Add llvm::enumerate() to stl extras

[Krzysztof Parzyszek via llvm-commits]

On 9/29/2016 1:23 PM, Zachary Turner via llvm-commits wrote:
> I frequently find myself resorting to index based enumeration because
> ranged based fors do not allow you to access the index.  With
> llvm::enumerate(), you can write something like this:
>
> for (auto X : enumerate(my_container)) {
>   if (X.Index == 1)
>     continue;
>   printf("%d", X.Value);
> }
>

How about enumerate(range) instead of container?

This way one could write
   for (auto X : enumerate(MI.operands())) {
     if (interesting(X.Value))
       use_op_index(X.Index);
   }

-Krzysztof

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, 
hosted by The Linux Foundation