[PATCH] #pragma vectorize

[Nadav Rotem]

On Apr 22, 2014, at 11:24 AM, Raul Silvera <rsilvera at google.com> wrote:

> Does this pragma widen also asserts safety, or does it depend on the compiler proving independence?

This specific pragma only affects the decision of the vectorizer 'cost model'. 

> 
> widen does seem to imply the data types are being widened -- also a form of vectorization. Perhaps interleave is another word to consider?

I also like ‘interleave’.  

> 
> Raúl E Silvera | SWE | rsilvera at google.com | 408-789-2846
> 
> 
> 
> On Tue, Apr 22, 2014 at 10:49 AM, Hal Finkel <hfinkel at anl.gov> wrote:
> ----- 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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