Handle indexed bit select of packed arrays.

This handles a few cases where the non-constant bit selects are
in the final index. This doesn't handle all the cases of packed
arrays, but it handles some common cases.

elab_expr.cc

@@ -3514,8 +3514,7 @@ NetExpr* PEIdent::elaborate_expr_net_bit_(Design*des, NetScope*scope,
 	// complicated task because we need to generate
 	// expressions to convert calculated bit select
 	// values to canonical values that are used internally.
-      assert(sig_packed.size() == 1);
-      mux = normalize_variable_base(mux, sig_packed, 1, true);
+      mux = normalize_variable_bit_base(prefix_indices, mux, net->sig());
 
       NetESelect*ss = new NetESelect(net, mux, 1);
       ss->set_line(*this);

elab_lval.cc

@@ -408,7 +408,7 @@ bool PEIdent::elaborate_lval_net_bit_(Design*des,
 	      // Non-constant bit mux. Correct the mux for the range
 	      // of the vector, then set the l-value part select
 	      // expression.
-	    mux = normalize_variable_base(mux, reg->packed_dims(), 1, true);
+	    mux = normalize_variable_bit_base(prefix_indices, mux, reg);
 	    lv->set_part(mux, 1);
 
       } else if (reg->vector_width() == 1 && reg->sb_is_valid(prefix_indices,lsb)) {

netmisc.cc

@@ -239,10 +239,13 @@ static unsigned num_bits(long arg)
 
 /*
  * This routine generates the normalization expression needed for a variable
- * bit select or a variable base expression for an indexed part select.
+ * bit select or a variable base expression for an indexed part
+ * select. This function doesn't actually look at the variable
+ * dimensions, it just does the final calculation using msb/lsb of the
+ * last slice, and the off of the slice in the variable.
  */
 NetExpr *normalize_variable_base(NetExpr *base, long msb, long lsb,
-                                 unsigned long wid, bool is_up)
+				 unsigned long wid, bool is_up, long soff)
 {
       long offset = lsb;
 
@@ -275,13 +278,13 @@ NetExpr *normalize_variable_base(NetExpr *base, long msb, long lsb,
                   base = tmp;
 	    }
 	      /* Normalize the expression. */
-	    base = make_sub_expr(offset, base);
+	    base = make_sub_expr(offset+soff, base);
       } else {
 	      /* Correct the offset if needed. */
 	    if (!is_up) offset += wid - 1;
 	      /* If the offset is zero then just return the base (index)
 	       * expression. */
-	    if (offset == 0) return base;
+	    if ((soff-offset) == 0) return base;
 	      /* Calculate the space needed for the offset. */
 	    unsigned min_wid = num_bits(-offset);
 	      /* We need enough space for the larger of the offset or the
@@ -304,7 +307,7 @@ NetExpr *normalize_variable_base(NetExpr *base, long msb, long lsb,
                   base = tmp;
 	    }
 	      /* Normalize the expression. */
-	    base = make_add_expr(base, -offset);
+	    base = make_add_expr(base, soff-offset);
       }
 
       return base;
@@ -325,6 +328,21 @@ NetExpr *normalize_variable_base(NetExpr *base,
       return normalize_variable_base(base, rng.msb, rng.lsb, wid, is_up);
 }
 
+NetExpr *normalize_variable_bit_base(const list<long>&indices, NetExpr*base,
+				     const NetNet*reg)
+{
+      const list<NetNet::range_t>&packed_dims = reg->packed_dims();
+      ivl_assert(*base, indices.size()+1 == packed_dims.size());
+
+	// Get the canonical offset of the slice within which we are
+	// addressing. We need that address as a slice offset to
+	// calculate the proper complete address
+      const NetNet::range_t&rng = packed_dims.back();
+      long slice_off = reg->sb_to_idx(indices, rng.lsb);
+
+      return normalize_variable_base(base, rng.msb, rng.lsb, 1, true, slice_off);
+}
+
 NetExpr *normalize_variable_slice_base(const list<long>&indices, NetExpr*base,
 				       const NetNet*reg, unsigned long&lwid)
 {

netmisc.h

@@ -99,10 +99,15 @@ extern NetNet*crop_to_width(Design*des, NetNet*n, unsigned w);
  * the provided vector/array information.
  */
 extern NetExpr*normalize_variable_base(NetExpr *base, long msb, long lsb,
-                                       unsigned long wid, bool is_up);
+                                       unsigned long wid, bool is_up,
+				       long slice_off =0);
 extern NetExpr*normalize_variable_base(NetExpr *base,
 				       const list<NetNet::range_t>&dims,
 				       unsigned long wid, bool is_up);
+
+extern NetExpr*normalize_variable_bit_base(const list<long>&indices, NetExpr *base,
+					   const NetNet*reg);
+
 extern NetExpr*normalize_variable_slice_base(const list<long>&indices, NetExpr *base,
 					     const NetNet*reg, unsigned long&lwid);
 extern NetExpr*normalize_variable_array_base(NetExpr *base, long offset,