[llvm] r206228 - [ARM64][MC] Set the default CPU string to generic.

[Tim Northover]

>> To fix this we could:
>> 1.) Extend the C interface to also specify the CPU type and warn JIT clients that don’t specify a CPU for ARM64
> This looks like the right approach to me.

I like this one too. Perhaps with a stronger encouragement to support
"native" for WebKit-like uses.

>> 3.) Every JIT client has to add the target processor attribute to the IR
> That sounds like a good safe belt, especially to reproduce failures (see http://llvm.org/bugs/show_bug.cgi?id=19483). That said, how this attribute is propagated?

This one might have the advantage of being a step towards the world
where we can compile (say) AVX & SSE versions of functions and have it
work nicely with "-flto". Depends on whether it's a module or function
annotation.

Of course, these two aren't necessarily mutually exclusive.

Cheers.

Tim.