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<p class="MsoPlainText">Thanks everybody for attending the Alias Analysis roundtable !<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">The minutes can be found here: <a href="https://docs.google.com/document/d/1kXauIBnrI73sgWi8tLK4rXwfTDvdG1wVy7Z554Mt1H0/edit">
https://docs.google.com/document/d/1kXauIBnrI73sgWi8tLK4rXwfTDvdG1wVy7Z554Mt1H0/edit</a><o:p></o:p></p>
<p class="MsoPlainText">and also below.<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">Greetings,<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">Jeroen Dobbelaere<o:p></o:p></p>
<p class="MsoPlainText">--<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p style="margin:0cm;margin-bottom:.0001pt"><span style="font-family:"Arial",sans-serif;color:black">Things discussed:</span><o:p></o:p></p>
<ul style="margin-top:0cm" type="disc">
<li style="color:black;margin-top:0cm;margin-bottom:0cm;margin-bottom:.0001pt;mso-list:l0 level1 lfo1;vertical-align:baseline">
<span style="font-family:"Arial",sans-serif">Fortran and !noalias, !alias.scope and scalability:<o:p></o:p></span></li></ul>
<ul style="margin-top:0cm" type="disc">
<ul style="margin-top:0cm" type="disc">
<li style="color:black;margin-top:0cm;margin-bottom:0cm;margin-bottom:.0001pt;mso-list:l0 level2 lfo2;vertical-align:baseline">
<span style="font-family:"Arial",sans-serif">Using the llvm.noalias with unique objectId might help in compressing the information. Experiment not done yet<o:p></o:p></span></li></ul>
<li style="color:black;margin-top:0cm;margin-bottom:0cm;margin-bottom:.0001pt;mso-list:l0 level1 lfo2;vertical-align:baseline">
<span style="font-family:"Arial",sans-serif">ptr_provenance: optional operand, mandatory operand or operand bundles ?<o:p></o:p></span></li><ul style="margin-top:0cm" type="disc">
<li style="color:black;margin-top:0cm;margin-bottom:0cm;margin-bottom:.0001pt;mso-list:l0 level2 lfo2;vertical-align:baseline">
<span style="font-family:"Arial",sans-serif">Current implementation has an optional operand that always takes space (for load/store instructions). Impact on speed is only for load/store instructions.<br>
When the ptr_provenance operand is not there, the original pointer is used for provenance.<o:p></o:p></span></li><li style="color:black;margin-top:0cm;margin-bottom:0cm;margin-bottom:.0001pt;mso-list:l0 level2 lfo2;vertical-align:baseline">
<span style="font-family:"Arial",sans-serif">llvm.noalias.arg.guard %ptr, %ptr_prov<br>
Is used to merge a pointer value with its provenance. This is used when passing as argument, storing to memory, returning from function<o:p></o:p></span></li><li style="color:black;margin-top:0cm;margin-bottom:0cm;margin-bottom:.0001pt;mso-list:l0 level2 lfo2;vertical-align:baseline">
<span style="font-family:"Arial",sans-serif">Ptr_provenance info is not used to decide on ‘pointer comparison’. The c++ standard might need an update to allow this (?)<o:p></o:p></span></li></ul>
<li style="color:black;margin-top:0cm;margin-bottom:0cm;margin-bottom:.0001pt;mso-list:l0 level1 lfo2;vertical-align:baseline">
<span style="font-family:"Arial",sans-serif">Comparable to ‘base pointer’ ? probably not completely the same.<o:p></o:p></span></li><li style="color:black;margin-top:0cm;margin-bottom:0cm;margin-bottom:.0001pt;mso-list:l0 level1 lfo2;vertical-align:baseline">
<span style="font-family:"Arial",sans-serif">inttoptr/ptrtoint casts, sroa<o:p></o:p></span></li></ul>
<p class="MsoNormal"><o:p> </o:p></p>
<p style="margin:0cm;margin-bottom:.0001pt"><span style="font-family:"Arial",sans-serif;color:black">All help with reviewing the patches is welcome ! The first one, provides the documentation on the implemented mechanism.
