chformal: Test -coverprecond and reuse the src attribute

passes/cmds/chformal.cc

@@ -273,8 +273,8 @@ struct ChformalPass : public Pass {
 			if (mode =='p')
 			{
 				for (auto cell : constr_cells)
-					module->addCover(NEW_ID, cell->getPort(ID::EN), State::S1,
+					module->addCover(NEW_ID_SUFFIX("coverprecond"),
-						"$auto$coverprecond$" + cell->get_src_attribute());
+						cell->getPort(ID::EN), State::S1, cell->get_src_attribute());
 			}
 			else
 			if (mode == 'c')

tests/various/chformal_coverprecond.ys

@@ -0,0 +1,25 @@
+read_verilog -formal <<EOT
+module top(input a, b, c, d);
+
+    always @* begin
+        if (a) assert (b == c);
+        if (!a) assert (b != c);
+        if (b) assume (c);
+        if (c) cover (d);
+    end
+
+endmodule
+EOT
+
+prep -top top
+
+select -assert-count 1 t:$cover
+
+chformal -cover -coverprecond
+select -assert-count 2 t:$cover
+
+chformal -assert -coverprecond
+select -assert-count 4 t:$cover
+
+chformal -assume -coverprecond
+select -assert-count 5 t:$cover