### Always-active EN removal.

read_verilog -icells <<EOT

module top(...);

input CLK;
input [1:0] D;
output [11:0] Q;
input SRST;
input ARST;
input [1:0] CLR;
input [1:0] SET;

$dffe #(.CLK_POLARITY(1'b1), .EN_POLARITY(1'b1), .WIDTH(2)) ff0 (.CLK(CLK), .EN(1'b1), .D(D), .Q(Q[1:0]));
$adffe #(.CLK_POLARITY(1'b1), .EN_POLARITY(1'b0), .ARST_POLARITY(1'b1), .ARST_VALUE(2'h2), .WIDTH(2)) ff1 (.CLK(CLK), .EN(1'b0), .ARST(ARST), .D(D), .Q(Q[3:2]));
$sdffe #(.CLK_POLARITY(1'b1), .EN_POLARITY(1'b1), .SRST_POLARITY(1'b1), .SRST_VALUE(2'h2), .WIDTH(2)) ff2 (.CLK(CLK), .EN(1'b1), .SRST(SRST), .D(D), .Q(Q[5:4]));
$sdffce #(.CLK_POLARITY(1'b1), .EN_POLARITY(1'b1), .SRST_POLARITY(1'b1), .SRST_VALUE(2'h2), .WIDTH(2)) ff3 (.CLK(CLK), .EN(1'b1), .SRST(SRST), .D(D), .Q(Q[7:6]));
$dffsre #(.CLK_POLARITY(1'b1), .EN_POLARITY(1'b0), .CLR_POLARITY(1'b1), .SET_POLARITY(1'b0), .WIDTH(2)) ff4 (.CLK(CLK), .EN(1'b0), .SET(SET), .CLR(CLR), .D(D), .Q(Q[9:8]));

$dlatch #(.EN_POLARITY(1'b1), .WIDTH(2)) ff5 (.EN(1'b1), .D(D), .Q(Q[11:10]));
$adlatch #(.EN_POLARITY(1'b0), .ARST_POLARITY(1'b1), .ARST_VALUE(2'h2), .WIDTH(2)) ff6 (.EN(1'b0), .ARST(ARST), .D(D), .Q(Q[13:12]));
$dlatchsr #(.EN_POLARITY(1'b0), .CLR_POLARITY(1'b1), .SET_POLARITY(1'b0), .WIDTH(2)) ff7 (.EN(1'b0), .SET(SET), .CLR(CLR), .D(D), .Q(Q[15:14]));

endmodule

EOT

design -save orig

# Equivalence check will fail for unmapped adlatch and dlatchsr due to negative hold hack.
delete top/ff6 top/ff7
equiv_opt -undef -assert -multiclock opt_dff

design -load orig
delete top/ff6 top/ff7
simplemap
equiv_opt -undef -assert -multiclock opt_dff

design -load orig
opt_dff
select -assert-count 0 t:$dffe
select -assert-count 0 t:$adffe
select -assert-count 0 t:$sdffe
select -assert-count 0 t:$sdffce
select -assert-count 0 t:$dffsre
select -assert-count 0 t:$dlatch
select -assert-count 0 t:$adlatch
select -assert-count 0 t:$dlatchsr
select -assert-count 1 t:$dff
select -assert-count 2 t:$sdff
select -assert-count 1 t:$adff
select -assert-count 1 t:$dffsr

design -load orig
simplemap
opt_dff
select -assert-count 0 t:$_DFFE_*
select -assert-count 0 t:$_SDFFE_*
select -assert-count 0 t:$_SDFFCE_*
select -assert-count 0 t:$_DFFSRE_*
select -assert-count 0 t:$_DLATCH*
select -assert-count 2 t:$_DFF_P_
select -assert-count 4 t:$_SDFF_PP?_
select -assert-count 2 t:$_DFF_PP?_
select -assert-count 2 t:$_DFFSR_PNP_

design -reset



### Never-active EN removal.

read_verilog -icells <<EOT

module top(...);

input CLK;
input [1:0] D;
(* init = 32'h55555555 *)
output [31:0] Q;
input SRST;
input ARST;
input [1:0] CLR;
input [1:0] SET;

$dffe #(.CLK_POLARITY(1'b1), .EN_POLARITY(1'b1), .WIDTH(2)) ff0 (.CLK(CLK), .EN(1'b0), .D(D), .Q(Q[1:0]));
$adffe #(.CLK_POLARITY(1'b1), .EN_POLARITY(1'b0), .ARST_POLARITY(1'b1), .ARST_VALUE(2'h2), .WIDTH(2)) ff1 (.CLK(CLK), .EN(1'b1), .ARST(ARST), .D(D), .Q(Q[3:2]));
$sdffe #(.CLK_POLARITY(1'b1), .EN_POLARITY(1'b1), .SRST_POLARITY(1'b1), .SRST_VALUE(2'h2), .WIDTH(2)) ff2 (.CLK(CLK), .EN(1'b0), .SRST(SRST), .D(D), .Q(Q[5:4]));
$sdffce #(.CLK_POLARITY(1'b1), .EN_POLARITY(1'b1), .SRST_POLARITY(1'b1), .SRST_VALUE(2'h2), .WIDTH(2)) ff3 (.CLK(CLK), .EN(1'b0), .SRST(SRST), .D(D), .Q(Q[7:6]));
$dffsre #(.CLK_POLARITY(1'b1), .EN_POLARITY(1'b0), .CLR_POLARITY(1'b1), .SET_POLARITY(1'b0), .WIDTH(2)) ff4 (.CLK(CLK), .EN(1'b1), .SET(SET), .CLR(CLR), .D(D), .Q(Q[9:8]));

