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<p class="MsoNormal"><span style="color:#1F497D">SelectionDAG has many overloaded methods of “getNode”, some of which don’t need to specify the Flags argument. This is reasonable because only FP nodes need that. But it also easily results in losing the Flags
in the FP nodes too.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Here’s an example <a href="https://reviews.llvm.org/D84518">
https://reviews.llvm.org/D84518</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">This problem has been greatly improved since
<a href="https://reviews.llvm.org/D87361">https://reviews.llvm.org/D87361</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">I think we have the similar problem in MIR based optimizations, but I didn’t dig into it.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Thanks<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Phoebe (Pengfei)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b>From:</b> Renato Golin <rengolin@gmail.com> <br>
<b>Sent:</b> Saturday, October 30, 2021 11:41 PM<br>
<b>To:</b> Wang, Pengfei <pengfei.wang@intel.com><br>
<b>Cc:</b> Kaylor, Andrew <andrew.kaylor@intel.com>; Yaxun Liu <yaxun.liu@amd.com>; Sebastian Pop <sebpop@gmail.com>; Ammarguellat, Zahira <zahira.ammarguellat@intel.com>; Ulrich Weigand <Ulrich.Weigand@de.ibm.com>; Ballman, Aaron <aaron.ballman@intel.com>;
llvm-dev@lists.llvm.org<br>
<b>Subject:</b> Re: [llvm-dev] [RFC] Eliminating non-IR floating-point controls in the selection DAG<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Sat, 30 Oct 2021 at 16:01, Wang, Pengfei <<a href="mailto:pengfei.wang@intel.com">pengfei.wang@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="color:#1F497D">I think the use of target option simply owe to the fact that DAG and other backend passes always lose the FMFs during transformation in the past.</span><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Ah! That's an interesting piece of information! And exacerbates Eric's original comment.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">At which level is that information lost?<o:p></o:p></p>
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