[compiler-rt] r347336 - [tsan] Add __cxa_guard_acquire hooks to support cooperative scheduling

[Vitaly Buka via llvm-commits]

Author: vitalybuka
Date: Tue Nov 20 10:21:42 2018
New Revision: 347336

URL: http://llvm.org/viewvc/llvm-project?rev=347336&view=rev
Log:
[tsan] Add __cxa_guard_acquire hooks to support cooperative scheduling

Reviewers: dvyukov

Subscribers: krytarowski, kubamracek, llvm-commits

Differential Revision: https://reviews.llvm.org/D54664

Added:
    compiler-rt/trunk/test/tsan/cxa_guard_acquire.cc
Modified:
    compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc

Modified: compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc?rev=347336&r1=347335&r2=347336&view=diff
==============================================================================
--- compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc (original)
+++ compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc Tue Nov 20 10:21:42 2018
@@ -228,6 +228,16 @@ void InitializeLibIgnore() {
   libignore()->OnLibraryLoaded(0);
 }
 
+// The following two hooks can be used by for cooperative scheduling when
+// locking.
+#ifdef TSAN_EXTERNAL_HOOKS
+void OnPotentiallyBlockingRegionBegin();
+void OnPotentiallyBlockingRegionEnd();
+#else
+SANITIZER_WEAK_CXX_DEFAULT_IMPL void OnPotentiallyBlockingRegionBegin() {}
+SANITIZER_WEAK_CXX_DEFAULT_IMPL void OnPotentiallyBlockingRegionEnd() {}
+#endif
+
 }  // namespace __tsan
 
 static ThreadSignalContext *SigCtx(ThreadState *thr) {
@@ -866,6 +876,8 @@ TSAN_INTERCEPTOR(int, posix_memalign, vo
 // Used in thread-safe function static initialization.
 STDCXX_INTERCEPTOR(int, __cxa_guard_acquire, atomic_uint32_t *g) {
   SCOPED_INTERCEPTOR_RAW(__cxa_guard_acquire, g);
+  OnPotentiallyBlockingRegionBegin();
+  auto on_exit = at_scope_exit(&OnPotentiallyBlockingRegionEnd);
   for (;;) {
     u32 cmp = atomic_load(g, memory_order_acquire);
     if (cmp == 0) {

Added: compiler-rt/trunk/test/tsan/cxa_guard_acquire.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/tsan/cxa_guard_acquire.cc?rev=347336&view=auto
==============================================================================
--- compiler-rt/trunk/test/tsan/cxa_guard_acquire.cc (added)
+++ compiler-rt/trunk/test/tsan/cxa_guard_acquire.cc Tue Nov 20 10:21:42 2018
@@ -0,0 +1,25 @@
+// RUN: %clangxx_tsan -O1 %s -o %t && %run %t 2>&1 | FileCheck %s
+
+#include <stdio.h>
+
+namespace __tsan {
+
+void OnPotentiallyBlockingRegionBegin() {
+  printf("Enter __cxa_guard_acquire\n");
+}
+
+void OnPotentiallyBlockingRegionEnd() { printf("Exit __cxa_guard_acquire\n"); }
+
+} // namespace __tsan
+
+int main(int argc, char **argv) {
+  // CHECK: Enter main
+  printf("Enter main\n");
+  // CHECK-NEXT: Enter __cxa_guard_acquire
+  // CHECK-NEXT: Exit __cxa_guard_acquire
+  static int s = argc;
+  (void)s;
+  // CHECK-NEXT: Exit main
+  printf("Exit main\n");
+  return 0;
+}