<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"><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 class=""><blockquote type="cite" class=""><div class="">On Mar 22, 2016, at 5:13 PM, Philip Reames <<a href="mailto:listmail@philipreames.com" class="">listmail@philipreames.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><br style="font-family: Helvetica; font-size: 10px; font-style: normal; font-variant-caps: 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; background-color: rgb(255, 255, 255);" class=""><br style="font-family: Helvetica; font-size: 10px; font-style: normal; font-variant-caps: 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; background-color: rgb(255, 255, 255);" class=""><div class="moz-cite-prefix" style="font-family: Helvetica; font-size: 10px; font-style: normal; font-variant-caps: 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; background-color: rgb(255, 255, 255);">On 03/20/2016 05:38 AM, Aries Gunawan via llvm-dev wrote:<br class=""></div><blockquote cite="mid:KL1PR03MB168552031E1F14CD172D7D73978E0@KL1PR03MB1685.apcprd03.prod.outlook.com" type="cite" style="font-family: Helvetica; font-size: 10px; font-style: normal; font-variant-caps: 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; background-color: rgb(255, 255, 255);" class=""><div class="WordSection1" style="page: WordSection1;"><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Hi everyone,<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">I am very interested in contributing to LLVM project in this year’s GSoC. I am new with LLVM, but this is used in the compiler course in my university. So, I am thinking to involve in LLVM development to have a better knowledge of the system. Currently, I am preparing the proposal.<span class="Apple-converted-space"> </span><o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">One of the project that caught my eyes is “New Transformations and Analysis”. Several code transformations and analyses have been introduced in the compiler course that I am currently taking. That’s why I am thinking to involve in writing some new transformations and code analyses. But the list of transformations in the LLVM Open Projects web page seems too brief for me and I need more details on those stuffs.<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><b class="">Loop Dependence Analysis Infrastructure.<span class="Apple-converted-space"> </span></b>I have looked in the source codes repo and I saw that there is a file named “DependenceAnalysis.cpp”. So, does that mean this analysis has been implemented?</div></div></blockquote><span style="font-family: Helvetica; font-size: 10px; font-style: normal; font-variant-caps: 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; background-color: rgb(255, 255, 255); float: none; display: inline !important;" class="">I believe major progress has been made it, but haven't been following it closely. I'd suggest talking to committers active in this file in the recent past to determine what useful work might be left of appropriate scope. <span class="Apple-converted-space"> \</span></span><br style="font-family: Helvetica; font-size: 10px; font-style: normal; font-variant-caps: 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; background-color: rgb(255, 255, 255);" class=""></div></blockquote><div class=""><br class=""></div><div class="">We actually have two DA frameworks at the moment. The file you mention is only used currently by the LoopInterchange pass that is off by default. There is also the other framework that I’ve been working on called LoopAccessAnalysis that’s currently used by the LoopVectorizer, LoopLoadElimination, LoopDistribution and LICMLoopVersioning (the latter two are off by default).</div><br class=""><blockquote type="cite" class=""><div class=""><blockquote cite="mid:KL1PR03MB168552031E1F14CD172D7D73978E0@KL1PR03MB1685.apcprd03.prod.outlook.com" type="cite" style="font-family: Helvetica; font-size: 10px; font-style: normal; font-variant-caps: 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; background-color: rgb(255, 255, 255);" class=""><div class="WordSection1" style="page: WordSection1;"><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><b class=""><o:p class=""> </o:p></b></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><b class="">Value range propagation pass.<span class="Apple-converted-space"> </span></b>There was a discussion about this topic (<a moz-do-not-send="true" href="https://groups.google.com/forum/#%21topic/llvm-dev/XXqfemtDX74/discussion" style="color: rgb(149, 79, 114); text-decoration: underline;" class="">https://groups.google.com/forum/#!topic/llvm-dev/XXqfemtDX74/discussion</a>). Someone already proposed to do this pass for several years ago GSoC. But I can’t find the progress of the work. If no progress, then does it mean that the VRP based on Patterson’s paper need to be implemented although range analysis has been implemented?</div></div></blockquote><span style="font-family: Helvetica; font-size: 10px; font-style: normal; font-variant-caps: 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; background-color: rgb(255, 255, 255); float: none; display: inline !important;" class="">This is largely stalled. The key problem is that between LazyValueInfo (constant ranges) and SCEV (symbolic ranges in loops), there's fairly little profit to be had and range analysis is relatively expensive. I'd strongly discourage you from implementing a traditional range analysis for LLVM without deeply understanding the history here. <span class="Apple-converted-space"> </span></span><br style="font-family: Helvetica; font-size: 10px; font-style: normal; font-variant-caps: 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; background-color: rgb(255, 255, 255);" class=""><blockquote cite="mid:KL1PR03MB168552031E1F14CD172D7D73978E0@KL1PR03MB1685.apcprd03.prod.outlook.com" type="cite" style="font-family: Helvetica; font-size: 10px; font-style: normal; font-variant-caps: 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; background-color: rgb(255, 255, 255);" class=""><div class="WordSection1" style="page: WordSection1;"><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><b class=""><o:p class=""> </o:p></b></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><b class="">Predictive Commoning.