$dlatch #(.EN_POLARITY(1'b1), .WIDTH(2)) ff5 (.EN(1'b0), .D(D), .Q(Q[11:10]));
$adlatch #(.EN_POLARITY(1'b0), .ARST_POLARITY(1'b1), .ARST_VALUE(2'h2), .WIDTH(2)) ff6 (.EN(1'b1), .ARST(ARST), .D(D), .Q(Q[13:12]));
$dlatchsr #(.EN_POLARITY(1'b0), .CLR_POLARITY(1'b1), .SET_POLARITY(1'b0), .WIDTH(2)) ff7 (.EN(1'b1), .SET(SET), .CLR(CLR), .D(D), .Q(Q[15:14]));

$dffe #(.CLK_POLARITY(1'b1), .EN_POLARITY(1'b1), .WIDTH(2)) ff8 (.CLK(CLK), .EN(1'bx), .D(D), .Q(Q[17:16]));
$adffe #(.CLK_POLARITY(1'b1), .EN_POLARITY(1'b0), .ARST_POLARITY(1'b1), .ARST_VALUE(2'h2), .WIDTH(2)) ff9 (.CLK(CLK), .EN(1'bx), .ARST(ARST), .D(D), .Q(Q[19:18]));
$sdffe #(.CLK_POLARITY(1'b1), .EN_POLARITY(1'b1), .SRST_POLARITY(1'b1), .SRST_VALUE(2'h2), .WIDTH(2)) ff10 (.CLK(CLK), .EN(1'bx), .SRST(SRST), .D(D), .Q(Q[21:20]));
$sdffce #(.CLK_POLARITY(1'b1), .EN_POLARITY(1'b1), .SRST_POLARITY(1'b1), .SRST_VALUE(2'h2), .WIDTH(2)) ff11 (.CLK(CLK), .EN(1'bx), .SRST(SRST), .D(D), .Q(Q[23:22]));
$dffsre #(.CLK_POLARITY(1'b1), .EN_POLARITY(1'b0), .CLR_POLARITY(1'b1), .SET_POLARITY(1'b0), .WIDTH(2)) ff12 (.CLK(CLK), .EN(1'bx), .SET(SET), .CLR(CLR), .D(D), .Q(Q[25:24]));

$dlatch #(.EN_POLARITY(1'b1), .WIDTH(2)) ff13 (.EN(1'bx), .D(D), .Q(Q[27:26]));
$adlatch #(.EN_POLARITY(1'b0), .ARST_POLARITY(1'b1), .ARST_VALUE(2'h2), .WIDTH(2)) ff14 (.EN(1'bx), .ARST(ARST), .D(D), .Q(Q[29:28]));
$dlatchsr #(.EN_POLARITY(1'b0), .CLR_POLARITY(1'b1), .SET_POLARITY(1'b0), .WIDTH(2)) ff15 (.EN(1'bx), .SET(SET), .CLR(CLR), .D(D), .Q(Q[31:30]));

endmodule

EOT

design -save orig

equiv_opt -undef -assert -multiclock opt_dff
design -load postopt
select -assert-count 2 t:$dffe
select -assert-count 4 t:$dlatch
select -assert-count 4 t:$sr
select -assert-none t:$dffe t:$dlatch t:$sr %% %n t:* %i

design -load orig

equiv_opt -undef -assert -multiclock opt_dff -keepdc
design -load postopt
select -assert-count 2 t:$dffe
select -assert-count 1 t:$adffe
select -assert-count 1 t:$sdffe
select -assert-count 1 t:$sdffce
select -assert-count 1 t:$dffsre
select -assert-count 3 t:$dlatch
select -assert-count 1 t:$adlatch
select -assert-count 1 t:$dlatchsr
select -assert-count 2 t:$sr

design -load orig
simplemap

equiv_opt -undef -assert -multiclock opt_dff
design -load postopt
select -assert-count 4 t:$_DFFE_??_
select -assert-count 8 t:$_DLATCH_?_
select -assert-count 8 t:$_SR_??_
select -assert-none t:$_DFFE_??_ t:$_DLATCH_?_ t:$_SR_??_ %% %n t:* %i

design -load orig
simplemap

equiv_opt -undef -assert -multiclock opt_dff -keepdc
design -load postopt
select -assert-count 4 t:$_DFFE_??_
select -assert-count 2 t:$_DFFE_????_
select -assert-count 2 t:$_SDFFE_????_
select -assert-count 2 t:$_SDFFCE_????_
select -assert-count 2 t:$_DFFSRE_????_
select -assert-count 6 t:$_DLATCH_?_
select -assert-count 2 t:$_DLATCH_???_
select -assert-count 2 t:$_DLATCHSR_???_
select -assert-count 4 t:$_SR_??_