RE: [sv-bc] mantis item 3608

In the case of parameters, a hierarchical reference is not allowed as part of a constant_expression, and would not be allowed there.

But is there any problem with non-forward member selects in parameters?

Shalom

> -----Original Message-----
> From: Gordon Vreugdenhil [mailto:gordonv@model.com]
> Sent: Tuesday, June 14, 2011 6:31 PM
> To: Francoise Martinolle
> Cc: Bresticker, Shalom; brad_pierce@acm.org; SV-BC
> Subject: Re: [sv-bc] mantis item 3608
>
> Francoise,
>
> I think this should be illegal based on the current LRM rules.
>
> The rules for a dotted name say that the first name resolves as a
> bare identifier. If it isn't found, the dotted name becomes a
> hierarchical reference. But a hierarchical reference must start
> with a scope name, not a variable name. So the hierarchical
> resolution should fail. If you preceded the name with the
> module name then it would be legal (as would any
> "forward" variable reference in that case) as the first name
> would then be a scope name.
>
> Gord.
>
> On 6/14/2011 8:26 AM, Francoise Martinolle wrote:
> > Both are issues.
> > The first one is that the dotted name resolution only talks about
> variables. It should
> > also apply to parameters and nets.
> > The description in that section does not specify which declarations a
> dotted name can bound to.
> > It is not clear if the text allows forward references for variables.
> >
> > For example, is this legal?
> > Ex1: fwd decl of variables
> > module top;
> > typedef struct {int m; } S;
> >
> > logic [31:0] v = w.m;
> > S w;
> >
> > endmodule
> >
> > In Verilog no forward references where allowed for any data object.
> > With the introduction of type parameters, resolving a name or a dotted
> name defers the resolution until
> > elaboration. At that point, the symbol tables are filled in and a simple
> look up mechanism may
> > find declarations after use.
> >
> > Ex2: fwd declaration of variables
> > module top;
> > typedef struct {int m; } S;
> > parameter type T = S;
> > logic [31:0] v = w.m;
> > T w;
> > endmodule
> >
> > If we allow fwd references then in the example below p.m would resolve to
> the variable p in g1
> > instead of parameter p in top.
> > Ex3:
> > ------------------------------------------------------------
> > module top;
> > typedef struct packed {int m; } S;
> > parameter S p = '{1};
> >
> > generate
> > if (1) begin : g1
> > var v2 = p.m; // does p resolves to top.p or g1.p?
> > var S p;
> > end
> > endgenerate
> > endmodule
> > --------------------------------------------------------------
> >
> > Ex4: Class testcase:
> > Type parameters delay the name resolution until the type parameter is
> resolved.
> > The simple name lookup will find the member p in class D which is declared
> after the reference to p.m
> >
> > package pkg;
> > class C;
> > int p;
> > endclass
> >
> > endpackage
> >
> > module top;
> > import pkg::*;
> > parameter type T = C;
> > typedef struct packed {int m; } S;
> > class D extends T;
> > login [31:0] v = p.m; // Does p resolves to p in C or p in D?
> > S p;
> > endclass
> > endmodule
> >
> >
> > Francoise
> > '
> >
> >
> > -----Original Message-----
> > From: Bresticker, Shalom [mailto:shalom.bresticker@intel.com]
> > Sent: Tuesday, June 14, 2011 7:55 AM
> > To: brad_pierce@acm.org; Francoise Martinolle
> > Cc: SV-BC
> > Subject: RE: [sv-bc] mantis item 3608
> >
> > See also Mantis 1235.
> >
> > Also, looking at the notes in 3608, is the issue member selects or is it
> forward references?
> >
> > Regards,
> > Shalom
> >
> >> -----Original Message-----
> >> From: owner-sv-bc@eda.org [mailto:owner-sv-bc@eda.org] On Behalf Of
> >> Brad Pierce
> >> Sent: Monday, June 13, 2011 6:24 PM
> >> To: Francoise Martinolle
> >> Cc: SV-BC
> >> Subject: Re: [sv-bc] mantis item 3608
> >>
> >> Can we say instead 'data object'? According to 6.2, "A data object is
> >> a named entity that has a data value and a data type associated with
> >> it, such as a parameter, a variable, or a net."
> >>
> >> -- Brad
> >>
> >> On Mon, Jun 13, 2011 at 6:34 AM, Francoise Martinolle<fm@cadence.com>
> >> wrote:
> >>> I created a mantis item and put a proposal for 3608.
> >>>
> >>> Can this mantis item be added to the next meeting agenda.
> >>> Francoise
> >>> '
> >>> --
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> Model Technology (Mentor Graphics) gordonv@model.com

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