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 be
11 // created while a the debugger is stepping in another thread.
12
13 #include <pthread.h>
14 #include <atomic>
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 std::atomic_int g_barrier;
29
30 volatile int g_thread_created = 0;
31 volatile int g_test = 0;
32
33 void *
step_thread_func(void * input)34 step_thread_func (void *input)
35 {
36 g_test = 0; // Set breakpoint here
37
38 while (!g_thread_created)
39 g_test++;
40
41 // One more time to provide a continue point
42 g_test++; // Continue from here
43
44 // Return
45 return NULL;
46 }
47
48 void *
create_thread_func(void * input)49 create_thread_func (void *input)
50 {
51 pthread_t *step_thread = (pthread_t*)input;
52
53 // Wait until the main thread knows this thread is started.
54 pseudo_barrier_wait(g_barrier);
55
56 // Wait until the other thread is done.
57 pthread_join(*step_thread, NULL);
58
59 // Return
60 return NULL;
61 }
62
main()63 int main ()
64 {
65 pthread_t thread_1;
66 pthread_t thread_2;
67
68 // Use a simple count to simulate a barrier.
69 pseudo_barrier_init(g_barrier, 2);
70
71 // Create a thread to hit the breakpoint.
72 pthread_create (&thread_1, NULL, step_thread_func, NULL);
73
74 // Wait until the step thread is stepping
75 while (g_test < 1)
76 do_nothing();
77
78 // Create a thread to exit while we're stepping.
79 pthread_create (&thread_2, NULL, create_thread_func, &thread_1);
80
81 // Wait until that thread is started
82 pseudo_barrier_wait(g_barrier);
83
84 // Let the stepping thread know the other thread is there
85 g_thread_created = 1;
86
87 // Wait for the threads to finish.
88 pthread_join(thread_2, NULL);
89 pthread_join(thread_1, NULL);
90
91 return 0;
92 }
93