<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=Windows-1252">
</head>
<body text="#000000" bgcolor="#FFFFFF">
<div class="moz-cite-prefix">On 12/4/18 3:28 PM, Yan Luo wrote:<br>
</div>
<blockquote type="cite" cite="mid:35A969DC8F98414CB2848824CBC6D28802F4BA643A@us01wembx1.internal.synopsys.com">
<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:Consolas;
panose-1:2 11 6 9 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;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri",sans-serif;
color:black;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:#0563C1;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:#954F72;
text-decoration:underline;}
p
{mso-style-priority:99;
mso-margin-top-alt:auto;
margin-right:0in;
mso-margin-bottom-alt:auto;
margin-left:0in;
font-size:12.0pt;
font-family:"Times New Roman",serif;
color:black;}
pre
{mso-style-priority:99;
mso-style-link:"HTML Preformatted Char";
margin:0in;
margin-bottom:.0001pt;
font-size:10.0pt;
font-family:"Courier New";
color:black;}
p.msonormal0, li.msonormal0, div.msonormal0
{mso-style-name:msonormal;
mso-margin-top-alt:auto;
margin-right:0in;
mso-margin-bottom-alt:auto;
margin-left:0in;
font-size:12.0pt;
font-family:"Times New Roman",serif;
color:black;}
span.EmailStyle19
{mso-style-type:personal;
font-family:"Calibri",sans-serif;
color:windowtext;}
span.HTMLPreformattedChar
{mso-style-name:"HTML Preformatted Char";
mso-style-priority:99;
mso-style-link:"HTML Preformatted";
font-family:Consolas;
color:black;}
span.EmailStyle22
{mso-style-type:personal;
font-family:"Calibri",sans-serif;
color:windowtext;}
span.EmailStyle23
{mso-style-type:personal-compose;
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;}
--></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]-->
<div class="WordSection1">
<p class="MsoNormal"><span style="color:windowtext">Hal,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:windowtext">Thanks for the reply. I am trying to understand the underlying concern. That means the inlining of a callee without unsafe-fp-math attribute set will block the unsafe optimization in its caller, right?</span></p>
</div>
</blockquote>
<p>That may have been true. In recent times, we have per-instruction fast-math attributes, so the unsafe-fp-math setting isn't the controlling factor.</p>
<p> -Hal<br>
</p>
<blockquote type="cite" cite="mid:35A969DC8F98414CB2848824CBC6D28802F4BA643A@us01wembx1.internal.synopsys.com">
<div class="WordSection1">
<p class="MsoNormal"><span style="color:windowtext"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:windowtext">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:windowtext">Yan<o:p></o:p></span></p>
<p class="MsoNormal"><a name="_MailEndCompose" moz-do-not-send="true"><span style="color:windowtext"><o:p> </o:p></span></a></p>
<span style="mso-bookmark:_MailEndCompose"></span>
<div>
<div style="border:none;border-top:solid #E1E1E1
1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span style="color:windowtext">From:</span></b><span style="color:windowtext"> Finkel, Hal J. [<a class="moz-txt-link-freetext" href="mailto:hfinkel@anl.gov">mailto:hfinkel@anl.gov</a>]
<br>
<b>Sent:</b> Tuesday, December 4, 2018 11:34 AM<br>
<b>To:</b> Yan Luo <a class="moz-txt-link-rfc2396E" href="mailto:yan.luo2@synopsys.com">
<yan.luo2@synopsys.com></a>; <a class="moz-txt-link-abbreviated" href="mailto:llvm-dev@lists.llvm.org">
llvm-dev@lists.llvm.org</a><br>
<b>Subject:</b> Re: [llvm-dev] [Unsafe-fp-math] Merge attribute for inlining<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p><o:p> </o:p></p>
<div>
<p class="MsoNormal">On 12/4/18 12:34 PM, Yan Luo via llvm-dev wrote:<o:p></o:p></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal">Hello dev,<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">I have a question about unsafe-fp-math function attribute. Currently LLVM merges this attribute for inlining with logical AND. That means if caller has this attribute set but callee has not, LLVM will reset this attribute on caller. But
shouldn’t we respect this attribute on caller? If caller wants to perform unsafe fp operation, any code that gets inlined should be allowed to do unsafe fp operation, right? Thanks!<o:p></o:p></p>
</blockquote>
<p>The answer, by design, is no. At this point, all frontends should be generating per-instruction fast-math flags, and that should also have the property that the relevant semantics are preserved across inlining. The underlying concern is that, under LTO,
code that was compiled without -ffast-math can be inlined into code compiled with -ffast-math, and this combined code must continue to work even when the strict semantics are required for correctness for the code compiled without -ffast-math.<o:p></o:p></p>
<p> -Hal<o:p></o:p></p>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Regards,<o:p></o:p></p>
<p class="MsoNormal">Yan <o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Times New
Roman",serif"><br>
<br>
<o:p></o:p></span></p>
<pre>_______________________________________________<o:p></o:p></pre>
<pre>LLVM Developers mailing list<o:p></o:p></pre>
<pre><a href="mailto:llvm-dev@lists.llvm.org" moz-do-not-send="true">llvm-dev@lists.llvm.org</a><o:p></o:p></pre>
<pre><a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.llvm.org_cgi-2Dbin_mailman_listinfo_llvm-2Ddev&d=DwMF-g&c=DPL6_X_6JkXFx7AXWqB0tg&r=VP6NpUwuwAXxdCugKYVKOuNr-I2x2_Cx1QkggUmrO9E&m=nJn7JadT9zarm-IAAqWE4edU5XSfeiXyjq-I8JYeBZE&s=uN17xN_M91org9jZEz_RmcsUYibXy91-9nuO0R0UvC8&e=" moz-do-not-send="true">http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev</a><o:p></o:p></pre>
</blockquote>
<pre>-- <o:p></o:p></pre>
<pre>Hal Finkel<o:p></o:p></pre>
<pre>Lead, Compiler Technology and Programming Languages<o:p></o:p></pre>
<pre>Leadership Computing Facility<o:p></o:p></pre>
<pre>Argonne National Laboratory<o:p></o:p></pre>
</div>
</blockquote>
<pre class="moz-signature" cols="72">--
Hal Finkel
Lead, Compiler Technology and Programming Languages
Leadership Computing Facility
Argonne National Laboratory</pre>
</body>
</html>