11 files changed, 560 insertions, 30 deletions
diff --git a/tests/arch/xilinx/adffs.ys b/tests/arch/xilinx/adffs.ys
index e73bfe0b9..c0ff6a2e2 100644
--- a/tests/arch/xilinx/adffs.ys
+++ b/tests/arch/xilinx/adffs.ys
@@ -32,10 +32,9 @@ equiv_opt -async2sync  -assert -map +/xilinx/cells_sim.v synth_xilinx # equivale
 design -load postopt # load the post-opt design (otherwise equiv_opt loads the pre-opt design)
 cd dffs # Constrain all select calls below inside the top module
 select -assert-count 1 t:BUFG
-select -assert-count 1 t:FDRE
-select -assert-count 1 t:LUT2
+select -assert-count 1 t:FDSE
 
-select -assert-none t:BUFG t:FDRE t:LUT2 %% t:* %D
+select -assert-none t:BUFG t:FDSE %% t:* %D
 
 
 design -load read
@@ -46,6 +45,6 @@ design -load postopt # load the post-opt design (otherwise equiv_opt loads the p
 cd ndffnr # Constrain all select calls below inside the top module
 select -assert-count 1 t:BUFG
 select -assert-count 1 t:FDRE_1
-select -assert-count 1 t:LUT2
+select -assert-count 1 t:INV
 
-select -assert-none t:BUFG t:FDRE_1 t:LUT2 %% t:* %D
+select -assert-none t:BUFG t:FDRE_1 t:INV %% t:* %D
diff --git a/tests/arch/xilinx/attributes_test.ys b/tests/arch/xilinx/attributes_test.ys
new file mode 100644
index 000000000..4c881b280
--- /dev/null
+++ b/tests/arch/xilinx/attributes_test.ys
@@ -0,0 +1,47 @@
+# Check that blockram memory without parameters is not modified
+read_verilog ../common/memory_attributes/attributes_test.v
+hierarchy -top block_ram
+synth_xilinx -top block_ram
+cd block_ram # Constrain all select calls below inside the top module
+select -assert-count 1 t:RAMB18E1
+ 
+# Check that distributed memory without parameters is not modified
+design -reset
+read_verilog ../common/memory_attributes/attributes_test.v
+hierarchy -top distributed_ram
+synth_xilinx -top distributed_ram
+cd distributed_ram # Constrain all select calls below inside the top module
+select -assert-count 8 t:RAM32X1D
+ 
+# Set ram_style distributed to blockram memory; will be implemented as distributed
+design -reset
+read_verilog ../common/memory_attributes/attributes_test.v
+prep
+setattr -mod -set ram_style "distributed" block_ram
+synth_xilinx -top block_ram
+cd block_ram # Constrain all select calls below inside the top module
+select -assert-count 32 t:RAM128X1D
+ 
+# Set synthesis, logic_block to blockram memory; will be implemented as distributed
+design -reset
+read_verilog ../common/memory_attributes/attributes_test.v
+prep
+setattr -mod -set logic_block 1 block_ram
+synth_xilinx -top block_ram
+cd block_ram # Constrain all select calls below inside the top module
+select -assert-count 0 t:RAMB18E1
+select -assert-count 32 t:RAM128X1D
+ 
+# Set ram_style block to a distributed memory; will be implemented as blockram
+design -reset
+read_verilog ../common/memory_attributes/attributes_test.v
+synth_xilinx -top distributed_ram_manual
+cd distributed_ram_manual # Constrain all select calls below inside the top module
+select -assert-count 1 t:RAMB18E1
+ 
+# Set synthesis, ram_block block to a distributed memory; will be implemented as blockram
+design -reset
+read_verilog ../common/memory_attributes/attributes_test.v
+synth_xilinx -top distributed_ram_manual_syn
+cd distributed_ram_manual_syn # Constrain all select calls below inside the top module
+select -assert-count 1 t:RAMB18E1
diff --git a/tests/arch/xilinx/blockram.ys b/tests/arch/xilinx/blockram.ys
new file mode 100644
index 000000000..bb908cbbf
--- /dev/null
+++ b/tests/arch/xilinx/blockram.ys
@@ -0,0 +1,97 @@
+### TODO: Not running equivalence checking because BRAM models does not exists
+###       currently. Checking instance counts instead.
