Add WIP test for unwrapping $__ICE40_CARRY_WRAPPER

tests/arch/ice40/wrapcarry.ys

@@ -20,3 +20,33 @@ EOT
 
 ice40_wrapcarry
 select -assert-count 1 t:$__ICE40_CARRY_WRAPPER
+
+design -reset
+read_verilog <<EOT
+module top(input A, B, CI, output O, CO);
+    (* foo = "bar", answer = 42 *)
+	SB_CARRY carry (
+		.I0(A),
+		.I1(B),
+		.CI(CI),
+		.CO(CO)
+	);
+    (* keep, blah="blah", answer = 43 *)
+	SB_LUT4 #(
+		.LUT_INIT(16'b 0110_1001_1001_0110)
+	) adder (
+		.I0(1'b0),
+		.I1(A),
+		.I2(B),
+		.I3(1'b0),
+		.O(O)
+	);
+endmodule
+EOT
+
+ice40_wrapcarry
+select -assert-count 1 t:$__ICE40_CARRY_WRAPPER
+select -assert-count 0 t:* t:$__ICE40_CARRY_WRAPPER %d
+select -assert-count 1 a:foo=bar a:answer=42 %i a:keep %i a:blah=blah %i
+techmap -map +/ice40/cells_map.v
+#TODO: Check unwrapped attributes