diff --git a/elaborate.cc b/elaborate.cc
index c37e28c30..7e4449dd8 100644
--- a/elaborate.cc
+++ b/elaborate.cc
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: elaborate.cc,v 1.363 2007/03/05 05:59:10 steve Exp $"
+#ident "$Id: elaborate.cc,v 1.364 2007/03/08 05:30:02 steve Exp $"
 #endif
 
 # include "config.h"
@@ -1442,8 +1442,9 @@ NetProc* PAssign::elaborate(Design*des, NetScope*scope) const
       bool unsized_flag = false;
       use_width = rval()->test_width(des, scope, use_width, use_width, unsized_flag);
 
-	/* Now elaborate to the expected width. */
-      NetExpr*rv = elab_and_eval(des, scope, rval(), use_width);
+	/* Now elaborate to the expected width. Pass the lwidth to
+	   prune any constant result to fit with the lvalue at hand. */
+      NetExpr*rv = elab_and_eval(des, scope, rval(), use_width, lv->lwidth());
       if (rv == 0) return 0;
       assert(rv);
 
@@ -3400,6 +3401,9 @@ Design* elaborate(list<perm_string>roots)
 
 /*
  * $Log: elaborate.cc,v $
+ * Revision 1.364  2007/03/08 05:30:02  steve
+ *  Limit the calculated widths of constants.
+ *
  * Revision 1.363  2007/03/05 05:59:10  steve
  *  Handle processes within generate loops.
  *
diff --git a/eval_tree.cc b/eval_tree.cc
index d2f74fc16..69a336555 100644
--- a/eval_tree.cc
+++ b/eval_tree.cc
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: eval_tree.cc,v 1.73 2007/01/16 05:44:15 steve Exp $"
+#ident "$Id: eval_tree.cc,v 1.74 2007/03/08 05:30:02 steve Exp $"
 #endif
 
 # include "config.h"
@@ -27,7 +27,7 @@
 
 # include  "netlist.h"
 
-NetExpr* NetExpr::eval_tree()
+NetExpr* NetExpr::eval_tree(int prune_to_width)
 {
       return 0;
 }
@@ -51,7 +51,7 @@ void NetEBinary::eval_sub_tree_()
       }
 }
 
-NetEConst* NetEBAdd::eval_tree()
+NetEConst* NetEBAdd::eval_tree(int prune_to_width)
 {
       eval_sub_tree_();
       NetEConst*lc = dynamic_cast<NetEConst*>(left_);
@@ -115,7 +115,7 @@ NetEConst* NetEBAdd::eval_tree()
       return 0;
 }
 
-NetEConst* NetEBBits::eval_tree()
+NetEConst* NetEBBits::eval_tree(int prune_to_width)
 {
       eval_sub_tree_();
 
@@ -690,7 +690,7 @@ NetEConst* NetEBComp::eval_neeqeq_()
       return res;
 }
 
-NetEConst* NetEBComp::eval_tree()
+NetEConst* NetEBComp::eval_tree(int prune_to_width)
 {
       eval_sub_tree_();
 
@@ -728,7 +728,7 @@ NetEConst* NetEBComp::eval_tree()
  * The NetEBDiv operator includes the / and % operators. First evaluate
  * the sub-expressions, then perform the required operation.
  */
-NetExpr* NetEBDiv::eval_tree()
+NetExpr* NetEBDiv::eval_tree(int prune_to_width)
 {
       eval_sub_tree_();
 
@@ -798,7 +798,7 @@ NetExpr* NetEBDiv::eval_tree()
       return 0;
 }
 
-NetEConst* NetEBLogic::eval_tree()
+NetEConst* NetEBLogic::eval_tree(int prune_to_width)
 {
       eval_sub_tree_();
       NetEConst*lc = dynamic_cast<NetEConst*>(left_);
@@ -917,7 +917,7 @@ NetExpr* NetEBMult::eval_tree_real_()
       return res;
 }
 
-NetExpr* NetEBMult::eval_tree()
+NetExpr* NetEBMult::eval_tree(int prune_to_width)
 {
       eval_sub_tree_();
 
@@ -990,7 +990,7 @@ NetExpr* NetEBPow::eval_tree_real_()
       return res;
 }
 
-NetExpr* NetEBPow::eval_tree()
+NetExpr* NetEBPow::eval_tree(int prune_to_width)
 {
       eval_sub_tree_();
 
