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

[Eric Christopher]

>> 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.
> The clients of the backend should not rely on any default CPU.
>
> What is the current behavior on X86?
>>
>> 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?
> In particular does ARM64 backend do the right thing if you set it.
>

I definitely like both of these options...

>> 4.) Revert this change
> This change has been actively discussed on the mailing list (http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20140414/212869.html) and IRC. This seemed to be the best approach especially with the merge with aarch64.
>
>>

and would be actively against this.

-eric