[m-rev.] for possible post-commit review: mlds_env_defn

[Julien Fischer]

On Fri, 14 Jul 2023, Zoltan Somogyi wrote:

> Since this diff deletes the only use of the put_nondet_env_on_heap
> option, would anyone object if I deleted it? It is not publicly documented.

No, go ahead and delete it.


> Represent environments using a bespoke type.

...


> diff --git a/compiler/mlds.m b/compiler/mlds.m
> index 9bd675bec..2a8de1a7a 100644
> --- a/compiler/mlds.m
> +++ b/compiler/mlds.m
> @@ -667,6 +668,51 @@
>                  mecd_ctors          :: list(mlds_function_defn)
>              ).
> 
> +    % The environment structure we use to package up the local variables
> +    % needed by model_non continuations.
> +    %
> +:- type mlds_env_defn
> +    --->    mlds_env_defn(
> +                med_env_name        :: string,
> +                med_context         :: prog_context,
> +
> +                med_field_vars      :: list(mlds_field_var_defn)
> +                % The field vars, both those representing HLDS variables
> +                % and those implementing accurate gc. Both kind will

s/kind/kinds/

> +                % always have flags per_instance, modifiable.
> +
> +                % The following comments specify the relationship between
> +                % this type and mlds_class_defn (from which mlds_env_defn
> +                % was derived).
> +                %
> +                % Environment structures never have any type parameters.
> +                % This means that their "arity" is always zero.
> +                % (We do include the _0 suffix in their names in the
> +                % C/C#/Java code we generate, at least for now.)
> +                %
> +                % We treat environment structures as structs when targeting C,
> +                % and as classes when targeting C# or Java.
> +                %
> +                % Environments structures inherit nothing when targeting C,
> +                % but inherit the generic env_ptr type when targeting C# or
> +                % Java.
> +                %
> +                % Environment structures are always class_private,
> +                % overridable, and modifiable.
> +                % XXX The overridable part is probably just an accident.
> +                % It is certainly irrelevant, because (a) users cannot create
> +                % references to environment structures, so they cannot possibly
> +                % inherit from it, and (b) the compiler itself never tries
> +                % to inherit from them either.

Agreed.

That's fine otherwise.

Julien.