<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On May 11, 2016, at 10:45 AM, Adam Nemet via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" class="">llvm-dev@lists.llvm.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><blockquote type="cite" class=""><div class=""><br class="Apple-interchange-newline">On May 11, 2016, at 3:37 AM, Hal Finkel <<a href="mailto:hfinkel@anl.gov" class="">hfinkel@anl.gov</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><span class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;">----- Original Message -----</span><br class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><blockquote type="cite" class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;">From: "Adam Nemet" <<a href="mailto:anemet@apple.com" class="">anemet@apple.com</a>><br class="">To: "Hal Finkel" <<a href="mailto:hfinkel@anl.gov" class="">hfinkel@anl.gov</a>><br class="">Cc: "llvm-dev (<a href="mailto:llvm-dev@lists.llvm.org" class="">llvm-dev@lists.llvm.org</a>)" <<a href="mailto:llvm-dev@lists.llvm.org" class="">llvm-dev@lists.llvm.org</a>><br class="">Sent: Wednesday, May 11, 2016 1:15:42 AM<br class="">Subject: Re: Filter optimization remarks by the hotness of the code region<br class=""><br class="">Hi Hal,<br class=""><br class=""><blockquote type="cite" class="">On May 10, 2016, at 5:39 PM, Hal Finkel <<a href="mailto:hfinkel@anl.gov" class="">hfinkel@anl.gov</a>> wrote:<br class=""><br class="">Hi Adam,<br class=""><br class="">I think would be a really useful feature to have. I don't think<br class="">that the backend should be responsible for filtering, but should<br class="">pass the relative hotness information to the frontend. Given that<br class="">these diagnostics are not just going to be used for -Rpass and<br class="">friends, but also for generating reports by other tools (see the<br class="">discussion around D19678, for example), I think it is important to<br class="">allow the frontend to filter.<br class=""></blockquote><br class="">I am not sure I follow, can you please elaborate. Are you saying<br class="">that for example in the listing use case we don’t want the filtered<br class="">diagnostics? In other words it should be up to the remark handler<br class="">to decide whether it wants filtered or unfiltered remarks?<br class=""></blockquote><br class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><span class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;">We might or might not want them. The user might want to select different ratios and filters.</span><br class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><br class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><blockquote type="cite" class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><blockquote type="cite" class="">The frontend, or other tool, might also want to collect information<br class="">from different compilation jobs to provide the user with an<br class="">overall ranking.<br class=""></blockquote><br class="">Strictly speaking about PGO, the different compilation jobs get the<br class="">same PGO with the aggregated profile, thus the hotness calculated<br class="">should be global. I am not sure why an extra aggregation step is<br class="">necessary.<br class=""></blockquote><br class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><span class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;">I agree. However, I think that the frontend might employ a combination of factors in deciding what information to present. We might, for example, have pick different hotness thresholds for different kinds of remarks.</span><br class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><br class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><span class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;">Especially since we're likely going with a design for the optimization reports where the frontend just creates some YAML files with the diagnostic information, and then a separate tool processes the files to produce reports, I think that we should give those tools the maximum about of practical flexibility. Such a tool might provide the user with non-trivial filtering options.</span><br class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"></div></blockquote><div class=""><br class=""></div><div class="">I think this all makes sense. So I guess the steps are:</div><div class=""><br class=""></div><div class="">1. YAML support for the existing remarks</div><div class="">2. Add optional relative hotness to the opt-remark API</div></div></div></blockquote><div><br class=""></div><div>I submitted for the first patch to implement this: <a href="http://reviews.llvm.org/D21771" class="">http://reviews.llvm.org/D21771</a></div><div><br class=""></div><div>Adam</div><br class=""><blockquote type="cite" class=""><div class=""><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><div class="">3. Exposed relative hotness in the YAML output</div><div class=""><br class=""></div><div class="">Are you working on 1 or should I get started?