Constant propagate addresses through NetRamDq read ports.

cprop.cc

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998-2003 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 1998-2006 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
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: cprop.cc,v 1.47.2.4 2005/09/11 02:50:51 steve Exp $"
+#ident "$Id: cprop.cc,v 1.47.2.5 2006/04/23 04:26:13 steve Exp $"
 #endif
 
 # include "config.h"
@@ -25,6 +25,7 @@
 # include  "netlist.h"
 # include  "netmisc.h"
 # include  "functor.h"
+# include  "compiler.h"
 # include  <assert.h>
 
 
@@ -48,6 +49,8 @@ struct cprop_functor  : public functor_t {
       virtual void lpm_logic(Design*des, NetLogic*obj);
       virtual void lpm_mux(Design*des, NetMux*obj);
       virtual void lpm_mux_large(Design*des, NetMux*obj);
+      virtual void lpm_ram_dq(Design*des, NetRamDq*obj);
+      bool lpm_ram_dq_const_address_(Design*des, NetRamDq*obj);
 };
 
 void cprop_functor::signal(Design*des, NetNet*obj)
@@ -1142,6 +1145,59 @@ void cprop_functor::lpm_mux_large(Design*des, NetMux*obj)
       count += 1;
 }
 
+void cprop_functor::lpm_ram_dq(Design*des, NetRamDq*obj)
+{
+      if (lpm_ram_dq_const_address_(des,obj))
+	    return;
+
+}
+
+/*
+ * Try to evaluate a constant address input. If we find it, then
+ * replace the NetRamDq with a direct link to the addressed word.
+ */
+bool cprop_functor::lpm_ram_dq_const_address_(Design*des, NetRamDq*obj)
+{
+      NetMemory*mem = obj->mem();
+      NetNet* reg = mem->reg_from_explode();
+
+	/* I only know how to do this on exploded memories. */
+      if (reg == 0)
+	    return false;
+
+      verinum sel (0UL, obj->awidth());
+      for (unsigned idx = 0 ;  idx < obj->awidth() ;  idx += 1) {
+	    if (! obj->pin_Address(idx).nexus()->drivers_constant())
+		  return false;
+
+	    sel.set(idx, obj->pin_Address(idx).nexus()->driven_value());
+      }
+
+      unsigned long address = sel.as_ulong();
+
+	/* If the address is outside the ram, then leave this to the
+	   code generator to figure out. */
+      if (address >= obj->size())
+	    return false;
+
+
+      unsigned base = address * obj->width();
+      assert(base+obj->width() <= reg->pin_count());
+
+      for (unsigned idx = 0 ;  idx < obj->width() ;  idx += 1)
+	    connect(reg->pin(base+idx), obj->pin_Q(idx));
+
+      if (debug_cprop) {
+	    cerr << obj->get_line() << ": debug: Replace read port with"
+		 << " fixed link to word " << address << "." << endl;
+      }
+
+      delete obj;
+      count += 1;
+      return true;
+}
+
+
 /*
  * This functor looks to see if the constant is connected to nothing
  * but signals. If that is the case, delete the dangling constant and
@@ -1260,6 +1316,9 @@ void cprop(Design*des)
 
 /*
  * $Log: cprop.cc,v $
+ * Revision 1.47.2.5  2006/04/23 04:26:13  steve
+ *  Constant propagate addresses through NetRamDq read ports.
+ *
  * Revision 1.47.2.4  2005/09/11 02:50:51  steve
  *  Fix overly agressive constant propagation through MUX causing lost Z bits.
  *

functor.cc

@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: functor.cc,v 1.32 2004/10/04 01:10:53 steve Exp $"
+#ident "$Id: functor.cc,v 1.32.2.1 2006/04/23 04:26:14 steve Exp $"
 #endif
 
 # include "config.h"
@@ -79,6 +79,9 @@ void functor_t::lpm_mux(class Design*, class NetMux*)
 {
 }
 
+void functor_t::lpm_ram_dq(class Design*, class NetRamDq*)
+{
+}
 
 void NetScope::run_functor(Design*des, functor_t*fun)
 {
@@ -206,6 +209,11 @@ void NetMux::functor_node(Design*des, functor_t*fun)
       fun->lpm_mux(des, this);
 }
 
