Move helper functions out of sse4.2 object

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

port/port_posix.cc

@@ -8,6 +8,10 @@
 #include <stdio.h>
 #include <string.h>
 
+#if 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 (__x86_64__ || __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

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

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;

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 (__x86_64__ || __i386__)
+  int cpu_info[4];
+  __cpuid(cpu_info, 1);
+  return (cpu_info[2] & (1 << 20)) != 0;
+#else
+  return false;
+#endif
+}
+
 }
 }

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);
 
 }

util/crc32c.cc

@@ -288,6 +288,10 @@ static inline uint32_t LE_LOAD32(const uint8_t *p) {
 // Determine if the CPU running this program can accelerate the CRC32C
 // calculation.
 static bool CanAccelerateCRC32C() {
+  if (!port::HasAcceleratedCRC32C())
+    return false;
+
+  // Double-check that the accelerated implementation functions correctly.
   // port::AcceleretedCRC32C returns zero when unable to accelerate.
   static const char kTestCRCBuffer[] = "TestCRCBuffer";
   static const char kBufSize = sizeof(kTestCRCBuffer) - 1;