<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><br><div><div>On Apr 22, 2014, at 11:24 AM, Raul Silvera <<a href="mailto:rsilvera@google.com">rsilvera@google.com</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div dir="ltr"><div class="gmail_default" style="font-family:verdana,sans-serif">Does this pragma widen also asserts safety, or does it depend on the compiler proving independence?</div></div></blockquote><div><br></div><div>This specific pragma only affects the decision of the vectorizer 'cost model'. </div><br><blockquote type="cite"><div dir="ltr"><div class="gmail_default" style="font-family:verdana,sans-serif">
<br></div><div class="gmail_default" style="font-family:verdana,sans-serif">widen does seem to imply the data types are being widened -- also a form of vectorization. Perhaps interleave is another word to consider?</div></div></blockquote><div><br></div><div>I also like ‘interleave’. </div><br><blockquote type="cite">
<div class="gmail_extra"><br clear="all"><div><div dir="ltr"><div style="line-height:1.5em;padding-top:10px;margin-top:10px;font-family:sans-serif;font-size:small"><span style="color:rgb(85,85,85);border-width:2px 0px 0px;border-style:solid;border-color:rgb(213,15,37);padding-top:2px;margin-top:2px">Raúl E Silvera |</span><span style="color:rgb(85,85,85);border-width:2px 0px 0px;border-style:solid;border-color:rgb(51,105,232);padding-top:2px;margin-top:2px"> SWE |</span><span style="color:rgb(85,85,85);border-width:2px 0px 0px;border-style:solid;border-color:rgb(0,153,57);padding-top:2px;margin-top:2px"> <a href="mailto:rsilvera@google.com" target="_blank">rsilvera@google.com</a> |</span><span style="border-width:2px 0px 0px;border-style:solid;border-color:rgb(238,178,17);padding-top:2px;margin-top:2px"><font color="#555555"> </font><font color="#0033bb"><u>408-789-2846</u></font></span></div>
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<br><br><div class="gmail_quote">On Tue, Apr 22, 2014 at 10:49 AM, Hal Finkel <span dir="ltr"><<a href="mailto:hfinkel@anl.gov" target="_blank">hfinkel@anl.gov</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex; position: static; z-index: auto;">
<div class="">----- Original Message -----<br>
> From: "Nadav Rotem" <<a href="mailto:nrotem@apple.com">nrotem@apple.com</a>><br>
> To: "Hal Finkel" <<a href="mailto:hfinkel@anl.gov">hfinkel@anl.gov</a>><br>
</div><div class="">> Cc: "Tyler Nowicki" <<a href="mailto:tnowicki@apple.com">tnowicki@apple.com</a>>, <a href="mailto:cfe-commits@cs.uiuc.edu">cfe-commits@cs.uiuc.edu</a>, "Alexey Bataev" <<a href="mailto:alexey.bataev@intel.com">alexey.bataev@intel.com</a>>,<br>
> "Alexander Musman" <<a href="mailto:alexander.musman@gmail.com">alexander.musman@gmail.com</a>>, "Chandler Carruth" <<a href="mailto:chandlerc@google.com">chandlerc@google.com</a>><br>
</div><div class="">> Sent: Tuesday, April 22, 2014 12:44:21 PM<br>
> Subject: Re: [PATCH] #pragma vectorize<br>
><br>
><br>
><br>
><br>
</div><div class="">> On Apr 22, 2014, at 10:38 AM, Hal Finkel < <a href="mailto:hfinkel@anl.gov">hfinkel@anl.gov</a> > wrote:<br>
><br>
><br>
> Okay, this is reasonable, but I'm still not sure it should be in a<br>
> pragma called 'vectorize'. This particular transformation can be<br>
> applied (and more often than not is applied) to scalar code.<br>
> Strictly speaking it is an optimization that exposes ILP, and has<br>
> little to do with vectorization.<br>
><br>
><br>
> This is a good point. Maybe ILP would be a better name?<br>
<br>
</div>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 ;)<br>
<span class="HOEnZb"><font color="#888888"><br>
-Hal<br>
</font></span><div class="im HOEnZb"><br>
><br>
><br>
><br>
><br>
><br>
> That having been said, the fact that the correctness model for this<br>
> 'widening' operation is similar (although not identical) to that for<br>
> vectorization, and thus implemented by the vectorizer, is not facet<br>
> of the implementation we should expose to the user. However, pragma<br>
> widen is fine with me too.<br>
><br>
<br>
</div><div class="HOEnZb"><div class="h5">--<br>
Hal Finkel<br>
Assistant Computational Scientist<br>
Leadership Computing Facility<br>
Argonne National Laboratory<br>
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