Debugging specialization

[Simon Peyton Jones]

Hi Alexis

|  I am trying to understand why GHC is not specializing an imported
|  INLINABLE instance method, and the information provided by -ddump-spec -
|  Wall-missed-specialisations has not been enough to help me figure it out.
|  Is there some easy/well-trodden way that I could build GHC with some
|  additional instrumentation in place to help me better understand the
|  decisions being made by the specializer, or is -ddump-spec the most
|  granularity available?

I'm afraid those are all the flags we currently have, yes.

|  I’ve noticed that Specialise.hs has handful of pprTrace calls sprinkled
|  about, but they are all commented out. Is the recommended method to just
|  uncomment these calls and rebuild GHC?

That's what I do.

But it would be better to stand back a bit and ask "what information would I really like to see?" and then design some logging mechanism to show it.  I'd be happy to advise.

Simon

|  -----Original Message-----
|  From: ghc-devs <ghc-devs-bounces at haskell.org> On Behalf Of Alexis King
|  Sent: 24 October 2019 18:13
|  To: ghc-devs at haskell.org
|  Subject: Debugging specialization
|  
|  Hi all,
|  
|  I am trying to understand why GHC is not specializing an imported
|  INLINABLE instance method, and the information provided by -ddump-spec -
|  Wall-missed-specialisations has not been enough to help me figure it out.
|  Is there some easy/well-trodden way that I could build GHC with some
|  additional instrumentation in place to help me better understand the
|  decisions being made by the specializer, or is -ddump-spec the most
|  granularity available?
|  
|  I’ve noticed that Specialise.hs has handful of pprTrace calls sprinkled
|  about, but they are all commented out. Is the recommended method to just
|  uncomment these calls and rebuild GHC?
|  
|  Thanks,
|  Alexis
|  
|  _______________________________________________
|  ghc-devs mailing list
|  ghc-devs at haskell.org
|  https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fmail.hask
|  ell.org%2Fcgi-bin%2Fmailman%2Flistinfo%2Fghc-
|  devs&data=02%7C01%7Csimonpj%40microsoft.com%7C000a160e4f6a40bdf56208d7
|  58a57f63%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637075340144181354&a
|  mp;sdata=uPk4mfRrgGE5t6SQpXZyfU0xQ%2F6d9BlM50I3%2FmYcyms%3D&reserved=0