<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">One thought I’ve had about this in the past —<div class=""><br class=""></div><div class="">SCEV is useful for proving two expressions are equivalent (in general, not just specifically for loop induction variables). This gets a little bit trickier with fast-math; for example, suppose two expressions are equivalent, but *only* with reassociativity allowed?</div><div class=""><br class=""></div><div class="">This would be useful to make N-ary reassociate or similar algorithms work with float, as it currently uses SCEV to prove equivalence, but fast-math makes it become much trickier (and without fast-math, there’s not much you can prove).</div><div class=""><br class=""></div><div class="">—escha</div><div class=""><br class=""><div class=""><blockquote type="cite" class=""><div class="">On May 16, 2016, at 6:07 AM, Demikhovsky, Elena via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" class="">llvm-dev@lists.llvm.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><font face="Calibri" size="2" style="font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><span style="font-size: 11pt;" class=""><div class="">Hi,</div><div class=""> </div><div class="">I’m working now on extending SCEV Analysis and adding FP support.</div><div class="">At the beginning, I want to vectorize this loop:</div><div class=""> </div><div class="">float fp_inc;</div><div class=""> </div><div class=""> float x = init;</div><div class=""> for (int i=0;i<N;i++){</div><div class=""> A[i] = x;</div><div class=""> x += fp_inc; // Loop invariant variable or constant</div><div class=""> }</div><div class=""> </div><div class="">In this loop “x” is a FP induction variable. But it is not the “primary” induction and loop trip count is still depends on integer induction “i”.</div><div class=""> </div><div class="">In the future, I plan to work on “primary” FP inductions.</div><div class="">Intel compiler vectorizes FP-induction loops, GCC does not.</div><div class=""> </div><div class="">I wanted to hear that community does not have any principal objections for this work.</div><div class="">Thank you.</div><div class=""> </div><ul style="margin: 0px; padding-left: 36pt;" class=""><font face="Times New Roman" size="3" color="#2F5496" class=""><span style="font-size: 12pt;" class=""><li class=""><b class=""><i class="">Elena</i></b></li></span></font></ul><div class=""> </div><div class=""> </div><div class=""> </div></span></font><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class=""></span><p style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">---------------------------------------------------------------------<br class="">Intel Israel (74) Limited</p><p style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">This e-mail and any attachments may contain confidential material for<br class="">the sole use of the intended recipient(s). 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