+void NetRamDq::functor_node(Design*des, functor_t*fun)
+{
+      fun->lpm_ram_dq(des, this);
+}
+
 proc_match_t::~proc_match_t()
 {
 }
@@ -267,6 +275,9 @@ int proc_match_t::event_wait(NetEvWait*)
 
 /*
  * $Log: functor.cc,v $
+ * Revision 1.32.2.1  2006/04/23 04:26:14  steve
+ *  Constant propagate addresses through NetRamDq read ports.
+ *
  * Revision 1.32  2004/10/04 01:10:53  steve
  *  Clean up spurious trailing white space.
  *

functor.h

@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: functor.h,v 1.20 2002/08/12 01:34:59 steve Exp $"
+#ident "$Id: functor.h,v 1.20.2.1 2006/04/23 04:26:14 steve Exp $"
 #endif
 
 /*
@@ -77,6 +77,9 @@ struct functor_t {
 
 	/* This method is called for each MUX. */
       virtual void lpm_mux(class Design*des, class NetMux*);
+
+	/* This is called for eacm RamDq device. */
+      virtual void lpm_ram_dq(class Design*des, class NetRamDq*);
 };
 
 struct proc_match_t {
@@ -92,6 +95,9 @@ struct proc_match_t {
 
 /*
  * $Log: functor.h,v $
+ * Revision 1.20.2.1  2006/04/23 04:26:14  steve
+ *  Constant propagate addresses through NetRamDq read ports.
+ *
  * Revision 1.20  2002/08/12 01:34:59  steve
  *  conditional ident string using autoconfig.
  *

netlist.cc

@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: netlist.cc,v 1.226.2.6 2006/04/16 19:26:38 steve Exp $"
+#ident "$Id: netlist.cc,v 1.226.2.7 2006/04/23 04:26:14 steve Exp $"
 #endif
 
 # include "config.h"
@@ -1625,6 +1625,11 @@ unsigned NetRamDq::size() const
       return 0;
 }
 
+NetMemory* NetRamDq::mem()
+{
+      return mem_;
+}
+
 const NetMemory* NetRamDq::mem() const
 {
       return mem_;
@@ -2481,6 +2486,9 @@ const NetProc*NetTaskDef::proc() const
 
 /*
  * $Log: netlist.cc,v $
+ * Revision 1.226.2.7  2006/04/23 04:26:14  steve
+ *  Constant propagate addresses through NetRamDq read ports.
+ *
  * Revision 1.226.2.6  2006/04/16 19:26:38  steve
  *  Fix handling of exploded memories with partial or missing resets.
  *

netlist.h

@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: netlist.h,v 1.321.2.16 2006/04/16 19:26:38 steve Exp $"
+#ident "$Id: netlist.h,v 1.321.2.17 2006/04/23 04:26:14 steve Exp $"
 #endif
 
 /*
@@ -995,6 +995,8 @@ class NetRamDq  : public NetNode {
       unsigned width() const;
       unsigned awidth() const;
       unsigned size() const;
+
+      NetMemory*mem();
       const NetMemory*mem() const;
 
       Link& pin_InClock();
@@ -1025,6 +1027,8 @@ class NetRamDq  : public NetNode {
 	// that are ports to the attached memory.
       unsigned count_partners() const;
 
+      void functor_node(Design*des, functor_t*fun);
+
     private:
       NetMemory*mem_;
       NetRamDq*next_;
@@ -3524,6 +3528,9 @@ extern ostream& operator << (ostream&, NetNet::Type);
 
 /*
  * $Log: netlist.h,v $
+ * Revision 1.321.2.17  2006/04/23 04:26:14  steve
+ *  Constant propagate addresses through NetRamDq read ports.
+ *
  * Revision 1.321.2.16  2006/04/16 19:26:38  steve
  *  Fix handling of exploded memories with partial or missing resets.
  *