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src: fix build for older clang
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Removes use of builtins that are unavailable for older clang. Per
benchmarks, only uses builtins on Windows, where speedup is
significant.

Fixes: nodejs#7618
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@zbjornson
zbjornson committed Sep 30, 2016
1 parent f5d997c commit 62ba6c8
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Showing 4 changed files with 113 additions and 115 deletions.
91 changes: 3 additions & 88 deletions src/node_buffer.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,6 @@

#include <string.h>
#include <limits.h>
#include <utility>

#define BUFFER_ID 0xB0E4

Expand Down Expand Up @@ -49,38 +48,6 @@
THROW_AND_RETURN_IF_OOB(end <= end_max); \
size_t length = end - start;

#if defined(__GNUC__) || defined(__clang__)
#define BSWAP_INTRINSIC_2(x) __builtin_bswap16(x)
#define BSWAP_INTRINSIC_4(x) __builtin_bswap32(x)
#define BSWAP_INTRINSIC_8(x) __builtin_bswap64(x)
#elif defined(__linux__)
#include <byteswap.h>
#define BSWAP_INTRINSIC_2(x) bswap_16(x)
#define BSWAP_INTRINSIC_4(x) bswap_32(x)
#define BSWAP_INTRINSIC_8(x) bswap_64(x)
#elif defined(_MSC_VER)
#include <intrin.h>
#define BSWAP_INTRINSIC_2(x) _byteswap_ushort(x);
#define BSWAP_INTRINSIC_4(x) _byteswap_ulong(x);
#define BSWAP_INTRINSIC_8(x) _byteswap_uint64(x);
#else
#define BSWAP_INTRINSIC_2(x) ((x) << 8) | ((x) >> 8)
#define BSWAP_INTRINSIC_4(x) \
(((x) & 0xFF) << 24) | \
(((x) & 0xFF00) << 8) | \
(((x) >> 8) & 0xFF00) | \
(((x) >> 24) & 0xFF)
#define BSWAP_INTRINSIC_8(x) \
(((x) & 0xFF00000000000000ull) >> 56) | \
(((x) & 0x00FF000000000000ull) >> 40) | \
(((x) & 0x0000FF0000000000ull) >> 24) | \
(((x) & 0x000000FF00000000ull) >> 8) | \
(((x) & 0x00000000FF000000ull) << 8) | \
(((x) & 0x0000000000FF0000ull) << 24) | \
(((x) & 0x000000000000FF00ull) << 40) | \
(((x) & 0x00000000000000FFull) << 56)
#endif

namespace node {

// if true, all Buffer and SlowBuffer instances will automatically zero-fill
Expand Down Expand Up @@ -1204,23 +1171,7 @@ void Swap16(const FunctionCallbackInfo<Value>& args) {
Environment* env = Environment::GetCurrent(args);
THROW_AND_RETURN_UNLESS_BUFFER(env, args[0]);
SPREAD_ARG(args[0], ts_obj);

CHECK_EQ(ts_obj_length % 2, 0);

int align = reinterpret_cast<uintptr_t>(ts_obj_data) % sizeof(uint16_t);

if (align == 0) {
uint16_t* data16 = reinterpret_cast<uint16_t*>(ts_obj_data);
size_t len16 = ts_obj_length / 2;
for (size_t i = 0; i < len16; i++) {
data16[i] = BSWAP_INTRINSIC_2(data16[i]);
}
} else {
for (size_t i = 0; i < ts_obj_length; i += 2) {
std::swap(ts_obj_data[i], ts_obj_data[i + 1]);
}
}

SwapBytes16(ts_obj_data, ts_obj_length);
args.GetReturnValue().Set(args[0]);
}

Expand All @@ -1229,24 +1180,7 @@ void Swap32(const FunctionCallbackInfo<Value>& args) {
Environment* env = Environment::GetCurrent(args);
THROW_AND_RETURN_UNLESS_BUFFER(env, args[0]);
SPREAD_ARG(args[0], ts_obj);

CHECK_EQ(ts_obj_length % 4, 0);

int align = reinterpret_cast<uintptr_t>(ts_obj_data) % sizeof(uint32_t);

if (align == 0) {
uint32_t* data32 = reinterpret_cast<uint32_t*>(ts_obj_data);
size_t len32 = ts_obj_length / 4;
for (size_t i = 0; i < len32; i++) {
data32[i] = BSWAP_INTRINSIC_4(data32[i]);
}
} else {
for (size_t i = 0; i < ts_obj_length; i += 4) {
std::swap(ts_obj_data[i], ts_obj_data[i + 3]);
std::swap(ts_obj_data[i + 1], ts_obj_data[i + 2]);
}
}

