[tsan] Fix os_id of main thread

[kubamracek]

Summary

Currently, os_id of the main thread contains the PID instead of a thread ID. Let's fix this.

compiler-rt/trunk/lib/tsan/rtl/tsan_rtl.cc

 #endif
 
   VPrintf(1, "***** Running under ThreadSanitizer v2 (pid %d) *****\n",
           (int)internal_getpid());
 
   // Initialize thread 0.
   int tid = ThreadCreate(thr, 0, 0, true);
   CHECK_EQ(tid, 0);
-  ThreadStart(thr, tid, internal_getpid());
+  ThreadStart(thr, tid, GetTid());
 #if TSAN_CONTAINS_UBSAN
   __ubsan::InitAsPlugin();
 #endif
   ctx->initialized = true;
 
 #if !SANITIZER_GO
   Symbolizer::LateInitialize();
 #endif

compiler-rt/trunk/test/tsan/Darwin/main_tid.mm

+// RUN: %clang_tsan %s -o %t -framework Foundation
+// RUN: %deflake %run %t 2>&1 | FileCheck %s
+
+#import <pthread.h>
+#import <stdio.h>
+#import <stdlib.h>
+
+extern "C" {
+void __tsan_on_report(void *report);
+int __tsan_get_report_thread(void *report, unsigned long idx, int *tid,
+                             unsigned long *os_id, int *running,
+                             const char **name, int *parent_tid, void **trace,
+                             unsigned long trace_size);
+}
+
+void __tsan_on_report(void *report) {
+  fprintf(stderr, "__tsan_on_report(%p)\n", report);
+
+  int tid;
+  unsigned long os_id;
+  int running;
+  const char *name;
+  int parent_tid;
+  void *trace[16] = {0};
+  __tsan_get_report_thread(report, 0, &tid, &os_id, &running, &name, &parent_tid, trace, 16);
+  fprintf(stderr, "tid = %d, os_id = %lu\n", tid, os_id);
+}
+
+int main() {
+  fprintf(stderr, "Hello world.\n");
+
+  uint64_t threadid;
+  pthread_threadid_np(NULL, &threadid);
+  fprintf(stderr, "pthread_threadid_np = %llu\n", threadid);
+
+  pthread_mutex_t m;
+  pthread_mutex_init(&m, NULL);
+  pthread_mutex_unlock(&m);
+  fprintf(stderr, "Done.\n");
+}
+
+// CHECK: Hello world.
+// CHECK: pthread_threadid_np = [[ADDR:[0-9]+]]
+// CHECK: WARNING: ThreadSanitizer
+// CHECK: tid = 0, os_id = [[ADDR]]
+// CHECK: Done.