This would be a sensible thing to be able to count with -ticky. Not hard to add either.
(Richard is asking for number of allocations, not what is live at any moment.)
Simon
| -----Original Message-----
| From: ghc-devs On Behalf Of Richard
| Eisenberg
| Sent: 23 May 2020 13:59
| To: GHC developers
| Subject: profiling a constructor?
|
| Hi devs,
|
| Is there a way to count the number of times a particular constructor is
| allocated? I might want to know, say, the total number of cons cells
| allocated over the course of a program, or (in my actual case) the total
| number of FunTy cells allocated over the course of a program.
|
| I can try to do this with an SCC. But it's very clunky:
| * The constructor may be used in a number of places; each such place
| would need the SCC.
| * SCCs can interfere with optimizations. In my use case, this would
| negate the usefulness of the exercise entirely, as I think some of the
| structures I wish to observe should never come into being, due to
| optimizations (e.g. case-of-known-constructor after inlining).
|
| Surely, the RTS must be able to count the number of times a constructor
| is used. But is there any way to access such a feature? If others agree
| that this would sometimes be helpful, perhaps we can build the feature.
| Now is not the first time I've wanted this.
|
| Thanks!
| Richard
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