+# Memory bits <= 18K; Data width <= 36; Address width <= 14: -> RAMB18E1
+read_verilog ../common/blockram.v
+chparam -set ADDRESS_WIDTH 10 -set DATA_WIDTH 1 sync_ram_sdp
+synth_xilinx -top sync_ram_sdp
+cd sync_ram_sdp
+select -assert-count 1 t:RAMB18E1
+
+design -reset
+read_verilog ../common/blockram.v
+chparam -set ADDRESS_WIDTH 8 -set DATA_WIDTH 18 sync_ram_sdp
+synth_xilinx -top sync_ram_sdp
+cd sync_ram_sdp
+select -assert-count 1 t:RAMB18E1
+
+design -reset
+read_verilog ../common/blockram.v
+chparam -set ADDRESS_WIDTH 14 -set DATA_WIDTH 1 sync_ram_sdp
+synth_xilinx -top sync_ram_sdp
+cd sync_ram_sdp
+select -assert-count 1 t:RAMB18E1
+
+design -reset
+read_verilog ../common/blockram.v
+chparam -set ADDRESS_WIDTH 9 -set DATA_WIDTH 36 sync_ram_sdp
+synth_xilinx -top sync_ram_sdp
+cd sync_ram_sdp
+select -assert-count 1 t:RAMB18E1
+
+# Anything memory bits < 1024 -> LUTRAM
+design -reset
+read_verilog ../common/blockram.v
+chparam -set ADDRESS_WIDTH 8 -set DATA_WIDTH 2 sync_ram_sdp
+synth_xilinx -top sync_ram_sdp
+cd sync_ram_sdp
+select -assert-count 0 t:RAMB18E1
+select -assert-count 4 t:RAM128X1D
+
+# More than 18K bits, data width <= 36 (TDP), and address width from 10 to 15b (non-cascaded) -> RAMB36E1
+design -reset
+read_verilog ../common/blockram.v
+chparam -set ADDRESS_WIDTH 10 -set DATA_WIDTH 36 sync_ram_sdp
+synth_xilinx -top sync_ram_sdp
+cd sync_ram_sdp
+select -assert-count 1 t:RAMB36E1
+
+
+### With parameters
+
+design -reset
+read_verilog ../common/blockram.v
+hierarchy -top sync_ram_sdp -chparam ADDRESS_WIDTH 10 -chparam DATA_WIDTH 1 
+setattr -set ram_style "block" m:memory
+synth_xilinx -top sync_ram_sdp
+cd sync_ram_sdp
+select -assert-count 1 t:RAMB18E1
+
+design -reset
+read_verilog ../common/blockram.v
+hierarchy -top sync_ram_sdp -chparam ADDRESS_WIDTH 10 -chparam DATA_WIDTH 1 
+setattr -set ram_block 1 m:memory
+synth_xilinx -top sync_ram_sdp
+cd sync_ram_sdp
+select -assert-count 1 t:RAMB18E1
+
+design -reset
+read_verilog ../common/blockram.v
+hierarchy -top sync_ram_sdp -chparam ADDRESS_WIDTH 10 -chparam DATA_WIDTH 1 
+setattr -set ram_style "dont_infer_a_ram_pretty_please" m:memory
+synth_xilinx -top sync_ram_sdp
+cd sync_ram_sdp
+select -assert-count 0 t:RAMB18E1
+
+design -reset
+read_verilog ../common/blockram.v
+hierarchy -top sync_ram_sdp -chparam ADDRESS_WIDTH 10 -chparam DATA_WIDTH 1 
+setattr -set logic_block 1 m:memory
+synth_xilinx -top sync_ram_sdp
+cd sync_ram_sdp
+select -assert-count 0 t:RAMB18E1
+
+design -reset
+read_verilog ../common/blockram.v
+hierarchy -top sync_ram_sdp -chparam ADDRESS_WIDTH 8 -chparam DATA_WIDTH 1
+setattr -set ram_style "block" m:memory
+synth_xilinx -top sync_ram_sdp
+cd sync_ram_sdp