@@ -1015,7 +1015,7 @@ NetExpr* NetEBPow::eval_tree()
  * Evaluate the shift operator if possible. For this to work, both
  * operands must be constant.
  */
-NetEConst* NetEBShift::eval_tree()
+NetEConst* NetEBShift::eval_tree(int prune_to_width)
 {
       eval_sub_tree_();
       NetEConst*re = dynamic_cast<NetEConst*>(right_);
@@ -1042,7 +1042,7 @@ NetEConst* NetEBShift::eval_tree()
 		  cerr << get_line() << ": debug: "
 		       << "Evaluate " << lv << "<<" << op() << ">> "
 		       << rv << ", wid=" << wid << ", shift=" << shift
-		       << ", lv.las_len()=" << lv.has_len() << endl;
+		       << ", lv.has_len()=" << lv.has_len() << endl;
 	    }
 
 	    if ((wid == 0) || ! lv.has_len()) {
@@ -1056,6 +1056,9 @@ NetEConst* NetEBShift::eval_tree()
 			wid = lv.len() + shift;
 	    }
 
+	    if (prune_to_width > 0 && wid > prune_to_width)
+		  wid = prune_to_width;
+
 	    assert(wid);
 	    verinum nv (verinum::V0, wid, lv.has_len());
 
@@ -1096,7 +1099,7 @@ NetEConst* NetEBShift::eval_tree()
       return res;
 }
 
-NetEConst* NetEConcat::eval_tree()
+NetEConst* NetEConcat::eval_tree(int prune_to_width)
 {
       unsigned repeat_val = repeat();
       unsigned local_errors = 0;
@@ -1190,7 +1193,7 @@ NetEConst* NetEConcat::eval_tree()
       return res;
 }
 
-NetExpr* NetEParam::eval_tree()
+NetExpr* NetEParam::eval_tree(int prune_to_width)
 {
       if (des_ == 0) {
 	    assert(scope_ == 0);
@@ -1297,7 +1300,7 @@ NetExpr* NetEParam::eval_tree()
       }
 }
 
-NetEConst* NetESelect::eval_tree()
+NetEConst* NetESelect::eval_tree(int prune_to_width)
 {
       NetEConst*expr = dynamic_cast<NetEConst*>(expr_);
       if (expr == 0) {
@@ -1370,7 +1373,7 @@ NetEConst* NetESelect::eval_tree()
  * evaluates to x or z, then merge the constant bits of the true and
  * false expressions.
  */
-NetExpr* NetETernary::eval_tree()
+NetExpr* NetETernary::eval_tree(int prune_to_width)
 {
       NetExpr*tmp;
 
@@ -1507,7 +1510,7 @@ void NetEUnary::eval_expr_()
       expr_ = oper;
 }
 
-NetEConst* NetEUnary::eval_tree()
+NetEConst* NetEUnary::eval_tree(int prune_to_width)
 {
       eval_expr_();
       NetEConst*rval = dynamic_cast<NetEConst*>(expr_);
@@ -1564,12 +1567,12 @@ NetEConst* NetEUnary::eval_tree()
 }
 
 
-NetEConst* NetEUBits::eval_tree()
+NetEConst* NetEUBits::eval_tree(int prune_to_width)
 {
-      return NetEUnary::eval_tree();
+      return NetEUnary::eval_tree(prune_to_width);
 }
 
-NetEConst* NetEUReduce::eval_tree()
+NetEConst* NetEUReduce::eval_tree(int prune_to_width)
 {
       eval_expr_();
       NetEConst*rval = dynamic_cast<NetEConst*>(expr_);
@@ -1652,6 +1655,9 @@ NetEConst* NetEUReduce::eval_tree()
 
 /*
  * $Log: eval_tree.cc,v $
+ * Revision 1.74  2007/03/08 05:30:02  steve
+ *  Limit the calculated widths of constants.
+ *
  * Revision 1.73  2007/01/16 05:44:15  steve
  *  Major rework of array handling. Memories are replaced with the
  *  more general concept of arrays. The NetMemory and NetEMemory
diff --git a/netlist.h b/netlist.h
index 9726f8bdd..4285b8755 100644
--- a/netlist.h
+++ b/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 1.371 2007/03/02 06:13:22 steve Exp $"
+#ident "$Id: netlist.h,v 1.372 2007/03/08 05:30:03 steve Exp $"
 #endif
 
 /*
@@ -1116,7 +1116,10 @@ class NetExpr  : public LineInfo {
 	// equivalent expression that is reduced as far as compile
 	// time knows how. Essentially, this is designed to fold
 	// constants.
-      virtual NetExpr*eval_tree();
+	//
+	// The prune_to_width is the maximum width that the result
+	// should be. If it is -1, then do not prune the result.
+      virtual NetExpr*eval_tree(int prune_to_width = -1);
 
