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Implement support for Intel crc32 instruction (SSE 4.2)
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@vadimskipin
vadimskipin committed Oct 2, 2015
1 parent 77948e7 commit fb6bd14
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Showing 2 changed files with 96 additions and 12 deletions.
28 changes: 17 additions & 11 deletions build_detect_platform
View file
Original file line number Diff line number Diff line change
Expand Up @@ -71,75 +71,81 @@ if [ "$CXX" = "g++" ]; then
MEMCMP_FLAG="-fno-builtin-memcmp"
fi

SSE_FLAG=
if [ "$CXX" = "g++" ]; then
# use hardware crc32 instruction
SSE_FLAG="-msse4.2"
fi

case "$TARGET_OS" in
CYGWIN_*)
PLATFORM=OS_LINUX
COMMON_FLAGS="$MEMCMP_FLAG -lpthread -DOS_LINUX -DCYGWIN"
COMMON_FLAGS="$MEMCMP_FLAG $SSE_FLAG -lpthread -DOS_LINUX -DCYGWIN"
PLATFORM_LDFLAGS="-lpthread"
PORT_FILE=port/port_posix.cc
;;
Darwin)
PLATFORM=OS_MACOSX
COMMON_FLAGS="$MEMCMP_FLAG -DOS_MACOSX"
COMMON_FLAGS="$MEMCMP_FLAG $SSE_FLAG -DOS_MACOSX"
PLATFORM_SHARED_EXT=dylib
[ -z "$INSTALL_PATH" ] && INSTALL_PATH=`pwd`
PLATFORM_SHARED_LDFLAGS="-dynamiclib -install_name $INSTALL_PATH/"
PORT_FILE=port/port_posix.cc
;;
Linux)
PLATFORM=OS_LINUX
COMMON_FLAGS="$MEMCMP_FLAG -pthread -DOS_LINUX"
COMMON_FLAGS="$MEMCMP_FLAG $SSE_FLAG -pthread -DOS_LINUX"
PLATFORM_LDFLAGS="-pthread"
PORT_FILE=port/port_posix.cc
;;
SunOS)
PLATFORM=OS_SOLARIS
COMMON_FLAGS="$MEMCMP_FLAG -D_REENTRANT -DOS_SOLARIS"
COMMON_FLAGS="$MEMCMP_FLAG $SSE_FLAG -D_REENTRANT -DOS_SOLARIS"
PLATFORM_LIBS="-lpthread -lrt"
PORT_FILE=port/port_posix.cc
;;
FreeBSD)
PLATFORM=OS_FREEBSD
COMMON_FLAGS="$MEMCMP_FLAG -D_REENTRANT -DOS_FREEBSD"
COMMON_FLAGS="$MEMCMP_FLAG $SSE_FLAG -D_REENTRANT -DOS_FREEBSD"
PLATFORM_LIBS="-lpthread"
PORT_FILE=port/port_posix.cc
;;
NetBSD)
PLATFORM=OS_NETBSD
COMMON_FLAGS="$MEMCMP_FLAG -D_REENTRANT -DOS_NETBSD"
COMMON_FLAGS="$MEMCMP_FLAG $SSE_FLAG -D_REENTRANT -DOS_NETBSD"
PLATFORM_LIBS="-lpthread -lgcc_s"
PORT_FILE=port/port_posix.cc
;;
OpenBSD)
PLATFORM=OS_OPENBSD
COMMON_FLAGS="$MEMCMP_FLAG -D_REENTRANT -DOS_OPENBSD"
COMMON_FLAGS="$MEMCMP_FLAG $SSE_FLAG -D_REENTRANT -DOS_OPENBSD"
PLATFORM_LDFLAGS="-pthread"
PORT_FILE=port/port_posix.cc
;;
DragonFly)
PLATFORM=OS_DRAGONFLYBSD
COMMON_FLAGS="$MEMCMP_FLAG -D_REENTRANT -DOS_DRAGONFLYBSD"
COMMON_FLAGS="$MEMCMP_FLAG $SSE_FLAG -D_REENTRANT -DOS_DRAGONFLYBSD"
PLATFORM_LIBS="-lpthread"
PORT_FILE=port/port_posix.cc
;;
OS_ANDROID_CROSSCOMPILE)
PLATFORM=OS_ANDROID
COMMON_FLAGS="$MEMCMP_FLAG -D_REENTRANT -DOS_ANDROID -DLEVELDB_PLATFORM_POSIX"
COMMON_FLAGS="$MEMCMP_FLAG $SSE_FLAG -D_REENTRANT -DOS_ANDROID -DLEVELDB_PLATFORM_POSIX"
PLATFORM_LDFLAGS="" # All pthread features are in the Android C library
PORT_FILE=port/port_posix.cc
CROSS_COMPILE=true
;;
HP-UX)
PLATFORM=OS_HPUX
COMMON_FLAGS="$MEMCMP_FLAG -D_REENTRANT -DOS_HPUX"
COMMON_FLAGS="$MEMCMP_FLAG $SSE_FLAG -D_REENTRANT -DOS_HPUX"
PLATFORM_LDFLAGS="-pthread"
PORT_FILE=port/port_posix.cc
# man ld: +h internal_name
PLATFORM_SHARED_LDFLAGS="-shared -Wl,+h -Wl,"
;;
IOS)
PLATFORM=IOS
COMMON_FLAGS="$MEMCMP_FLAG -DOS_MACOSX"
COMMON_FLAGS="$MEMCMP_FLAG $SSE_FLAG -DOS_MACOSX"
[ -z "$INSTALL_PATH" ] && INSTALL_PATH=`pwd`
PORT_FILE=port/port_posix.cc
PLATFORM_SHARED_EXT=
Expand Down
80 changes: 79 additions & 1 deletion util/crc32c.cc
View file
Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,27 @@
#include <stdint.h>
#include "util/coding.h"

