[Haskell-cafe] GHC debug plugin

[Daneel Yaitskov]

On Sun, Dec 12, 2021 at 3:54 PM Vanessa McHale <vamchale at gmail.com> wrote:

> Have you tried the -xc flag yet?
>
> Thanks for -xc option. Does program run without CPU overhead when -xc is
off? I see that object file must be bigger, but CPU/RAM requirement is not
clear.
-xc has an issue <https://gitlab.haskell.org/ghc/ghc/-/issues/20536> I
encountered recently. Some libraries (e.g. directory) use exceptions for
normal control flow.
So lots of stack traces could be produced. There is no control over what
exception stack trace should be displayed.
The app is based on a Haskell interpreter to run user scripts.
It would be hard to understand such output for users.

If you do a profiling build and then run your program with +RTS -xc it will
> give a stack trace on exceptions.
>
> (I think your idea still has some content but ^ is easier because it
> already exists!)
> On 12/12/21 2:01 PM, Daneel Yaitskov wrote:
>
> Hi,
>
> I would like to enable stack traces at launch time and run program without
> HasCallStack overhead by default.
> I've got an idea to use GHC plugin which would duplicate all functions in
> modules with specified prefix. Duplicated functions should get
> disambiguating prefix (e.g. "debug") and HasCallStack constraint. Bodies of
> prefixed functions should be rewritten to use prefixed functions from
> matching modules (should be easy to do - hook just after renaming GHC phase
> when all names are fully qualified?).
>
> This way main function could choose "runLib" or "debugRunLib".
>
> Did anybody make something similar?
>
>
>
> --
>
> Best regards,
> Daniil Iaitskov
>
>
>
>
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-- 

Best regards,
Daniil Iaitskov
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