[tsan] Add Mutex annotation flag for constant-initialized __tsan_mutex_linker_init behavior

Add a new flag, _⁠_tsan_mutex_not_static, which has the opposite sense
of _⁠_tsan_mutex_linker_init. When the new _⁠_tsan_mutex_not_static flag
is passed to _⁠_tsan_mutex_destroy, tsan ignores the destruction unless
the mutex was also created with the _⁠_tsan_mutex_not_static flag.

This is useful for constructors that otherwise woud set
_⁠_tsan_mutex_linker_init but cannot, because they are declared constexpr.

Google has a custom mutex with two constructors, a "linker initialized"
constructor that relies on zero-initialization and sets
⁠_⁠_tsan_mutex_linker_init, and a normal one which sets no tsan flags.
The "linker initialized" constructor is morally constexpr, but we can't
declare it constexpr because of the need to call into tsan as a side effect.

With this new flag, the normal c'tor can set _⁠_tsan_mutex_not_static,
the "linker initialized" constructor can rely on tsan's lazy initialization,
and _⁠_tsan_mutex_destroy can still handle both cases correctly.

Author: Greg Falcon (gfalcon)
Reviewed in: https://reviews.llvm.org/D39095



git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@316209 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 6 insertions, 4 deletions

diff --git a/test/tsan/custom_mutex.h b/test/tsan/custom_mutex.h
index e3ac7a9a5..8e226a170 100644
--- a/test/tsan/custom_mutex.h
+++ b/test/tsan/custom_mutex.h
@@ -6,15 +6,16 @@
 // A very primitive mutex annotated with tsan annotations.
 class Mutex {
  public:
-  Mutex(bool prof, unsigned flags)
+  Mutex(bool prof, unsigned create_flags, unsigned destroy_flags=0)
       : prof_(prof)
       , locked_(false)
-      , seq_(0) {
-    __tsan_mutex_create(this, flags);
+      , seq_(0)
+      , destroy_flags_(destroy_flags) {
+    __tsan_mutex_create(this, create_flags);
   }
 
   ~Mutex() {
-    __tsan_mutex_destroy(this, 0);
+    __tsan_mutex_destroy(this, destroy_flags_);
   }
 
   void Lock() {
@@ -57,6 +58,7 @@ class Mutex {
   const bool prof_;
   std::atomic<bool> locked_;
   int seq_;
+  unsigned destroy_flags_;
 
   // This models mutex profiling subsystem.
   static Mutex prof_mu_;