[LLVMdev] RFC: Should we have (something like) -extra-vectorizer-passes in -O2?

Nadav Rotem nrotem at apple.com
Tue Oct 14 11:31:04 PDT 2014


> On Oct 14, 2014, at 11:21 AM, Andrew Trick <atrick at apple.com> wrote:
> 
>> I actually agree with you in principle, but I would rather run the pass now (and avoid hacks downstream to essentially do CSE in the backend) than hold up progress on the hope of advanced on-demand CSE layers being added to the vectorizers. I don't know of anyone actually working on that, and so I'm somewhat concerned it will never materialize.

The SLP vectorizer already has a built-in CSE.  The Loop vectorizer does not need a CSE AFAIK, but it does need InstCombine to cleanup the code that we generate for induction variables and scatter/gather. 
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