[PATCH] [SCEV] make SCEV smarter about proving no-wrap.

[Andrew Trick]

> On Mar 3, 2015, at 11:07 PM, Sanjoy Das <sanjoy at playingwithpointers.com> wrote:
> 
> ================
> Comment at: lib/Analysis/ScalarEvolution.cpp:1357
> @@ +1356,3 @@
> +//
> +// If (S-T)+T does not overflow  ... (3)
> +//
> ----------------
> atrick wrote:
>> I still don't see the bug. How can (3) be false with (1) and (2)? A counter example would help.
> You're right, (3) is just (1) in the 0th iteration.  I'll fix this.

Well, step (X) could be less than (T), but either way it’s covered by (1) or (2).
-Andy

> 
> http://reviews.llvm.org/D7980
> 
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