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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Verdana",sans-serif;color:#1F497D">Thanks for the tip. Indeed the current plan is to have Julia functions the correspond to both
</span><span style="font-size:10.0pt;font-family:"Verdana",sans-serif">llvm.fmuladd and llvm.fma. Discussion is at
<a href="https://github.com/JuliaLang/julia/pull/8112">https://github.com/JuliaLang/julia/pull/8112</a><span style="color:#1F497D"> .
<o:p></o:p></span></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Verdana",sans-serif;color:#1F497D">- Arch<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Lang Hames [mailto:lhames@gmail.com]
<br>
<b>Sent:</b> Friday, December 12, 2014 11:16 AM<br>
<b>To:</b> Robison, Arch<br>
<b>Cc:</b> Jingyue Wu; llvmdev@cs.uiuc.edu<br>
<b>Subject:</b> Re: [LLVMdev] Best way for JIT to query whether llvm.fma.* is fast?<o:p></o:p></span></p>
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<p class="MsoNormal">Hi Arch,<o:p></o:p></p>
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<p class="MsoNormal">Also, consider just emitting the llvm.fmuladd intrinsic instead of llvm.fma. fmuladd is lowered to llvm.fma in codegen if the optimizer determines that it's beneficial, otherwise it is expanded to a mul and an add.<o:p></o:p></p>
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<p class="MsoNormal">At the moment I think SelectionDAG is just checking <span style="font-size:10.0pt">isFMAFasterThanFMulAndFAdd anyway, but that condition could be refined in the future.</span><o:p></o:p></p>
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<p class="MsoNormal">Cheers,<o:p></o:p></p>
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<p class="MsoNormal">Lang.<o:p></o:p></p>
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<p class="MsoNormal">On Wed, Dec 10, 2014 at 1:17 PM, Robison, Arch <<a href="mailto:arch.robison@intel.com" target="_blank">arch.robison@intel.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Thanks! That’s probably close enough for practical purposes. I looked at the overrides on various
targets, and they all return true if the FMA hardware exists.</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">- Arch</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Jingyue Wu [mailto:<a href="mailto:jingyue@google.com" target="_blank">jingyue@google.com</a>]
<br>
<b>Sent:</b> Wednesday, December 10, 2014 2:56 PM<br>
<b>To:</b> Robison, Arch<br>
<b>Cc:</b> <a href="mailto:llvmdev@cs.uiuc.edu" target="_blank">llvmdev@cs.uiuc.edu</a><br>
<b>Subject:</b> Re: [LLVMdev] Best way for JIT to query whether llvm.fma.* is fast?</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Does TargetLowering::isFMAFasterThanFMulAndFAdd (<a href="http://llvm.org/docs/doxygen/html/TargetLowering_8h_source.html#l01499" target="_blank">http://llvm.org/docs/doxygen/html/TargetLowering_8h_source.html#l01499</a>)
help? <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Jingyue<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">On Wed, Dec 10, 2014 at 12:48 PM, Robison, Arch <<a href="mailto:arch.robison@intel.com" target="_blank">arch.robison@intel.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">For the Julia language JIT, we’d like be able to tell whether the llvm.fma.* intrinsic has hardware support. What’s
the best way to query LLVM (JIT) for this information?</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> </span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">The information would be used in situations where the user wants to use different algorithms depending on whether
FMA hardware is present or not.</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> </span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">- Arch D. Robison
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