28 files changed, 545 insertions, 51 deletions

diff --git a/tests/xilinx/.gitignore b/tests/xilinx/.gitignore
index 54733fb71..c99b79371 100644
--- a/tests/xilinx/.gitignore
+++ b/tests/xilinx/.gitignore
@@ -2,3 +2,4 @@
 /*.out
 /run-test.mk
 /*_uut.v
+/test_macc
diff --git a/tests/xilinx/add_sub.v b/tests/xilinx/add_sub.v
new file mode 100644
index 000000000..177c32e30
--- /dev/null
+++ b/tests/xilinx/add_sub.v
@@ -0,0 +1,13 @@
+module top
+(
+ input [3:0] x,
+ input [3:0] y,
+
+ output [3:0] A,
+ output [3:0] B
+ );
+
+assign A =  x + y;
+assign B =  x - y;
+
+endmodule
diff --git a/tests/xilinx/add_sub.ys b/tests/xilinx/add_sub.ys
new file mode 100644
index 000000000..f06e7fa01
--- /dev/null
+++ b/tests/xilinx/add_sub.ys
@@ -0,0 +1,11 @@
+read_verilog add_sub.v
+hierarchy -top top
+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 top # Constrain all select calls below inside the top module
+select -assert-count 14 t:LUT2
+select -assert-count 6 t:MUXCY
+select -assert-count 8 t:XORCY
+select -assert-none t:LUT2 t:MUXCY t:XORCY %% t:* %D
+
diff --git a/tests/xilinx/adffs.v b/tests/xilinx/adffs.v
new file mode 100644
index 000000000..223b52d21
--- /dev/null
+++ b/tests/xilinx/adffs.v
@@ -0,0 +1,47 @@
+module adff
+    ( input d, clk, clr, output reg q );
+    initial begin
+      q = 0;
+    end
+	always @( posedge clk, posedge clr )
+		if ( clr )
+			q <= 1'b0;
+		else
+            q <= d;
+endmodule
+
+module adffn
+    ( input d, clk, clr, output reg q );
+    initial begin
+      q = 0;
+    end
+	always @( posedge clk, negedge clr )
+		if ( !clr )
+			q <= 1'b0;
+		else
+            q <= d;
+endmodule
+
+module dffs
+    ( input d, clk, pre, clr, output reg q );
+    initial begin
+      q = 0;
+    end
+	always @( posedge clk )
+		if ( pre )
+			q <= 1'b1;
+		else
+            q <= d;
+endmodule
+
+module ndffnr
+    ( input d, clk, pre, clr, output reg q );
+    initial begin
+      q = 0;
+    end
+	always @( negedge clk )
+		if ( !clr )
+			q <= 1'b0;
+		else
+            q <= d;
+endmodule
diff --git a/tests/xilinx/adffs.ys b/tests/xilinx/adffs.ys
new file mode 100644
index 000000000..1923b9802
--- /dev/null
+++ b/tests/xilinx/adffs.ys
@@ -0,0 +1,51 @@
+read_verilog adffs.v
+design -save read
+
+hierarchy -top adff
+proc
+equiv_opt -async2sync  -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 adff # Constrain all select calls below inside the top module
+select -assert-count 1 t:BUFG
+select -assert-count 1 t:FDCE
+
+select -assert-none t:BUFG t:FDCE %% t:* %D
+
+
+design -load read
+hierarchy -top adffn
+proc
+equiv_opt -async2sync  -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 adffn # Constrain all select calls below inside the top module
+select -assert-count 1 t:BUFG
+select -assert-count 1 t:FDCE
+select -assert-count 1 t:LUT1
+
+select -assert-none t:BUFG t:FDCE t:LUT1 %% t:* %D
+
+
+design -load read
+hierarchy -top dffs
+proc
+equiv_opt -async2sync  -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 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-none t:BUFG t:FDRE t:LUT2 %% t:* %D
+
+
+design -load read
+hierarchy -top ndffnr
+proc
+equiv_opt -async2sync  -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 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-none t:BUFG t:FDRE_1 t:LUT2 %% t:* %D
diff --git a/tests/xilinx/counter.v b/tests/xilinx/counter.v
new file mode 100644
index 000000000..52852f8ac
--- /dev/null
+++ b/tests/xilinx/counter.v
@@ -0,0 +1,17 @@
+module top    (

+out,

+clk,

+reset

+);

+    output [7:0] out;

+    input clk, reset;

+    reg [7:0] out;

+

+    always @(posedge clk, posedge reset)

+		if (reset) begin

+			out <= 8'b0 ;

+		end else

+			out <= out + 1;

