[M3devel] "looping to get all types declared first"

[Tony Hosking]

I don't understand the purpose of all this.  Can't you just maintain one global table mapping type id to type?

On Oct 31, 2010, at 12:43 AM, Jay K wrote:

> 
> There is this "replay" thing I put in the backend.
> It isn't quite right.
> 
> 
> I would like to have multiple passes, where if
> all the types haven't been declared yet, non-type-declaration
> operations do nothing.
> 
> There are approximately three approaches.
> 
> 1) the frontend front-loads all type declarations
> so as soon as non-type declaration seen, that is the end,
> ok to loop; I don't know if this is true.
> 
> 
> 2) in each operand implementation, check if all the types
>  have been declared yet and if not and if the operation
>  isn't a declaration, immediately return
>  This isn't entirely true. Some things like begin unit/procedure/block
>  need to do anything, to track lexical location for building
>  prefixes on type names, or somesuch.
> 
> Actually, I think all the type data structures might need
> to be in a linked list going from inner scope to outer scope
> and searches have to search them in order and take the first hit. ?
> 
> 
> 3) or, similarly, but the question is, do we loop
>  over the serialized form, or do we first deserialize
>  into an in-memory form, and then loop over that?
> 
> 
> Those are my main questions:
>   a) does the front end front-load declarations? I can trace a bit in cm3cg and guess.
>   b) if not, do people prefer multiple passes over the serialized form or
>   first deserialize into an in-memory form, and then loop over that
>   c) change frontend to front-load declarations
> 
> 
> My preference is b.
> It is isn't the most efficient, but the efficiency should be plenty adequate.
> 
> 
> I understand typeids are hashes, so scope is sort of irrelevant.
> But typenames specifically are scoped.
> 
> 
> - Jay