similar to: [GSoC 2016] Introduction & Feedback - Better Alias Analysis

On 05/11/2016 05:16 PM, George Burgess IV via llvm-dev wrote: > > After applying the patch on r267335 and bootstrap LLVM/clang with > cfl-aa enabled on its own as well as behind basic-aa on an x86 > machine, I ran test-suite with lit and saw no failed test cases > > Woohoo! This is great news. :D Awesome! > > I'm not sure how closely everyone is reading the intro

(Just to note: the other issue i remember with CFL-AA is that it currently causes performance loss. This is quite common when you increase precision, because things move/change things they couldn't before, and often do so without the natural bounds imprecision provided before :P) On Thu, May 12, 2016 at 12:29 AM, James Molloy via llvm-dev < llvm-dev at lists.llvm.org> wrote: > Yep,

It's something that I am certainly interested in and qualified to do. However, the way I read Daniel's reply in this thread is: "LLVM, in its current form, is unlikely to benefit from a more precise aa". He did mention that cfl-aa is "more understandable and maintainable", and is "fast enough", but nothing is said about the benefits. There was some

It's found more and more like "get CFL-AA turned on by default" might be a viable GSoC project for the right student. It would require someone with existing knowledge of AA and a willingness to debug nasty problems, but it sounds like there's definitely interest in the community in seeing this happen. If the student finished early (unlikely), they could start on SCEV-AA as

Hi Geoff, Thank you so much for the effort! It's good to hear that cfl-aa didn't break anything. However, the fact that it doesn't quite affect code generation is also concerning. I'll definitely look into the issue. On 05/19/2016 02:03 PM, Geoff Berry wrote: > Hi Jia, > > We did some testing with CFL-AA enabled on an aarch64 OoO target on the > llvm test-suite and

Hello everyone, If you've read through my previous introduction email (http://lists.llvm.org/pipermail/llvm-dev/2016-May/099573.html), you can safely ignore this message. The short story is: CFL-AA does not seem to be broken anymore. Please try it out and help us find more bugs / performance issues if switching to it in the future sounds interesting to you. Here are more backgrounds: I

Hi David, I am the one who's responsible for CFLAA's refactoring in the summer. I've sent out another email on llvm-dev, and you can find more about my work in my GSoC final report. I think it is fantastic that you have done such an interesting work. I'll definitely try to help getting the code reviewed and merged in the current. After a quick glance at your patch, it seems

----- Original Message ----- > From: "Daniel Berlin via llvm-dev" <llvm-dev at lists.llvm.org> > To: "Renato Golin" <renato.golin at linaro.org>, "George Burgess IV" > <george.burgess.iv at gmail.com> > Cc: "llvm-dev" <llvm-dev at lists.llvm.org>, "Jia Chen" > <jchen at cs.utexas.edu> > Sent: Monday,

Hi Daniel, On 03/21/2016 11:05 AM, Daniel Berlin wrote: > > > On Tue, Mar 15, 2016 at 1:37 PM, Jia Chen via llvm-dev > <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote: > > Dear llvm devs, > > tl;dr: What prevents llvm from switching to a fancier pointer > analysis? > > > Nothing. > > > Currently,

As of late-August 2015, putting CFL-AA behind BasicAA caused miscompiles when trying to bootstrap Clang/LLVM, yeah. It didn't seem that there were many new errors (I think it caused ~10 tests to fail, where fail = either segv or produce the wrong output), but it did end up breaking things. I don't recall if standalone CFL-AA causes miscompiles, but I highly doubt the breakages I observed

> It is merely a demand-driven way of implementing existing > analyses, by extending those algorithms to track additional > "pointed-to-by" information. Laziness may help with the running > time of the cfl analysis when only partial points-to info is > needed, but if the client wants to do a whole-program analysis and > require whole-program

Dear LLVM devs, My GSoC project this year is about alias analysis, and I wrote a short article describing what I've done during the summer: https://github.com/grievejia/GSoC2016/raw/master/writeup.pdf In the report you can find an overview of what the current status of CFL-AA. There are also some numbers in the end, but please take those numbers with a grain of salt as they were rather

On 21 March 2016 at 18:59, Daniel Berlin <dberlin at dberlin.org> wrote: > Which is why i've never mentioned it or used it in the community ;) Makes sense. :) > I would rather see someone spend their time getting SCEV-AA on by default or > CFL-AA on by default than doing another evaluation. But those may not be simple enough for a GSOC, that's why I mentioned it. The

> > > > I’m still a big fan of context sensitive, flow insensitive, unification > based models. > CFL can emulate this in the same time bound. > Contrary to your claim, context sensitivity *is* useful for mod-ref > analysis, e.g. “can I hoist a load across this call”? Context sensitivity > improves the precision of the mod/ref set of the call. > > -Chris >

> You can solve andersens and steengaards and everything else using > standard dataflow solvers, and that's an implementation strategy, but > it will be really slow. > > Part of the tradeoff is how fast something runs, and approaches that > are orders of magnitude faster often change the calculus of what > people do. For example, before hardekopf's work, andersens

Dear LLVM Community, This is a brief summary of what I've done so far for CFL-AA, and what I plan to do next. tl;dr: CFL-AA is getting saner. Low-hanging fruits on its improvement have almost been picked up. I can either make CFL-AA more precise (with certain performance cost), or teach other passes to capitalize on CFL-AA better as the next step. Comments and suggestions are more than

On 03/25/2016 08:26 PM, Daniel Berlin wrote: > > Yeah. > It depends entirely on your goal. In reality, often what you really > want is something to say "hey, i've got this pointer over here, and i > really want to hoist it up here. Do something, tell me if that is > possible". > And this is one motivation of my current research: how can various precision

Dear llvm devs, tl;dr: What prevents llvm from switching to a fancier pointer analysis? Currently, there exists a variety of general-purpose alias analyses in the LLVM codebase: basic-aa, globalsmodref-aa, tbaa, scev-aa, and cfl-aa. However, only the first three are actually turned on when invoking clang with -O2 or -O3 (please correct me if I'm wrong about this). If one looks at

Oops thanks for the reminder. I did use another email address and am terribly sorry for it. Let me just post the link: https://docs.google.com/document/d/1Kvepb-v5Ta8ug_lLK1kZeexPNlpvj62K5iIF0fMuLyM/edit?usp=sharing On 03/25/2016 11:44 AM, John Criswell wrote: > Dear Jia, > > I don't see your proposal in the system. What is the title of your > proposal, and under what email

Dear llvm devs, Based on an earlier discussion about existing pointer analyses in LLVM, I quickly hacked up a GSoC proposal on enabling cfl-aa by default. The decision to write it was made two days before the application deadline, hence the writing quality may not be very satisfactory: the background section could be less verbose, and the implementation section could be more formal. Also it