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/*
* Copyright (c) 1999 Stephen Williams (steve@icarus.com)
*
* This source code is free software; you can redistribute it
* and/or modify it in source code form under the terms of the GNU
* General Public License as published by the Free Software
* Foundation; either version 2 of the License, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#ifdef HAVE_CVS_IDENT
#ident "$Id: nodangle.cc,v 1.19 2003/06/25 04:46:03 steve Exp $"
#endif

# include "config.h"

/*
* This functor scans the design looking for dangling objects and
* excess local signals. These deletions are not necessarily required
* for proper functioning of anything, but they can clean up the
* appearance of design files that are generated.
*/
# include "functor.h"
# include "netlist.h"
# include "compiler.h"

class nodangle_f : public functor_t {
    public:
      void event(Design*des, NetEvent*ev);
      void signal(Design*des, NetNet*sig);

      unsigned count_;
      unsigned stotal, etotal;
};

void nodangle_f::event(Design*des, NetEvent*ev)
{
/* If there are no references to this event, then go right
ahead and delete in. There is no use looking further at
it. */
      if ((ev->nwait() + ev->ntrig() + ev->nexpr()) == 0) {
delete ev;
etotal += 1;
return;
      }

/* Try to find all the events that are similar to me, and
replace their references with references to me. */
      list<NetEvent*> match;
      ev->find_similar_event(match);
      for (list<NetEvent*>::iterator idx = match.begin()
; idx != match.end() ; idx ++) {

NetEvent*tmp = *idx;
assert(tmp != ev);
tmp ->replace_event(ev);
      }

}

void nodangle_f::signal(Design*des, NetNet*sig)
{
/* Cannot delete signals referenced in an expression
or an l-value. */
      if (sig->get_refs() > 0)
return;

/* Cannot delete the ports of tasks or functions. There are
too many places where they are referenced. */
      if ((sig->port_type() != NetNet::NOT_A_PORT)
&& (sig->scope()->type() == NetScope::TASK))
return;

      if ((sig->port_type() != NetNet::NOT_A_PORT)
&& (sig->scope()->type() == NetScope::FUNC))
return;

/* Can't delete ports of cells. */
      if ((sig->port_type() != NetNet::NOT_A_PORT)
&& (sig->scope()->attribute("ivl_synthesis_cell") != verinum()))
return;

/* Check to see if the signal is completely unconnected. If
all the bits are unlinked, then delete it. */
      bool linked_flag = false;
      for (unsigned idx = 0 ; idx < sig->pin_count() ; idx += 1)
if (sig->pin(idx).is_linked()) {
linked_flag = true;
break;
}

      if (! linked_flag) {
delete sig;
stotal += 1;
return;
      }

/* The remaining things can only be done to synthesized
signals, not ones that appear in the original Verilog. */
      if (! sig->local_flag())
return;

/* Check to see if there is some significant signal connected
to every pin of this signal. */
      unsigned significant_flags = 0;
      for (unsigned idx = 0 ; idx < sig->pin_count() ; idx += 1) {
Nexus*nex = sig->pin(idx).nexus();

for (Link*cur = nex->first_nlink()
; cur ; cur = cur->next_nlink()) {

if (cur == &sig->pin(idx))
continue;

NetNet*cursig = dynamic_cast<NetNet*>(cur->get_obj());
if (cursig == 0)
continue;

if (cursig->local_flag())
continue;

significant_flags += 1;
break;
}

if (significant_flags <= idx)
break;
      }

/* If every pin is connected to another significant signal,
then I can delete this one. */
      if (significant_flags == sig->pin_count()) {
count_ += 1;
delete sig;
stotal += 1;
      }
}

void nodangle(Design*des)
{
      nodangle_f fun;
      unsigned count_iterations = 0;
      fun.stotal = 0;
      fun.etotal = 0;

      do {
fun.count_ = 0;
des->functor(&fun);
count_iterations += 1;

if (verbose_flag) {
cout << " ... " << count_iterations << " iterations"
<< " deleted " << fun.stotal << " dangling signals"
<< " and " << fun.etotal << " events."
<< " (count=" << fun.count_ << ")" << endl;
}

      } while (fun.count_ > 0);

}

/*
* $Log: nodangle.cc,v $
* Revision 1.19 2003/06/25 04:46:03 steve
* Do not elide ports of cells.
*
* Revision 1.18 2003/04/22 04:48:30 steve
* Support event names as expressions elements.
*
* Revision 1.17 2002/08/12 01:35:00 steve
* conditional ident string using autoconfig.
*
* Revision 1.16 2002/07/24 16:24:45 steve
* Rewrite find_similar_event to support doing
* all event matching and replacement in one
* shot, saving time in the scans.
*
* Revision 1.15 2002/05/26 01:39:02 steve
* Carry Verilog 2001 attributes with processes,
* all the way through to the ivl_target API.
*
* Divide signal reference counts between rval
* and lval references.
*
* Revision 1.14 2002/02/02 06:13:38 steve
* event find_similar should not find self.
*
* Revision 1.13 2001/07/27 02:41:55 steve
* Fix binding of dangling function ports. do not elide them.
*
* Revision 1.12 2001/07/25 03:10:49 steve
* Create a config.h.in file to hold all the config
* junk, and support gcc 3.0. (Stephan Boettcher)
*
* Revision 1.11 2001/02/17 05:14:35 steve
* Cannot elide task ports.
*
* Revision 1.10 2000/11/19 20:48:53 steve
* Killing some signals might make others killable.
*
* Revision 1.9 2000/11/18 05:12:45 steve
* Delete unreferenced signals no matter what.
*
* Revision 1.8 2000/06/25 19:59:42 steve
* Redesign Links to include the Nexus class that
* carries properties of the connected set of links.
*
* Revision 1.7 2000/05/31 02:26:49 steve
* Globally merge redundant event objects.
*
* Revision 1.6 2000/05/07 04:37:56 steve
* Carry strength values from Verilog source to the
* pform and netlist for gates.
*
* Change vvm constants to use the driver_t to drive
* a constant value. This works better if there are
* multiple drivers on a signal.
*
* Revision 1.5 2000/04/28 21:00:29 steve
* Over agressive signal elimination in constant probadation.
*
* Revision 1.4 2000/04/18 04:50:20 steve
* Clean up unneeded NetEvent objects.
*
* Revision 1.3 2000/02/23 02:56:55 steve
* Macintosh compilers do not support ident.
*
* Revision 1.2 1999/11/28 23:42:02 steve
* NetESignal object no longer need to be NetNode
* objects. Let them keep a pointer to NetNet objects.
*
* Revision 1.1 1999/11/18 03:52:20 steve
* Turn NetTmp objects into normal local NetNet objects,
* and add the nodangle functor to clean up the local
* symbols generated by elaboration and other steps.
*
*/
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