+

+

+endmodule

diff --git a/tests/xilinx/counter.ys b/tests/xilinx/counter.ys
new file mode 100644
index 000000000..459541656
--- /dev/null
+++ b/tests/xilinx/counter.ys
@@ -0,0 +1,14 @@
+read_verilog counter.v
+hierarchy -top top
+proc
+flatten
+equiv_opt -async2sync -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 top # Constrain all select calls below inside the top module
+
+select -assert-count 1 t:BUFG
+select -assert-count 8 t:FDCE
+select -assert-count 1 t:LUT1
+select -assert-count 7 t:MUXCY
+select -assert-count 8 t:XORCY
+select -assert-none t:BUFG t:FDCE t:LUT1 t:MUXCY t:XORCY %% t:* %D
diff --git a/tests/xilinx/dffs.v b/tests/xilinx/dffs.v
new file mode 100644
index 000000000..3418787c9
--- /dev/null
+++ b/tests/xilinx/dffs.v
@@ -0,0 +1,15 @@
+module dff
+    ( input d, clk, output reg q );
+	always @( posedge clk )
+            q <= d;
+endmodule
+
+module dffe
+    ( input d, clk, en, output reg q );
+    initial begin
+      q = 0;
+    end
+	always @( posedge clk )
+		if ( en )
+			q <= d;
+endmodule
diff --git a/tests/xilinx/dffs.ys b/tests/xilinx/dffs.ys
new file mode 100644
index 000000000..f1716dabb
--- /dev/null
+++ b/tests/xilinx/dffs.ys
@@ -0,0 +1,25 @@
+read_verilog dffs.v
+design -save read
+
+hierarchy -top dff
+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 dff # Constrain all select calls below inside the top module
+select -assert-count 1 t:BUFG
+select -assert-count 1 t:FDRE
+
+select -assert-none t:BUFG t:FDRE %% t:* %D
+
+
+design -load read
+hierarchy -top dffe
+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 dffe # Constrain all select calls below inside the top module
+select -assert-count 1 t:BUFG
+select -assert-count 1 t:FDRE
+
+select -assert-none t:BUFG t:FDRE %% t:* %D
+
diff --git a/tests/xilinx/fsm.v b/tests/xilinx/fsm.v
new file mode 100644
index 000000000..368fbaace
--- /dev/null
+++ b/tests/xilinx/fsm.v
@@ -0,0 +1,55 @@
+ module fsm (

+ clock,

+ reset,

+ req_0,

+ req_1,

+ gnt_0,

+ gnt_1

+ );

+ input   clock,reset,req_0,req_1;

+ output  gnt_0,gnt_1;

+ wire    clock,reset,req_0,req_1;

+ reg     gnt_0,gnt_1;

+

+ parameter SIZE = 3           ;

+ parameter IDLE  = 3'b001,GNT0 = 3'b010,GNT1 = 3'b100,GNT2 = 3'b101 ;

+

+ reg [SIZE-1:0] state;

+ reg [SIZE-1:0] next_state;

+

+ always @ (posedge clock)

+ begin : FSM

+ if (reset == 1'b1) begin

+   state <=  #1  IDLE;

+   gnt_0 <= 0;

+   gnt_1 <= 0;

+ end else

+  case(state)

+    IDLE : if (req_0 == 1'b1) begin

+                 state <=  #1  GNT0;

+                 gnt_0 <= 1;

+               end else if (req_1 == 1'b1) begin

+                 gnt_1 <= 1;

+                 state <=  #1  GNT0;

+               end else begin

+                 state <=  #1  IDLE;

+               end

+    GNT0 : if (req_0 == 1'b1) begin

+                 state <=  #1  GNT0;

+               end else begin

+                 gnt_0 <= 0;

+                 state <=  #1  IDLE;

+               end

+    GNT1 : if (req_1 == 1'b1) begin

+                 state <=  #1  GNT2;

+				 gnt_1 <= req_0;

+               end

+    GNT2 : if (req_0 == 1'b1) begin

+                 state <=  #1  GNT1;

+				 gnt_1 <= req_1;

+               end

+    default : state <=  #1  IDLE;