+select -assert-count 1 t:RAMB18E1
+
+design -reset
+read_verilog ../common/blockram.v
+hierarchy -top sync_ram_sdp -chparam ADDRESS_WIDTH 8 -chparam DATA_WIDTH 1
+setattr -set ram_block 1 m:memory
+synth_xilinx -top sync_ram_sdp
+cd sync_ram_sdp
+select -assert-count 1 t:RAMB18E1
diff --git a/tests/arch/xilinx/bug1460.ys b/tests/arch/xilinx/bug1460.ys
new file mode 100644
index 000000000..2018071cc
--- /dev/null
+++ b/tests/arch/xilinx/bug1460.ys
@@ -0,0 +1,34 @@
+read_verilog <<EOT
+module register_file(
+    input wire clk,
+    input wire write_enable,
+    input wire [63:0] write_data,
+    input wire [4:0] write_reg,
+    input wire [4:0] read1_reg,
+    input wire [4:0] read2_reg,
+    input wire [4:0] read3_reg,
+    output reg [63:0] read1_data,
+    output reg [63:0] read2_data,
+    output reg [63:0] read3_data
+    );
+
+    reg [63:0] registers[0:31];
+
+    always @(posedge clk) begin
+      if (write_enable == 1'b1) begin
+        registers[write_reg] <= write_data;
+      end
+    end
+
+    always @(all) begin
+      read1_data <= registers[read1_reg];
+      read2_data <= registers[read2_reg];
+      read3_data <= registers[read3_reg];
+    end
+endmodule
+EOT
+
+synth_xilinx
+cd register_file
+select -assert-count 32 t:RAM32M
+select -assert-none t:* t:BUFG %d t:RAM32M %d
diff --git a/tests/arch/xilinx/fsm.ys b/tests/arch/xilinx/fsm.ys
index 2a72c34e8..f03400fe7 100644
--- a/tests/arch/xilinx/fsm.ys
+++ b/tests/arch/xilinx/fsm.ys
@@ -11,8 +11,9 @@ design -load postopt # load the post-opt design (otherwise equiv_opt loads the p
 cd fsm # Constrain all select calls below inside the top module
 
 select -assert-count 1 t:BUFG
-select -assert-count 5 t:FDRE
-select -assert-count 1 t:LUT3
-select -assert-count 2 t:LUT4
-select -assert-count 4 t:LUT6
-select -assert-none t:BUFG t:FDRE t:LUT3 t:LUT4 t:LUT6 %% t:* %D
+select -assert-count 4 t:FDRE
+select -assert-count 1 t:FDSE
+select -assert-count 1 t:LUT2
+select -assert-count 3 t:LUT5
+select -assert-count 1 t:LUT6
+select -assert-none t:BUFG t:FDRE t:FDSE t:LUT2 t:LUT5 t:LUT6 %% t:* %D
diff --git a/tests/arch/xilinx/lutram.ys b/tests/arch/xilinx/lutram.ys
new file mode 100644
index 000000000..6c9d1eae1
--- /dev/null
+++ b/tests/arch/xilinx/lutram.ys
@@ -0,0 +1,137 @@
+#read_verilog ../common/lutram.v
+#hierarchy -top lutram_1w1r -chparam A_WIDTH 4
+#proc
+#memory -nomap
+#equiv_opt -run :prove -map +/xilinx/cells_sim.v synth_xilinx
+#memory
+#opt -full
+#
+#miter -equiv -flatten -make_assert -make_outputs gold gate miter
+#sat -verify -prove-asserts -seq 3 -set-init-zero -show-inputs -show-outputs miter
+#
+#design -load postopt
+#cd lutram_1w1r
+#select -assert-count 1 t:BUFG
+#select -assert-count 8 t:FDRE
