[VRP] Improve value ranges for unsigned division

[Jeff Law]

On 06/24/2015 12:36 AM, Kugan wrote:
>
>
> On 23/06/15 01:09, Richard Biener wrote:
>> On Sat, Jun 20, 2015 at 9:12 AM, Kugan
>> <kugan.vivekanandarajah@linaro.org> wrote:
>>> As discussed in PR64130, this patch improves the VRP value ranges for
>>> unsigned division.
>>>
>>> Bootstrapped and regression tested on x86_64-linux-gnu and regression
>>> tested on arm-none-linux-gnu with no new regression.
>>>
>>> Is this OK for trunk?
>>
>> Hum, the patch is at least incomplete not covering the
>> cmp == -1 case in the max value computation, no?
>
> Thanks for the review. Attached patch adds this as well.
Please add a testcase for the cmp == -1 case too.  With that addition 
this is OK for the trunk.

jeff