 	// Make a duplicate of myself, and subexpressions if I have
 	// any. This is a deep copy operation.
@@ -2635,7 +2638,7 @@ class NetEBAdd : public NetEBinary {
 
       virtual bool set_width(unsigned w, bool last_chance);
       virtual NetEBAdd* dup_expr() const;
-      virtual NetEConst* eval_tree();
+      virtual NetEConst* eval_tree(int prune_to_width = -1);
       virtual NetNet* synthesize(Design*);
 };
 
@@ -2654,7 +2657,7 @@ class NetEBDiv : public NetEBinary {
 
       virtual bool set_width(unsigned w, bool last_chance);
       virtual NetEBDiv* dup_expr() const;
-      virtual NetExpr* eval_tree();
+      virtual NetExpr* eval_tree(int prune_to_width = -1);
       virtual NetNet* synthesize(Design*);
 };
 
@@ -2680,7 +2683,7 @@ class NetEBBits : public NetEBinary {
 
       virtual bool set_width(unsigned w, bool last_chance);
       virtual NetEBBits* dup_expr() const;
-      virtual NetEConst* eval_tree();
+      virtual NetEConst* eval_tree(int prune_to_width = -1);
 
       virtual NetNet* synthesize(Design*);
 };
@@ -2711,7 +2714,7 @@ class NetEBComp : public NetEBinary {
       virtual bool has_width() const;
       virtual ivl_variable_type_t expr_type() const;
       virtual NetEBComp* dup_expr() const;
-      virtual NetEConst* eval_tree();
+      virtual NetEConst* eval_tree(int prune_to_width = -1);
 
       virtual NetNet* synthesize(Design*);
 
@@ -2741,7 +2744,7 @@ class NetEBLogic : public NetEBinary {
 
       virtual bool set_width(unsigned w, bool last_chance);
       virtual NetEBLogic* dup_expr() const;
-      virtual NetEConst* eval_tree();
+      virtual NetEConst* eval_tree(int prune_to_width = -1);
       virtual NetNet* synthesize(Design*);
 
     private:
@@ -2761,7 +2764,7 @@ class NetEBMult : public NetEBinary {
 
       virtual bool set_width(unsigned w, bool last_chance);
       virtual NetEBMult* dup_expr() const;
-      virtual NetExpr* eval_tree();
+      virtual NetExpr* eval_tree(int prune_to_width = -1);
       virtual NetNet* synthesize(Design*);
 
     private:
@@ -2783,7 +2786,7 @@ class NetEBPow : public NetEBinary {
 
       virtual bool set_width(unsigned w, bool last_chance);
       virtual NetEBPow* dup_expr() const;
-      virtual NetExpr* eval_tree();
+      virtual NetExpr* eval_tree(int prune_to_width = -1);
       virtual NetNet* synthesize(Design*);
 
     private:
@@ -2814,7 +2817,7 @@ class NetEBShift : public NetEBinary {
       virtual bool has_width() const;
 
       virtual NetEBShift* dup_expr() const;
-      virtual NetEConst* eval_tree();
+      virtual NetEConst* eval_tree(int prune_to_width = -1);
 
       virtual NetNet* synthesize(Design*);
 
@@ -2849,7 +2852,7 @@ class NetEConcat  : public NetExpr {
       virtual bool has_width() const;
       virtual bool set_width(unsigned w, bool last_chance =false);
       virtual NetEConcat* dup_expr() const;
-      virtual NetEConst*  eval_tree();
+      virtual NetEConst*  eval_tree(int prune_to_width = -1);
       virtual NetNet*synthesize(Design*);
       virtual void expr_scan(struct expr_scan_t*) const;
       virtual void dump(ostream&) const;
@@ -2881,7 +2884,7 @@ class NetEParam  : public NetExpr {
       virtual bool set_width(unsigned w, bool last_chance);
       virtual bool has_width() const;
       virtual void expr_scan(struct expr_scan_t*) const;
-      virtual NetExpr* eval_tree();
+      virtual NetExpr* eval_tree(int prune_to_width = -1);
       virtual NetEParam* dup_expr() const;
 
       virtual void dump(ostream&) const;
@@ -2920,7 +2923,7 @@ class NetESelect  : public NetExpr {
       virtual bool set_width(unsigned w, bool last_chance =false);
       virtual bool has_width() const;
       virtual void expr_scan(struct expr_scan_t*) const;
-      virtual NetEConst* eval_tree();
+      virtual NetEConst* eval_tree(int prune_to_width = -1);
       virtual NetESelect* dup_expr() const;
       virtual NetNet*synthesize(Design*des);
       virtual void dump(ostream&) const;
@@ -3030,7 +3033,7 @@ class NetETernary  : public NetExpr {
       const NetExpr*false_expr() const;
 
       virtual NetETernary* dup_expr() const;
-      virtual NetExpr* eval_tree();
+      virtual NetExpr* eval_tree(int prune_to_width = -1);
 
       virtual ivl_variable_type_t expr_type() const;
       virtual NexusSet* nex_input();
@@ -3071,7 +3074,7 @@ class NetEUnary  : public NetExpr {
       virtual bool set_width(unsigned w, bool last_chance);
 
       virtual NetEUnary* dup_expr() const;
-      virtual NetEConst* eval_tree();
+      virtual NetEConst* eval_tree(int prune_to_width = -1);
 
       virtual ivl_variable_type_t expr_type() const;
       virtual NexusSet* nex_input();
@@ -3093,7 +3096,7 @@ class NetEUBits : public NetEUnary {
 
       virtual NetNet* synthesize(Design*);
 
