Squashed 'src/leveldb/' changes from 196962ff0..c521b3ac6

c521b3ac6 Merge #11: fixup define checks. Cleans up some oopses from #5.
8b1cd3753 fixup define checks. Cleans up some oopses from #5.
6b1508d6d Merge #6: Fixes typo
fceb80542 Merge #10: Clean up compile-time warnings (gcc 7.1)
0ec2a343f Clean up compile-time warnings (gcc 7.1)
d4c268a35 Merge #5: Move helper functions out of sse4.2 object
8d4eb0847 Add HasAcceleratedCRC32C to port_win.h
77cfbfd25 crc32: move helper functions out of port_posix_sse.cc
4c1e9e016 silence compiler warnings about uninitialized variables
495316485 Merge #2: Prefer std::atomic over MemoryBarrier
2953978ef Fixes typo
f134284a1 Merge #1: Merge upstream LevelDB 1.20
ba8a445fd Prefer std::atomic over MemoryBarrier

git-subtree-dir: src/leveldb
git-subtree-split: c521b3ac654cfbe009c575eacf7e5a6e189bb5bb

1 files changed, 25 insertions, 22 deletions

diff --git a/port/atomic_pointer.h b/port/atomic_pointer.h
index 1c4c7aafc6..d79a02230d 100644
--- a/port/atomic_pointer.h
+++ b/port/atomic_pointer.h
@@ -46,6 +46,30 @@
 namespace leveldb {
 namespace port {
 
+// AtomicPointer based on <cstdatomic> if available
+#if defined(LEVELDB_ATOMIC_PRESENT)
+class AtomicPointer {
+ private:
+  std::atomic<void*> rep_;
+ public:
+  AtomicPointer() { }
+  explicit AtomicPointer(void* v) : rep_(v) { }
+  inline void* Acquire_Load() const {
+    return rep_.load(std::memory_order_acquire);
+  }
+  inline void Release_Store(void* v) {
+    rep_.store(v, std::memory_order_release);
+  }
+  inline void* NoBarrier_Load() const {
+    return rep_.load(std::memory_order_relaxed);
+  }
+  inline void NoBarrier_Store(void* v) {
+    rep_.store(v, std::memory_order_relaxed);
+  }
+};
+
+#else
+
 // Define MemoryBarrier() if available
 // Windows on x86
 #if defined(OS_WIN) && defined(COMPILER_MSVC) && defined(ARCH_CPU_X86_FAMILY)
@@ -142,28 +166,6 @@ class AtomicPointer {
   }
 };
 
-// AtomicPointer based on <cstdatomic>
-#elif defined(LEVELDB_ATOMIC_PRESENT)
-class AtomicPointer {
- private:
-  std::atomic<void*> rep_;
- public:
-  AtomicPointer() { }
-  explicit AtomicPointer(void* v) : rep_(v) { }
-  inline void* Acquire_Load() const {
-    return rep_.load(std::memory_order_acquire);
-  }
-  inline void Release_Store(void* v) {
-    rep_.store(v, std::memory_order_release);
-  }
-  inline void* NoBarrier_Load() const {
-    return rep_.load(std::memory_order_relaxed);
-  }
-  inline void NoBarrier_Store(void* v) {
-    rep_.store(v, std::memory_order_relaxed);
-  }
-};
-
 // Atomic pointer based on sparc memory barriers
 #elif defined(__sparcv9) && defined(__GNUC__)
 class AtomicPointer {
@@ -229,6 +231,7 @@ class AtomicPointer {
 #error Please implement AtomicPointer for this platform.
 
 #endif
+#endif
 
 #undef LEVELDB_HAVE_MEMORY_BARRIER
 #undef ARCH_CPU_X86_FAMILY