Re: vectorisation code?

I think there is significant infrastructure in the parser, not sure how that could be managed via a plugin. Alan On Thu, Jan 22, 2015 at 10:55 AM, Jan Stolarek wrote:

Would it be possible to turn vectorisation into a compiler plugin? This would kill two birds with one stone: vectorisation would be removed from GHC sources and at the same time the code could be maintained by Geoffrey or anyone else who would want to take it up. I'm not sure what would happen with DPH in that scenario.

Janek

Dnia czwartek, 22 stycznia 2015, Manuel M T Chakravarty napisał:

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Thanks for the offer, Geoff.

Under these circumstances, I would also very much prefer for Geoff getting the code in order and leaving it in GHC.

Manuel

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Geoffrey Mainland :

I'm sorry I'm a bit late to the game here, but there is also the option of reconnecting DPH to the build.

When I patched DPH for the new version of the vector library, I did not perform this step---now I'm sorry I didn't.

I am willing to get DPH in working order again---I believe the required work will be minimal. However, that only makes sense if we 1) re-enable DPH in the nightly builds (and also by default for validate?), and 2) folks will not object too strenuously to having DPH stick around.

My fear is that without making it part of the nightly builds, accumulated bitrot will make it extremely difficult to ever re-integrate DPH. I would hate to see that happen.

Geoff

On 01/21/2015 04:11 PM, Simon Peyton Jones wrote:

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I’ve had a chat to Manuel. He is content for us to remove DPH code altogether (not just CPP/comment it out), provided we are careful to signpost what has gone and how to get it back.

I am no Git expert, so can I leave it to you guys to work out what to do? The specification is:

· It should be clear how to revert the change; that is, to re-introduce the deleted code. I guess that might be “git revert <some horrible hash>”

· If someone trips over more DPH code later, and wants to remove that too, it should be clear how to add it to the list of things to be revertred.

· We should have a Trac ticket “Resume work on DPH and vectorisation” or something like that, which summarises the reversion process.

Just to be clear, this does not indicate any lack of interest in DPH on my part. (Quite the reverse.) It’s just that while no one is actually working on it, we should use our source code control system to move it out of the way, as others on this thread have persuasively argued.

Manuel, yell if I got anything wrong.

Thanks!

Simon

*From:*ghc-devs [mailto:ghc-devs-bounces@haskell.org] *On Behalf Of *Carter Schonwald *Sent:* 21 January 2015 03:32 *To:* RodLogic *Cc:* Manuel M T Chakravarty; ghc-devs@haskell.org *Subject:* Re: vectorisation code?

moving it to its own submodule is just a complicated version of cutting a branch that has the code Right before deleting it from master.

afaik, the amount of love needed is roughly "one or more full time grad students really owning it", though i could be wrong.

On Tue, Jan 20, 2015 at 5:39 AM, RodLogic mailto:dev@rodlogic.net> wrote:

(disclaimer: I know nothing about the vectorization code)

Now, is the vectorization code really dead code or it is code that needs love to come back to life? By removing it from the code base, you are probably sealing it's fate as dead code as we are limiting new or existing contributors to act on it (even if it's a commit hash away). If it is code that needs love to come back to life, grep noise or conditional compilation is a small price to pay here, imho.

As a compromise, is it possible to move vectorization code into it's own submodule in git or is it too intertwined with core GHC? So that it can be worked on independent of GHC?

On Tue, Jan 20, 2015 at 6:47 AM, Herbert Valerio Riedel mailto:hvriedel@gmail.com> wrote:

On 2015-01-20 at 09:37:25 +0100, Jan Stolarek wrote:

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Here's an alternate suggestion: in SimplCore, keep the call

to vectorise

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around, but commented out

Yuck. Carter and Brandon are right here - we have git, let

it do the

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job. I propose that we remove vectorization code, create a

Trac ticket

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about vectorization & DPH needing love and record the commit

hash in

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the ticket so that we can revert it easily in the future.

I'm also against commenting out dead code in the presence of a VCS.

Btw, here's two links discussing the issues related to commenting out if anyone's interested in knowing more:

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http://programmers.stackexchange.com/questions/190096/can-commented-out-

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code-be-valuable-documentation

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http://programmers.stackexchange.com/questions/45378/is-commented-out-co

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de-really-always-bad

Cheers, hvr

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