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<div class="moz-cite-prefix">On 5/14/2018 2:21 AM,
Gopalasubramanian, Ganesh wrote:<br>
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<ul style="margin-top:0in" type="disc">
<li class="MsoNormal" style="color:windowtext;mso-list:l0
level1 lfo1"><span style="color:black">Looks like some sort
of pass ordering issue; it will vectorize if indvars runs
sometime between loop unswitch and the vectorizer.</span><o:p></o:p></li>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="margin-left:.25in">That insight is
helpful. I scheduled Canonicalization of induction variable
before loop vectorization and could get the loop vectorized.<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.25in">The indvars are
heavily dependent on SCEV. If there a scalar like tmp which is
of real type, we may not be able to get the indvars sorted out
because of the integer type limitation in SCEV!<o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:12.0pt;margin-left:.25in">Is
there a way out when we have a scalar float computation that
is dependent on induction variable?</p>
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<br>
In general, a loop can't be vectorized if there's a PHI node; a
scalar dependency means the iterations have to run in order. But
there are some special cases for reductions and induction
variables. For the LLVM loop vectorizer, see
LoopVectorizationLegality::canVectorizeInstrs.<br>
<br>
-Eli<br>
<br>
<pre class="moz-signature" cols="72">--
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project</pre>
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