[PATCH][FastISel] Let the target decide first if it wants to materialize a constant.

[Chad Rosier]

I reapplied r215597 and everything continued to pass.  Thus, I think
r215588 is the only issue.

 Chad

> That is the commit that actually reversed the order for materializing a
> constant by invoking the target-specific code first. I guess there must be
> a bug in the AArch64 target-specific materialization code that got exposed
> by switching the order. Let me see if I can reproduce the error locally
> and come up with a fix.
>
> -Juergen
>
> On Aug 14, 2014, at 1:05 PM, Chad Rosier <mcrosier at codeaurora.org> wrote:
>
>> The problem child is r215588.
>>
>>> Ok, let me revert all changes and see if that fixes it.
>>>
>>> -Juergen
>>>
>>> On Aug 14, 2014, at 12:47 PM, Chad Rosier <mcrosier at codeaurora.org>
>>> wrote:
>>>
>>>> I don't think r215597 is the culprit.  All tests previously failing
>>>> are
>>>> continuing to fail.
>>>>