[llvm-dev] [GSoC 2021] Utilize LoopNest Pass

[uint256_t via llvm-dev]

Hello,

I have a question about finding good passes for utilizing LoopNest pass.

> The LoopFullUnrollPass is not a good candidate for the change, as it is a
loop pass and it is being used as a loop pass.
Then you mean that passes which are  implemented as not a loop pass (=
function pass) and not already used as a loop pass are good for this
change?
I didn't get that. Could you tell me why it is?

Thanks in advance,
Toshiki Maekawa

On Fri, Mar 12, 2021, 1:20 AM uint256_t <konndennsa at gmail.com> wrote:

> Thank you for your advice. As you mentioned, LoopUnrollAndJam seems to be
> a good candidate.
> I'm going to find another analyse/transform pass suitable for loop nest
> pass.
>
> Best,
> Toshiki Maekawa
>
> 2021年3月10日(水) 23:32 Whitney T Tsang <whitneyt at ca.ibm.com>:
>
>> Sure, in this project, we plan to utilize the LoopNest pass in some
>> existing passes.
>> As an example, here is one of the patches to transform the loop
>> interchange pass: https://reviews.llvm.org/D97847.
>> On top of doing the code changes, we want to understand what are the pros
>> and cons of the change.
>> We can do that by collecting some data, e.g. compile time.
>>
>> There are two loop unroller, LoopFullUnrollPass and LoopUnrollPass.
>> The LoopFullUnrollPass is not a good candidate for the change, as it is a
>> loop pass and it is being used as a loop pass.
>> It is written to be traverse from inner to outer loop, with other loop
>> transformations in between in the loop pipeline.
>> The LoopUnrollPass could be a candidate, but the LoopUnrollAndJamPass can
>> be an easier to understand candidate,
>> as unroll and jam transformation naturally operate on more than one loop
>> (LoopNest).
>>
>> Regards,
>> Whitney Tsang
>>
>> [image: Inactive hide details for uint256_t ---2021/03/10 07:52:17
>> AM---I'm glad to get in touch with you two. I'm planning to utilize]uint256_t
>> ---2021/03/10 07:52:17 AM---I'm glad to get in touch with you two. I'm
>> planning to utilize LoopNest pass for some passes like lo
>>
>> From: uint256_t <konndennsa at gmail.com>
>> To:
>> Cc: llvm-dev <llvm-dev at lists.llvm.org>, etiotto at ca.ibm.com,
>> whitneyt at ca.ibm.com
>> Date: 2021/03/10 07:52 AM
>> Subject: [EXTERNAL] Re: [llvm-dev] [GSoC 2021] Utilize LoopNest Pass
>> ------------------------------
>>
>>
>> ZjQcmQRYFpfptBannerEnd
>> I'm glad to get in touch with you two.
>> I'm planning to utilize LoopNest pass for some passes like loop unrolling.
>> Could you tell me more about this project if any?
>>
>> 2021年3月9日(火) 20:47 Whitney Tsang <*whitney.uwaterloo at gmail.com*
>> <whitney.uwaterloo at gmail.com>>:
>>
>>    + Whitney, Ettore
>>
>>    On Tue, Mar 9, 2021, 3:00 AM uint256_t via llvm-dev <
>>    *llvm-dev at lists.llvm.org* <llvm-dev at lists.llvm.org>> wrote:
>>    Hello,
>>
>>    I'm thinking of participating in GSoC at LLVM.
>>    I've already talked about ideas with some project mentors but a newly
>>    added project idea "Utilize LoopNest Pass" attracted me.
>>    I want to get in touch with its mentors (Whitney Tsang, Ettore
>>    Tiotto), whose email I couldn't find out.
>>
>>    Sincerely,
>>    Toshiki Maekawa
>>    _______________________________________________
>>    LLVM Developers mailing list
>> *llvm-dev at lists.llvm.org* <llvm-dev at lists.llvm.org>
>> *https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev*
>>    <https://urldefense.proofpoint.com/v2/url?u=https-3A__lists.llvm.org_cgi-2Dbin_mailman_listinfo_llvm-2Ddev&d=DwMFaQ&c=jf_iaSHvJObTbx-siA1ZOg&r=p0DGcdtx8-l1bvwJTLSk1zBTXpb78Y1slqHKTsTpRTE&m=xZta8ysMk2YLuaeN6hu48YbOcAibTj8EHetJ7EUKsC8&s=HbDn2cNobhWts-Cp8E5W7XgWSCD6ebFSWkwl_zDmusk&e=>
>>
>>
>>
>>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20210315/b0bc66e2/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: graycol.gif
Type: image/gif
Size: 105 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20210315/b0bc66e2/attachment.gif>