[PATCH][AArch64] implement aarch64 neon instruction class AdvSIMD (3 diff)

[Tim Northover]

> I think essentially you are intending to remove some of the builtins from 32-bit ARM target.

Yep, that's correct. And your list matches with my plans for now too.

> Do you mean to use lshr instead of shl, because addhn is to get high narrow, so we could have,

Yes, I did sorry. I'd discovered this, and was planning to mention it when posting the patches.

Cheers.

Tim.