1 files changed, 44 insertions, 0 deletions
diff --git a/third_party/crc32c/src/src/crc32c_prefetch.h b/third_party/crc32c/src/src/crc32c_prefetch.h
new file mode 100644
index 0000000000..e8df540494
--- /dev/null
+++ b/third_party/crc32c/src/src/crc32c_prefetch.h
@@ -0,0 +1,44 @@
+// Copyright 2017 The CRC32C Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#ifndef CRC32C_CRC32C_PREFETCH_H_
+#define CRC32C_CRC32C_PREFETCH_H_
+
+#include <cstddef>
+#include <cstdint>
+
+#include "crc32c/crc32c_config.h"
+
+#if HAVE_MM_PREFETCH
+
+#if defined(_MSC_VER)
+#include <intrin.h>
+#else  // !defined(_MSC_VER)
+#include <xmmintrin.h>
+#endif  // defined(_MSC_VER)
+
+#endif  // HAVE_MM_PREFETCH
+
+namespace crc32c {
+
+// Ask the hardware to prefetch the data at the given address into the L1 cache.
+inline void RequestPrefetch(const uint8_t* address) {
+#if HAVE_BUILTIN_PREFETCH
+  // Clang and GCC implement the __builtin_prefetch non-standard extension,
+  // which maps to the best instruction on the target architecture.
+  __builtin_prefetch(reinterpret_cast<const char*>(address), 0 /* Read only. */,
+                     0 /* No temporal locality. */);
+#elif HAVE_MM_PREFETCH
+  // Visual Studio doesn't implement __builtin_prefetch, but exposes the
+  // PREFETCHNTA instruction via the _mm_prefetch intrinsic.
+  _mm_prefetch(reinterpret_cast<const char*>(address), _MM_HINT_NTA);
+#else
+  // No prefetch support. Silence compiler warnings.
+  (void)address;
+#endif  // HAVE_BUILTIN_PREFETCH
+}
+
+}  // namespace crc32c
+
+#endif  // CRC32C_CRC32C_ROUND_UP_H_