Add support for tsan annotations (thread sanitizer, a valgrind-based tool).

These annotations are disabled entirely when either ENABLE_THREADS is off, or
building a release build. When enabled, they add calls to functions with no
statements to ManagedStatic's getters.

Use these annotations to inform tsan that the race used inside ManagedStatic
initialization is actually benign. Thanks to Kostya Serebryany for helping
write this patch!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@144567 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 45 insertions, 0 deletions

diff --git a/include/llvm/Support/Valgrind.h b/include/llvm/Support/Valgrind.h
index 7662eaaff5..0ecd33b6dd 100644
--- a/include/llvm/Support/Valgrind.h
+++ b/include/llvm/Support/Valgrind.h
@@ -16,8 +16,25 @@
 #ifndef LLVM_SYSTEM_VALGRIND_H
 #define LLVM_SYSTEM_VALGRIND_H
 
+#include "llvm/Support/Compiler.h"
+#include "llvm/Config/config.h"
 #include <stddef.h>
 
+#if ENABLE_THREADS != 0 && !defined(NDEBUG)
+// tsan (Thread Sanitizer) is a valgrind-based tool that detects these exact
+// functions by name.
+extern "C" {
+LLVM_ATTRIBUTE_NOINLINE void AnnotateHappensAfter(const char *file, int line,
+                                                  const volatile void *cv);
+LLVM_ATTRIBUTE_NOINLINE void AnnotateHappensBefore(const char *file, int line,
+                                                   const volatile void *cv);
+LLVM_ATTRIBUTE_NOINLINE void AnnotateIgnoreWritesBegin(const char *file,
+                                                       int line);
+LLVM_ATTRIBUTE_NOINLINE void AnnotateIgnoreWritesEnd(const char *file,
+                                                     int line);
+}
+#endif
+
 namespace llvm {
 namespace sys {
   // True if Valgrind is controlling this process.
@@ -26,6 +43,34 @@ namespace sys {
   // Discard valgrind's translation of code in the range [Addr .. Addr + Len).
   // Otherwise valgrind may continue to execute the old version of the code.
   void ValgrindDiscardTranslations(const void *Addr, size_t Len);
+
+#if ENABLE_THREADS != 0 && !defined(NDEBUG)
+  // Thread Sanitizer is a valgrind tool that finds races in code.
+  // See http://code.google.com/p/data-race-test/wiki/DynamicAnnotations .
+
+  // This marker is used to define a happens-before arc. The race detector will
+  // infer an arc from the begin to the end when they share the same pointer
+  // argument.
+  #define TsanHappensBefore(cv) \
+    AnnotateHappensBefore(__FILE__, __LINE__, cv)
+
+  // This marker defines the destination of a happens-before arc.
+  #define TsanHappensAfter(cv) \
+    AnnotateHappensAfter(__FILE__, __LINE__, cv)
+
+  // Ignore any races on writes between here and the next TsanIgnoreWritesEnd.
+  #define TsanIgnoreWritesBegin() \
+    AnnotateIgnoreWritesBegin(__FILE__, __LINE__)
+
+  // Resume checking for racy writes.
+  #define TsanIgnoreWritesEnd() \
+    AnnotateIgnoreWritesEnd(__FILE__, __LINE__)
+#else
+  #define TsanHappensBefore(cv)
+  #define TsanHappensAfter(cv)
+  #define TsanIgnoreWritesBegin()
+  #define TsanIgnoreWritesEnd()
+#endif
 }
 }