[Threading][TSan] Rearrange things again.

We need ThreadSanitizer.cpp in libswiftCore for the runtime case, but
we also need it in libswiftThreading for non-runtime cases.

rdar://1106655213

Author: al45tair

lib/Threading/CMakeLists.txt

@@ -10,4 +10,5 @@ add_swift_host_library(swiftThreading STATIC
   Linux.cpp
   Pthreads.cpp
   Win32.cpp
-  Errors.cpp)
+  Errors.cpp
+  ThreadSanitizer.cpp)

stdlib/public/runtime/ThreadSanitizer.cpp lib/Threading/ThreadSanitizer.cpp

@@ -25,15 +25,18 @@
 namespace swift {
 namespace threading_impl {
 
-SWIFT_RUNTIME_EXPORT bool _swift_tsan_enabled = false;
-SWIFT_RUNTIME_EXPORT void (*_swift_tsan_acquire)(const void *) = nullptr;
-SWIFT_RUNTIME_EXPORT void (*_swift_tsan_release)(const void *) = nullptr;
+extern "C" SWIFT_ATTRIBUTE_FOR_EXPORTS
+bool _swift_tsan_enabled = false;
+extern "C" SWIFT_ATTRIBUTE_FOR_EXPORTS
+void (*_swift_tsan_acquire)(const void *) = nullptr;
+extern "C" SWIFT_ATTRIBUTE_FOR_EXPORTS
+void (*_swift_tsan_release)(const void *) = nullptr;
 
 #if __has_include(<dlfcn.h>)
 #include <dlfcn.h>
 
 // The TSan library code will call this function when it starts up
-SWIFT_RUNTIME_EXPORT
+extern "C" SWIFT_ATTRIBUTE_FOR_EXPORTS
 void __tsan_on_initialize() {
   _swift_tsan_enabled = true;
   _swift_tsan_acquire = (void (*)(const void *))dlsym(RTLD_DEFAULT,

stdlib/public/Threading/CMakeLists.txt

@@ -4,6 +4,7 @@
 list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/../../cmake/modules")
 include(AddSwiftStdlib)
 
+# This should *not* include ThreadSanitizer.cpp, as that is part of libswiftCore
 add_swift_target_library(swiftThreading OBJECT_LIBRARY
   "${SWIFT_SOURCE_DIR}/lib/Threading/C11.cpp"
   "${SWIFT_SOURCE_DIR}/lib/Threading/Linux.cpp"

stdlib/public/runtime/CMakeLists.txt

@@ -76,11 +76,16 @@ set(swift_runtime_sources
     SwiftDtoa.cpp
     SwiftTLSContext.cpp
     ThreadingError.cpp
-    ThreadSanitizer.cpp
     Tracing.cpp
     AccessibleFunction.cpp
     Win32.cpp)
 
+# We pull this in separately here because other dylibs will need it, but only
+# will have the __tsan_on_initialize called, and on Darwin, RTLD_NEXT can't be
+# used to call subsequence dylibs' copies of that.
+set(swift_runtime_threading_sources
+  ${SWIFT_SOURCE_DIR}/lib/Threading/ThreadSanitizer.cpp)
+
 set(swift_runtime_backtracing_sources
   Backtrace.cpp
   CrashHandlerMacOS.cpp
@@ -133,6 +138,7 @@ add_swift_target_library(swiftRuntime OBJECT_LIBRARY
   ${swift_runtime_sources}
   ${swift_runtime_objc_sources}
   ${swift_runtime_leaks_sources}
+  ${swift_runtime_threading_sources}
   C_COMPILE_FLAGS
     ${swift_runtime_library_compile_flags}
   LINK_FLAGS ${swift_runtime_linker_flags}