How to inline early in a GHC plugin?

[Conal Elliott]

Thanks for the pointers, Simon. Some more specific questions:

*   To access an unfolding, is `maybeUnfoldingTemplate (idUnfolding v)` the
recommended recipe?
*   Is it the case that this recipe succeeds (`Just`) in some compiler
phases and not others?
    If so, is this difference due to Ids being altered (presumably via
`setUnfoldingInfo` being called between phases)?
*   Before an Id is ready for general inlining by the simplifier, can I get
the Id's unfolding another way so that I can substitute it early?

A short Skype chat might easily clear up my questions and confusions if you
have time and inclination.

Regards, - Conal

On Fri, Dec 2, 2016 at 9:07 AM, Simon Peyton Jones <simonpj at microsoft.com>
wrote:

> I don’t really understand your question clearly.  So I’ll guess
>
>
>
> Unfoldings are added to Ids in Simplify.completeBind (look for
> setUnfoldingInfo).  Apart from INLINE pragmas, that’s about the only place
> it happens.
>
>
>
> Does that help?
>
>
>
> S
>
>
>
> *From:* ghc-devs [mailto:ghc-devs-bounces at haskell.org] *On Behalf Of *Conal
> Elliott
> *Sent:* 01 December 2016 21:51
> *To:* ghc-devs at haskell.org
> *Subject:* How to inline early in a GHC plugin?
>
>
>
> I'm implementing a GHC plugin that installs a `BuiltInRule` that does the
> work, and I'd like to learn how to inline more flexibly. Given an
> identifier `v`, I'm using `maybeUnfoldingTemplate (realIdUnfolding v)` to
> get a `Maybe CoreExpr`. Sometimes this recipe yields `Nothing` until a
> later compiler phase. Meanwhile, I guess my variable `v` has been replaced
> by one with inlining info. First, am I understanding this mechanism
> correctly? A GHC source pointer to how inlining is made available would
> help me. Second, can I access the inlining info before it's made available
> to the rest of the simplifier?
>
>
>
> Thanks,  - Conal
>
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