a team effort), but  I just spoke to the person who was (Andre Vieira). He said that _he_ doesn't know of any other case that can reach that code, and that if he'd seen the same warning then he would have added the llvm_unreachable. (And if it later fails, then we'll know what else *can* reach that code :-) 

Will you add it (since you've got a compiler that gives the warning, to test against), or shall I?

Cheers,
Simon