Export of internal Abseil changes

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69b3ab092ee0fef3d27f589e709280c341f006c6 by Greg Falcon <gfalcon@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 321005878

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3a4038cd0cea6455453a7ae82f2de7e91d7e2bc1 by Abseil Team <absl-team@google.com>:

Google-internal changes only.

PiperOrigin-RevId: 320994821

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f9d9a93782924df6ffc351a271c239ca4bdff3c8 by Derek Mauro <dmauro@google.com>:

Update Linux latest toolchains, most notably to GCC 10.1

This create a new "hybrid" docker image that includes the latest
versions of both GCC and LLVM. Since the LLVM build targets Debian 10,
but Debian 10 uses an older version of libstdc++ that doesn't have
full C++20 support, the easiest solution is to use the GCC/Debian 10
base image from DockerHub and copy LLVM into it.

This also includes fixes to get the build working with the
new toolchains.

PiperOrigin-RevId: 320991795

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43129cd66dc4439b36d85030800a3929f20d9f86 by Abseil Team <absl-team@google.com>:

Rollback import of CCTZ from GitHub (breaks MSAN tests)

  - e87b391f0d10ae9c3d2e70e4a3633337d2c5e643 handle "slim" TZif files in TimeZoneInfo::ExtendTransitio... by Bradley White <14679271+devbww@users.noreply.github.com>

PiperOrigin-RevId: 320978767

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2a343a55f297d433c1521920f0bd20ddd2dc71e8 by Derek Mauro <dmauro@google.com>:

Use ABSL_HAVE_ATTRIBUTE in thread_annotations.h

PiperOrigin-RevId: 320956378

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f6f3e8333c9ef6e6441586be6587bbfb1c8c8127 by Gennadiy Rozental <rogeeff@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 320952592

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3cc2bcce3533ac1233c0536232b07eea45fe8ed0 by Derek Mauro <dmauro@google.com>:

Internal change

PiperOrigin-RevId: 320862698

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4e22066476744609e42c475b55e3cbd874f04c39 by Gennadiy Rozental <rogeeff@google.com>:

Internal change

PiperOrigin-RevId: 320461277
GitOrigin-RevId: 69b3ab092ee0fef3d27f589e709280c341f006c6
Change-Id: I36f547711e7078d52f2e0a1ff3f4c903056a2b9e

1 files changed, 24 insertions, 9 deletions

diff --git a/absl/synchronization/mutex.cc b/absl/synchronization/mutex.cc
index c7968f06..aafeb674 100644
--- a/absl/synchronization/mutex.cc
+++ b/absl/synchronization/mutex.cc
@@ -59,6 +59,7 @@
 
 using absl::base_internal::CurrentThreadIdentityIfPresent;
 using absl::base_internal::PerThreadSynch;
+using absl::base_internal::SchedulingGuard;
 using absl::base_internal::ThreadIdentity;
 using absl::synchronization_internal::GetOrCreateCurrentThreadIdentity;
 using absl::synchronization_internal::GraphCycles;
@@ -141,7 +142,9 @@ static const MutexGlobals& GetMutexGlobals() {
 namespace {
   enum DelayMode { AGGRESSIVE, GENTLE };
 };
-static int Delay(int32_t c, DelayMode mode) {
+
+namespace synchronization_internal {
+int MutexDelay(int32_t c, int mode) {
   // If this a uniprocessor, only yield/sleep.  Otherwise, if the mode is
   // aggressive then spin many times before yielding.  If the mode is
   // gentle then spin only a few times before yielding.  Aggressive spinning is
@@ -153,6 +156,7 @@ static int Delay(int32_t c, DelayMode mode) {
     // Spin.
     c++;
   } else {
+    SchedulingGuard::ScopedEnable enable_rescheduling;
     ABSL_TSAN_MUTEX_PRE_DIVERT(nullptr, 0);
     if (c == limit) {
       // Yield once.
@@ -167,6 +171,7 @@ static int Delay(int32_t c, DelayMode mode) {
   }
   return c;
 }
+}  // namespace synchronization_internal
 
 // --------------------------Generic atomic ops
 // Ensure that "(*pv & bits) == bits" by doing an atomic update of "*pv" to
@@ -1051,6 +1056,7 @@ static PerThreadSynch *DequeueAllWakeable(PerThreadSynch *head,
 // Try to remove thread s from the list of waiters on this mutex.
 // Does nothing if s is not on the waiter list.
 void Mutex::TryRemove(PerThreadSynch *s) {
+  SchedulingGuard::ScopedDisable disable_rescheduling;
   intptr_t v = mu_.load(std::memory_order_relaxed);
   // acquire spinlock & lock
   if ((v & (kMuWait | kMuSpin | kMuWriter | kMuReader)) == kMuWait &&
@@ -1115,7 +1121,7 @@ ABSL_XRAY_LOG_ARGS(1) void Mutex::Block(PerThreadSynch *s) {
       this->TryRemove(s);
       int c = 0;
       while (s->next != nullptr) {
-        c = Delay(c, GENTLE);
+        c = synchronization_internal::MutexDelay(c, GENTLE);
         this->TryRemove(s);
       }
       if (kDebugMode) {
@@ -1894,6 +1900,7 @@ static void CheckForMutexCorruption(intptr_t v, const char* label) {
 }
 
