Re: [sv-bc] @* vs. always_comb

Gordon Vreugdenhil wrote:
> 
> I don't know how much detail I can talk about here.  But in general,
> if you consider the static prefix rules, the LRM requires you to
> be sensitive to *all* subelements (the expansion) of a prefix.  The
> determination of the prefix depends on the LRM definition of
> constantness.  If there are things that synthesis might treat as
> constant that fall outside the LRM definition, then the synthesis
> results (the actual topology) would not include connectivity that the
> simulation would be sensitive to.  This can cause simulation/synthesis
> mismatches.

<blush>

Bad example -- obviously that isn't an issue since if the logic
is actually combinational, having additional simulation time
evaluations won't change the results.

It may indeed be that for combinational logic we may just have
a superset of synthesized behavior accepted for simulation
(i.e. that there are blocks that are simulatable using always_comb
that aren't synthesizable) which is not really an issue.

Let me have a bit more coffee first...

Gord.

-- 
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Gordon Vreugdenhil                                503-685-0808
Model Technology (Mentor Graphics)                gordonv@model.com