[PATCH][VECTORIZER] Refactor ReductionDescriptor to also support floating-point recurrences

[Tyler Nowicki]

Thanks, committed in r239835 and r239862.

> On Jun 15, 2015, at 11:24 AM, Arnold Schwaighofer <aschwaighofer at apple.com> wrote:
> 
> LGTM.
> 
>> On Jun 13, 2015, at 6:58 PM, Tyler Nowicki <tnowicki at apple.com> wrote:
>> 
>> Hi,
>> 
>> Could get a review of these patches?
>> 
>> Thanks,
>> 
>> Tyler
>> 
>>> On Jun 7, 2015, at 12:54 PM, Tyler Nowicki <tnowicki at apple.com> wrote:
>>> 
>>> Hi,
>>> 
>>> I would appreciate a review of this refactoring.
>>> 
>>> Thanks,
>>> 
>>> Tyler
>>> 
>>>> On Jun 3, 2015, at 1:56 PM, Tyler Nowicki <tnowicki at apple.com> wrote:
>>>> 
>>>> Hi Hal,
>>>> 
>>>> Thanks for the review.
>>>> 
>>>> I’ve made the changes you asked for. Here are the patches. Soon I’ll start another thread for a patch builds on these to identify basic recurrences that are not reductions.
>>>> 
>>>> Thanks,
>>>> 
>>>> Tyler
>>>> 
>>>> <0001-Renamed-reduction-structures-to-recurrence-structure.patch>
>>>> <0002-Moved-RecurrenceInstDesc-into-RecurrenceDescriptor.patch>
>