SwapBytes32(ts_obj_data, ts_obj_length);
args.GetReturnValue().Set(args[0]);
}

Expand All @@ -1255,26 +1189,7 @@ void Swap64(const FunctionCallbackInfo<Value>& args) {
Environment* env = Environment::GetCurrent(args);
THROW_AND_RETURN_UNLESS_BUFFER(env, args[0]);
SPREAD_ARG(args[0], ts_obj);

CHECK_EQ(ts_obj_length % 8, 0);

int align = reinterpret_cast<uintptr_t>(ts_obj_data) % sizeof(uint64_t);

if (align == 0) {
uint64_t* data64 = reinterpret_cast<uint64_t*>(ts_obj_data);
size_t len32 = ts_obj_length / 8;
for (size_t i = 0; i < len32; i++) {
data64[i] = BSWAP_INTRINSIC_8(data64[i]);
}
} else {
for (size_t i = 0; i < ts_obj_length; i += 8) {
std::swap(ts_obj_data[i], ts_obj_data[i + 7]);
std::swap(ts_obj_data[i + 1], ts_obj_data[i + 6]);
std::swap(ts_obj_data[i + 2], ts_obj_data[i + 5]);
std::swap(ts_obj_data[i + 3], ts_obj_data[i + 4]);
}
}

SwapBytes64(ts_obj_data, ts_obj_length);
args.GetReturnValue().Set(args[0]);
}

Expand Down
34 changes: 11 additions & 23 deletions src/string_bytes.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -309,27 +309,13 @@ size_t StringBytes::Write(Isolate* isolate,
if (chars_written != nullptr)
*chars_written = nchars;

if (!IsBigEndian())
break;

// Node's "ucs2" encoding wants LE character data stored in
// the Buffer, so we need to reorder on BE platforms. See
// http://nodejs.org/api/buffer.html regarding Node's "ucs2"
// encoding specification
if (IsBigEndian())
SwapBytes16(buf, nbytes);

const bool is_aligned =
reinterpret_cast<uintptr_t>(buf) % sizeof(uint16_t);
if (is_aligned) {
uint16_t* const dst = reinterpret_cast<uint16_t*>(buf);
SwapBytes(dst, dst, nchars);
}

ASSERT_EQ(sizeof(uint16_t), 2);
for (size_t i = 0; i < nchars; i++) {
char tmp = buf[i * 2];
buf[i * 2] = buf[i * 2 + 1];
buf[i * 2 + 1] = tmp;
}
break;
}

Expand Down Expand Up @@ -705,17 +691,19 @@ Local<Value> StringBytes::Encode(Isolate* isolate,
Local<Value> StringBytes::Encode(Isolate* isolate,
const uint16_t* buf,
size_t buflen) {
Local<String> val;
// Node's "ucs2" encoding expects LE character data inside a
// Buffer, so we need to reorder on BE platforms. See
// http://nodejs.org/api/buffer.html regarding Node's "ucs2"
// encoding specification
std::vector<uint16_t> dst;
if (IsBigEndian()) {
// Node's "ucs2" encoding expects LE character data inside a
// Buffer, so we need to reorder on BE platforms. See
// http://nodejs.org/api/buffer.html regarding Node's "ucs2"
// encoding specification
dst.resize(buflen);
SwapBytes(&dst[0], buf, buflen);
dst.assign(buf, buf + buflen);
size_t nbytes = buflen * sizeof(dst[0]);
SwapBytes16(reinterpret_cast<char*>(&dst[0]), nbytes);
buf = &dst[0];
}

Local<String> val;
if (buflen < EXTERN_APEX) {
val = String::NewFromTwoByte(isolate,
buf,
Expand Down
97 changes: 94 additions & 3 deletions src/util-inl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,30 @@
#if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS

