<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="Generator" content="Microsoft Word 15 (filtered medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:DengXian;
panose-1:2 1 6 0 3 1 1 1 1 1;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:"\@DengXian";
panose-1:2 1 6 0 3 1 1 1 1 1;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
p.MsoListParagraph, li.MsoListParagraph, div.MsoListParagraph
{mso-style-priority:34;
margin-top:0in;
margin-right:0in;
margin-bottom:0in;
margin-left:.5in;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
span.apple-converted-space
{mso-style-name:apple-converted-space;}
span.EmailStyle19
{mso-style-type:personal-reply;
font-family:"Calibri",sans-serif;
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
/* List Definitions */
@list l0
{mso-list-id:337587158;
mso-list-template-ids:-795581472;}
@list l1
{mso-list-id:1267537020;
mso-list-type:hybrid;
mso-list-template-ids:839430146 67698703 67698713 67698715 67698703 67698713 67698715 67698703 67698713 67698715;}
@list l1:level1
{mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;}
@list l1:level2
{mso-level-number-format:alpha-lower;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;}
@list l1:level3
{mso-level-number-format:roman-lower;
mso-level-tab-stop:none;
mso-level-number-position:right;
text-indent:-9.0pt;}
@list l1:level4
{mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;}
@list l1:level5
{mso-level-number-format:alpha-lower;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;}
@list l1:level6
{mso-level-number-format:roman-lower;
mso-level-tab-stop:none;
mso-level-number-position:right;
text-indent:-9.0pt;}
@list l1:level7
{mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;}
@list l1:level8
{mso-level-number-format:alpha-lower;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;}
@list l1:level9
{mso-level-number-format:roman-lower;
mso-level-tab-stop:none;
mso-level-number-position:right;
text-indent:-9.0pt;}
ol
{margin-bottom:0in;}
ul
{margin-bottom:0in;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang="EN-US" link="blue" vlink="purple" style="word-wrap:break-word">
<div class="WordSection1">
<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I discussed with Florian for a solution at <a href="https://reviews.llvm.org/D99152">
https://reviews.llvm.org/D99152</a>. Florian suggest introducing a specific intrinsic to replace bitcast in front-end, and backend need extra effort to optimize or eliminate the intrinsic. This idea looks good to me. Here is my plan.<o:p></o:p></p>
<ol style="margin-top:0in" start="1" type="1">
<li class="MsoListParagraph" style="margin-left:0in;mso-list:l1 level1 lfo2">specify x86_amx in LangRef and verify the IR. Patches were uploaded at
<a href="https://reviews.llvm.org/D100032">https://reviews.llvm.org/D100032</a> and
<a href="https://reviews.llvm.org/D100472">https://reviews.llvm.org/D100472</a>.<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l1 level1 lfo2">Add llvm.x86.tile.cast intrinsic in LLVM.<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l1 level1 lfo2">Optimize some of llvm.x86.tile.cast code as bitcast does, and transform llvm.x86.tile.cast to amx intrinsic if it can't be eliminated.<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l1 level1 lfo2">After the above 3 items are finished, replace bitcast with llvm.x86.tile.cast in front-end when generate IR for amx builtin.<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l1 level1 lfo2">After some time for stabilization, remove bitcast transform code from LLVM.<o:p></o:p></li></ol>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks<o:p></o:p></p>
<p class="MsoNormal">Yuanke<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b>From:</b> Florian Hahn <florian_hahn@apple.com> <br>
<b>Sent:</b> Tuesday, March 23, 2021 6:16 PM<br>
<b>To:</b> Luo, Yuanke <yuanke.luo@intel.com><br>
<b>Cc:</b> llvm-dev <llvm-dev@lists.llvm.org>; Zhang, Xiang1 <xiang1.zhang@intel.com>; James Y Knight <jyknight@google.com><br>
<b>Subject:</b> Re: [llvm-dev] Does middle-end pass need to consider some special type when doing optimization? Or letting back-end to revert the optimization accordingly?<o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal"><br>
<br>
<o:p></o:p></p>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<p class="MsoNormal">On Mar 23, 2021, at 08:21, Luo, Yuanke <<a href="mailto:yuanke.luo@intel.com">yuanke.luo@intel.com</a>> wrote:<o:p></o:p></p>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div>
<p class="MsoNormal">I prototyped the approach 1 at<span class="apple-converted-space"> </span><a href="https://reviews.llvm.org/D99152">https://reviews.llvm.org/D99152</a><span class="apple-converted-space"> </span>and I realized that sometimes bitcast optimization
in middle-end is helpful. For the test case of inner_product(), we need extra effort eliminate llvm.x86.vector.amx.cast.x86amx.v256i32 by ourselves.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
</div>
</blockquote>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal">I think that’s expected, you might need to add some optimizations for the conversion intrinsic. But that can easily be limited to the AMX specific passes and all existing LLVM transformations should remain correct without changes.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Cheers,<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">Florian<o:p></o:p></p>
</div>
</div>
</body>
</html>