tsan: don't create sync objects on acquire

Creating sync objects on acquire is pointless:
acquire of a just created sync object if a no-op.



git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@273862 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 16 insertions, 14 deletions

diff --git a/lib/tsan/rtl/tsan_rtl_mutex.cc b/lib/tsan/rtl/tsan_rtl_mutex.cc
index 3d700d824..1806acf06 100644
--- a/lib/tsan/rtl/tsan_rtl_mutex.cc
+++ b/lib/tsan/rtl/tsan_rtl_mutex.cc
@@ -84,7 +84,7 @@ void MutexCreate(ThreadState *thr, uptr pc, uptr addr,
 void MutexDestroy(ThreadState *thr, uptr pc, uptr addr) {
   DPrintf("#%d: MutexDestroy %zx\n", thr->tid, addr);
   StatInc(thr, StatMutexDestroy);
-  SyncVar *s = ctx->metamap.GetIfExistsAndLock(addr);
+  SyncVar *s = ctx->metamap.GetIfExistsAndLock(addr, true);
   if (s == 0)
     return;
   if (s->is_linker_init) {
@@ -122,7 +122,7 @@ void MutexDestroy(ThreadState *thr, uptr pc, uptr addr) {
     rep.AddLocation(addr, 1);
     OutputReport(thr, rep);
 
-    SyncVar *s = ctx->metamap.GetIfExistsAndLock(addr);
+    SyncVar *s = ctx->metamap.GetIfExistsAndLock(addr, true);
     if (s != 0) {
       s->Reset(thr->proc());
       s->mtx.Unlock();
@@ -363,7 +363,9 @@ void Acquire(ThreadState *thr, uptr pc, uptr addr) {
   DPrintf("#%d: Acquire %zx\n", thr->tid, addr);
   if (thr->ignore_sync)
     return;
-  SyncVar *s = ctx->metamap.GetOrCreateAndLock(thr, pc, addr, false);
+  SyncVar *s = ctx->metamap.GetIfExistsAndLock(addr, false);
+  if (!s)
+    return;
   AcquireImpl(thr, pc, &s->clock);
   s->mtx.ReadUnlock();
 }
diff --git a/lib/tsan/rtl/tsan_rtl_report.cc b/lib/tsan/rtl/tsan_rtl_report.cc
index 3fd6c2a1f..810119b93 100644
--- a/lib/tsan/rtl/tsan_rtl_report.cc
+++ b/lib/tsan/rtl/tsan_rtl_report.cc
@@ -273,7 +273,7 @@ u64 ScopedReport::AddMutex(u64 id) {
   u64 uid = 0;
   u64 mid = id;
   uptr addr = SyncVar::SplitId(id, &uid);
-  SyncVar *s = ctx->metamap.GetIfExistsAndLock(addr);
+  SyncVar *s = ctx->metamap.GetIfExistsAndLock(addr, true);
   // Check that the mutex is still alive.
   // Another mutex can be created at the same address,
   // so check uid as well.
diff --git a/lib/tsan/rtl/tsan_sync.cc b/lib/tsan/rtl/tsan_sync.cc
index 50fe151a0..58b26802b 100644
--- a/lib/tsan/rtl/tsan_sync.cc
+++ b/lib/tsan/rtl/tsan_sync.cc
@@ -198,8 +198,8 @@ SyncVar* MetaMap::GetOrCreateAndLock(ThreadState *thr, uptr pc,
   return GetAndLock(thr, pc, addr, write_lock, true);
 }
 
-SyncVar* MetaMap::GetIfExistsAndLock(uptr addr) {
-  return GetAndLock(0, 0, addr, true, false);
+SyncVar* MetaMap::GetIfExistsAndLock(uptr addr, bool write_lock) {
+  return GetAndLock(0, 0, addr, write_lock, false);
 }
 