#include "util.h"
#include <cstring>

#if defined(_MSC_VER)
#include <intrin.h>
#define BSWAP_2(x) _byteswap_ushort(x)
#define BSWAP_4(x) _byteswap_ulong(x)
#define BSWAP_8(x) _byteswap_uint64(x)
#else
#define BSWAP_2(x) ((x) << 8) | ((x) >> 8)
#define BSWAP_4(x) \
(((x) & 0xFF) << 24) | \
(((x) & 0xFF00) << 8) | \
(((x) >> 8) & 0xFF00) | \
(((x) >> 24) & 0xFF)
#define BSWAP_8(x) \
(((x) & 0xFF00000000000000ull) >> 56) | \
(((x) & 0x00FF000000000000ull) >> 40) | \
(((x) & 0x0000FF0000000000ull) >> 24) | \
(((x) & 0x000000FF00000000ull) >> 8) | \
(((x) & 0x00000000FF000000ull) << 8) | \
(((x) & 0x0000000000FF0000ull) << 24) | \
(((x) & 0x000000000000FF00ull) << 40) | \
(((x) & 0x00000000000000FFull) << 56)
#endif

namespace node {

Expand Down Expand Up @@ -200,9 +224,76 @@ TypeName* Unwrap(v8::Local<v8::Object> object) {
return static_cast<TypeName*>(pointer);
}

void SwapBytes(uint16_t* dst, const uint16_t* src, size_t buflen) {
for (size_t i = 0; i < buflen; i += 1)
dst[i] = (src[i] << 8) | (src[i] >> 8);
void SwapBytes16(char* data, size_t nbytes) {
CHECK_EQ(nbytes % 2, 0);

#if defined(_MSC_VER)
int align = reinterpret_cast<uintptr_t>(data) % sizeof(uint16_t);
if (align == 0) {
// MSVC has no strict aliasing, and is able to highly optimize this case.
uint16_t* data16 = reinterpret_cast<uint16_t*>(data);
size_t len16 = nbytes / sizeof(*data16);
for (size_t i = 0; i < len16; i++) {
data16[i] = BSWAP_2(data16[i]);
}
return;
}
#endif

uint16_t temp;
for (size_t i = 0; i < nbytes; i += sizeof(temp)) {
memcpy(&temp, &data[i], sizeof(temp));
temp = BSWAP_2(temp);
memcpy(&data[i], &temp, sizeof(temp));
}
}

void SwapBytes32(char* data, size_t nbytes) {
CHECK_EQ(nbytes % 4, 0);

#if defined(_MSC_VER)
int align = reinterpret_cast<uintptr_t>(data) % sizeof(uint32_t);
// MSVC has no strict aliasing, and is able to highly optimize this case.
if (align == 0) {
uint32_t* data32 = reinterpret_cast<uint32_t*>(data);
size_t len32 = nbytes / sizeof(*data32);
for (size_t i = 0; i < len32; i++) {
data32[i] = BSWAP_4(data32[i]);
}
return;
}
#endif

uint32_t temp;
for (size_t i = 0; i < nbytes; i += sizeof(temp)) {
memcpy(&temp, &data[i], sizeof(temp));
temp = BSWAP_4(temp);
memcpy(&data[i], &temp, sizeof(temp));
}
}

void SwapBytes64(char* data, size_t nbytes) {
CHECK_EQ(nbytes % 8, 0);

#if defined(_MSC_VER)
int align = reinterpret_cast<uintptr_t>(data) % sizeof(uint64_t);
if (align == 0) {
// MSVC has no strict aliasing, and is able to highly optimize this case.
uint64_t* data64 = reinterpret_cast<uint64_t*>(data);
size_t len64 = nbytes / sizeof(*data64);
for (size_t i = 0; i < len64; i++) {
data64[i] = BSWAP_8(data64[i]);
}
return;
}
#endif

uint64_t temp;
for (size_t i = 0; i < nbytes; i += sizeof(temp)) {
memcpy(&temp, &data[i], sizeof(temp));
temp = BSWAP_8(temp);
memcpy(&data[i], &temp, sizeof(temp));
}
}

char ToLower(char c) {
Expand Down
6 changes: 5 additions & 1 deletion src/util.h
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Original file line number Diff line number Diff line change
Expand Up @@ -254,7 +254,11 @@ inline void ClearWrap(v8::Local<v8::Object> object);
template <typename TypeName>
inline TypeName* Unwrap(v8::Local<v8::Object> object);

inline void SwapBytes(uint16_t* dst, const uint16_t* src, size_t buflen);
// Swaps bytes in place. nbytes is the number of bytes to swap and must be a
// multiple of the word size (checked by function).
inline void SwapBytes16(char* data, size_t nbytes);
inline void SwapBytes32(char* data, size_t nbytes);
inline void SwapBytes64(char* data, size_t nbytes);

// tolower() is locale-sensitive. Use ToLower() instead.
inline char ToLower(char c);
Expand Down

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