similar to: [RFC] Supporting ARM's SVE in LLVM

Hi David, Responses below. -Graham On 11 Jun 2018, at 22:19, David A. Greene <dag at cray.com<mailto:dag at cray.com>> wrote: Graham Hunter <Graham.Hunter at arm.com<mailto:Graham.Hunter at arm.com>> writes: ======== 1. Types ======== To represent a vector of unknown length a boolean `Scalable` property has been added to the `VectorType` class, which indicates that

Hi all, It's been a while since we've given an update on scalable vector support in LLVM. Over the last 12 months a lot of work has been done to make LLVM cope with scalable vectors. This effort is now starting to bear fruit with LLVM gaining more capabilities, including an intrinsics interface for AArch64 SVE/SVE2, LLVM IR Codegen for scalable vectors, and several loop-vectorization

Hi Graham, One high level comment without reading the patchset too much - it seems 'vscale' in particular could be just as easy to implement as an intrinsic, which would be a less invasive patch. Is there a reason you didn't go down the intrinsic route? James On Thu, 24 Nov 2016 at 15:39, Graham Hunter via llvm-dev < llvm-dev at lists.llvm.org> wrote: > Hi, > > Paul

Hi Renato, Thanks for taking a look. Answers inline below, let me know if I've missed something out. -Graham > On 5 Jun 2017, at 17:55, Renato Golin <renato.golin at linaro.org> wrote: > > Hi Graham, > > Just making sure some people who voiced concerns are copied + cfe-dev. > > On 1 June 2017 at 15:22, Graham Hunter via llvm-dev > <llvm-dev at

Hi, Here's the updated RFC for representing scalable vector types and associated constants in IR. I added a section to address questions that came up on the recent patch review. -Graham =================================================== Supporting Scalable Vector Architectures in LLVM IR =================================================== ========== Background ========== *ARMv8-A

I'm sorry.. may I interrupt for a minute and try to grok things for a bit different angle.. While the VL can vary.. in practice wouldn't the cost of vectorization and width be tied more to the hardware implementation than anything else? The cost of vectorizing thread 1 vs 2 isn't likely to change? (Am I drunk and mistaken?) If the above holds true then the the length would be only

On 27 November 2016 at 13:59, Paul Walker <Paul.Walker at arm.com> wrote: > Thanks Renato, my takeaway is that I am presenting the design out of order. So let's focus purely on the vector length (VL) and ignore everything else. For SVE the vector length is unknown and can vary across an as yet undetermined boundary (process, library....). Within a boundary we propose making VL a

Hi, i am the main author of RV, the Region Vectorizer (github.com/cdl-saarland/rv). I want to share our standpoint as potential users of the proposed vector-length agnostic IR (RISC-V, ARM SVE). -- support for `llvm.experimental.vector.reduce.*` intrinsics -- RV relies heavily on predicate reductions (`or` and `and` reduction) to tame divergent loops and provide a vector-length agnostic

Hi All, I have read the links from Joel. It seems one of its main focus is vectorization of loop with vector predicate register. I am not sure we need the scalable vector type for it. Let's see a simple example from the white paper. 1 void example01(int *restrict a, const int *b, const int *c, long N) 2 { 3 long i; 4 for (i = 0; i < N; ++i) 5 a[i] = b[i] + c[i]; 6 }

Hi Graham, Thanks for your kind explanation. There was internal discussion about it. If possible, can you let me know the Clang/LLVM CodeGen patches for the vector type on phabricator please? I would like to check what kinds of the restrictions the type causes on Clang/LLVM. Thanks, JinGu Kang ________________________________ From: Graham Hunter <Graham.Hunter at arm.com> Sent: 28 May

Just spitballing... why not have a splat construct straight through LLVM? It would make the IR more readable, opposed to the insert+shuffle method. On Thu, Aug 29, 2019 at 19:06 Amara Emerson via llvm-dev < llvm-dev at lists.llvm.org> wrote: > +1 to a new node, we’d very likely do the same thing for GlobalISel and > move to a canonical spat representation for all targets. > >

JinGu: I’m not Graham, but you might find the following link a good starting point. https://community.arm.com/developer/tools-software/hpc/b/hpc-blog/posts/technology-update-the-scalable-vector-extension-sve-for-the-armv8-a-architecture The question you ask doesn’t have a short answer. The compiler and the instruction set design work together to allow programs to be compiled without knowing

In the RISC-V V extension, there is no upper limit to the size vector registers can be in a future CPU. (Formally, the upper limit is at least 2^31 bytes) Generic code can enquire the size, dynamically allocate space, and transparently save and restore the contents of a vector register or registers. On Fri, May 24, 2019 at 11:28 AM JinGu Kang via llvm-dev <llvm-dev at lists.llvm.org>

Hi, Are there any objections to going ahead with this? If not, we'll try to get the patches reviewed and committed after the 7.0 branch occurs. -Graham > On 2 Jul 2018, at 10:53, Graham Hunter <Graham.Hunter at arm.com> wrote: > > Hi, > > I've updated the RFC slightly based on the discussion within the thread, reposted below. Let me know if I've missed

On 07/30/2018 05:34 AM, Chandler Carruth wrote: > I strongly suspect that there remains widespread concern with the > direction of this, I know I have them. > > I don't think that many of the people who have that concern have had > time to come back to this RFC and make progress on it, likely because > of other commitments or simply the amount of churn around SVE related >

Hi, I would like to restart the conversation regarding adding SVE support to LLVM. This time I am framing things from the code generation point of view because our immediate priority is llvm-mc support rather than auto-vectorisation. Can you please review the following text outlining MVT changes we would like to make so SVE instructions can be added to the AArch64 Target. My overriding

Hi Graham, I'll look into the patches next, but first some questions after reading the available white papers on the net. On 24 November 2016 at 15:39, Graham Hunter <Graham.Hunter at arm.com> wrote: > This complex constant represents the runtime value of `n` for any scalable type > `<n x m x ty>`. This is primarily used to increment induction variables and > generate

Hi, Now that Sander has committed enough MC support for SVE, here's an updated RFC for variable length vector support with a set of 14 patches (listed at the end) to demonstrate code generation for SVE using the extensions proposed in the RFC. I have some ideas about how to support RISC-V's upcoming extension alongside SVE; I'll send an email with some additional comments on

Hi all, On 11/5/20 10:32 AM, Roger Ferrer Ibáñez wrote: Hi Sjoerd, thanks for pointing us to this intrinsic. I see it returns a mask/predicate type. My understanding is that VPred intrinsics have both a vector length operand and a mask operand. It looks to me that a "popcount" of get.active.lane.mask would correspond to the vector length operand. Then additional "control

Hi, During the discussion on introducing scalable vectors we established that we could use the canonical IR form for splats of scalable vector types (insert element into lane 0 of an undef vector, shuffle that with another undef vector of the same type and a zeroinitializer mask). We do run into a problem for lowering to SelectionDAG however, since the canonical form there is a BUILD_VECTOR with