Adding support for stopping all threads of multithreaded inferiors on Linux.  Also adding multithreaded test cases.

llvm-svn: 182809
diff --git a/lldb/test/functionalities/thread/thread_exit/main.cpp b/lldb/test/functionalities/thread/thread_exit/main.cpp
new file mode 100644
index 0000000..94ed517
--- /dev/null
+++ b/lldb/test/functionalities/thread/thread_exit/main.cpp
@@ -0,0 +1,89 @@
+//===-- main.cpp ------------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// This test verifies the correct handling of child thread exits.
+
+#include <pthread.h>
+#include <atomic>
+
+// Note that although hogging the CPU while waiting for a variable to change
+// would be terrible in production code, it's great for testing since it
+// avoids a lot of messy context switching to get multiple threads synchronized.
+#define do_nothing()
+
+#define pseudo_barrier_wait(bar) \
+    --bar;                       \
+    while (bar > 0)              \
+        do_nothing();
+
+#define pseudo_barrier_init(bar, count) (bar = count)
+
+std::atomic_int g_barrier1;
+std::atomic_int g_barrier2;
+std::atomic_int g_barrier3;
+
+void *
+thread1 (void *input)
+{
+    // Synchronize with the main thread.
+    pseudo_barrier_wait(g_barrier1);
+
+    // Synchronize with the main thread and thread2.
+    pseudo_barrier_wait(g_barrier2);
+
+    // Return
+    return NULL;                                      // Set second breakpoint here
+}
+
+void *
+thread2 (void *input)
+{
+    // Synchronize with thread1 and the main thread.
+    pseudo_barrier_wait(g_barrier2);
+
+    // Synchronize with the main thread.
+    pseudo_barrier_wait(g_barrier3);
+
+    // Return
+    return NULL;
+}
+
+int main ()
+{
+    pthread_t thread_1;
+    pthread_t thread_2;
+    pthread_t thread_3;
+
+    pseudo_barrier_init(g_barrier1, 2);
+    pseudo_barrier_init(g_barrier2, 3);
+    pseudo_barrier_init(g_barrier3, 2);
+
+    // Create a thread.
+    pthread_create (&thread_1, NULL, thread1, NULL);
+
+    // Wait for thread1 to start.
+    pseudo_barrier_wait(g_barrier1);
+
+    // Create another thread.
+    pthread_create (&thread_2, NULL, thread2, NULL);  // Set first breakpoint here
+
+    // Wait for thread2 to start.
+    pseudo_barrier_wait(g_barrier2);
+
+    // Wait for the first thread to finish
+    pthread_join(thread_1, NULL);
+
+    // Synchronize with the remaining thread
+    pseudo_barrier_wait(g_barrier3);                  // Set third breakpoint here
+
+    // Wait for the second thread to finish
+    pthread_join(thread_2, NULL);
+
+    return 0;                                         // Set fourth breakpoint here
+}