similar to: Does OpenMP hints bypass the vectorisation legality check in llvm

Hi all, I am currently looking into how "#pragma omp for simd" is actually recognized in llvm. To my knowledge, clang will parse it and set metadata in IR to indicate this force-vectorization hint and later optimization passes would read it and vectorize the marked loop. Therefore, the loop should be vectorized even the compiler think it might not be safe to do so? So my

Xinmin, > Tom, your understanding is correct per OpenMP SIMD model. Our implementation behaves as you stated. > Which is not part of LLVM main trunk yet. Is that the implementation that is based on the intrinsics in the RFC you and Hal Finkel had sent out to the list? Or is it a different implementation (and if so, is there some plan to merge the two)? Thanks, --Vikram Adve //

Thanks Krzysztof. That's very helpful - I was missing the distinction between a register containing an undefined value and a register marked as containing an undefined value. Cheers! On 1/23/18, via llvm-dev <llvm-dev at lists.llvm.org> wrote: > Send llvm-dev mailing list submissions to > llvm-dev at lists.llvm.org > > To subscribe or unsubscribe via the World Wide Web,

Thanks, Hal. I plan to post a patch w/o HW Legality early bailout first. That should enable further discussion on where the initial very high cost for "illegal masked load/store/gather/scatter" should be coming from --- like should LoopVectorize provide it? Or should it be provided by TTI? I prefer the latter (TTI) but the first revision of the patch will intentionally do the former

@Xinmin, Saito: If Clang/the frontend generates the version there is no problem, or is there? The frontend knows about the original source type and it's ABI specific lowering already. @Francesco, we should even consider putting the generating capabilities outside of the OpenMP code generation (in the future). That could allow easier reuse by other frontends. Get Outlook for

>Thank you everybody for their input, and for your patience. This is proving harder than expected! :) Thank you for doing the hard part of the work. Hideki -----Original Message----- From: Francesco Petrogalli [mailto:Francesco.Petrogalli at arm.com] Sent: Monday, June 24, 2019 11:26 AM To: Saito, Hideki <hideki.saito at intel.com> Cc: Doerfert, Johannes <jdoerfert at anl.gov>;

Amara, >I support this direction Thanks for the support. >but are there actually any real world workloads where gather/scatter scalarisation would be worth it, on any micro-architecture? If we don’t have examples and the compile time cost is non-negligible then I think we’d still like to keep the early >bailouts in some form.’ It's not like I have specific application code in

On 01/05/2018 06:28 PM, Saito, Hideki wrote: > Amara, > >> I support this direction > Thanks for the support. > >> but are there actually any real world workloads where gather/scatter scalarisation would be worth it, on any micro-architecture? If we don’t have examples and the compile time cost is non-negligible then I think we’d still like to keep the early >bailouts in

>In all cases, the IR type of the parameters in `foo` is i64, therefore is not possible to distinguish what C type generated the signature of `foo`. Ouch. >I don’t know if this is going to be a problem for other architectures I haven't checked what IA-32/Intel64 should do for type 2, but I fully agree that this needs to be done properly according to the ABI. >Therefore, I would

For example, Type 2 case, scalar-foo used call by value while vector-foo used call by ref. The question Johannes is asking is whether we can decipher that after the fact, only by looking at the two function signatures, or need some more info (what kind, what's minimal)? I think we need to list up cases of interest, and for each vector ABI of interest, we need to work on the requirements and

> On Jun 24, 2019, at 10:53 AM, Tian, Xinmin <xinmin.tian at intel.com> wrote: > > To me, it is also an issue related to SIMD signature matching when the vectorizer kicks in. Losing info from FE to BE is not good in general. > Yes, we cannot loose such information. In particular, the three examples I reported are all generating i64 in the scalar function signature: // Type 1

All, I'm trying to refactor LoopVectorize such that it has better conformance to VPlan vision going forward (http://www.llvm.org/docs/Proposals/VectorizationPlan.html). All VP*Recipe class definitions are now moved to VPlan.h, and I have a patch under review to move LoopVectorizationPlanner class out of LoopVectorize.cpp (https://reviews.llvm.org/D41420). Next thing I'm working on is

> On 5 Jan 2018, at 21:01, Saito, Hideki via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > > All, > > I'm trying to refactor LoopVectorize such that it has better conformance to VPlan vision going forward > (http://www.llvm.org/docs/Proposals/VectorizationPlan.html). All VP*Recipe class definitions are now > moved to VPlan.h, and I have a patch under review

Hey folks, Do we have proposals for an HPC focused BoF at EuroLLVM? I'd like to discuss the current efforts around integrating Polly, parallel IR efforts and vectoriser support in VPlan (like outer loop), as well as coordination on the next steps around Flang. -- cheers, --renato

Status Update on VPlan ---- where we are currently, and what's ahead of us ==========================================================   Goal: ----- Extending Loop Vectorizer (LV) such that it can handle outer loops, via uplifting its infrastructure with VPlan. The goal of this status update is to summarize the progress and the future steps needed.   Background: ----------- This is related to

I have an RFC for first-class complex types in LLVM IR pending for some internal review. I hope to post it soon. That should help address this problem. Then the vector function signature generation could stay in LLVM, if I'm understanding the issue correctly. -David Francesco Petrogalli via llvm-dev <llvm-dev at lists.llvm.org> writes: > Hi all - I am

I agree with Simon. This looks good conceptually. I have minor implementation comments but that can wait till the code reviews. Sorry for the delay and thanks for working on this. Get Outlook for Android<https://aka.ms/ghei36> ________________________________ From: Simon Moll <moll at cs.uni-saarland.de> Sent: Monday, June 17, 2019 10:02:58 AM To: Francesco Petrogalli; LLVM

Hi Xinmin, I have updated the clang patch using the standard name mangling you suggested - I was not fully aware of the C++ mangling convention “_ZVG”. I am using “D” for 64-bit NEON and “Q” for 128-bit NEON, which makes NEON vector symbols look as follows: _ZVGQN2v__Z1fd _ZVGDN2v__Z1ff _ZVGQN4v__Z1ff Here “Q” means -> NEON 128-bit, “D” means -> NEON 64-bit Please notice that although

Hi Francesco, a bit more information. GCC veclib is implemented based on GCC VectorABI for declare simd as well. For name mangling, we have to follow certain rules of C/C++ (e.g. prefix needs to _ZVG ....). David Majnemer who is the owner and stakeholder for approval for Clang and LLVM. Also, we need to pay attention to GCC compatibility. I would suggest you look into how GCC VectorABI can

Hi Francesco, On 06/03, Francesco Petrogalli wrote: > > On Jun 3, 2019, at 1:43 PM, Andrea Bocci <andrea.bocci at cern.ch> wrote: > > as a candidate future user of the proposed extension, I think I like the simplified proposal better than the original RFC. > > > > The only part of the syntax that I would find not very much user-friendly is having to mangle the