Merge pull request #799 from larsclausen/foreach-omit

Allow to omit dimensions in foreach loop

elaborate.cc

@@ -5379,9 +5379,6 @@ NetProc* PForeach::elaborate_static_array_(Design*des, NetScope*scope,
 		 << "Handle as array with static dimensions." << endl;
       }
 
-      ivl_assert(*this, index_vars_.size() > 0);
-      ivl_assert(*this, dims.size() >= index_vars_.size());
-
       NetProc*sub;
       if (statement_)
 	    sub = statement_->elaborate(des, scope);
@@ -5389,9 +5386,23 @@ NetProc* PForeach::elaborate_static_array_(Design*des, NetScope*scope,
 	    sub = new NetBlock(NetBlock::SEQU, 0);
       NetForLoop*stmt = 0;
 
+      if (index_vars_.size() > dims.size()) {
+	    delete sub;
+	    cerr << get_fileline() << ": error: Number of foreach loop variables"
+	         << "(" << index_vars_.size() << ") must not exceed number of "
+		 << "array dimensions (" << dims.size() << ")." << endl;
+	    des->errors++;
+	    return nullptr;
+      }
+
       for (int idx_idx = index_vars_.size()-1 ; idx_idx >= 0 ; idx_idx -= 1) {
 	    const netrange_t&idx_range = dims[idx_idx];
 
+	      // It is possible to skip dimensions by not providing a identifier
+	      // name for it. E.g. `int x[1][2][3]; foreach(x[a,,b]) ...`
+	    if (index_vars_[idx_idx].nil())
+		  continue;
+
 	      // Get the $high and $low constant values for this slice
 	      // of the array.
 	    NetEConst*hig_expr = make_const_val_s(idx_range.get_msb());
@@ -5430,7 +5441,13 @@ NetProc* PForeach::elaborate_static_array_(Design*des, NetScope*scope,
 	    sub = stmt;
       }
 
-      return stmt? stmt : sub;
+        // If there are no loop variables elide the whole block
+      if (!stmt) {
+	    delete sub;
+	    return new NetBlock(NetBlock::SEQU, 0);
+      }
+
+      return stmt;
 }
 
 /*

ivtest/gold/sv_foreach8.gold

@@ -0,0 +1,9 @@
+          0          0
+          0          1
+          0          2
+          0          3
+          1          0
+          1          1
+          1          2
+          1          3
+PASSED

ivtest/ivltests/sv_foreach6.v

@@ -0,0 +1,21 @@
+// Check that foreach loops without an index list work as expected. This is not
+// particularly useful, but it is legal code.
+
+module test;
+
+  logic a[10];
+  int i = 0;
+
+  initial begin
+    foreach(a[]) begin
+      i++;
+    end
+
+    if (i == 0) begin
+      $display("PASSED");
+    end else begin
+      $display("FAILED");
+    end
+  end
+
+endmodule

ivtest/ivltests/sv_foreach7.v

@@ -0,0 +1,21 @@
+// Check that foreach loops with only empty indices works as expected. This is
+// not particularly useful, but it is legal code.
+
+module test;
+
+  logic a[2][3][4];
+  int i = 0;
+
+  initial begin
+    foreach(a[,,]) begin
+      i++;
+    end
+
+    if (i == 0) begin
+      $display("PASSED");
+    end else begin
+      $display("FAILED");
+    end
+  end
+
+endmodule

ivtest/ivltests/sv_foreach8.v

@@ -0,0 +1,22 @@
+// Check that it is possible to omit a dimensions in a foreach loop by not
+// specifying a loop identifiers for the dimension.
+
+module test;
+
+  logic a[2][3][4];
+  int k = 0;
+
+  initial begin
+    foreach(a[i,,j]) begin
+      $display(i, j);
+      k++;
+    end
+
+    if (k == 8) begin
+      $display("PASSED");
+    end else begin
+      $display("FAILED");
+    end
+  end
+
+endmodule

ivtest/ivltests/sv_foreach_fail1.v

@@ -0,0 +1,14 @@
+// Check that an error is reported if the number of loop indices exceeds the
+// number of array dimensions in a foreach loop.
+
+module test;
+
+  logic a[10];
+
+  initial begin
+    foreach(a[i,j]) begin
+      $display("FAILED");
+    end
+  end
+
+endmodule

ivtest/regress-sv.list

@@ -600,6 +600,10 @@ sv_foreach2		normal,-g2009		ivltests
 sv_foreach3		normal,-g2009		ivltests
 sv_foreach4		normal,-g2009		ivltests
 sv_foreach5		normal,-g2009		ivltests
+sv_foreach6		normal,-g2009		ivltests
+sv_foreach7		normal,-g2009		ivltests
+sv_foreach8		normal,-g2009		ivltests gold=sv_foreach8.gold
+sv_foreach_fail1	CE,-g2009		ivltests
 sv_immediate_assert	normal,-g2009		ivltests gold=sv_immediate_assert.gold
 sv_immediate_assume	normal,-g2009		ivltests gold=sv_immediate_assume.gold
 sv_macro		normal,-g2009		ivltests

ivtest/regress-vlog95.list

@@ -954,6 +954,9 @@ struct_signed		normal,-g2009,-pallowsigned=1	ivltests
 sv_for_variable  normal,-g2009,-pallowsigned=1	ivltests
 sv_foreach1		normal,-g2009,-pallowsigned=1	ivltests
 sv_foreach5		normal,-g2009,-pallowsigned=1	ivltests
+sv_foreach6		normal,-g2009,-pallowsigned=1	ivltests
+sv_foreach7		normal,-g2009,-pallowsigned=1	ivltests
+sv_foreach8		normal,-g2009,-pallowsigned=1	ivltests
 sv_package		normal,-g2009,-pallowsigned=1	ivltests
 sv_package2		normal,-g2009,-pallowsigned=1	ivltests
 sv_package5		normal,-g2009,-pallowsigned=1	ivltests

parse.y

@@ -1799,12 +1799,22 @@ loop_variables /* IEEE1800-2005: A.6.8 */
 	delete[]$3;
 	$$ = tmp;
       }
+  | loop_variables ','
+      { std::list<perm_string>*tmp = $1;
+	tmp->push_back(perm_string());
+	$$ = tmp;
+      }
   | IDENTIFIER
       { std::list<perm_string>*tmp = new std::list<perm_string>;
 	tmp->push_back(lex_strings.make($1));
 	delete[]$1;
 	$$ = tmp;
       }
+  |
+      { std::list<perm_string>*tmp = new std::list<perm_string>;
+	tmp->push_back(perm_string());
+	$$ = tmp;
+      }
   ;
 
 method_qualifier /* IEEE1800-2005: A.1.8 */

pform.cc

@@ -994,6 +994,8 @@ void pform_make_foreach_declarations(const struct vlltype&loc,
       list<decl_assignment_t*>assign_list;
       for (list<perm_string>::const_iterator cur = loop_vars->begin()
 		 ; cur != loop_vars->end() ; ++ cur) {
+	    if (cur->nil())
+		  continue;
 	    decl_assignment_t*tmp_assign = new decl_assignment_t;
 	    tmp_assign->name = lex_strings.make(*cur);
 	    assign_list.push_back(tmp_assign);