<html><head><meta http-equiv="Content-Type" content="text/html charset=iso-8859-1"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">Hi Renato,<div><br></div><div>You're right. Strictly speaking, using NEON for scalar floating point isn't completely safe for exactly this reason (also NaNs, IIRC). We generally do it anyway because on common cores (cortex-a8) VFP is pretty terrible and the NEON approximation is correct for the vast majority of use-cases that people care about. Yes, that's cutting some corners. Would you mind making this change depend on platform? Darwin should continue to use NEON by default for these operations.</div><div><br></div><div>-Jim</div><div><br><div><div>On Mar 19, 2013, at 11:17 AM, Renato Golin <<a href="mailto:renato.golin@linaro.org">renato.golin@linaro.org</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div style="letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;"><div dir="ltr"><div>Hi folks,</div><div><br></div><div>I just "fixed" a bug on ARM LNT regarding lowering of a VMUL.f32 as NEON and not VFP. The former is not IEEE 754 compliant, while the latter is, and that was failing TSVC.</div><div><br></div><div>The question is:</div><div> * is this a problem with the test, that shouldn't be expecting values below FLT_MIN, or</div><div> * is it a bug in the lowering, that should only be lowering to NEON's VMUL when unsafe-math is on, or</div><div> * neither, and people should disable that when they want correctness?</div><div><br></div><div>The bugs in question...</div><div><br></div><div>Possible unsafe maths bug in NEON VMUL.f32<br></div><a href="http://llvm.org/bugs/show_bug.cgi?id=15546">http://llvm.org/bugs/show_bug.cgi?id=15546</a><br><div><br></div><div>MultiSource/Benchmarks/TSVC/Reductions-flt tests beyond FLT_MIN<br></div><div><a href="http://llvm.org/bugs/show_bug.cgi?id=15545">http://llvm.org/bugs/show_bug.cgi?id=15545</a><br></div><div><br></div><div>cheers,</div><div>--renato</div></div>_______________________________________________<br>LLVM Developers mailing list<br><a href="mailto:LLVMdev@cs.uiuc.edu">LLVMdev@cs.uiuc.edu</a><span class="Apple-converted-space"> </span> <a href="http://llvm.cs.uiuc.edu/">http://llvm.cs.uiuc.edu</a><br><a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev</a></div></blockquote></div><br></div></body></html>