Re: [External] Re: Specialising NOINLINE functions

I can look into this, sure, but it wouldn’t exactly solve my original problem, which is that I would like to turn this on wholesale, not definition by definition.

What is "this" that you want to turn on, precisely? why would I ever not want to specialize a definition

I think the only downside is compilation time and code bloat. I think you are concerned about cross-module specialisation. There are two things in play: 1. Whether the defining module exposes the definition 2. Whether the importing module specialises the thus-exposed definition For (1) there are two choices: - (1a) Currently INLINEABLE captures the RHS of the function *exactly as the user wrote it*, and allows that to be specialised. - (1b) On the other hand, -fexpose-all-unfoldings does not attempt to capture the functions the user wrote; instead, it exposes the *post-optimisation *RHSs of all functions, regardless of per-function pragmas. I believe that (1b) is closer to what you want. For (2) one might wonder whether to - (2a) specialise every imported (type-class-overloaded) function whose unfolding we can see - (2b) specialise only imported functions with a SPECIALISABLE pragma - (2c) specialise imported functions only with -fspecialise-aggressively I think GHC currently does (2c). Maybe this taxonomy helps you a bit? Simon On Mon, 9 May 2022 at 02:38, Erdi, Gergo wrote:

PUBLIC

I can look into this, sure, but it wouldn’t exactly solve my original problem, which is that I would like to turn this on wholesale, not definition by definition. It seems that all past discussion about this was in the context of a per-definition pragma (and sadly, a large part of that was bikeshedding over the name of the pragma…). But is the reason for that spelled out explicitly somewhere? In other words, what is the cost of specialisation, why would I ever not want to specialize a definition (inlinable or not)? I’d like to understand this first before reviving the proposal.

*From:* ghc-devs *On Behalf Of *Simon Peyton Jones *Sent:* Friday, May 6, 2022 5:26 PM *To:* Oleg Grenrus ; ÉRDI Gergő *Cc:* GHC developers *Subject:* [External] Re: Specialising NOINLINE functions

There is a (stale) ghc-proposal for that, https://github.com/ghc-proposals/ghc-proposals/pull/357 https://clicktime.symantec.com/3NuNFMzg65dA5k5kXHX5U196xU?u=https%3A%2F%2Fgi...

So there is! Thank you.

Gergo: would you like to take over this proposal, revise it if necessary in the light of the comments, and submit it?

Simon

On Fri, 6 May 2022 at 10:08, Oleg Grenrus wrote:

There is a (stale) ghc-proposal for that, https://github.com/ghc-proposals/ghc-proposals/pull/357 https://clicktime.symantec.com/3NuNFMzg65dA5k5kXHX5U196xU?u=https%3A%2F%2Fgi...

- Oleg

On 6.5.2022 12.04, Simon Peyton Jones wrote:

...

Dear devs

At the moment the INLINEABLE pragma means "capture my right-hand side, regardless of how big it is, so that it can be type-class-specialised, including in other modules". But it /also /says "feel free to inline me".

Some users (eg Gergo) want to say NOINLINE on some functions. But for these they'd still like to generate type-class-specialised versions. After all, if we aren't going to inline them, specialising is the next best thing.

But we have no way to say both "specialise me" and "don't inline me", because you can't say both INLINEABLE and NOINLINE. (That would look silly.)

I think we should probably just bite the bullet and add a SPECIALISABLE pragma, /orthogonal to INLINE/NOINLNE/, which say "capture my right-hand side, regardless of how big it is, so that it can be type-class-specialised, including in other modules". It behaves exactly like INLINEABLE except that you can specify it along with INLINE/NOINLINE.

Any thoughts? Do you think this needs a GHC proposal?

See #21036 < https://gitlab.haskell.org/ghc/ghc/-/issues/21036#note_407930 https://clicktime.symantec.com/3SB6vTf6r7gWFXH7FGMko9a6xU?u=https%3A%2F%2Fgi...

Simon

_______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs https://clicktime.symantec.com/37EyM1zQDopVjPevRNvP7f96xU?u=http%3A%2F%2Fmai...

---

ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs https://clicktime.symantec.com/37EyM1zQDopVjPevRNvP7f96xU?u=http%3A%2F%2Fmai...

This email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please delete all copies and notify the sender immediately. You may wish to refer to the incorporation details of Standard Chartered PLC, Standard Chartered Bank and their subsidiaries at https: //www.sc.com/en/our-locations

Where you have a Financial Markets relationship with Standard Chartered PLC, Standard Chartered Bank and their subsidiaries (the "Group"), information on the regulatory standards we adhere to and how it may affect you can be found in our Regulatory Compliance Statement at https: // www.sc.com/rcs/ and Regulatory Compliance Disclosures at http: // www.sc.com/rcs/fm

Insofar as this communication is not sent by the Global Research team and contains any market commentary, the market commentary has been prepared by the sales and/or trading desk of Standard Chartered Bank or its affiliate. It is not and does not constitute research material, independent research, recommendation or financial advice. Any market commentary is for information purpose only and shall not be relied on for any other purpose and is subject to the relevant disclaimers available at https: // www.sc.com/en/regulatory-disclosures/#market-disclaimer.

Insofar as this communication is sent by the Global Research team and contains any research materials prepared by members of the team, the research material is for information purpose only and shall not be relied on for any other purpose, and is subject to the relevant disclaimers available at https: // research.sc.com/research/api/application/static/terms-and-conditions.

Insofar as this e-mail contains the term sheet for a proposed transaction, by responding affirmatively to this e-mail, you agree that you have understood the terms and conditions in the attached term sheet and evaluated the merits and risks of the transaction. We may at times also request you to sign the term sheet to acknowledge the same.

Please visit https: //www.sc.com/en/regulatory-disclosures/dodd-frank/ for important information with respect to derivative products.