 SyncVar* MetaMap::GetAndLock(ThreadState *thr, uptr pc,
diff --git a/lib/tsan/rtl/tsan_sync.h b/lib/tsan/rtl/tsan_sync.h
index a1d4a1640..2bc2f41fb 100644
--- a/lib/tsan/rtl/tsan_sync.h
+++ b/lib/tsan/rtl/tsan_sync.h
@@ -79,7 +79,7 @@ class MetaMap {
 
   SyncVar* GetOrCreateAndLock(ThreadState *thr, uptr pc,
                               uptr addr, bool write_lock);
-  SyncVar* GetIfExistsAndLock(uptr addr);
+  SyncVar* GetIfExistsAndLock(uptr addr, bool write_lock);
 
   void MoveMemory(uptr src, uptr dst, uptr sz);
 
diff --git a/lib/tsan/tests/unit/tsan_sync_test.cc b/lib/tsan/tests/unit/tsan_sync_test.cc
index 9e57a374c..801665478 100644
--- a/lib/tsan/tests/unit/tsan_sync_test.cc
+++ b/lib/tsan/tests/unit/tsan_sync_test.cc
@@ -53,7 +53,7 @@ TEST(MetaMap, Sync) {
   MetaMap *m = &ctx->metamap;
   u64 block[4] = {};  // fake malloc block
   m->AllocBlock(thr, 0, (uptr)&block[0], 4 * sizeof(u64));
-  SyncVar *s1 = m->GetIfExistsAndLock((uptr)&block[0]);
+  SyncVar *s1 = m->GetIfExistsAndLock((uptr)&block[0], true);
   EXPECT_EQ(s1, (SyncVar*)0);
   s1 = m->GetOrCreateAndLock(thr, 0, (uptr)&block[0], true);
   EXPECT_NE(s1, (SyncVar*)0);
@@ -64,9 +64,9 @@ TEST(MetaMap, Sync) {
   EXPECT_EQ(s2->addr, (uptr)&block[1]);
   s2->mtx.ReadUnlock();
   m->FreeBlock(thr->proc(), (uptr)&block[0]);
-  s1 = m->GetIfExistsAndLock((uptr)&block[0]);
+  s1 = m->GetIfExistsAndLock((uptr)&block[0], true);
   EXPECT_EQ(s1, (SyncVar*)0);
-  s2 = m->GetIfExistsAndLock((uptr)&block[1]);
+  s2 = m->GetIfExistsAndLock((uptr)&block[1], true);
   EXPECT_EQ(s2, (SyncVar*)0);
   m->OnProcIdle(thr->proc());
 }
@@ -93,15 +93,15 @@ TEST(MetaMap, MoveMemory) {
   mb2 = m->GetBlock((uptr)&block2[3]);
   EXPECT_NE(mb2, (MBlock*)0);
   EXPECT_EQ(mb2->siz, 1 * sizeof(u64));
-  s1 = m->GetIfExistsAndLock((uptr)&block1[0]);
+  s1 = m->GetIfExistsAndLock((uptr)&block1[0], true);
   EXPECT_EQ(s1, (SyncVar*)0);
-  s2 = m->GetIfExistsAndLock((uptr)&block1[1]);
+  s2 = m->GetIfExistsAndLock((uptr)&block1[1], true);
   EXPECT_EQ(s2, (SyncVar*)0);
-  s1 = m->GetIfExistsAndLock((uptr)&block2[0]);
+  s1 = m->GetIfExistsAndLock((uptr)&block2[0], true);
   EXPECT_NE(s1, (SyncVar*)0);
   EXPECT_EQ(s1->addr, (uptr)&block2[0]);
   s1->mtx.Unlock();
-  s2 = m->GetIfExistsAndLock((uptr)&block2[1]);
+  s2 = m->GetIfExistsAndLock((uptr)&block2[1], true);
   EXPECT_NE(s2, (SyncVar*)0);
   EXPECT_EQ(s2->addr, (uptr)&block2[1]);
   s2->mtx.Unlock();