Add bench example

test/gc/bench.py

@@ -0,0 +1,35 @@
+class Bar:
+    def __init__(self, a):
+        self.a = a
+
+class Foo:
+    def __init__(self, x):
+        self.x = x
+        self.y = None
+
+    def setY(self, b):
+        self.y = b
+
+def foo(N, M):
+    foo = [None] * N # ????
+    outer = None
+
+    i = 1
+    while i <= N:
+        o1 = Foo(i)
+        if i % 3 == 0:
+            foo[i % M - 1] = o1
+
+        o2 = Bar(i)
+        if i % 5 == 0:
+            o1.setY(o2)
+        outer = o1
+
+        i += 1
+
+def main():
+    N = 4000000
+    M = 1000
+    foo(N, M)
+
+main()