-      virtual NetEConst* eval_tree();
+      virtual NetEConst* eval_tree(int prune_to_width = -1);
       virtual ivl_variable_type_t expr_type() const;
 };
 
@@ -3106,7 +3109,7 @@ class NetEUReduce : public NetEUnary {
       virtual bool set_width(unsigned w, bool last_chance);
       virtual NetNet* synthesize(Design*);
       virtual NetEUReduce* dup_expr() const;
-      virtual NetEConst* eval_tree();
+      virtual NetEConst* eval_tree(int prune_to_width = -1);
       virtual ivl_variable_type_t expr_type() const;
 };
 
@@ -3492,6 +3495,9 @@ extern ostream& operator << (ostream&, NetNet::Type);
 
 /*
  * $Log: netlist.h,v $
+ * Revision 1.372  2007/03/08 05:30:03  steve
+ *  Limit the calculated widths of constants.
+ *
  * Revision 1.371  2007/03/02 06:13:22  steve
  *  Add support for edge sensitive spec paths.
  *
diff --git a/netmisc.cc b/netmisc.cc
index df99fa5d7..fc9083fda 100644
--- a/netmisc.cc
+++ b/netmisc.cc
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: netmisc.cc,v 1.12 2006/06/02 04:48:50 steve Exp $"
+#ident "$Id: netmisc.cc,v 1.13 2007/03/08 05:30:03 steve Exp $"
 #endif
 
 # include "config.h"
@@ -124,13 +124,13 @@ NetExpr* make_sub_expr(long val, NetExpr*expr)
 }
 
 NetExpr* elab_and_eval(Design*des, NetScope*scope,
-		       const PExpr*pe, int expr_wid)
+		       const PExpr*pe, int expr_wid, int prune_width)
 {
       NetExpr*tmp = pe->elaborate_expr(des, scope, expr_wid, false);
       if (tmp == 0)
 	    return 0;
 
-      if (NetExpr*tmp2 = tmp->eval_tree()) {
+      if (NetExpr*tmp2 = tmp->eval_tree(prune_width)) {
 	    delete tmp;
 	    tmp = tmp2;
       }
@@ -141,6 +141,9 @@ NetExpr* elab_and_eval(Design*des, NetScope*scope,
 
 /*
  * $Log: netmisc.cc,v $
+ * Revision 1.13  2007/03/08 05:30:03  steve
+ *  Limit the calculated widths of constants.
+ *
  * Revision 1.12  2006/06/02 04:48:50  steve
  *  Make elaborate_expr methods aware of the width that the context
  *  requires of it. In the process, fix sizing of the width of unary
diff --git a/netmisc.h b/netmisc.h
index 21e8978d7..b20e1f822 100644
--- a/netmisc.h
+++ b/netmisc.h
@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: netmisc.h,v 1.28 2007/02/26 19:49:49 steve Exp $"
+#ident "$Id: netmisc.h,v 1.29 2007/03/08 05:30:03 steve Exp $"
 #endif
 
 # include  "netlist.h"
@@ -112,14 +112,22 @@ extern unsigned count_lval_width(const class NetAssign_*first);
  * it can. If the expression cannot be elaborated, return 0.
  *
  * The expr_width is the width of the context where the expression is
- * being elaborated, or -1 if the expression is self-determinted width.
+ * being elaborated, or -1 if the expression is self-determined width.
+ *
+ * Also, the prune_width is the maximum width of the result, and it
+ * passed to the eval_tree method of the expression to limit constant
+ * results if possible.
  */
 class PExpr;
 extern NetExpr* elab_and_eval(Design*des, NetScope*scope,
-			      const PExpr*pe, int expr_wid);
+			      const PExpr*pe, int expr_wid,
+			      int prune_width =-1);
 
 /*
  * $Log: netmisc.h,v $
+ * Revision 1.29  2007/03/08 05:30:03  steve
+ *  Limit the calculated widths of constants.
+ *
  * Revision 1.28  2007/02/26 19:49:49  steve
  *  Spelling fixes (larry doolittle)
  *