+#select -assert-count 8 t:RAM16X1D
+#select -assert-none t:BUFG t:FDRE t:RAM16X1D %% t:* %D
+
+
+design -reset
+read_verilog ../common/lutram.v
+hierarchy -top lutram_1w1r -chparam A_WIDTH 5
+proc
+memory -nomap
+equiv_opt -run :prove -map +/xilinx/cells_sim.v synth_xilinx
+memory
+opt -full
+
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -seq 3 -set-init-zero -show-inputs -show-outputs miter
+
+design -load postopt
+cd lutram_1w1r
+select -assert-count 1 t:BUFG
+select -assert-count 8 t:FDRE
+select -assert-count 8 t:RAM32X1D
+select -assert-none t:BUFG t:FDRE t:RAM32X1D %% t:* %D
+
+
+design -reset
+read_verilog ../common/lutram.v
+hierarchy -top lutram_1w1r
+proc
+memory -nomap
+equiv_opt -run :prove -map +/xilinx/cells_sim.v synth_xilinx
+memory
+opt -full
+
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -seq 3 -set-init-zero -show-inputs -show-outputs miter
+
+design -load postopt
+cd lutram_1w1r
+select -assert-count 1 t:BUFG
+select -assert-count 8 t:FDRE
+select -assert-count 8 t:RAM64X1D
+select -assert-none t:BUFG t:FDRE t:RAM64X1D %% t:* %D
+
+
+design -reset
+read_verilog ../common/lutram.v
+hierarchy -top lutram_1w3r
+proc
+memory -nomap
+equiv_opt -run :prove -map +/xilinx/cells_sim.v synth_xilinx
+memory
+opt -full
+
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -seq 3 -set-init-zero -show-inputs -show-outputs miter
+
+design -load postopt
+cd lutram_1w3r
+select -assert-count 1 t:BUFG
+select -assert-count 24 t:FDRE
+select -assert-count 4 t:RAM32M
+select -assert-none t:BUFG t:FDRE t:RAM32M %% t:* %D
+
+
+design -reset
+read_verilog ../common/lutram.v
+hierarchy -top lutram_1w3r -chparam A_WIDTH 6
+proc
+memory -nomap
+equiv_opt -run :prove -map +/xilinx/cells_sim.v synth_xilinx
+memory
+opt -full
+
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -seq 3 -set-init-zero -show-inputs -show-outputs miter
+
+design -load postopt
+cd lutram_1w3r
+select -assert-count 1 t:BUFG
+select -assert-count 24 t:FDRE
+select -assert-count 8 t:RAM64M
+select -assert-none t:BUFG t:FDRE t:RAM64M %% t:* %D
+
+
+design -reset
+read_verilog ../common/lutram.v
+hierarchy -top lutram_1w1r -chparam A_WIDTH 5 -chparam D_WIDTH 6
+proc
+memory -nomap
+equiv_opt -run :prove -map +/xilinx/cells_sim.v synth_xilinx
+memory
+opt -full
+
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -seq 3 -set-init-zero -show-inputs -show-outputs miter
+
+design -load postopt
+cd lutram_1w1r
+select -assert-count 1 t:BUFG
+select -assert-count 6 t:FDRE
+select -assert-count 1 t:RAM32M
+select -assert-none t:BUFG t:FDRE t:RAM32M %% t:* %D
+
+
+design -reset
+read_verilog ../common/lutram.v
+hierarchy -top lutram_1w1r -chparam A_WIDTH 6 -chparam D_WIDTH 6
