<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 Apr 30, 2015, at 2:46 PM, Jonathan Roelofs <<a href="mailto:jonathan@codesourcery.com" class="">jonathan@codesourcery.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><br 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 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=""><span 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; float: none; display: inline !important;" class="">On 4/30/15 3:34 PM, Sanjay Patel wrote:</span><br 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=""><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="">Thanks all. Between Owen's GPU description and Mehdi's test cases, I can<br class="">see how this patch went off the rails.<br class=""><br class="">I'm back to wondering if we can still do this as a DAG combine with the<br class="">help of a target hook:<br class=""><br class="">TLI.getReassociationLimit(Opcode, EVT)<br class=""><br class="">For some operation on some data type, does it make sense to attempt to<br class="">extract some ILP? By default, we'd make this 0. For a machine that has<br class="">no exposed superscalar / pipelining ILP opportunities, it would always<br class="">return 0. If non-zero, the number would be a value that's based on the<br class="">number of registers and/or issue width and/or pipe stages for the given<br class="">operation. Something like the 'vectorization factor' or 'interleave<br class="">factor' used by the vectorizers?<br class=""><br class="">unsigned CombineCount = 0;<br class="">while (CombineCount < TLI.getReassociationLimit(Opcode, EVT))<br class=""> if (tryTheCombine(Opcode, EVT)<br class=""> CombineCount++;<br class=""></blockquote><br 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=""><span 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; float: none; display: inline !important;" class="">How about TLI.canReassociate(), TLI.shouldReassociate(), and TLI.doReassociate()?... then the target could make an even more educated decision than this heuristic count.</span><br 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></blockquote></div><br class=""><div class="">Can you illustrate how you would expect those to work? I’m not seeing it offhand?</div><div class=""><br class=""></div><div class="">—Owen</div></body></html>