</span><a href="https://reviews.llvm.org/D68484"><span style="font-family:"Arial",sans-serif;color:#1155CC">https://reviews.llvm.org/D68484</span></a><o:p></o:p></p>
<p style="margin:0cm;margin-bottom:.0001pt"><span style="font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
<p style="margin:0cm;margin-bottom:.0001pt"><span style="font-family:"Arial",sans-serif;color:black">Join us on the 4-weekly LLVM Alias Analysis Call. Meeting info:</span><o:p></o:p></p>
<p style="margin:0cm;margin-bottom:.0001pt"><a href="https://docs.google.com/document/d/1ybwEKDVtIbhIhK50qYtwKsL50K-NvB6LfuBsfepBZ9Y/edit#heading=h.vpxs8lkuxy79"><span style="font-family:"Arial",sans-serif;color:#1155CC">https://docs.google.com/document/d/1ybwEKDVtIbhIhK50qYtwKsL50K-NvB6LfuBsfepBZ9Y/edit#heading=h.vpxs8lkuxy79</span></a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p style="margin:0cm;margin-bottom:.0001pt"><span style="font-family:"Arial",sans-serif;color:black">-----</span><o:p></o:p></p>
<p style="margin:0cm;margin-bottom:.0001pt"><span style="font-family:"Arial",sans-serif;color:black">Notes in the ‘chat’:</span><o:p></o:p></p>
<p style="mso-margin-top-alt:12.0pt;margin-right:0cm;margin-bottom:12.0pt;margin-left:0cm">
<span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:black">From Me to Everyone: 08:58 PM</span><o:p></o:p></p>
<p style="mso-margin-top-alt:12.0pt;margin-right:0cm;margin-bottom:12.0pt;margin-left:0cm">
<span style="font-family:"Arial",sans-serif;color:black">https://docs.google.com/document/d/1kXauIBnrI73sgWi8tLK4rXwfTDvdG1wVy7Z554Mt1H0/edit</span><o:p></o:p></p>
<p style="mso-margin-top-alt:12.0pt;margin-right:0cm;margin-bottom:12.0pt;margin-left:0cm">
<span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:black">From John Reagan to Everyone: 09:07 PM</span><o:p></o:p></p>
<p style="mso-margin-top-alt:12.0pt;margin-right:0cm;margin-bottom:12.0pt;margin-left:0cm">
<span style="font-family:"Arial",sans-serif;color:black">Our proprietary code generator for Alpha/Itanium has a "base pointer" for such loads in our IR which provides the equivalent of your provenance for alignment</span><o:p></o:p></p>
<p style="mso-margin-top-alt:12.0pt;margin-right:0cm;margin-bottom:12.0pt;margin-left:0cm">
<span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:black">From Jason Eckhardt to Everyone: 09:17 PM</span><o:p></o:p></p>
<p style="mso-margin-top-alt:12.0pt;margin-right:0cm;margin-bottom:12.0pt;margin-left:0cm">
<span style="font-family:"Arial",sans-serif;color:black">please mute if not speaking-- hearing extraneous noise</span><o:p></o:p></p>
<p style="mso-margin-top-alt:12.0pt;margin-right:0cm;margin-bottom:12.0pt;margin-left:0cm">
<span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:black">From John Reagan to Everyone: 09:18 PM</span><o:p></o:p></p>
<p style="mso-margin-top-alt:12.0pt;margin-right:0cm;margin-bottom:12.0pt;margin-left:0cm">
<span style="font-family:"Arial",sans-serif;color:black">Our old CG also has an explicit 'basedref' IR tuple that can provide additional alignment, based-on, etc. info.</span><o:p></o:p></p>
<p style="mso-margin-top-alt:12.0pt;margin-right:0cm;margin-bottom:12.0pt;margin-left:0cm">
<span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:black">From Roman Lebedev to Everyone: 09:20 PM</span><o:p></o:p></p>
<p style="mso-margin-top-alt:12.0pt;margin-right:0cm;margin-bottom:12.0pt;margin-left:0cm">
<span style="font-family:"Arial",sans-serif;color:black">loss of inttoptr-ptrtoint casts is mostly bug, i think it will be resolved<br>
sadly there are more places where we introduce inttoptr(load), e.g. because instcombine expands memcpy</span><o:p></o:p></p>
<p style="mso-margin-top-alt:12.0pt;margin-right:0cm;margin-bottom:12.0pt;margin-left:0cm">
<span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:black">From Matt Arsenault to Everyone: 09:25 PM</span><o:p></o:p></p>
<p style="mso-margin-top-alt:12.0pt;margin-right:0cm;margin-bottom:12.0pt;margin-left:0cm">
<span style="font-family:"Arial",sans-serif;color:black">Need to allow no-op bitcasts between same sized address spaces to avoid one place we interpret ptrtoint/inttoptr pairs</span><o:p></o:p></p>
<p style="mso-margin-top-alt:12.0pt;margin-right:0cm;margin-bottom:12.0pt;margin-left:0cm">
<span style="font-family:"Arial",sans-serif;color:black">From John Reagan to Everyone: 09:25 PM</span><o:p></o:p></p>
<p style="mso-margin-top-alt:12.0pt;margin-right:0cm;margin-bottom:12.0pt;margin-left:0cm">
<span style="font-family:"Arial",sans-serif;color:black">Yes, it has worked well. I can discuss elsewhere if interested</span><o:p></o:p></p>
<p style="mso-margin-top-alt:12.0pt;margin-right:0cm;margin-bottom:12.0pt;margin-left:0cm">
<span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:black">From John Reagan to Everyone: 09:26 PM</span><o:p></o:p></p>
<p style="mso-margin-top-alt:12.0pt;margin-right:0cm;margin-bottom:12.0pt;margin-left:0cm">
<span style="font-family:"Arial",sans-serif;color:black">Yes, it has worked well. I can discuss elsewhere if interested<br>
Perfect. I'll watch for that.</span><o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
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