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Source file test/stack.go

Documentation: test

     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  
    11  package main
    12  
    13  type T [20]int
    14  
    15  func 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  
    23  func 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  
    34  func 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  
    41  func 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  
    55  func f2() [3000]byte {
    56  	// just take up space
    57  	return [3000]byte{}
    58  }
    59  
    60  var c = make(chan int)
    61  var t T
    62  var b = []byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
    63  
    64  func 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  
    95  func main() {
    96  	for i := 0; i < len(t); i++ {
    97  		t[i] = 1
    98  	}
    99  	recur(8000)
   100  }
   101  

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