+proc
+memory -nomap
+equiv_opt -run :prove -map +/xilinx/cells_sim.v synth_xilinx
+memory
+opt -full
+
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -seq 3 -set-init-zero -show-inputs -show-outputs miter
+
+design -load postopt
+cd lutram_1w1r
+select -assert-count 1 t:BUFG
+select -assert-count 6 t:FDRE
+select -assert-count 2 t:RAM64M
+select -assert-none t:BUFG t:FDRE t:RAM64M %% t:* %D
diff --git a/tests/arch/xilinx/macc.ys b/tests/arch/xilinx/macc.ys
index 6e884b35a..11e959976 100644
--- a/tests/arch/xilinx/macc.ys
+++ b/tests/arch/xilinx/macc.ys
@@ -23,9 +23,10 @@ miter -equiv -flatten -make_assert -make_outputs gold gate miter
 sat -verify -prove-asserts -seq 10 -show-inputs -show-outputs miter
 design -load postopt # load the post-opt design (otherwise equiv_opt loads the pre-opt design)
 cd macc2 # Constrain all select calls below inside the top module
+
 select -assert-count 1 t:BUFG
 select -assert-count 1 t:DSP48E1
 select -assert-count 1 t:FDRE
 select -assert-count 1 t:LUT2
-select -assert-count 41 t:LUT3
+select -assert-count 40 t:LUT3
 select -assert-none t:BUFG t:DSP48E1 t:FDRE t:LUT2 t:LUT3 %% t:* %D
diff --git a/tests/arch/xilinx/memory.ys b/tests/arch/xilinx/memory.ys
deleted file mode 100644
index da1ed0e49..000000000
--- a/tests/arch/xilinx/memory.ys
+++ /dev/null
@@ -1,17 +0,0 @@
-read_verilog ../common/memory.v
-hierarchy -top top
-proc
-memory -nomap
-equiv_opt -run :prove -map +/xilinx/cells_sim.v synth_xilinx
-memory
-opt -full
-
-miter -equiv -flatten -make_assert -make_outputs gold gate miter
-sat -verify -prove-asserts -seq 5 -set-init-zero -show-inputs -show-outputs miter
-
-design -load postopt
-cd top
-select -assert-count 1 t:BUFG
-select -assert-count 8 t:FDRE
-select -assert-count 8 t:RAM64X1D
-select -assert-none t:BUFG t:FDRE t:RAM64X1D %% t:* %D
diff --git a/tests/arch/xilinx/mux.ys b/tests/arch/xilinx/mux.ys
index 821d0fab7..388272449 100644
--- a/tests/arch/xilinx/mux.ys
+++ b/tests/arch/xilinx/mux.ys
@@ -40,6 +40,8 @@ proc
 equiv_opt -assert -map +/xilinx/cells_sim.v synth_xilinx # equivalency check
 design -load postopt # load the post-opt design (otherwise equiv_opt loads the pre-opt design)
 cd mux16 # Constrain all select calls below inside the top module
-select -assert-count 5 t:LUT6
+select -assert-min 5 t:LUT6
+select -assert-max 7 t:LUT6
+select -assert-max 2 t:MUXF7
 
-select -assert-none t:LUT6 %% t:* %D
+select -assert-none t:LUT6 t:MUXF7 %% t:* %D
diff --git a/tests/arch/xilinx/xilinx_dffopt.ys b/tests/arch/xilinx/xilinx_dffopt.ys
new file mode 100644
index 000000000..dc036acfd
--- /dev/null
+++ b/tests/arch/xilinx/xilinx_dffopt.ys
@@ -0,0 +1,216 @@
+read_verilog << EOT
+
+// FDRE, mergeable CE and R.
