RE: [sv-bc] Virtual interfaces in always_comb

I think such an interpretation of the longest static prefix subclause of the LRM (11.5.3) is arguable at best.

Shalom

________________________________
From: owner-sv-bc@server.eda.org [mailto:owner-sv-bc@server.eda.org] On Behalf Of Rich, Dave
Sent: Tuesday, September 08, 2009 1:07 AM
To: Daniel Mlynek; sv-bc@server.eda.org
Subject: RE: [sv-bc] Virtual interfaces in always_comb

I believe if you apply the principals of the longest static prefix rules, this is already illegal.

Dave


________________________________
From: owner-sv-bc@server.eda.org [mailto:owner-sv-bc@server.eda.org] On Behalf Of Daniel Mlynek
Sent: Monday, September 07, 2009 2:45 AM
To: sv-bc@server.eda.org
Subject: [sv-bc] Virtual interfaces in always_comb

Should virtual interfaces be allowed to be assigned in always_comb blocks? This leads to situation like below- vi1.i  nad vi2.i point the same output variable while this is forbidden for variable driven from always comb to be driven in other processes (lrm:  "The variables written on the left-hand side of assignments shall not be written to by any other process.". Such situation can be detected only on runtime.
As always_comb was added to be used in synthethisabe combitional processses maybe there should be a rule saying that this is forbidden to drive virtual interface drives (similar for class handles)


interface iface1;
 bit [7:0] i;
endinterface

module top;
  iface1 ifci1();
  virtual iface1 vi1 = ifci1, vi2 = ifci1; bit [7:0] ii1 = 1; bit [7:0]  ii2 = 2;

 always_comb
    vi1.i = ii1;

 always_comb
   vi2.i = ii2;

 initial #2 $finish;

endmodule



DANiel

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