Re: [sv-cc] DPI context - setting/preserving&resetting a scope

Subject: Re: [sv-cc] DPI context - setting/preserving&resetting a scope
From: Michael Rohleder (michael.rohleder@motorola.com)
Date: Thu Mar 13 2003 - 14:10:54 PST

Hello Andrzej,

thanks a lot for bringing this up. My comments are interspersed.

-Michael

Andrzej Litwiniuk wrote:

> Joao,
>
> Consider the folowing sequence of DPI calls (interleaved context and
> non-context functions):
> SV --> context_cfunc1 --> SV --> non_context_cfunc2 --> SV
>
> The scope set at the call of context_cfunc1 is preserved and that way
> still avaialble while non_context_cfunc2 is executed; we don't want
> to do anything with a scope (overhead!) for non-context calls, do we?

I don't think it makes sense to dive into such details. I would simply stay with banning calling SV functions from non-context
functions.

Calling SV from a non-context function is considered illegal and the result is therefore undefined. This should be also true, when
the context might be set by other means. Make it simple for users: if you call SV from a non-context function, you do something
illegal - that's it.

> I have no problem with such a scenario; I don't want to prohibit it.
> It simply makes the description of semantics more complicated.
> Because what's weird in this scenario, is that non-context function
> called from SV may successfully call an exported SV function.
> Of course, this could be viewed in a different way, too: a context function
> is allowed to call SV also indirectly, regardless whether a call chain goes
> thru SV functions and non-context functions, or not:
> SV --> context_cfunc1 --> ....... --> SV
> [transparent call chain]

Of course this is just true, if a context function is called at an earlier point in time. You can not control this, another user
might instantiate the corresponding SV function and call the DPI function without a context set. This would be a real problem and
hard to identify. At the end, it would compromise reuse. Not nice. 

--

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