#if defined(_MSC_VER)
#include <intrin.h>
static inline bool IsSSE42Available() {
int cpu_info[4];
__cpuid(cpu_info, 1);
return (cpu_info[2] & (1 << 20)) != 0;
}
#elif defined(__GNUC__)
#include <cpuid.h>
#include <nmmintrin.h>
static inline bool IsSSE42Available() {
unsigned int eax, ebx, ecx, edx;
__get_cpuid(1, &eax, &ebx, &ecx, &edx);
return (ecx & (1 << 20)) != 0;
}
#else
static inline bool IsSSE42Available() {
return false;
}
#endif

namespace leveldb {
namespace crc32c {

Expand Down Expand Up @@ -283,7 +304,12 @@ static inline uint32_t LE_LOAD32(const uint8_t *p) {
return DecodeFixed32(reinterpret_cast<const char*>(p));
}

uint32_t Extend(uint32_t crc, const char* buf, size_t size) {
// Used to fetch a naturally-aligned 64-bit word in little endian byte-order
static inline uint64_t LE_LOAD64(const uint8_t *p) {
return DecodeFixed64(reinterpret_cast<const char*>(p));
}

static uint32_t Extend_NoSSE(uint32_t crc, const char* buf, size_t size) {
const uint8_t *p = reinterpret_cast<const uint8_t *>(buf);
const uint8_t *e = p + size;
uint32_t l = crc ^ 0xffffffffu;
Expand Down Expand Up @@ -328,5 +354,57 @@ uint32_t Extend(uint32_t crc, const char* buf, size_t size) {
return l ^ 0xffffffffu;
}

// For further improvements see Intel publication at:
// http://download.intel.com/design/intarch/papers/323405.pdf
static uint32_t Extend_SSE42(uint32_t crc, const char* buf, size_t size) {
const uint8_t *p = reinterpret_cast<const uint8_t *>(buf);
const uint8_t *e = p + size;
uint32_t l = crc ^ 0xffffffffu;

#define STEP1 do { \
l = _mm_crc32_u8(l, *p++); \
} while (0)
#define STEP4 do { \
l = _mm_crc32_u32(l, LE_LOAD32(p)); \
p += 4; \
} while (0)
#define STEP8 do { \
l = _mm_crc32_u64(l, LE_LOAD64(p)); \
p += 8; \
} while (0)

if (size > 16) {
// Process unaligned bytes
for (unsigned int i = reinterpret_cast<uintptr_t>(p) % 8; i; --i) {
STEP1;
}
// Process 8 bytes at a time
while ((e-p) >= 8) {
STEP8;
}
// Process 4 bytes at a time
if ((e-p) >= 4) {
STEP4;
}
}
// Process the last few bytes
while (p != e) {
STEP1;
}
#undef STEP4
#undef STEP1
return l ^ 0xffffffffu;
}

uint32_t Extend(uint32_t crc, const char* buf, size_t size) {
static int flag = -1;
if (flag == -1) {
flag = IsSSE42Available() ? 1 : 0;
}
return flag
? Extend_SSE42(crc, buf, size)
: Extend_NoSSE(crc, buf, size);
}

} // namespace crc32c
} // namespace leveldb

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