</div><div class=""><br class=""></div><div class="">There was another issue that came up while discussing this with John McCall. We could have a pretty large number of such remarks. I imagine that if the post-processing is performed by the external tool, it may be useful to effectively enable all optimization remarks (i.e. -Rpass/-Rpass-missed/-Rpass-analysis=loop-vectorize/inline/etc.). For large programs this may not be feasible and we may need to locally filter the remarks in LLVM. This however seems like a somewhat orthogonal issue that we could probably postpone for now.</div><div class=""><br class=""></div><div class="">Thanks for your input!</div><div class="">Adam</div><br class=""><blockquote type="cite" class=""><div class=""><br class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><span class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;">Thanks again,</span><br class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><span class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;">Hal</span><br class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><br class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><blockquote type="cite" class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><br class=""><blockquote type="cite" class="">The default diagnostic, furthermore, does not provide enough<br class="">information to identify a code "region". I think that the pass<br class="">generating the diagnostic needs to provide the information,<br class="">however, we could certainly create some utility functions that<br class="">take a pointer to the BFI analysis and a Value* that can do the<br class="">right thing in most simple cases.<br class=""></blockquote><br class="">Good point.<br class=""><br class="">Thanks for your feedback.<br class=""><br class="">Adam<br class=""><br class=""><blockquote type="cite" class=""><br class="">Thanks again,<br class="">Hal<br class=""><br class="">----- Original Message -----<br class=""><blockquote type="cite" class="">From: "Adam Nemet" <<a href="mailto:anemet@apple.com" class="">anemet@apple.com</a>><br class="">To: "llvm-dev (<a href="mailto:llvm-dev@lists.llvm.org" class="">llvm-dev@lists.llvm.org</a>)" <<a href="mailto:llvm-dev@lists.llvm.org" class="">llvm-dev@lists.llvm.org</a>><br class="">Cc: "Hal Finkel" <<a href="mailto:hfinkel@anl.gov" class="">hfinkel@anl.gov</a>><br class="">Sent: Wednesday, May 4, 2016 1:12:17 PM<br class="">Subject: Filter optimization remarks by the hotness of the code<br class="">region<br class=""><br class="">This idea came up a few times recently [1][2] so I’d like start<br class="">prototyping it. To summarize, we can emit optimization remarks<br class="">using the -Rpass* options. These are currently emitted by<br class="">optimizations like vectorization[3], unrolling, inlining and since<br class="">last week loop distribution.<br class=""><br class="">For large programs however this can amount to a lot of diagnostics<br class="">output to sift through. Filtering this by the hotness of the<br class="">region<br class="">can help to focus the user on performance opportunities that are<br class="">likely to pay off.<br class=""><br class="">The approach I am thinking of taking is to install a wrapper as<br class="">the<br class="">diagnostics handler that will only forward to the original handler<br class="">if the region of code is considered hot. This will be installed<br class="">by<br class="">a new pass that will use BlockFrequencyInfo to determine the top N<br class="">hot regions.<br class=""><br class="">This is at very early stage right now. I would appreciate any<br class="">feedback.<br class=""><br class="">Thanks,<br class="">Adam<br class=""><br class="">[1]<br class=""><a href="http://lists.llvm.org/pipermail/llvm-dev/2016-April/098492.html" class="">http://lists.llvm.org/pipermail/llvm-dev/2016-April/098492.html</a><br class="">[2] <a href="http://lists.llvm.org/pipermail/cfe-dev/2016-April/048526.html" class="">http://lists.llvm.org/pipermail/cfe-dev/2016-April/048526.html</a><br class="">[3]<br class=""><a href="http://blog.llvm.org/2014/11/loop-vectorization-diagnostics-and.html" class="">http://blog.llvm.org/2014/11/loop-vectorization-diagnostics-and.html</a><br class=""></blockquote><br class="">--<br class="">Hal Finkel<br class="">Assistant Computational Scientist<br class="">Leadership Computing Facility<br class="">Argonne National Laboratory<br class=""></blockquote><br class=""><br class=""></blockquote><br class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><span class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;">--<span class="Apple-converted-space"> </span></span><br class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><span class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;">Hal Finkel</span><br class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><span class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;">Assistant Computational Scientist</span><br class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><span class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;">Leadership Computing Facility</span><br class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><span class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;">Argonne National Laboratory</span></div></blockquote></div><br class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">_______________________________________________</span><br style="font-family: Helvetica; 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