1 //===-- main.cpp ------------------------------------------------*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9
10 // This test is intended to create a situation in which one thread will exit
11 // while a the debugger is stepping in another thread.
12
13 #include <pthread.h>
14 #include <unistd.h>
15
16 // Note that although hogging the CPU while waiting for a variable to change
17 // would be terrible in production code, it's great for testing since it
18 // avoids a lot of messy context switching to get multiple threads synchronized.
19 #define do_nothing()
20
21 #define pseudo_barrier_wait(bar) \
22 --bar; \
23 while (bar > 0) \
24 do_nothing();
25
26 #define pseudo_barrier_init(bar, count) (bar = count)
27
28 // A barrier to synchronize thread start.
29 volatile int g_barrier;
30
31 volatile int g_thread_exited = 0;
32
33 volatile int g_test = 0;
34
35 void *
step_thread_func(void * input)36 step_thread_func (void *input)
37 {
38 // Wait until both threads are started.
39 pseudo_barrier_wait(g_barrier);
40
41 g_test = 0; // Set breakpoint here
42
43 while (!g_thread_exited)
44 g_test++;
45
46 // One more time to provide a continue point
47 g_test++; // Continue from here
48
49 // Return
50 return NULL;
51 }
52
53 void *
exit_thread_func(void * input)54 exit_thread_func (void *input)
55 {
56 // Wait until both threads are started.
57 pseudo_barrier_wait(g_barrier);
58
59 // Wait until the other thread is stepping.
60 while (g_test == 0)
61 do_nothing();
62
63 // Return
64 return NULL;
65 }
66
main()67 int main ()
68 {
69 pthread_t thread_1;
70 pthread_t thread_2;
71
72 // Synchronize thread start so that doesn't happen during stepping.
73 pseudo_barrier_init(g_barrier, 2);
74
75 // Create a thread to hit the breakpoint.
76 pthread_create (&thread_1, NULL, step_thread_func, NULL);
77
78 // Create a thread to exit while we're stepping.
79 pthread_create (&thread_2, NULL, exit_thread_func, NULL);
80
81 // Wait for the exit thread to finish.
82 pthread_join(thread_2, NULL);
83
84 // Let the stepping thread know the other thread is gone.
85 g_thread_exited = 1;
86
87 // Wait for the stepping thread to finish.
88 pthread_join(thread_1, NULL);
89
90 return 0;
91 }
92