+
+module t0 (...);
+input wire clk;
+input wire [7:0] i;
+output wire [7:0] o;
+
+wire [7:0] tmp ;
+
+LUT2 #(.INIT(4'h6)) lut0 (.I0(i[0]), .I1(i[1]), .O(tmp[0]));
+LUT2 #(.INIT(4'h6)) lut1 (.I0(i[1]), .I1(i[2]), .O(tmp[1]));
+LUT2 #(.INIT(4'h6)) lut2 (.I0(i[3]), .I1(i[4]), .O(tmp[2]));
+
+FDRE ff (.D(tmp[0]), .CE(tmp[1]), .R(tmp[2]), .Q(o[0]));
+
+endmodule
+
+EOT
+
+design -save t0
+
+equiv_opt -blacklist xilinx_dffopt_blacklist.txt -assert -map +/xilinx/cells_sim.v xilinx_dffopt
+design -load postopt
+clean
+
+select -assert-count 1 t:FDRE
+select -assert-count 1 t:LUT6
+select -assert-count 3 t:LUT2
+select -assert-none t:FDRE t:LUT6 t:LUT2 %% t:* %D
+
+design -load t0
+
+equiv_opt -blacklist xilinx_dffopt_blacklist.txt -assert -map +/xilinx/cells_sim.v xilinx_dffopt -lut4
+design -load postopt
+clean
+
+select -assert-count 1 t:FDRE
+select -assert-count 1 t:LUT4
+select -assert-count 3 t:LUT2
+select -assert-none t:FDRE t:LUT4 t:LUT2 %% t:* %D
+
+design -reset
+
+
+read_verilog << EOT
+
+// FDSE, mergeable CE and S, inversions.
+
+module t0 (...);
+input wire clk;
+input wire [7:0] i;
+output wire [7:0] o;
+
+wire [7:0] tmp ;
+
+LUT2 #(.INIT(4'h6)) lut0 (.I0(i[0]), .I1(i[1]), .O(tmp[0]));
+LUT2 #(.INIT(4'h6)) lut1 (.I0(i[1]), .I1(i[2]), .O(tmp[1]));
+LUT2 #(.INIT(4'h6)) lut2 (.I0(i[3]), .I1(i[4]), .O(tmp[2]));
+
+FDSE #(.IS_D_INVERTED(1'b1), .IS_S_INVERTED(1'b1)) ff (.D(tmp[0]), .CE(tmp[1]), .S(tmp[2]), .Q(o[0]));
+
+endmodule
+
+EOT
+
+design -save t0
+
+equiv_opt -blacklist xilinx_dffopt_blacklist.txt -assert -map +/xilinx/cells_sim.v xilinx_dffopt
+design -load postopt
+clean
+
+select -assert-count 1 t:FDSE
+select -assert-count 1 t:LUT6
+select -assert-count 3 t:LUT2
+select -assert-none t:FDSE t:LUT6 t:LUT2 %% t:* %D
+
+design -load t0
+
+equiv_opt -blacklist xilinx_dffopt_blacklist.txt -assert -map +/xilinx/cells_sim.v xilinx_dffopt -lut4
+design -load postopt
+clean
+
+select -assert-count 1 t:FDSE
+select -assert-count 1 t:LUT4
+select -assert-count 3 t:LUT2
+select -assert-none t:FDSE t:LUT4 t:LUT2 %% t:* %D
+
+design -reset
+
+
+read_verilog << EOT
+
+// FDCE, mergeable CE.
+
+module t0 (...);
+input wire clk;
+input wire [7:0] i;
+output wire [7:0] o;
+
+wire [7:0] tmp ;
+
+LUT2 #(.INIT(4'h6)) lut0 (.I0(i[0]), .I1(i[1]), .O(tmp[0]));
+LUT2 #(.INIT(4'h6)) lut1 (.I0(i[1]), .I1(i[2]), .O(tmp[1]));
+LUT2 #(.INIT(4'h6)) lut2 (.I0(i[3]), .I1(i[4]), .O(tmp[2]));
+
+FDCE ff (.D(tmp[0]), .CE(tmp[1]), .CLR(tmp[2]), .Q(o[0]));
+
+endmodule
+
+EOT
+
+design -save t0
+
+equiv_opt -async2sync -blacklist xilinx_dffopt_blacklist.txt -assert -map +/xilinx/cells_sim.v xilinx_dffopt
+design -load postopt
+clean
+
+select -assert-count 1 t:FDCE
+select -assert-count 1 t:LUT4
+select -assert-count 3 t:LUT2
+select -assert-none t:FDCE t:LUT4 t:LUT2 %% t:* %D
+
+design -reset
+
+
+read_verilog << EOT
+
+// FDSE, mergeable CE and S, but CE only not worth it.
