test(effect): test DCE with unused result of subexpression

Author: BeyondMagic

tests/pass/effect.c

@@ -0,0 +1,10 @@
+int add(int k, int y)
+{
+	return k + y;
+}
+
+int main(int K)
+{
+	int a = add(10, 20);
+	return 0;
+}

tests/pass/effect.lua

@@ -0,0 +1,10 @@
+local function add(k, y)
+	return (k + y)
+end
+
+os.exit((function(args)
+	local args_table = args
+	local K = args_table and tonumber(args_table[1]) or 0
+	add(10, 20)
+	return 0
+end)(arg))