Occurrence info on binders and STG

Gabor Greif ggreif at gmail.com
Tue Aug 1 15:02:12 UTC 2017

Hi devs!

I just had a short exchange with Joachim, he sent me to this place.

Can anybody explain how occurrence info is used in STG?

Cheers and thanks,


---------- Forwarded message ----------
From: Joachim Breitner <mail at joachim-breitner.de>
Date: Tue, 01 Aug 2017 10:47:48 -0400
Subject: Re: [commit: ghc] master: Simplify OccurAnal.tagRecBinders (b311096)
To: Gabor Greif <ggreif at gmail.com>


feel free to CC the mailing list on such questions. I often don’t know
things perfectly either.

Am Dienstag, den 01.08.2017, 16:43 +0200 schrieb Gabor Greif:

> Loosely related question:

Very loosely :-)

>  - when doing STG Cse, the occurrence info is not updated when a
> wild(card)-binder is used. Is there a recommended way to re-run
> occ-analysis on STG? (I fear there is not.)

I fear that too. It the occ info used past that stage?

>  - I noticed that "wild"-binders sometimes do not appear at their
> binding site (after "of" and "{") in STG dumps. Dumping gets
> suppressed when they are deemed dead. Should STG consider occ-info at
> all?

Good questions. I remember that Simon commented on that before, but I
don’t remember where…

> oachim
Joachim “nomeata” Breitner
  mail at joachim-breitner.dehttps://www.joachim-breitner.de/
  XMPP: nomeata at joachim-breitner.de • OpenPGP-Key: 0xF0FBF51F
  Debian Developer: nomeata at debian.org

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