+
+module t0 (...);
+input wire clk;
+input wire [7:0] i;
+output wire [7:0] o;
+
+wire [7:0] tmp ;
+
+LUT2 #(.INIT(4'h6)) lut0 (.I0(i[0]), .I1(i[1]), .O(tmp[0]));
+LUT2 #(.INIT(4'h6)) lut1 (.I0(i[1]), .I1(i[2]), .O(tmp[1]));
+
+FDSE ff (.D(tmp[0]), .CE(i[7]), .S(tmp[1]), .Q(o[0]));
+
+endmodule
+
+EOT
+
+design -save t0
+
+equiv_opt -blacklist xilinx_dffopt_blacklist.txt -assert -map +/xilinx/cells_sim.v xilinx_dffopt
+design -load postopt
+clean
+
+select -assert-count 1 t:FDSE
+select -assert-count 1 t:LUT5
+select -assert-count 2 t:LUT2
+select -assert-none t:FDSE t:LUT5 t:LUT2 %% t:* %D
+
+design -load t0
+
+equiv_opt -blacklist xilinx_dffopt_blacklist.txt -assert -map +/xilinx/cells_sim.v xilinx_dffopt -lut4
+design -load postopt
+clean
+
+select -assert-count 1 t:FDSE
+select -assert-count 2 t:LUT2
+select -assert-none t:FDSE t:LUT2 %% t:* %D
+
+design -reset
+
+
+read_verilog << EOT
+
+// FDRSE, mergeable CE, S, R.
+
+module t0 (...);
+input wire clk;
+input wire [7:0] i;
+output wire [7:0] o;
+
+wire [7:0] tmp ;
+
+LUT2 #(.INIT(4'h6)) lut0 (.I0(i[0]), .I1(i[1]), .O(tmp[0]));
+LUT2 #(.INIT(4'h6)) lut1 (.I0(i[1]), .I1(i[2]), .O(tmp[1]));
+LUT2 #(.INIT(4'h8)) lut2 (.I0(i[2]), .I1(i[0]), .O(tmp[2]));
+LUT2 #(.INIT(4'h6)) lut3 (.I0(i[3]), .I1(i[4]), .O(tmp[3]));
+
+FDRSE ff (.D(tmp[0]), .CE(tmp[1]), .S(tmp[2]), .R(tmp[3]), .Q(o[0]));
+
+endmodule
+
+EOT
+
+design -save t0
+
+equiv_opt -blacklist xilinx_dffopt_blacklist.txt -assert -map +/xilinx/cells_sim.v xilinx_dffopt
+design -load postopt
+clean
+
+select -assert-count 1 t:FDRSE
+select -assert-count 1 t:LUT6
+select -assert-count 4 t:LUT2
+select -assert-none t:FDRSE t:LUT6 t:LUT2 %% t:* %D
+
+design -load t0
+
+equiv_opt -blacklist xilinx_dffopt_blacklist.txt -assert -map +/xilinx/cells_sim.v xilinx_dffopt -lut4
+design -load postopt
+clean
+
+select -assert-count 1 t:FDRSE
+select -assert-count 1 t:LUT4
+select -assert-count 4 t:LUT2
+select -assert-none t:FDRSE t:LUT4 t:LUT2 %% t:* %D
+
+design -reset
diff --git a/tests/arch/xilinx/xilinx_dffopt_blacklist.txt b/tests/arch/xilinx/xilinx_dffopt_blacklist.txt
new file mode 100644
index 000000000..6a31a0cd3
--- /dev/null
+++ b/tests/arch/xilinx/xilinx_dffopt_blacklist.txt
@@ -0,0 +1,13 @@
+lut0
+lut1
+lut2
+lut3
+ff
+ff.D
+ff.R
+ff.S
+ff.CE
+ff.d
+ff.r
+ff.s
+ff.ce