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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">There is no fixed latency/throughput to LLVM IR instructions. Instructions are lowered to target instructions based on the target and the subtarget, and these
lowerings can have multiple IR instructions coalesced into a single target instruction or one IR instruction split into several instructions. Latency/throughput is provided for target instructions based on the *Schedule.td files, but there is no easy mapping
between these instructions and LLVM IR. Some ad-hoc estimation for the IR level is provided by TargetLowering and especially TargetTransformInfo, but these do not provide complete coverage and only provide coarse estimates.<o:p></o:p></span></p>
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<p class="MsoNormal"><a name="_____replyseparator"></a><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"> llvm-dev [mailto:llvm-dev-bounces@lists.llvm.org]
<b>On Behalf Of </b>Duan Bing via llvm-dev<br>
<b>Sent:</b> Sunday, May 12, 2019 21:59<br>
<b>To:</b> LLVM Developers Mailing List <llvm-dev@lists.llvm.org><br>
<b>Subject:</b> [llvm-dev] How shall I evaluate the latency of each instruction in LLVM IR?<o:p></o:p></span></p>
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<p class="MsoNormal">Inspired by <a href="https://www.agner.org/optimize/instruction_tables.pdf">https://www.agner.org/optimize/instruction_tables.pdf</a>, which gives us the latency and reciprocal throughput of each instruction in the different architecture
of X86, Is there anybody taking the effort to do a similar job for LLVM IR? <o:p></o:p></p>
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<p class="MsoNormal">Thanks!<o:p></o:p></p>
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