+ endcase

+ end

+

+endmodule

diff --git a/tests/xilinx/fsm.ys b/tests/xilinx/fsm.ys
new file mode 100644
index 000000000..a9e94c2c0
--- /dev/null
+++ b/tests/xilinx/fsm.ys
@@ -0,0 +1,14 @@
+read_verilog fsm.v
+hierarchy -top fsm
+proc
+flatten
+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 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
diff --git a/tests/xilinx/latches.v b/tests/xilinx/latches.v
index 83bad7f35..adb5d5319 100644
--- a/tests/xilinx/latches.v
+++ b/tests/xilinx/latches.v
@@ -1,19 +1,19 @@
 module latchp
-    ( input d, en, output reg q );
+    ( input d, clk, en, output reg q );
 	always @*
 		if ( en )
 			q <= d;
 endmodule
 
 module latchn
-    ( input d, en, output reg q );
+    ( input d, clk, en, output reg q );
 	always @*
 		if ( !en )
 			q <= d;
 endmodule
 
 module latchsr
-    ( input d, en, clr, pre, output reg q );
+    ( input d, clk, en, clr, pre, output reg q );
 	always @*
 		if ( clr )
 			q <= 1'b0;
@@ -22,37 +22,3 @@ module latchsr
 		else if ( en )
 			q <= d;
 endmodule
-
-
-module top (
-input clk,
-input clr,
-input pre,
-input a,
-output b,b1,b2
-);
-
-
-latchp u_latchp (
-        .en (clk ),
-        .d (a ),
-        .q (b )
-    );
-
-
-latchn u_latchn (
-        .en (clk ),
-        .d (a ),
-        .q (b1 )
-    );
-
-
-latchsr u_latchsr (
-        .en (clk ),
-        .clr (clr),
-        .pre (pre),
-        .d (a ),
-        .q (b2 )
-    );
-
-endmodule
diff --git a/tests/xilinx/latches.ys b/tests/xilinx/latches.ys
index ac1102896..3eb550a42 100644
--- a/tests/xilinx/latches.ys
+++ b/tests/xilinx/latches.ys
@@ -1,15 +1,35 @@
 read_verilog latches.v
+design -save read
 
+hierarchy -top latchp
 proc
-flatten
-equiv_opt -assert -run :prove -map +/xilinx/cells_sim.v synth_xilinx # equivalency check
-async2sync
-equiv_opt -assert -run prove: -map +/xilinx/cells_sim.v synth_xilinx # equivalency check
-
-design -load preopt
-synth_xilinx
-cd top
+equiv_opt -async2sync -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 latchp # Constrain all select calls below inside the top module
+select -assert-count 1 t:LDCE
+
+select -assert-none t:LDCE %% t:* %D
+
+
+design -load read
+hierarchy -top latchn
+proc
+equiv_opt -async2sync -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 latchn # Constrain all select calls below inside the top module
+select -assert-count 1 t:LDCE
 select -assert-count 1 t:LUT1
+
+select -assert-none t:LDCE t:LUT1 %% t:* %D
+
+
+design -load read
+hierarchy -top latchsr
+proc
+equiv_opt -async2sync -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 latchsr # Constrain all select calls below inside the top module
+select -assert-count 1 t:LDCE
 select -assert-count 2 t:LUT3
-select -assert-count 3 t:LDCE
-select -assert-none t:LUT1 t:LUT3 t:LDCE %% t:* %D
+
+select -assert-none t:LDCE t:LUT3 %% t:* %D
diff --git a/tests/xilinx/logic.v b/tests/xilinx/logic.v
new file mode 100644
index 000000000..e5343cae0
--- /dev/null
+++ b/tests/xilinx/logic.v
@@ -0,0 +1,18 @@
+module top
+(
+ input [0:7] in,
+ output B1,B2,B3,B4,B5,B6,B7,B8,B9,B10
+ );
+
+   assign     B1 =  in[0] & in[1];
+   assign     B2 =  in[0] | in[1];
+   assign     B3 =  in[0] ~& in[1];
+   assign     B4 =  in[0] ~| in[1];
+   assign     B5 =  in[0] ^ in[1];
+   assign     B6 =  in[0] ~^ in[1];
+   assign     B7 =  ~in[0];
+   assign     B8 =  in[0];
+   assign     B9 =  in[0:1] && in [2:3];
+   assign     B10 =  in[0:1] || in [2:3];
+
+endmodule
diff --git a/tests/xilinx/logic.ys b/tests/xilinx/logic.ys
new file mode 100644
index 000000000..9ae5993aa
--- /dev/null
+++ b/tests/xilinx/logic.ys
@@ -0,0 +1,11 @@
+read_verilog logic.v
+hierarchy -top top
+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 top # Constrain all select calls below inside the top module
+
+select -assert-count 1 t:LUT1
+select -assert-count 6 t:LUT2
+select -assert-count 2 t:LUT4
+select -assert-none t:LUT1 t:LUT2 t:LUT4 %% t:* %D
diff --git a/tests/xilinx/macc.ys b/tests/xilinx/macc.ys
index 417a3b21b..6e884b35a 100644
--- a/tests/xilinx/macc.ys
+++ b/tests/xilinx/macc.ys
@@ -1,8 +1,8 @@
 read_verilog macc.v
 design -save read
 
