yosys/tests/verific/memory_semantics.ys

verific -sv <<EOF

module top(clk);
input wire clk;

parameter DEPTH_LOG2 = 4;
parameter DEPTH = 2**DEPTH_LOG2;
parameter BYTEWIDTH = 8;
parameter WIDTH = BYTEWIDTH*4;
parameter PRIME1 = 237481091;
parameter PRIME2 = 296851369;

(* ram_style = "block" *)
reg [WIDTH-1:0] mem [DEPTH-1:0];

integer i;
initial begin
    for (i = 0; i < DEPTH; i = i + 1) begin
        // Make up data by multiplying a large prime with the address,
        // then cropping and retaining the lower bits
        mem[i] = PRIME1 * i;
    end
end

reg [DEPTH_LOG2-1:0] counter = 0;
reg done = 1'b0;
always @(posedge clk) begin
    if (!done)
        counter = counter + 1'b1;
    if (counter == 0)
        done = 1'b1;
end

wire [WIDTH-1:0] old_data = PRIME1 * counter;
wire [WIDTH-1:0] new_data = PRIME2 * counter;

reg [WIDTH-1:0] expect_old_data;
reg [WIDTH-1:0] expect_mixed_data;

always @(posedge clk) begin
    if (!done) begin
        expect_old_data <= mem[counter];
        mem[counter][31:24] <= new_data[31:24];
        mem[counter][23:16] = new_data[23:16]; // !!! is blocking
        mem[counter][15:8] <= new_data[15:8];
        mem[counter][7:0] <= new_data[7:0];
        expect_mixed_data <= mem[counter];
    end
end

reg done_delay1 = 1'b1;
reg [WIDTH-1:0] new_data_delay1 = 1'b1;
reg [WIDTH-1:0] old_data_delay1 = 1'b1;

always @(posedge clk) begin
    if (!done_delay1) begin
        assert(expect_old_data == old_data_delay1);
        assert(expect_mixed_data[31:24] == old_data_delay1[31:24]);
        assert(expect_mixed_data[23:16] == new_data_delay1[23:16]);
        assert(expect_mixed_data[15:0] == old_data_delay1[15:0]);
    end
end

reg [DEPTH_LOG2-1:0] counter_delay1;
always @(posedge clk) begin
    counter_delay1 <= counter;
    done_delay1 <= done;
    new_data_delay1 <= new_data;
    old_data_delay1 <= old_data;
end

reg [DEPTH_LOG2-1:0] counter_delay2;
reg done_delay2 = 1'b1;
reg [WIDTH-1:0] new_data_delay2 = 1'b1;
always @(posedge clk) begin
    counter_delay2 <= counter_delay1;
    done_delay2 <= done_delay1;
    new_data_delay2 <= new_data_delay1;
end

always @(posedge clk) begin
    if (!done_delay2)
        assert(mem[counter_delay2] == new_data_delay2);
end

endmodule
EOF

hierarchy -top top
proc
opt_clean
memory -nomap -nordff
select -assert-count 1 t:$mem_v2
sim -assert -clock clk -n 20