<html><head><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=""><div class="">I think that the pattern below should be canonicalized into a vector ’select’ instruction with a constant mask. I think that we already have code for canonicalizing select-like shuffles into selects. </div><div class=""><br class=""></div><div class=""><div><blockquote type="cite" class=""><div class="">On Oct 6, 2014, at 12:36 PM, Rafael Espíndola <<a href="mailto:rafael.espindola@gmail.com" class="">rafael.espindola@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div 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 26 September 2014 19:22, Sean Silva <</span><a href="mailto:chisophugis@gmail.com" 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="">chisophugis@gmail.com</a><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="">> 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="">Hi, I received an internal test case from a game team (it wasn't about this<br class="">in particular), and I was wondering if there was maybe an opportunity to<br class="">canonicalize a particular code pattern:<br class=""><br class=""> %inputi = bitcast <4 x float> %input to <4 x i32><br class=""><br class=""> %row0i = and <4 x i32> %inputi, <i32 -1, i32 0, i32 0, i32 0><br class=""> %row0 = bitcast <4 x i32> %row0i to <4 x float><br class=""><br class=""> %row1i = and <4 x i32> %inputi, <i32 0, i32 -1, i32 0, i32 0><br class=""> %row1 = bitcast <4 x i32> %row1i to <4 x float><br class=""><br class=""> %row2i = and <4 x i32> %inputi, <i32 0, i32 0, i32 -1, i32 0><br class=""> %row2 = bitcast <4 x i32> %row2i to <4 x float><br class=""><br class=""> %row3i = and <4 x i32> %inputi, <i32 0, i32 0, i32 0, i32 -1><br class=""> %row3 = bitcast <4 x i32> %row3i to <4 x float><br class=""><br class="">This arises from code which expands a vector of scale factors into the<br class="">diagonal of a 4x4 diagonal matrix. This code pattern is coming from<br class="">intrinsics which are explicitly doing the masking like this.<br class=""><br class="">My question is: should we canonicalize this to:<br class=""><br class=""> %row0 = shufflevector <4 x float> %input, <4 x float> zeroinitializer, <4<br class="">x i32> <i32 0, i32 4, i32 4, i32 4><br class=""> %row1 = shufflevector <4 x float> %input, <4 x float> zeroinitializer, <4<br class="">x i32> <i32 4, i32 1, i32 4, i32 4><br class=""> %row2 = shufflevector <4 x float> %input, <4 x float> zeroinitializer, <4<br class="">x i32> <i32 4, i32 4, i32 2, i32 4><br class=""> %row3 = shufflevector <4 x float> %input, <4 x float> zeroinitializer, <4<br class="">x i32> <i32 4, i32 4, i32 4, i32 3><br class=""><br class=""></blockquote></div></blockquote><div><br class=""></div><div>I think that there is a bug in the shuffle pattern. It should be <i32 4, i32 5, i32 6, i32 3>. </div><div><br class=""></div><blockquote type="cite" class=""><div 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="">which seems to better express the intent, or a sequence of insertelement and<br class="">extract element (which is what we get for the attached code), or leave it as<br class="">is? (or any better ideas?)<br class=""><br class="">Forgive my naivete if there's something obvious I'm missing since I haven't<br class="">done much w.r.t. vectors in LLVM.<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="">shufflevector does look more canonical. In the past I think we avoided</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=""><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="">creating shufflevector for fear of producing bad code in CodeGen, but</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=""><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="">I think Chandler just fixed that :-)</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><div>Excellent!</div><br class=""><blockquote type="cite" class=""><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=""><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="">Cheers,</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=""><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="">Rafael</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=""><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; 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