[NFC][ASAN] Remove redundant fields of AsanThread

compiler-rt/lib/asan/asan_interceptors.cpp

@@ -177,9 +177,9 @@ static thread_return_t THREAD_CALLING_CONV asan_thread_start(void *arg) {
   SetCurrentThread(t);
   auto self = GetThreadSelf();
   auto args = asanThreadArgRetval().GetArgs(self);
-  thread_return_t retval = t->ThreadStart(GetTid());
+  thread_return_t retval =
+      t->ThreadStart(GetTid(), args.routine, args.arg_retval);
   asanThreadArgRetval().Finish(self, retval);
-  CHECK_EQ(args.arg_retval, t->get_arg());
   return retval;
 }
 
@@ -197,8 +197,7 @@ INTERCEPTOR(int, pthread_create, void *thread, void *attr,
   }();
 
   u32 current_tid = GetCurrentTidOrInvalid();
-  AsanThread *t =
-      AsanThread::Create(start_routine, arg, current_tid, &stack, detached);
+  AsanThread *t = AsanThread::Create(current_tid, &stack, detached);
 
   int result;
   {

compiler-rt/lib/asan/asan_thread.cpp

@@ -91,14 +91,11 @@ AsanThreadContext *GetThreadContextByTidLocked(u32 tid) {
 
 // AsanThread implementation.
 
-AsanThread *AsanThread::Create(thread_callback_t start_routine, void *arg,
-                               u32 parent_tid, StackTrace *stack,
+AsanThread *AsanThread::Create(u32 parent_tid, StackTrace *stack,
                                bool detached) {
   uptr PageSize = GetPageSizeCached();
   uptr size = RoundUpTo(sizeof(AsanThread), PageSize);
   AsanThread *thread = (AsanThread *)MmapOrDie(size, __func__);
-  thread->start_routine_ = start_routine;
-  thread->arg_ = arg;
   AsanThreadContext::CreateThreadContextArgs args = {thread, stack};
   asanThreadRegistry().CreateThread(0, detached, parent_tid, &args);
 
@@ -273,22 +270,23 @@ void AsanThread::Init(const InitOptions *options) {
 // asan_fuchsia.c definies CreateMainThread and SetThreadStackAndTls.
 #if !SANITIZER_FUCHSIA
 
-thread_return_t AsanThread::ThreadStart(tid_t os_id) {
+thread_return_t AsanThread::ThreadStart(tid_t os_id, void *(*routine)(void *),
+                                        void *arg) {
   Init();
   asanThreadRegistry().StartThread(tid(), os_id, ThreadType::Regular, nullptr);
 
   if (common_flags()->use_sigaltstack)
     SetAlternateSignalStack();
 
-  if (!start_routine_) {
+  if (!routine) {
     // start_routine_ == 0 if we're on the main thread or on one of the
     // OS X libdispatch worker threads. But nobody is supposed to call
     // ThreadStart() for the worker threads.
-    CHECK_EQ(tid(), 0);
+    CHECK_EQ(tid(), kMainTid);
     return 0;
   }
 
-  thread_return_t res = start_routine_(arg_);
+  thread_return_t res = (*routine)(arg);
 
   // On POSIX systems we defer this to the TSD destructor. LSan will consider
   // the thread's memory as non-live from the moment we call Destroy(), even
@@ -303,10 +301,10 @@ thread_return_t AsanThread::ThreadStart(tid_t os_id) {
 
 AsanThread *CreateMainThread() {
   AsanThread *main_thread = AsanThread::Create(
-      /* start_routine */ nullptr, /* arg */ nullptr, /* parent_tid */ kMainTid,
+      /* parent_tid */ kMainTid,
       /* stack */ nullptr, /* detached */ true);
   SetCurrentThread(main_thread);
-  main_thread->ThreadStart(internal_getpid());
+  main_thread->ThreadStart(internal_getpid(), nullptr, nullptr);
   return main_thread;
 }
 

compiler-rt/lib/asan/asan_thread.h

@@ -59,15 +59,14 @@ COMPILER_CHECK(sizeof(AsanThreadContext) <= 256);
 // AsanThread are stored in TSD and destroyed when the thread dies.
 class AsanThread {
  public:
-  static AsanThread *Create(thread_callback_t start_routine, void *arg,
-                            u32 parent_tid, StackTrace *stack, bool detached);
+  static AsanThread *Create(u32 parent_tid, StackTrace *stack, bool detached);
   static void TSDDtor(void *tsd);
   void Destroy();
 
   struct InitOptions;
   void Init(const InitOptions *options = nullptr);
 
-  thread_return_t ThreadStart(tid_t os_id);
+  thread_return_t ThreadStart(tid_t os_id, void *(*routine)(void *), void *arg);
 
   uptr stack_top();
   uptr stack_bottom();
@@ -130,8 +129,6 @@ class AsanThread {
 
   void *extra_spill_area() { return &extra_spill_area_; }
 
-  void *get_arg() const { return arg_; }
-
  private:
   // NOTE: There is no AsanThread constructor. It is allocated
   // via mmap() and *must* be valid in zero-initialized state.
@@ -148,8 +145,6 @@ class AsanThread {
   StackBounds GetStackBounds() const;
 
   AsanThreadContext *context_;
-  thread_callback_t start_routine_;
-  void *arg_;
 
   uptr stack_top_;
   uptr stack_bottom_;