7 files changed, 56 insertions, 41 deletions
diff --git a/src/leveldb/port/atomic_pointer.h b/src/leveldb/port/atomic_pointer.h
index 1c4c7aafc6..d79a02230d 100644
--- a/src/leveldb/port/atomic_pointer.h
+++ b/src/leveldb/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
diff --git a/src/leveldb/port/port_example.h b/src/leveldb/port/port_example.h
index 97bd669a5e..5b1d027de5 100644
--- a/src/leveldb/port/port_example.h
+++ b/src/leveldb/port/port_example.h
@@ -129,6 +129,10 @@ extern bool Snappy_Uncompress(const char* input_data, size_t input_length,
 // The concatenation of all "data[0,n-1]" fragments is the heap profile.
 extern bool GetHeapProfile(void (*func)(void*, const char*, int), void* arg);
 
+// Determine whether a working accelerated crc32 implementation exists
+// Returns true if AcceleratedCRC32C is safe to call
+bool HasAcceleratedCRC32C();
+
 // Extend the CRC to include the first n bytes of buf.
 //
 // Returns zero if the CRC cannot be extended using acceleration, else returns
diff --git a/src/leveldb/port/port_posix.cc b/src/leveldb/port/port_posix.cc
index 30e8007ae3..ec39e92195 100644
--- a/src/leveldb/port/port_posix.cc
+++ b/src/leveldb/port/port_posix.cc
@@ -8,6 +8,10 @@
 #include <stdio.h>
 #include <string.h>
 
+#if (defined(__x86_64__) || defined(__i386__)) && defined(__GNUC__)
+#include <cpuid.h>
+#endif
+
 namespace leveldb {
 namespace port {
 
@@ -49,5 +53,15 @@ void InitOnce(OnceType* once, void (*initializer)()) {
   PthreadCall("once", pthread_once(once, initializer));
 }
 
+bool HasAcceleratedCRC32C() {
+#if (defined(__x86_64__) || defined(__i386__)) && defined(__GNUC__)
+  unsigned int eax, ebx, ecx, edx;
+  __get_cpuid(1, &eax, &ebx, &ecx, &edx);
+  return (ecx & (1 << 20)) != 0;
+#else
+  return false;
+#endif
+}
+
 }  // namespace port
 }  // namespace leveldb
diff --git a/src/leveldb/port/port_posix.h b/src/leveldb/port/port_posix.h
index 7e8213b22e..d85fa5d63f 100644
--- a/src/leveldb/port/port_posix.h
+++ b/src/leveldb/port/port_posix.h
@@ -152,6 +152,7 @@ inline bool GetHeapProfile(void (*func)(void*, const char*, int), void* arg) {
   return false;
 }
 
+bool HasAcceleratedCRC32C();
 uint32_t AcceleratedCRC32C(uint32_t crc, const char* buf, size_t size);
 
 } // namespace port
diff --git a/src/leveldb/port/port_posix_sse.cc b/src/leveldb/port/port_posix_sse.cc
index 1e519ba0b6..2d49c21dd8 100644
--- a/src/leveldb/port/port_posix_sse.cc
+++ b/src/leveldb/port/port_posix_sse.cc
@@ -19,7 +19,6 @@
 #include <intrin.h>
 #elif defined(__GNUC__) && defined(__SSE4_2__)
 #include <nmmintrin.h>
-#include <cpuid.h>
 #endif
 
 #endif  // defined(LEVELDB_PLATFORM_POSIX_SSE)
@@ -48,20 +47,6 @@ static inline uint64_t LE_LOAD64(const uint8_t *p) {
 
 #endif  // defined(_M_X64) || defined(__x86_64__)
 
-static inline bool HaveSSE42() {
-#if defined(_MSC_VER)
-  int cpu_info[4];
-  __cpuid(cpu_info, 1);
-  return (cpu_info[2] & (1 << 20)) != 0;
-#elif defined(__GNUC__)
-  unsigned int eax, ebx, ecx, edx;
-  __get_cpuid(1, &eax, &ebx, &ecx, &edx);
-  return (ecx & (1 << 20)) != 0;
-#else
-  return false;
-#endif
-}
-
 #endif  // defined(LEVELDB_PLATFORM_POSIX_SSE)
 
 // For further improvements see Intel publication at:
@@ -70,10 +55,6 @@ uint32_t AcceleratedCRC32C(uint32_t crc, const char* buf, size_t size) {
 #if !defined(LEVELDB_PLATFORM_POSIX_SSE)
   return 0;
 #else
-  static bool have = HaveSSE42();
-  if (!have) {
-    return 0;
-  }
 
   const uint8_t *p = reinterpret_cast<const uint8_t *>(buf);
   const uint8_t *e = p + size;
diff --git a/src/leveldb/port/port_win.cc b/src/leveldb/port/port_win.cc
index 1b0f060a19..1be9e8d5b0 100644
--- a/src/leveldb/port/port_win.cc
+++ b/src/leveldb/port/port_win.cc
@@ -32,6 +32,7 @@
 
 #include <windows.h>
 #include <cassert>
+#include <intrin.h>
 
 namespace leveldb {
 namespace port {
@@ -143,5 +144,15 @@ void AtomicPointer::NoBarrier_Store(void* v) {
   rep_ = v;
 }
 
+bool HasAcceleratedCRC32C() {
+#if defined(__x86_64__) || defined(__i386__)
+  int cpu_info[4];
+  __cpuid(cpu_info, 1);
+  return (cpu_info[2] & (1 << 20)) != 0;
+#else
+  return false;
+#endif
+}
+
 }
 }
diff --git a/src/leveldb/port/port_win.h b/src/leveldb/port/port_win.h
index 5009004822..e8bf46ef27 100644
--- a/src/leveldb/port/port_win.h
+++ b/src/leveldb/port/port_win.h
@@ -168,6 +168,7 @@ inline bool GetHeapProfile(void (*func)(void*, const char*, int), void* arg) {
   return false;
 }
 
+bool HasAcceleratedCRC32C();
 uint32_t AcceleratedCRC32C(uint32_t crc, const char* buf, size_t size);
 
 }