diff --git a/include/llvm/Support/ManagedStatic.h b/include/llvm/Support/ManagedStatic.h index 53e73ad35f4..4171d1bec8d 100644 --- a/include/llvm/Support/ManagedStatic.h +++ b/include/llvm/Support/ManagedStatic.h @@ -16,6 +16,7 @@ #include "llvm/Support/Atomic.h" #include "llvm/Support/Threading.h" +#include "llvm/Support/Valgrind.h" namespace llvm { @@ -65,6 +66,7 @@ public: void* tmp = Ptr; if (llvm_is_multithreaded()) sys::MemoryFence(); if (!tmp) RegisterManagedStatic(object_creator, object_deleter::call); + TsanHappensAfter(this); return *static_cast(Ptr); } @@ -72,6 +74,7 @@ public: void* tmp = Ptr; if (llvm_is_multithreaded()) sys::MemoryFence(); if (!tmp) RegisterManagedStatic(object_creator, object_deleter::call); + TsanHappensAfter(this); return static_cast(Ptr); } @@ -79,6 +82,7 @@ public: void* tmp = Ptr; if (llvm_is_multithreaded()) sys::MemoryFence(); if (!tmp) RegisterManagedStatic(object_creator, object_deleter::call); + TsanHappensAfter(this); return *static_cast(Ptr); } @@ -86,6 +90,7 @@ public: void* tmp = Ptr; if (llvm_is_multithreaded()) sys::MemoryFence(); if (!tmp) RegisterManagedStatic(object_creator, object_deleter::call); + TsanHappensAfter(this); return static_cast(Ptr); } diff --git a/include/llvm/Support/Valgrind.h b/include/llvm/Support/Valgrind.h index 7662eaaff5a..0ecd33b6dd1 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 +#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 } } diff --git a/lib/Support/ManagedStatic.cpp b/lib/Support/ManagedStatic.cpp index c767c15e71c..098cccb68df 100644 --- a/lib/Support/ManagedStatic.cpp +++ b/lib/Support/ManagedStatic.cpp @@ -27,8 +27,15 @@ void ManagedStaticBase::RegisterManagedStatic(void *(*Creator)(), if (Ptr == 0) { void* tmp = Creator ? Creator() : 0; + TsanHappensBefore(this); sys::MemoryFence(); + + // This write is racy against the first read in the ManagedStatic + // accessors. The race is benign because it does a second read after a + // memory fence, at which point it isn't possible to get a partial value. + TsanIgnoreWritesBegin(); Ptr = tmp; + TsanIgnoreWritesEnd(); DeleterFn = Deleter; // Add to list of managed statics. @@ -72,4 +79,3 @@ void llvm::llvm_shutdown() { if (llvm_is_multithreaded()) llvm_stop_multithreaded(); } - diff --git a/lib/Support/Valgrind.cpp b/lib/Support/Valgrind.cpp index 703448524ed..078d705183d 100644 --- a/lib/Support/Valgrind.cpp +++ b/lib/Support/Valgrind.cpp @@ -52,3 +52,14 @@ void llvm::sys::ValgrindDiscardTranslations(const void *Addr, size_t Len) { } #endif // !HAVE_VALGRIND_VALGRIND_H + +// These functions require no implementation, tsan just looks at the arguments +// they're called with. +extern "C" { +void AnnotateHappensBefore(const char *file, int line, + const volatile void *cv) {} +void AnnotateHappensAfter(const char *file, int line, + const volatile void *cv) {} +void AnnotateIgnoreWritesBegin(const char *file, int line) {} +void AnnotateIgnoreWritesEnd(const char *file, int line) {} +} diff --git a/unittests/Support/ManagedStatic.cpp b/unittests/Support/ManagedStatic.cpp new file mode 100644 index 00000000000..f1f03208c1f --- /dev/null +++ b/unittests/Support/ManagedStatic.cpp @@ -0,0 +1,39 @@ +//===- llvm/unittest/Support/ManagedStatic.cpp - ManagedStatic tests ------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +#include "llvm/Support/ManagedStatic.h" +#include "llvm/Support/Threading.h" +#include + +#include "gtest/gtest.h" + +using namespace llvm; + +namespace { + +namespace test1 { + llvm::ManagedStatic ms; + void *helper(void*) { + *ms; + return NULL; + } +} + +TEST(Initialize, MultipleThreads) { + // Run this test under tsan: http://code.google.com/p/data-race-test/ + + llvm_start_multithreaded(); + pthread_t t1, t2; + pthread_create(&t1, NULL, test1::helper, NULL); + pthread_create(&t2, NULL, test1::helper, NULL); + pthread_join(t1, NULL); + pthread_join(t2, NULL); + llvm_stop_multithreaded(); +} + +} // anonymous namespace