 void Mutex::LockSlowLoop(SynchWaitParams *waitp, int flags) {
+  SchedulingGuard::ScopedDisable disable_rescheduling;
   int c = 0;
   intptr_t v = mu_.load(std::memory_order_relaxed);
   if ((v & kMuEvent) != 0) {
@@ -1995,7 +2002,8 @@ void Mutex::LockSlowLoop(SynchWaitParams *waitp, int flags) {
     ABSL_RAW_CHECK(
         waitp->thread->waitp == nullptr || waitp->thread->suppress_fatal_errors,
         "detected illegal recursion into Mutex code");
-    c = Delay(c, GENTLE);          // delay, then try again
+    // delay, then try again
+    c = synchronization_internal::MutexDelay(c, GENTLE);
   }
   ABSL_RAW_CHECK(
       waitp->thread->waitp == nullptr || waitp->thread->suppress_fatal_errors,
@@ -2013,6 +2021,7 @@ void Mutex::LockSlowLoop(SynchWaitParams *waitp, int flags) {
 // or it is in the process of blocking on a condition variable; it must requeue
 // itself on the mutex/condvar to wait for its condition to become true.
 ABSL_ATTRIBUTE_NOINLINE void Mutex::UnlockSlow(SynchWaitParams *waitp) {
+  SchedulingGuard::ScopedDisable disable_rescheduling;
   intptr_t v = mu_.load(std::memory_order_relaxed);
   this->AssertReaderHeld();
   CheckForMutexCorruption(v, "Unlock");
@@ -2289,7 +2298,8 @@ ABSL_ATTRIBUTE_NOINLINE void Mutex::UnlockSlow(SynchWaitParams *waitp) {
       mu_.store(nv, std::memory_order_release);
       break;  // out of for(;;)-loop
     }
-    c = Delay(c, AGGRESSIVE);  // aggressive here; no one can proceed till we do
+    // aggressive here; no one can proceed till we do
+    c = synchronization_internal::MutexDelay(c, AGGRESSIVE);
   }                            // end of for(;;)-loop
 
   if (wake_list != kPerThreadSynchNull) {
@@ -2328,6 +2338,7 @@ void Mutex::Trans(MuHow how) {
 // It will later acquire the mutex with high probability.  Otherwise, we
 // enqueue thread w on this mutex.
 void Mutex::Fer(PerThreadSynch *w) {
+  SchedulingGuard::ScopedDisable disable_rescheduling;
   int c = 0;
   ABSL_RAW_CHECK(w->waitp->cond == nullptr,
                  "Mutex::Fer while waiting on Condition");
@@ -2377,7 +2388,7 @@ void Mutex::Fer(PerThreadSynch *w) {
         return;
       }
     }
-    c = Delay(c, GENTLE);
+    c = synchronization_internal::MutexDelay(c, GENTLE);
   }
 }
 
@@ -2426,6 +2437,7 @@ CondVar::~CondVar() {
 
 // Remove thread s from the list of waiters on this condition variable.
 void CondVar::Remove(PerThreadSynch *s) {
+  SchedulingGuard::ScopedDisable disable_rescheduling;
   intptr_t v;
   int c = 0;
   for (v = cv_.load(std::memory_order_relaxed);;
@@ -2454,7 +2466,8 @@ void CondVar::Remove(PerThreadSynch *s) {
                 std::memory_order_release);
       return;
     } else {
-      c = Delay(c, GENTLE);            // try again after a delay
+      // try again after a delay
+      c = synchronization_internal::MutexDelay(c, GENTLE);
     }
   }
 }
@@ -2487,7 +2500,7 @@ static void CondVarEnqueue(SynchWaitParams *waitp) {
          !cv_word->compare_exchange_weak(v, v | kCvSpin,
                                          std::memory_order_acquire,
                                          std::memory_order_relaxed)) {
-    c = Delay(c, GENTLE);
+    c = synchronization_internal::MutexDelay(c, GENTLE);
     v = cv_word->load(std::memory_order_relaxed);
   }
   ABSL_RAW_CHECK(waitp->thread->waitp == nullptr, "waiting when shouldn't be");
@@ -2586,6 +2599,7 @@ void CondVar::Wakeup(PerThreadSynch *w) {
 }
 
 void CondVar::Signal() {
+  SchedulingGuard::ScopedDisable disable_rescheduling;
   ABSL_TSAN_MUTEX_PRE_SIGNAL(nullptr, 0);
   intptr_t v;
   int c = 0;
@@ -2618,7 +2632,7 @@ void CondVar::Signal() {
       ABSL_TSAN_MUTEX_POST_SIGNAL(nullptr, 0);
       return;
     } else {
-      c = Delay(c, GENTLE);
+      c = synchronization_internal::MutexDelay(c, GENTLE);
     }
   }
   ABSL_TSAN_MUTEX_POST_SIGNAL(nullptr, 0);
@@ -2655,7 +2669,8 @@ void CondVar::SignalAll () {
       ABSL_TSAN_MUTEX_POST_SIGNAL(nullptr, 0);
       return;
     } else {
-      c = Delay(c, GENTLE);           // try again after a delay
+      // try again after a delay
+      c = synchronization_internal::MutexDelay(c, GENTLE);
     }
   }
   ABSL_TSAN_MUTEX_POST_SIGNAL(nullptr, 0);