<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;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Jan 16, 2015, at 3:47 PM, Quentin Colombet <<a href="mailto:qcolombet@apple.com" class="">qcolombet@apple.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 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="Apple-interchange-newline">On Jan 16, 2015, at 3:44 PM, Mehdi Amini <<a href="mailto:mehdi.amini@apple.com" class="">mehdi.amini@apple.com</a>> wrote:</div><br class="Apple-interchange-newline" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 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;"><blockquote type="cite" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 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=""><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><br class=""><div class=""><blockquote type="cite" class=""><div class="">On Jan 16, 2015, at 3:04 PM, Chandler Carruth <<a href="mailto:chandlerc@google.com" class="">chandlerc@google.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class=""><div class="gmail_extra"><br class=""><div class="gmail_quote">On Fri, Jan 16, 2015 at 2:40 PM, Quentin Colombet<span class="Apple-converted-space"> </span><span dir="ltr" class=""><<a href="mailto:qcolombet@apple.com" target="_blank" class="">qcolombet@apple.com</a>></span><span class="Apple-converted-space"> </span>wrote:<br class=""><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;"><div class="">Well, that may be the conclusion: The performance impact may be within the noise.</div><div class="">Since this kind of patterns are very specific, this is not surprising.</div><div class="">For the record, I tend to ignore the tests that run for less than 1 second (too noisy). Then, the noise level is usually around 1% on a quiet computer with fixed frequency, which is not too bad. </div></blockquote></div><br class="">Numbers would mostly be nice because I don't know if other targets have the thing that makes this such a huge win on x86 -- implicit concat with undef to form 2x-wide vectors.</div><div class="gmail_extra"><br class=""></div><div class="gmail_extra">This may be an x86-specific win, in which case it should just be added as a target-specific combine.</div></div></div></blockquote><div class=""><br class=""></div><div class=""><br class=""></div><div class="">We are filling half of a vector (v8), and we have to choose between concat two v4 to v8 and then shuffle, or shuffle in v4 and then concat with undef to have a v8.</div><div class="">I’m not sure I necessarily see the “target specific part” here, isn’t it a sort of canonicalization in the DAG? </div></div></div></blockquote><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 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=""></div><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 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="">In some sense it is, but this was not what we were doing so far, and it may introduce regressiosn on other targets, since they were not expecting this pattern.</div><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 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="">That is why Chandler and I are willing to get evidence that it works well for other targets.</div><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 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=""></div></div></blockquote><div><br class=""></div><div>Oh yeah I totally understand that it can lead to regression and we should check for that.</div><div>I was more trying to see this under the angle that we can still consider that this is the “right" canonical form in the DAG and then fix the Codegen for the target that regressed.</div><div><br class=""></div><div>Mehdi</div><div><br class=""></div></div></body></html>