Improved fix for GitHub issue #112.

This does a better job of setting the intermediate expression types
and widths when calculating the canonical index into a packed array.
It still doesn't properly handle out-of-bound indices (br953).

netmisc.cc

@@ -203,7 +203,7 @@ static NetExpr* make_add_expr(NetExpr*expr, long val)
       }
 
       verinum val_v (val, expr->expr_width());
-      val_v.has_sign(true);
+      val_v.has_sign(expr->has_sign());
 
       NetEConst*val_c = new NetEConst(val_v);
       val_c->set_line(*expr);
@@ -236,7 +236,7 @@ static NetExpr* make_add_expr(const LineInfo*loc, NetExpr*expr1, NetExpr*expr2)
 static NetExpr* make_sub_expr(long val, NetExpr*expr)
 {
       verinum val_v (val, expr->expr_width());
-      val_v.has_sign(true);
+      val_v.has_sign(expr->has_sign());
 
       NetEConst*val_c = new NetEConst(val_v);
       val_c->set_line(*expr);
@@ -254,7 +254,7 @@ static NetExpr* make_sub_expr(long val, NetExpr*expr)
 static NetExpr* make_sub_expr(NetExpr*expr, long val)
 {
       verinum val_v (val, expr->expr_width());
-      val_v.has_sign(true);
+      val_v.has_sign(expr->has_sign());
 
       NetEConst*val_c = new NetEConst(val_v);
       val_c->set_line(*expr);
@@ -268,7 +268,7 @@ static NetExpr* make_sub_expr(NetExpr*expr, long val)
 
 
 /*
- * Multiple an existing expression by a signed positive number.
+ * Multiply an existing expression by a signed positive number.
  * This does a lossless multiply, so the arguments will need to be
  * sized to match the output size.
  */
@@ -277,7 +277,7 @@ static NetExpr* make_mult_expr(NetExpr*expr, unsigned long val)
       const unsigned val_wid = ceil(log2((double)val)) ;
       unsigned use_wid = expr->expr_width() + val_wid;
       verinum val_v (val, use_wid);
-      val_v.has_sign(true);
+      val_v.has_sign(expr->has_sign());
 
       NetEConst*val_c = new NetEConst(val_v);
       val_c->set_line(*expr);
@@ -457,23 +457,35 @@ NetExpr *normalize_variable_slice_base(const list<long>&indices, NetExpr*base,
       long loff;
       reg->sb_to_slice(indices, sb, loff, lwid);
 
-	/* Calculate the space needed for the offset. */
-      unsigned min_wid = num_bits(-loff);
-	/* We need enough space for the larger of the offset or the
-	 * base expression. */
-      if (min_wid < base->expr_width()) min_wid = base->expr_width();
-	/* Pad the base expression to the correct width. */
+      unsigned min_wid = base->expr_width();
+      if ((sb < 0) && !base->has_sign()) min_wid += 1;
+      if (min_wid < num_bits(pcur->get_lsb())) min_wid = pcur->get_lsb();
+      if (min_wid < num_bits(pcur->get_msb())) min_wid = pcur->get_msb();
       base = pad_to_width(base, min_wid, *base);
+      if ((sb < 0) && !base->has_sign()) {
+	    NetESelect *tmp = new NetESelect(base, 0 , min_wid);
+	    tmp->set_line(*base);
+	    tmp->cast_signed(true);
+            base = tmp;
+      }
 
       if (pcur->get_msb() >= pcur->get_lsb()) {
 	    if (pcur->get_lsb() != 0)
 		  base = make_sub_expr(base, pcur->get_lsb());
 	    base = make_mult_expr(base, lwid);
+	    min_wid = base->expr_width();
+	    if (min_wid < num_bits(loff)) min_wid = num_bits(loff);
+	    if (loff != 0) min_wid += 1;
+	    base = pad_to_width(base, min_wid, *base);
 	    base = make_add_expr(base, loff);
       } else {
 	    if (pcur->get_msb() != 0)
 		  base = make_sub_expr(base, pcur->get_msb());
 	    base = make_mult_expr(base, lwid);
+	    min_wid = base->expr_width();
+	    if (min_wid < num_bits(loff)) min_wid = num_bits(loff);
+	    if (loff != 0) min_wid += 1;
+	    base = pad_to_width(base, min_wid, *base);
 	    base = make_sub_expr(loff, base);
       }
       return base;