From 8a8c9674601ba00b47ef9ca4be8aeb8ef7395a49 Mon Sep 17 00:00:00 2001
From: Min Wei <min.mwei@gmail.com>
Date: Wed, 29 Mar 2017 17:34:36 -0700
Subject: [PATCH] Enable Fast CRC32 for Win64

Summary:
Currently the fast crc32 path is not enabled on Windows. I am trying to enable it here, hopefully, with the minimum impact to the existing code structure.
Closes https://github.com/facebook/rocksdb/pull/2033

Differential Revision: D4770635

Pulled By: siying

fbshipit-source-id: 676f8b8
---
 CMakeLists.txt | 13 +++++++++++--
 util/crc32c.cc | 25 +++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 56b91490924..28a320e5d27 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -42,6 +42,11 @@ endif()
 list(APPEND CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/cmake/modules/")
 
 if(WIN32)
+  if (DEFINED AVX2)
+    set(USE_AVX2 ${AVX2})
+  else ()
+    set(USE_AVX2 1)
+  endif ()
   include(${CMAKE_CURRENT_SOURCE_DIR}/thirdparty.inc)
 else()
   option(WITH_JEMALLOC "build with JeMalloc" OFF)
@@ -111,7 +116,11 @@ add_library(build_version OBJECT ${BUILD_VERSION_CC})
 target_include_directories(build_version PRIVATE
   ${CMAKE_CURRENT_SOURCE_DIR}/util)
 if(WIN32)
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /Zi /nologo  /EHsc /GS /Gd /GR /GF /fp:precise /Zc:wchar_t /Zc:forScope /errorReport:queue")
+  if (${USE_AVX2} EQUAL 1)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /Zi /nologo  /arch:AVX2 /EHsc /GS /Gd /GR /GF /fp:precise /Zc:wchar_t /Zc:forScope /errorReport:queue")
+  else ()
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /Zi /nologo  /EHsc /GS /Gd /GR /GF /fp:precise /Zc:wchar_t /Zc:forScope /errorReport:queue")
+  endif ()
 
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /FC /d2Zi+ /W3 /wd4127 /wd4800 /wd4996 /wd4351")
 else()
@@ -378,7 +387,7 @@ set(SOURCES
         util/histogram_windowing.cc
         util/instrumented_mutex.cc
         util/iostats_context.cc
-        
+
         util/lru_cache.cc
         tools/ldb_cmd.cc
         tools/ldb_tool.cc
diff --git a/util/crc32c.cc b/util/crc32c.cc
index ce574544e15..42bedc2445a 100644
--- a/util/crc32c.cc
+++ b/util/crc32c.cc
@@ -16,6 +16,11 @@
 #ifdef __SSE4_2__
 #include <nmmintrin.h>
 #endif
+#if defined(_WIN64)
+#ifdef __AVX2__
+#include <nmmintrin.h>
+#endif
+#endif
 #include "util/coding.h"
 
 namespace rocksdb {
@@ -299,6 +304,13 @@ static inline uint64_t LE_LOAD64(const uint8_t *p) {
 #endif
 #endif
 
+#if defined(_WIN64)
+#ifdef __AVX2__
+static inline uint64_t LE_LOAD64(const uint8_t *p) {
+  return DecodeFixed64(reinterpret_cast<const char*>(p));
+}
+#endif
+#endif
 static inline void Slow_CRC32(uint64_t* l, uint8_t const **p) {
   uint32_t c = static_cast<uint32_t>(*l ^ LE_LOAD32(*p));
   *p += 4;
@@ -326,6 +338,13 @@ static inline void Fast_CRC32(uint64_t* l, uint8_t const **p) {
   *l = _mm_crc32_u32(static_cast<unsigned int>(*l), LE_LOAD32(*p));
   *p += 4;
 #endif
+#elif defined(_WIN64)
+#ifdef __AVX2__
+  *l = _mm_crc32_u64(*l, LE_LOAD64(*p));
+  *p += 8;
+#else
+  Slow_CRC32(l, p);
+#endif
 #else
   Slow_CRC32(l, p);
 #endif
@@ -381,6 +400,10 @@ static bool isSSE42() {
   uint32_t d_;
   __asm__("cpuid" : "=c"(c_), "=d"(d_) : "a"(1) : "ebx");
   return c_ & (1U << 20);  // copied from CpuId.h in Folly.
+#elif defined(_WIN64)
+  int info[4];
+  __cpuidex(info, 0x00000001, 0);
+  return (info[2] & ((int)1 << 20)) != 0;
 #else
   return false;
 #endif
@@ -395,6 +418,8 @@ static inline Function Choose_Extend() {
 bool IsFastCrc32Supported() {
 #ifdef __SSE4_2__
   return isSSE42();
+#elif defined(_WIN64)
+  return isSSE42();
 #else
   return false;
 #endif