[tsan] Fix a crash when exiting the main thread (e.g. dispatch_main)

This patch fixes the custom ThreadState destruction on OS X to avoid crashing when dispatch_main calls pthread_exit which quits the main thread.

Differential Revision: http://reviews.llvm.org/D18496

llvm-svn: 264627

1 files changed, 5 insertions, 1 deletions

diff --git a/compiler-rt/lib/tsan/rtl/tsan_platform_mac.cc b/compiler-rt/lib/tsan/rtl/tsan_platform_mac.cc
index 31caf37dee5..6109ef28b33 100644
--- a/compiler-rt/lib/tsan/rtl/tsan_platform_mac.cc
+++ b/compiler-rt/lib/tsan/rtl/tsan_platform_mac.cc
@@ -91,7 +91,11 @@ ThreadState *cur_thread() {
 // handler will try to access the unmapped ThreadState.
 void cur_thread_finalize() {
   uptr thread_identity = (uptr)pthread_self();
-  CHECK_NE(thread_identity, main_thread_identity);
+  if (thread_identity == main_thread_identity) {
+    // Calling dispatch_main() or xpc_main() actually invokes pthread_exit to
+    // exit the main thread. Let's keep the main thread's ThreadState.
+    return;
+  }
   ThreadState **fake_tls = (ThreadState **)MemToShadow(thread_identity);
   internal_munmap(*fake_tls, sizeof(ThreadState));
   *fake_tls = nullptr;