<div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr">On Wed, Aug 29, 2018 at 1:51 PM, Stephen Canon <span dir="ltr"><<a href="mailto:scanon@apple.com" target="_blank">scanon@apple.com</a>></span> wrote:<br><div class="gmail_extra"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex"><div style="word-wrap:break-word;line-break:after-white-space"><span class="gmail-"><blockquote type="cite">On Aug 29, 2018, at 1:22 PM, Cameron McInally via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>> wrote:<br></blockquote><div><blockquote type="cite"><div><div style="font-family:Helvetica;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration:none;font-size:12.800000190734863px"><br class="gmail-m_2919396084355721082Apple-interchange-newline">FSUB(-0.0,  NaN) = NaN</div><div style="font-family:Helvetica;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration:none;font-size:12.800000190734863px">FSUB(-0.0, -NaN) = NaN</div></div></blockquote></div><br></span><div>Some specific architecture may define this, or APFloat might, but IEEE 754 does not interpret the sign of NaN except in four operations (copy, abs, negate, copysign), so it doesn’t say anything about these.</div><div></div></div></blockquote></div><br></div><div class="gmail_extra">Good point. I suppose one could argue that the behavior is undefined.</div></div></div></div></div></div>