similar to: Loop Optimization Working Group

Displaying 20 results from an estimated 2000 matches similar to: "Loop Optimization Working Group"

2019 Sep 13
3
Loop Opt WG Meeting Minutes for Sep 11, 2019
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
2019 May 15
3
Delinearization validity checks in DependenceAnalysis
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 +
2019 May 16
2
Delinearization validity checks in DependenceAnalysis
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 >
2019 May 22
2
Delinearization validity checks in DependenceAnalysis
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
2019 May 13
3
Delinearization validity checks in DependenceAnalysis
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
2019 Jul 17
3
Loop Opt WG Meeting Minutes for July 17, 2019
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:
2020 Mar 30
2
Scalar Evolution Expressions Involving Sibling Loops
Forwarding to the dev list, in case others ran into similar issues and/or have input on this topic. Bardia Mahjour ----- Forwarded by Bardia Mahjour/Toronto/IBM on 2020/03/30 02:25 PM ----- From: Bardia Mahjour/Toronto/IBM To: listmail at philipreames.com Cc: "Michael Kruse" <llvm at meinersbur.de> Date: 2020/03/26 11:47 AM Subject: Scalar Evolution Expressions Involving Sibling
2020 Mar 30
2
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++)
2020 Apr 16
2
Scalar Evolution Expressions Involving Sibling Loops
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
2020 Apr 17
2
Scalar Evolution Expressions Involving Sibling Loops
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
2020 Jul 13
2
Loop Opt WG Meeting Agenda for July 15, 2020
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>
2020 Apr 23
2
Incorrect behavior in the LLVM dependence analyzer
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
2019 May 24
2
Delinearization validity checks in DependenceAnalysis
[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
2019 Sep 11
2
Loop Opt WG Meeting Minutes for Sep 11, 2019
--------------------------- 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
2019 Jun 27
3
Status of the New Pass Manager
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
2019 May 07
2
[NEW] LLVM / Clang Social in Chicago
So, there will be an LLVM Social in the Chicago area. We know what you now think, an LLVM Social in Chicagoland? Finally! If you are interested in showing up __ for the first meeting __, use the doodle [0] to indicate your preferred dates. Note that the weekend was chosen for the first meeting only. We expect to discuss future meeting details (times, locations, style, ...) at this first
2010 Jan 16
1
CentOS 5 and webex wrf files?
Anyone have experience playing back a Webex wrf file on their CentOS 5.x system? I have a newly installed CentOS 5.4 i386 system and want to play such a file, but the Webex.com web site says it only supports Windows and MacOS for playback. Any other options next to creating a VM of Windows (I'm not buying a Mac for this). Thanks. Scott
2017 Jan 11
10
[RFC] IR-level Region Annotations
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
2017 Jan 11
2
[RFC] IR-level Region Annotations
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:
2017 Jan 11
3
[RFC] IR-level Region Annotations
+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,