similar to: Scalar Evolution Expressions Involving Sibling Loops

> I'm not following your example.  If you have two sibling loops with the same parent, one will frequently, but not always dominate the other.  Can you give a specific example of when forming a recurrence between two siblings (without one dominating the other), is useful? The situation can happen with guarded loops or with a user guard like below: if (c) { for (i = 0; i < n; i++)

Hi Jimmy, It's good to know that the problem is not specific to the case I ran into. May be you can provide your example as well, since Philip seems to be interested in some specific examples. If the assertion in getAddrExpr is deemed necessary, then I think a condition check would be the next best solution as it helps client code guard against such cases and make alternative arrangements to

Thanks for sharing the known problem. I think to solve the problem properly, we need to fully understand why that assumption about dominance is there and the implications of removing it. It would be good if you could be more specific about your idea of nullptr or SCEV_unknown (eg which function would return those values and when), but returning nullptr from getAddExpr or getSCEVAtScope may be

Thanks Florian. Tim you said: > Some cases can be undone by rematerialization, but not all, and it can involve a lot of effort which increases compile time. Do you have examples of cases where rematerialization is not possible? We are interested in learning about any previous attempts at trying to address the issue in RA. Have you tried it? Bardia Mahjour Compiler Optimizations IBM Toronto

Hello Yes, I agree that the SCEV cannot be simplified. Is my understanding correct that it is passed to a function like "isKnownNegative"? Which could still be able to prove is always true. The delinearisation may be valid, depending on exactly how you define delinearisation (under what conditions it should be giving results). It would be invalid for DA to return a dependency of [0

Hi David, Thank you very much for your response. I also get correct results for my example (for a 64-bit target) if the upper bounds are changed to unsigned. The reason is simply because clang zero-extends `m` for address calculations but sign-extends it for the loop upper bound. This prevents SCEV from canceling out the 'm' term from the difference expression that looks like `(-3 +

Hello Under the proviso that it's been a while since I looked into any of these things... On 05/15, Bardia Mahjour via llvm-dev wrote: > I also get correct results for my example (for a 64-bit target) if the upper > bounds are changed to unsigned. The reason is simply because clang zero-extends > `m` for address calculations but sign-extends it for the loop upper bound. This >

--------------------------- Wed, Sep 11, 2019: --------------------------- - LICM vs Loop Sink Strategy (Whitney) - LICM and SCEV expander host code with no regards to increased live-ranges. This is a long standing issue where historically preference has been to keep LICM more aggressive. - Two questions from IBM side: a. This problem is not specific to the POWER

Hi all, When writing new passes we currently have two pass manager interfaces to consider. In many cases we resort to implementing both interfaces because the NPM is not enabled by default while we want our pass to be enabled by default. It is my understanding that the new pass manager interface is going to replace the old one soon. However, it is not clear to me if anyone is actively working on

Hi all, Apparently some people had trouble joining today. I also had trouble using the attendee ID provided by webex. I've canceled the meeting series and will be scheduling a new one with an updated link. Please remember to update your calendars with the new invite. My apologies to those who couldn't join today, and to everyone for the churn. Today's Meeting Minutes:

Dear LLVM community, we would like to form a working group that focuses on loop optimizations and the loop optimization pipeline in LLVM. This working group would meet at a regular cadence (weekly or bi-weekly depending on people's schedules) and discuss topics relevant to loop optimizations. These topics would include: - Implementation of current loop optimizations - Proposals for

Hi all, I have been looking at the `DependenceAnalysis` pass in `llvm/include/llvm/Analysis/DependenceAnalysis.h`. In order for this analysis to produce accurate dependence vectors for multi-dimensional arrays in nested loops, it needs to "delinearize" array element accesses to recover the subscripts in each dimension of the array. I believe that the current implementation of

[CC bollu, mferguson, shil] Am Do., 23. Mai 2019 um 17:13 Uhr schrieb Bardia Mahjour < bmahjour at ca.ibm.com>: > Thanks David and Michael for the clarification. > > I think I understand the rational behind those checks in delinearization > now. > > > Some other languages have stronger guarantees about their array > dimensions accesses being in range. But this being

Agenda for the meeting of July 15 @ 11:00 am (EST): - Loop-Hierachical IR Representation Design (Michael Kruse) - Status Updates -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20200713/44b826a0/attachment.html>

Hi all, I am trying to use the dependence analyzer in a pass that I am writing and I was surprised to see an incorrect behavior when I try to query DependenceInfo for dependences between instructions. Specifically, if the two instructions are loads/stores accessing an array in a loop, the depend() method would return a dependence regardless of the order of instructions specified. (i.e. if the two

David, one quick question, is there a way to preserve and associate a set of “properties, value info/attr ” to the given region using Token? Thanks, Xinmin From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of David Majnemer via llvm-dev Sent: Wednesday, January 11, 2017 2:18 PM To: Hal Finkel <hfinkel at anl.gov> Cc: llvm-dev <llvm-dev at lists.llvm.org> Subject:

+1, tokens are the current True Way to create single-entry multi-exit regions. Your example for an annotated loop would look like: %region = call token @llvm.openmp.regionstart(metadata ...) ; whatever parameters you need here loop call void @llvm.openmp.regionend(token %region) If you use tokens, I would recommend proposal (c), where you introduce new intrinsics for every new kind of region,

A Proposal for adding an experimental IR-level region-annotation infrastructure ============================================================================= Hal Finkel (ANL) and Xinmin Tian (Intel) This is a proposal for adding an experimental infrastructure to support annotating regions in LLVM IR, making use of intrinsics and metadata, and a generic analysis to allow transformations to

Would you send us the LLVM IR for below example using token and OpBundle. So, we can understand better. Thanks. #pragma omp target teams distribute parallel for simd shared(xp, yp) linear(i) firstprivate(m, n) map(m, n) for (i=0; i<2*N; i++) { xp[i*m + j] = -1; yp[i*n +j] = -2; } #pragma prefetch x:1:20 y:0:10 for (i=0; i<2*N; i++) { xp[i*m + j] = -1; yp[i*n +j] = -2; } From: Hongbin

Mehdi, thanks for good questions. >>>>>Something isn’t clear to me about how do you preserve the validity of the region annotations since regular passes don’t know about the attached semantic? There are some small changes we have to make in some optimizations to make sure the optimizations does not validation attached annotation semantics. 1) provide hand-shaking / query utils for