sv: Add tests for SV always types

Signed-off-by: David Shah <dave@ds0.me>

tests/various/svalways.sh

@@ -0,0 +1,63 @@
+#!/bin/bash
+
+trap 'echo "ERROR in svalways.sh" >&2; exit 1' ERR
+
+# Good case
+../../yosys -f "verilog -sv" -qp proc - <<EOT
+module top(input clk, en, d, output reg p, q, r);
+
+always_ff @(posedge clk)
+	p <= d;
+
+always_comb
+	q = ~d;
+
+always_latch
+	if (en) r = d;
+
+endmodule
+EOT
+
+# Incorrect always_comb syntax
+((../../yosys -f "verilog -sv" -qp proc -|| true) <<EOT
+module top(input d, output reg q);
+
+always_comb @(d)
+	q = ~d;
+
+endmodule
+EOT
+) 2>&1 | grep -F "<stdin>:3: ERROR: syntax error, unexpected '@'" > /dev/null
+
+# Incorrect use of always_comb
+((../../yosys -f "verilog -sv" -qp proc -|| true) <<EOT
+module top(input en, d, output reg q);
+
+always_comb
+	if (en) q = d;
+
+endmodule
+EOT
+) 2>&1 | grep -F "ERROR: Latch inferred for signal \`\\top.\\q' from always_comb process" > /dev/null
+
+# Incorrect use of always_latch
+((../../yosys -f "verilog -sv" -qp proc -|| true) <<EOT
+module top(input en, d, output reg q);
+
+always_latch
+	q = !d;
+
+endmodule
+EOT
+) 2>&1 | grep -F "ERROR: No latch inferred for signal \`\\top.\\q' from always_latch process" > /dev/null
+
+# Incorrect use of always_ff
+((../../yosys -f "verilog -sv" -qp proc -|| true) <<EOT
+module top(input en, d, output reg q);
+
+always_ff @(*)
+	q = !d;
+
+endmodule
+EOT
+) 2>&1 | grep -F "ERROR: Found non edge/level sensitive event in always_ff process" > /dev/null