[PATCH] #pragma vectorize

Hal Finkel hfinkel at anl.gov
Tue Apr 22 10:49:17 PDT 2014


----- Original Message -----
> From: "Nadav Rotem" <nrotem at apple.com>
> To: "Hal Finkel" <hfinkel at anl.gov>
> Cc: "Tyler Nowicki" <tnowicki at apple.com>, cfe-commits at cs.uiuc.edu, "Alexey Bataev" <alexey.bataev at intel.com>,
> "Alexander Musman" <alexander.musman at gmail.com>, "Chandler Carruth" <chandlerc at google.com>
> Sent: Tuesday, April 22, 2014 12:44:21 PM
> Subject: Re: [PATCH] #pragma vectorize
> 
> 
> 
> 
> On Apr 22, 2014, at 10:38 AM, Hal Finkel < hfinkel at anl.gov > wrote:
> 
> 
> Okay, this is reasonable, but I'm still not sure it should be in a
> pragma called 'vectorize'. This particular transformation can be
> applied (and more often than not is applied) to scalar code.
> Strictly speaking it is an optimization that exposes ILP, and has
> little to do with vectorization.
> 
> 
> This is a good point. Maybe ILP would be a better name?

No, actually I like widen better because it is an action word. I don't think that ILP gives any idea of what the compiler is being asked to do. Not that I'm in love with widen, but I don't have a better suggestion -- unsequenced_unrolling or unsequenced_iterations, etc. all seem a bit bulky ;)

 -Hal

> 
> 
> 
> 
> 
> That having been said, the fact that the correctness model for this
> 'widening' operation is similar (although not identical) to that for
> vectorization, and thus implemented by the vectorizer, is not facet
> of the implementation we should expose to the user. However, pragma
> widen is fine with me too.
> 

-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory



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