-proc
 hierarchy -top macc
+proc
 #equiv_opt -assert -map +/xilinx/cells_sim.v synth_xilinx ### TODO
 equiv_opt -run :prove -map +/xilinx/cells_sim.v synth_xilinx
 miter -equiv -flatten -make_assert -make_outputs gold gate miter
@@ -15,8 +15,8 @@ select -assert-count 1 t:DSP48E1
 select -assert-none t:BUFG t:FDRE t:DSP48E1 %% t:* %D
 
 design -load read
-proc
 hierarchy -top macc2
+proc
 #equiv_opt -assert -map +/xilinx/cells_sim.v synth_xilinx ### TODO
 equiv_opt -run :prove -map +/xilinx/cells_sim.v synth_xilinx
 miter -equiv -flatten -make_assert -make_outputs gold gate miter
diff --git a/tests/xilinx/memory.v b/tests/xilinx/memory.v
new file mode 100644
index 000000000..cb7753f7b
--- /dev/null
+++ b/tests/xilinx/memory.v
@@ -0,0 +1,21 @@
+module top
+(
+	input [7:0] data_a,
+	input [6:1] addr_a,
+	input we_a, clk,
+	output reg [7:0] q_a
+);
+	// Declare the RAM variable
+	reg [7:0] ram[63:0];
+
+	// Port A
+	always @ (posedge clk)
+	begin
+		if (we_a)
+		begin
+			ram[addr_a] <= data_a;
+			q_a <= data_a;
+		end
+		q_a <= ram[addr_a];
+	end
+endmodule
diff --git a/tests/xilinx/memory.ys b/tests/xilinx/memory.ys
new file mode 100644
index 000000000..5402513a2
--- /dev/null
+++ b/tests/xilinx/memory.ys
@@ -0,0 +1,17 @@
+read_verilog 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/xilinx/mul.v b/tests/xilinx/mul.v
new file mode 100644
index 000000000..d5b48b1d7
--- /dev/null
+++ b/tests/xilinx/mul.v
@@ -0,0 +1,11 @@
+module top
+(
+ input [5:0] x,
+ input [5:0] y,
+
+ output [11:0] A,
+ );
+
+assign A =  x * y;
+
+endmodule
diff --git a/tests/xilinx/mul.ys b/tests/xilinx/mul.ys
new file mode 100644
index 000000000..66a06efdc
--- /dev/null
+++ b/tests/xilinx/mul.ys
@@ -0,0 +1,9 @@
+read_verilog mul.v
+hierarchy -top top
+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 top # Constrain all select calls below inside the top module
+
+select -assert-count 1 t:DSP48E1
+select -assert-none t:DSP48E1 %% t:* %D
diff --git a/tests/xilinx/mul_unsigned.ys b/tests/xilinx/mul_unsigned.ys
index 77990bd68..62495b90c 100644
--- a/tests/xilinx/mul_unsigned.ys
+++ b/tests/xilinx/mul_unsigned.ys
@@ -1,6 +1,7 @@
 read_verilog mul_unsigned.v
-proc
 hierarchy -top mul_unsigned
+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 mul_unsigned # Constrain all select calls below inside the top module
diff --git a/tests/xilinx/mux.v b/tests/xilinx/mux.v
new file mode 100644
index 000000000..27bc0bf0b
--- /dev/null
+++ b/tests/xilinx/mux.v
@@ -0,0 +1,65 @@
+module mux2 (S,A,B,Y);
+    input S;
+    input A,B;
+    output reg Y;
+
+    always @(*)
+		Y = (S)? B : A;
+endmodule
+
+module mux4 ( S, D, Y );
+
+input[1:0] S;
+input[3:0] D;
+output Y;
+
+reg Y;
+wire[1:0] S;
+wire[3:0] D;
+
+always @*
+begin
+    case( S )
+       0 : Y = D[0];
+       1 : Y = D[1];
+       2 : Y = D[2];
+       3 : Y = D[3];
+   endcase
+end
+
+endmodule
+
+module mux8 ( S, D, Y );
+
+input[2:0] S;
+input[7:0] D;
+output Y;
+
+reg Y;
+wire[2:0] S;
+wire[7:0] D;
+
+always @*
+begin
+   case( S )
+       0 : Y = D[0];
+       1 : Y = D[1];
+       2 : Y = D[2];
+       3 : Y = D[3];
+       4 : Y = D[4];
+       5 : Y = D[5];
+       6 : Y = D[6];
+       7 : Y = D[7];
+   endcase
+end
+
+endmodule
+
+module mux16 (D, S, Y);
+ 	input  [15:0] D;
+ 	input  [3:0] S;
+ 	output Y;
+
+assign Y = D[S];
+
+endmodule
diff --git a/tests/xilinx/mux.ys b/tests/xilinx/mux.ys
new file mode 100644
index 000000000..420dece4e
--- /dev/null
+++ b/tests/xilinx/mux.ys
@@ -0,0 +1,45 @@
+read_verilog mux.v
+design -save read
+
+hierarchy -top mux2
+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 mux2 # Constrain all select calls below inside the top module
+select -assert-count 1 t:LUT3
+
+select -assert-none t:LUT3 %% t:* %D
+
+
+design -load read
+hierarchy -top mux4
+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 mux4 # Constrain all select calls below inside the top module
+select -assert-count 1 t:LUT6
+
+select -assert-none t:LUT6 %% t:* %D
+
+
+design -load read
+hierarchy -top mux8
+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 mux8 # Constrain all select calls below inside the top module
+select -assert-count 1 t:LUT3
+select -assert-count 2 t:LUT6
+
+select -assert-none t:LUT3 t:LUT6 %% t:* %D
+
+
+design -load read
+hierarchy -top mux16
+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-none t:LUT6 %% t:* %D
diff --git a/tests/xilinx/run-test.sh b/tests/xilinx/run-test.sh
index ea56b70f0..46716f9a0 100755
--- a/tests/xilinx/run-test.sh
+++ b/tests/xilinx/run-test.sh
@@ -6,7 +6,7 @@ for x in *.ys; do
 	echo "all:: run-$x"
 	echo "run-$x:"
 	echo "	@echo 'Running $x..'"
-	echo "	@../../yosys -ql ${x%.ys}.log $x"
+	echo "	@../../yosys -ql ${x%.ys}.log -w 'Yosys has only limited support for tri-state logic at the moment.' $x"
 done
 for s in *.sh; do
 	if [ "$s" != "run-test.sh" ]; then
diff --git a/tests/xilinx/shifter.v b/tests/xilinx/shifter.v
new file mode 100644
index 000000000..04ae49d83
--- /dev/null
+++ b/tests/xilinx/shifter.v
@@ -0,0 +1,16 @@
+module top    (

