[PATCH] D52327: [Loop Vectorizer] Abandon vectorization when no integer IV found

[Hal Finkel via Phabricator via llvm-commits]

hfinkel added a comment.

In https://reviews.llvm.org/D52327#1242567, @efriedma wrote:

> > Interesting, although given that the loop runs for more than one iteration, would that i1 variable work correctly?
>
> The i1 variable doesn't actually get used for anything; the vectorizer makes a new induction variable to track the iteration count.


Ah, okay. Interesting. I certainly see your point - if it is never used for anything, then we don't need to require it.

> 
> 
>> can we compute the trip count for these loops?
> 
> SCEV can compute the trip count for this testcase, yes.  See ScalarEvolution::computeExitCountExhaustively.

Sure. That will do it.


https://reviews.llvm.org/D52327