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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 was working on a GSoC project, whose first step is to fix cfl-aa. After a bug was patched up in r2682...

...mentptr inbounds double* %11, i64 1 LICM hoisting to while.body.lr.ph: %arrayidx81 = getelementptr inbounds double* %11, i64 2 LICM hoisting to for.body.lr.ph: %2 = ptrtoint i32* %Index to i64 clang --target=aarch64-linux-gnu -c -mcpu=cortex-a57 -Ofast -fno-math-errno test.c -S -o test-cflaa.s -mllvm -use-cfl-aa -mllvm -debug-only=licm LICM hoisting to for.body.lr.ph: %2 = ptrtoint i32* %Index to i64 Why CFL AA cannot allow hoisting this out: %21 = load double** %arrayidx8, align 8, !tbaa !5 Which leads to this extra load in assembly code: ldr x14, [x4, x9, lsl #3] Thanks! Ana....

(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 &lt...

...m using -E? I don't have a machine handy that has headers that target that arch. On Tue Jan 13 2015 at 4:33:29 PM Daniel Berlin <dberlin at dberlin.org> wrote: > Anything other than noalias or mustalias should be getting passed down the > stack, so either that is not happening or CFL aa is giving better answers > and something does worse with those better answers. I'll take a look this > evening > On Jan 13, 2015 3:58 PM, "Ana Pazos" <apazos at codeaurora.org> wrote: > >> Hi folks, >> >> Moving the discussion to llvm.dev. >&...

Hello everyone, One of Google's summer interns, George Burgess IV, created an implementation of the CFL pointer-aliasing analysis algorithm, and this has now been added to LLVM trunk. Now we should determine whether it is worthwhile adding this to the default optimization pipeline. For ease of testing, I've added the command line option -use-cfl-aa which will cause the CFL analysis to be added to...

On 13 January 2015 at 22:11, Daniel Berlin <dberlin at dberlin.org> wrote: > This is caused by CFLAA returning PartialAlias for a query that BasicAA > can prove is NoAlias. > One of them is wrong. Which one? I'm not sure from your description that this is a chaining issue. PartialAlias doesn't chain and isn't supposed to, it's a final answer just like NoAlias and MustAlia...

Dear LLVM community, I am a GSoC student this year working on the project of improving alias analysis in LLVM. The proposal initially came from a discussion I had with various devs on the mailing list some time ago [1]. The general goal of this project is to make alias analysis (in particular, cfl-aa) "better", and to be more concrete here is a list of objectives I had in mind: - Evaluating the current state of cfl-aa, and fix all known bugs. - Improving the precision of cfl-aa. Although flow sensitivity may not be very helpful for LLVM in its current form, field sensitivity sho...

In lto+pgo some (5 out of 12 with usual suspect like perlbench and gcc among them using -flto -Wl,-mllvm,-use-cfl-aa -Wl,-mllvm,-use-cfl-aa-in-codegen) the CINT2006 benchmarks don’t compile. Has the implementation been tested with lto? If not, please stress the implementation more. Do we know reasons for gains? Where did you expect the biggest gains? Some of the losses will likely boil down to increased regist...

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 emails, so we > may get more help if we also se...

....gov> > Cc: "LLVM Dev" <llvmdev at cs.uiuc.edu>, "Jiangning Liu" <liujiangning1 at gmail.com>, "George Burgess IV" > <george.burgess.iv at gmail.com> > Sent: Monday, September 15, 2014 7:58:59 PM > Subject: Re: [LLVMdev] Testing the new CFL alias analysis > > I filed bugzilla pr20954. Thanks! -Hal > > > -Gerolf > > > > > > > On Sep 15, 2014, at 2:56 PM, Gerolf Hoflehner < ghoflehner at apple.com > > wrote: > > > > On CINT2006 ARM64/ref input/lto+pgo I practically...

...10:49 AM, Daniel Berlin <dberlin at dberlin.org> wrote: > > > >> On Tue, Jan 13, 2015 at 11:26 PM, Nick Lewycky <nlewycky at google.com> wrote: >>> On 13 January 2015 at 22:11, Daniel Berlin <dberlin at dberlin.org> wrote: >>> This is caused by CFLAA returning PartialAlias for a query that BasicAA can prove is NoAlias. >> >> One of them is wrong. Which one? > CFL-AA. > > Right now it checks whether two things come out to be the same stratified info and have the same index, and if so, returns PartialAlias. This is wrong...

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...

...t;, "George Burgess IV" <george.burgess.iv at gmail.com>, "Hal Finkel" >> <hfinkel at anl.gov> >> Cc: "LLVM Dev" <llvmdev at cs.uiuc.edu> >> Sent: Sunday, September 14, 2014 12:15:02 AM >> Subject: Re: [LLVMdev] Testing the new CFL alias analysis >> >> In lto+pgo some (5 out of 12 with usual suspect like perlbench and >> gcc among them using -flto -Wl,-mllvm,-use-cfl-aa >> -Wl,-mllvm,-use-cfl-aa-in-codegen) the CINT2006 benchmarks don’t >> compile. > > On what platform? Could you bugpoint...

...Ana. > > > > *From:* George Burgess IV [mailto:george.burgess.iv at gmail.com] > *Sent:* Wednesday, January 14, 2015 10:31 AM > *To:* Daniel Berlin > *Cc:* Nick Lewycky; Ana Pazos; Jiangning Liu; LLVM Developers Mailing List > *Subject:* Re: [LLVMdev] question about enabling cfl-aa and collecting > a57 numbers > > > > Inline > > - George > > > On Jan 14, 2015, at 10:49 AM, Daniel Berlin <dberlin at dberlin.org> wrote: > > > > > > On Tue, Jan 13, 2015 at 11:26 PM, Nick Lewycky <nlewycky at google.com> > wrote: &...

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 suggestio...

...Fixes that select was unifying the condition to the other pieces (the condition does not need to be processed :P). This was causing unnecessary aliasing. 4. Adds a regression test to must-and-partial 5. Fixes the pass ordering 6. Does not alias non-pointer arguments to random things :) 7. Fixes the CFL test cases that break with above. On Thu, Jan 15, 2015 at 11:33 AM, Ana Pazos <apazos at codeaurora.org> wrote: > Daniel, don’t we need to fix the order of invoking alias analyses in > lib/Transforms/IPO/PassManagerBuilder.cpp as well? > > > > Your patch fixed the order...

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 finis...

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 discussions I could find back in 2014, which basically says that cfl-aa offers no significant improvement in performance. Things may got greatly improve...

...g > > > 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. > > CFL-AA should just be fixing performance regressions, and maybe a > little bug fixing, which is hopefully easy enough. It...

...specially given the error message I get that indicates I can't do this using an 'if' statement. Essentially, I have data where I think a relationship enters when a variable (here Pwd) is below some value (z). I don't know that value, so I want to fit it. The data is Pw, Tsoil, and Cfl. nlstest=nls(if(Pw>z){Cfl~K*exp(-b*Pw)+c }else{ Cfl~K*(exp(-a*Tsoil))*exp(-b*Pw)+c },start=c(K=5.5, a=0.1, b=0.1, c=2, z=5)) Which returns the error: Error in inherits(object, "formula") : object 'z' not found Is there a better way to try and allow a conditional variable...