+out,

+clk,

+in

+);

+    output [7:0] out;

+    input signed clk, in;

+    reg signed [7:0] out = 0;

+

+    always @(posedge clk)

+	begin

+		out    <= out >> 1;

+		out[7] <= in;

+	end

+

+endmodule

diff --git a/tests/xilinx/shifter.ys b/tests/xilinx/shifter.ys
new file mode 100644
index 000000000..84e16f41e
--- /dev/null
+++ b/tests/xilinx/shifter.ys
@@ -0,0 +1,11 @@
+read_verilog shifter.v
+hierarchy -top top
+proc
+flatten
+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 top # Constrain all select calls below inside the top module
+
+select -assert-count 1 t:BUFG
+select -assert-count 8 t:FDRE
+select -assert-none t:BUFG t:FDRE %% t:* %D
diff --git a/tests/xilinx/tribuf.v b/tests/xilinx/tribuf.v
new file mode 100644
index 000000000..c64468253
--- /dev/null
+++ b/tests/xilinx/tribuf.v
@@ -0,0 +1,8 @@
+module tristate (en, i, o);
+    input en;
+    input i;
+    output reg o;
+    
+    always @(en or i)
+		o <= (en)? i : 1'bZ;
+endmodule
diff --git a/tests/xilinx/tribuf.ys b/tests/xilinx/tribuf.ys
new file mode 100644
index 000000000..c9cfb8546
--- /dev/null
+++ b/tests/xilinx/tribuf.ys
@@ -0,0 +1,12 @@
+read_verilog tribuf.v
+hierarchy -top tristate
+proc
+tribuf
+flatten
+synth
+equiv_opt -assert -map +/xilinx/cells_sim.v -map +/simcells.v synth_xilinx # equivalency check
+design -load postopt # load the post-opt design (otherwise equiv_opt loads the pre-opt design)
+cd tristate # Constrain all select calls below inside the top module
+# TODO :: Tristate logic not yet supported; see https://github.com/YosysHQ/yosys/issues/1225
+select -assert-count 1 t:$_TBUF_
+select -assert-none t:$_TBUF_ %% t:* %D