1// run
2
3// Copyright 2009 The Go Authors. All rights reserved.
4// Use of this source code is governed by a BSD-style
5// license that can be found in the LICENSE file.
6
7// Test stack splitting code.
8// Try to tickle stack splitting bugs by doing
9// go, defer, and closure calls at different stack depths.
10
11package main
12
13type T [20]int
14
15func g(c chan int, t T) {
16	s := 0
17	for i := 0; i < len(t); i++ {
18		s += t[i]
19	}
20	c <- s
21}
22
23func d(t T) {
24	s := 0
25	for i := 0; i < len(t); i++ {
26		s += t[i]
27	}
28	if s != len(t) {
29		println("bad defer", s)
30		panic("fail")
31	}
32}
33
34func f0() {
35	// likely to make a new stack for f0,
36	// because the call to f1 puts 3000 bytes
37	// in our frame.
38	f1()
39}
40
41func f1() [3000]byte {
42	// likely to make a new stack for f1,
43	// because 3000 bytes were used by f0
44	// and we need 3000 more for the call
45	// to f2.  if the call to morestack in f1
46	// does not pass the frame size, the new
47	// stack (default size 5k) will not be big
48	// enough for the frame, and the morestack
49	// check in f2 will die, if we get that far
50	// without faulting.
51	f2()
52	return [3000]byte{}
53}
54
55func f2() [3000]byte {
56	// just take up space
57	return [3000]byte{}
58}
59
60var c = make(chan int)
61var t T
62var b = []byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
63
64func recur(n int) {
65	ss := string(b)
66	if len(ss) != len(b) {
67		panic("bad []byte -> string")
68	}
69	go g(c, t)
70	f0()
71	s := <-c
72	if s != len(t) {
73		println("bad go", s)
74		panic("fail")
75	}
76	f := func(t T) int {
77		s := 0
78		for i := 0; i < len(t); i++ {
79			s += t[i]
80		}
81		s += n
82		return s
83	}
84	s = f(t)
85	if s != len(t)+n {
86		println("bad func", s, "at level", n)
87		panic("fail")
88	}
89	if n > 0 {
90		recur(n - 1)
91	}
92	defer d(t)
93}
94
95func main() {
96	for i := 0; i < len(t); i++ {
97		t[i] = 1
98	}
99	recur(8000)
100}
101