Add additional checks

simple_reviewed/dff2dffe/dff2dffe_unmap.ys

@@ -2,10 +2,13 @@ read_verilog ../top.v
 proc
 dff2dffe
 dff2dffe -unmap
+
+select -assert-none t:$dffe
 dump
 synth -top top
 dff2dffe
 dff2dffe -unmap
+select -assert-none t:$dffe
 flatten
 opt
 opt_rmdff

simple_reviewed/dff2dffe/dff2dffe_unmap_direct.ys

@@ -7,6 +7,7 @@ dump
 synth -top top
 dff2dffe -direct $_DFF_P_ $_DFFE_PP_
 dff2dffe -unmap
+select -assert-none t:$_DFFE_PP_
 flatten
 opt
 opt_rmdff

simple_reviewed/dff2dffe/dff2dffe_unmap_direct_match.ys

@@ -3,6 +3,8 @@ proc
 synth -top top
 dff2dffe -direct-match $_DFF_P_
 dff2dffe -unmap
+
+select -assert-none t:$dffe
 flatten
 opt
 opt_rmdff

simple_reviewed/dff2dffe/dff2dffe_unmap_mince.ys

@@ -2,10 +2,14 @@ read_verilog ../top.v
 proc
 dff2dffe
 dff2dffe -unmap-mince 2
+
+select -assert-none t:$dffe
 dump
 synth -top top
 dff2dffe
 dff2dffe -unmap-mince 2
+
+select -assert-none t:$dffe
 flatten
 opt
 opt_rmdff

simple_reviewed/opt_demorgan/opt_demorgan_reduce.ys

@@ -2,3 +2,4 @@ read_verilog ../top_reduce.v
 techmap -autoproc
 extract_reduce
 opt_demorgan top
+select -assert-count 3 t:$not