3 files changed, 41 insertions, 37 deletions
diff --git a/src/google/protobuf/stubs/int128.cc b/src/google/protobuf/stubs/int128.cc
index a5090801..7b993e8f 100644
--- a/src/google/protobuf/stubs/int128.cc
+++ b/src/google/protobuf/stubs/int128.cc
@@ -76,52 +76,36 @@ static inline int Fls128(uint128 n) {
   return Fls64(Uint128Low64(n));
 }
 
-// Long division/modulo for uint128 implemented using the shift-subtract
-// division algorithm adapted from:
-// http://stackoverflow.com/questions/5386377/division-without-using
 void uint128::DivModImpl(uint128 dividend, uint128 divisor,
                          uint128* quotient_ret, uint128* remainder_ret) {
   if (divisor == 0) {
     GOOGLE_LOG(FATAL) << "Division or mod by zero: dividend.hi=" << dividend.hi_
                       << ", lo=" << dividend.lo_;
-  }
-
-  if (divisor > dividend) {
+  } else if (dividend < divisor) {
     *quotient_ret = 0;
     *remainder_ret = dividend;
     return;
-  }
-
-  if (divisor == dividend) {
-    *quotient_ret = 1;
-    *remainder_ret = 0;
-    return;
-  }
-
-  uint128 denominator = divisor;
-  uint128 position = 1;
-  uint128 quotient = 0;
-
-  // Left aligns the MSB of the denominator and the dividend.
-  int shift = Fls128(dividend) - Fls128(denominator);
-  denominator <<= shift;
-  position <<= shift;
-
-  // Uses shift-subtract algorithm to divide dividend by denominator. The
-  // remainder will be left in dividend.
-  while (position > 0) {
-    if (dividend >= denominator) {
-      dividend -= denominator;
-      quotient |= position;
+  } else {
+    int dividend_bit_length = Fls128(dividend);
+    int divisor_bit_length = Fls128(divisor);
+    int difference = dividend_bit_length - divisor_bit_length;
+    uint128 quotient = 0;
+    while (difference >= 0) {
+      quotient <<= 1;
+      uint128 shifted_divisor = divisor << difference;
+      if (shifted_divisor <= dividend) {
+        dividend -= shifted_divisor;
+        quotient += 1;
+      }
+      difference -= 1;
     }
-    position >>= 1;
-    denominator >>= 1;
+    //record the final quotient and remainder
+    *quotient_ret = quotient;
+    *remainder_ret = dividend;
   }
-
-  *quotient_ret = quotient;
-  *remainder_ret = dividend;
 }
 
+
 uint128& uint128::operator/=(const uint128& divisor) {
   uint128 quotient = 0;
   uint128 remainder = 0;
diff --git a/src/google/protobuf/stubs/mutex.h b/src/google/protobuf/stubs/mutex.h
index b9b7d2e1..47edb7a3 100644
--- a/src/google/protobuf/stubs/mutex.h
+++ b/src/google/protobuf/stubs/mutex.h
@@ -34,6 +34,18 @@
 
 #include <google/protobuf/stubs/macros.h>
 
+// Define thread-safety annotations for use below, if we are building with
+// Clang.
+#if defined(__clang__) && !defined(SWIG)
+#define GOOGLE_PROTOBUF_ACQUIRE(...) \
+  __attribute__((acquire_capability(__VA_ARGS__)))
+#define GOOGLE_PROTOBUF_RELEASE(...) \
+  __attribute__((release_capability(__VA_ARGS__)))
+#else
+#define GOOGLE_PROTOBUF_ACQUIRE(...)
+#define GOOGLE_PROTOBUF_RELEASE(...)
+#endif
+
 // ===================================================================
 // emulates google3/base/mutex.h
 namespace google {
@@ -48,8 +60,8 @@ namespace internal {
 class LIBPROTOBUF_EXPORT WrappedMutex {
  public:
   WrappedMutex() = default;
-  void Lock() { mu_.lock(); }
-  void Unlock() { mu_.unlock(); }
+  void Lock() GOOGLE_PROTOBUF_ACQUIRE() { mu_.lock(); }
+  void Unlock() GOOGLE_PROTOBUF_RELEASE() { mu_.unlock(); }
   // Crash if this Mutex is not held exclusively by this thread.
   // May fail to crash when it should; will never crash when it should not.
   void AssertHeld() const {}
@@ -123,8 +135,10 @@ using internal::ReaderMutexLock;
 using internal::WriterMutexLock;
 using internal::MutexLockMaybe;
 
-
 }  // namespace protobuf
 }  // namespace google
 
+#undef GOOGLE_PROTOBUF_ACQUIRE
+#undef GOOGLE_PROTOBUF_RELEASE
+
 #endif  // GOOGLE_PROTOBUF_STUBS_MUTEX_H_
diff --git a/src/google/protobuf/stubs/platform_macros.h b/src/google/protobuf/stubs/platform_macros.h
index c3a64dd2..ff4dea7b 100644
--- a/src/google/protobuf/stubs/platform_macros.h
+++ b/src/google/protobuf/stubs/platform_macros.h
@@ -99,6 +99,7 @@ GOOGLE_PROTOBUF_PLATFORM_ERROR
 
 #if defined(__APPLE__)
 #define GOOGLE_PROTOBUF_OS_APPLE
+#include <Availability.h>
 #include <TargetConditionals.h>
 #if TARGET_OS_IPHONE
 #define GOOGLE_PROTOBUF_OS_IPHONE
@@ -125,4 +126,9 @@ GOOGLE_PROTOBUF_PLATFORM_ERROR
 #define GOOGLE_PROTOBUF_NO_THREADLOCAL
 #endif
 
+#if defined(__MAC_OS_X_VERSION_MIN_REQUIRED) && __MAC_OS_X_VERSION_MIN_REQUIRED < 1070
+// __thread keyword requires at least 10.7
+#define GOOGLE_PROTOBUF_NO_THREADLOCAL
+#endif
+
 #endif  // GOOGLE_PROTOBUF_PLATFORM_MACROS_H_