[llvm-dev] questionabout loop rotation

Stefanos Baziotis via llvm-dev llvm-dev at lists.llvm.org
Sat Mar 21 12:42:33 PDT 2020


Hi Aditya,

Glad to hear that. I want to read the patch but it's kind of big and
unfortunately right now I so don't have time.
I'll try to take a look when there is some time. In the meantime, you may
want to add Kit Barton and Michael Kruse
as reviewers.

One question though. Are you sure that this:
> This helps with LICM when instructions inside a conditional is loop
invariant
is not achieved with the current LoopRotate pass? Because AFAIK, it does.
Basically it inserts
a guard (that branches to the preheader) and then passes like LICM hoist
invariant instructions to the preheader.
Also, it does itself host some invariant instructions but only on the
header and very limited ones.

Kind regards,
Stefanos Baziotis

P.S. I re-CC'd the other participants.


Στις Σάβ, 21 Μαρ 2020 στις 8:41 μ.μ., ο/η Aditya K via llvm-dev <
llvm-dev at lists.llvm.org> έγραψε:

> hi,
> I had an implementation of loop-rotation that peels the loop such that
> each conditional is executed at least once.
> https://reviews.llvm.org/D22630
>
> This helps with LICM when instructions inside a conditional is loop
> invariant. The patch has decent number of test cases.
> All the requested comments were addressed at that time. I'm happy to
> rebase and put the patch again.
>
> -Aditya
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
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