<span class="Apple-converted-space"> </span></b>The presentation side by Arie Tal seems provide quite clear explanation and examples of the algorithm. I guess the implementation should be straightforward, isn’t it?</div></div></blockquote><span style="font-family: Helvetica; font-size: 10px; font-style: normal; font-variant-caps: 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; background-color: rgb(255, 255, 255); float: none; display: inline !important;" class="">The closest I know of to this in tree is LoadLoadElimination.cpp and (in some cases) the PRE code inside GVN.cpp. Building something like this on top of SCEV could be quite interesting. You should definitely talk to Adam Nemet (CC'd) about this</span></div></blockquote><div class=""><br class=""></div><div class="">Yes, I think the memory operations can be handled in LoopLoadElimination. The algorithm is different from the above paper though. We use the loop-carried dependences to find opportunities to reuse loaded values from earlier iterations. Thus our approach is more similar to Loop Scalar Replacement by Steve Carr et al. It may be possible to extend this to expressions that are derived from these loads to also cover the additions in the mgrid example cited by the slides.</div><div class=""><br class=""></div><div class="">Adam</div><br class=""><blockquote type="cite" class=""><div class=""><span style="font-family: Helvetica; font-size: 10px; font-style: normal; font-variant-caps: 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; background-color: rgb(255, 255, 255); float: none; display: inline !important;" class="">.</span><br style="font-family: Helvetica; font-size: 10px; font-style: normal; font-variant-caps: 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; background-color: rgb(255, 255, 255);" class=""><blockquote cite="mid:KL1PR03MB168552031E1F14CD172D7D73978E0@KL1PR03MB1685.apcprd03.prod.outlook.com" type="cite" style="font-family: Helvetica; font-size: 10px; font-style: normal; font-variant-caps: 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; background-color: rgb(255, 255, 255);" class=""><div class="WordSection1" style="page: WordSection1;"><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><b class=""><o:p class=""> </o:p></b></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><b class="">Type Inference (aka. Devirtualization) and Value assertions.</b><o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Can I get more details of these topics? Does the type inference mean the translation of<span class="Apple-converted-space"> </span><u class="">auto</u><span class="Apple-converted-space"> </span>keyword or something else? For value assertions, “unreachable” intrinsic seems has been implemented cause I can find the usage in some of the testcases.</div></div></blockquote><span style="font-family: Helvetica; font-size: 10px; font-style: normal; font-variant-caps: 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; background-color: rgb(255, 255, 255); float: none; display: inline !important;" class="">I believe the "value assertions" link may be stale. If I'm reading that correctly, it looks like the motivation for @llvm.assume.</span><br style="font-family: Helvetica; font-size: 10px; font-style: normal; font-variant-caps: 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; background-color: rgb(255, 255, 255);" class=""><blockquote cite="mid:KL1PR03MB168552031E1F14CD172D7D73978E0@KL1PR03MB1685.apcprd03.prod.outlook.com" type="cite" style="font-family: Helvetica; font-size: 10px; font-style: normal; font-variant-caps: 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; background-color: rgb(255, 255, 255);" class=""><div class="WordSection1" style="page: WordSection1;"><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Finally, for this project, must I propose to do all of these analyses and transformations in my GSoC proposal or can I just propose some of them? In addition, I am also looking for a mentor for guidance?</div></div></blockquote><span style="font-family: Helvetica; font-size: 10px; font-style: normal; font-variant-caps: 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; background-color: rgb(255, 255, 255); float: none; display: inline !important;" class="">If you want further ideas, consider the list I just sent to llvm-dev a few moments ago titled "A couple ideas for possible GSoC projects". <span class="Apple-converted-space"> </span></span><br style="font-family: Helvetica; font-size: 10px; font-style: normal; font-variant-caps: 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; background-color: rgb(255, 255, 255);" class=""><blockquote cite="mid:KL1PR03MB168552031E1F14CD172D7D73978E0@KL1PR03MB1685.apcprd03.prod.outlook.com" type="cite" style="font-family: Helvetica; font-size: 10px; font-style: normal; font-variant-caps: 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; background-color: rgb(255, 255, 255);" class=""><div class="WordSection1" style="page: WordSection1;"><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Looking forward for your comments and feedbacks.<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Thank you.<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Best regards,<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Aries Thio.<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div></div><br class=""><fieldset class="mimeAttachmentHeader"></fieldset><br class=""><pre wrap="" class="">_______________________________________________
LLVM Developers mailing list
<a class="moz-txt-link-abbreviated" href="mailto:llvm-dev@lists.llvm.org" style="color: rgb(149, 79, 114); text-decoration: underline;">llvm-dev@lists.llvm.org</a>
<a class="moz-txt-link-freetext" href="http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev" style="color: rgb(149, 79, 114); text-decoration: underline;">http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev</a>
</pre></blockquote><br style="font-family: Helvetica; font-size: 10px; font-style: normal; font-variant-caps: 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; background-color: rgb(255, 255, 255);" class=""><br class="Apple-interchange-newline"></div></blockquote></div><br class=""></body></html>