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Implemented faster itoa with bit counting and reverse write

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This commit is contained in:
Milo Yip 2014-07-17 02:26:20 +08:00
parent 8b963dc7ad
commit 46eeb46a61
2 changed files with 502 additions and 59 deletions
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1
include/rapidjson/rapidjson.h
View File

@ -362,6 +362,7 @@ struct GenericInsituStringStream {
// Write
Ch* PutBegin() { return dst_ = src_; }
void Put(Ch c) { RAPIDJSON_ASSERT(dst_ != 0); *dst_++ = c; }
Ch* Allocate(size_t count) { Ch* begin = dst_; dst_ += count; return begin; }
void Flush() {}
size_t PutEnd(Ch* begin) { return static_cast<size_t>(dst_ - begin); }

560
test/perftest/misctest.cpp
View File

@ -3,14 +3,23 @@
#if TEST_MISC
#define __STDC_FORMAT_MACROS
#define strtk_no_tr1_or_boost
#include "strtk/strtk.hpp"
#include "rapidjson/stringbuffer.h"
#ifdef _MSC_VER
#pragma warning (push)
#pragma warning (disable: 4245; disable: 4512)
#pragma warning (disable: 4996)
#endif
#define strtk_no_tr1_or_boost
#include "strtk/strtk.hpp"
#ifdef _MSC_VER
#pragma warning (pop)
#endif
#ifdef _MSC_VER
#pragma warning (push)
#pragma warning (disable: 4245; disable: 4512; disable: 4996)
#endif
#include "cppformat/format.h"
@ -76,6 +85,154 @@ TEST_F(Misc, Hoehrmann_IsUTF8) {
}
}
////////////////////////////////////////////////////////////////////////////////
// CountDecimalDigit: Count number of decimal places
inline unsigned CountDecimalDigit_naive(unsigned n) {
unsigned count = 1;
while (n >= 10) {
n /= 10;
count++;
}
return count;
}
inline unsigned CountDecimalDigit_enroll4(unsigned n) {
unsigned count = 1;
while (n >= 10000) {
n /= 10000u;
count += 4;
}
if (n < 10) return count;
if (n < 100) return count + 1;
if (n < 1000) return count + 2;
return count + 3;
}
inline unsigned CountDecimalDigit64_enroll4(uint64_t n) {
unsigned count = 1;
while (n >= 10000) {
n /= 10000u;
count += 4;
}
if (n < 10) return count;
if (n < 100) return count + 1;
if (n < 1000) return count + 2;
return count + 3;
}
inline unsigned CountDecimalDigit_fast(unsigned n) {
static const uint32_t powers_of_10[] = {
0,
10,
100,
1000,
10000,
100000,
1000000,
10000000,
100000000,
1000000000
};
unsigned long i = 0;
// uint32_t t = (32 - __builtin_clz(n | 1)) * 1233 >> 12;
_BitScanReverse(&i, n | 1);
uint32_t t = (i + 1) * 1233 >> 12;
return t - (n < powers_of_10[t]) + 1;
}
inline unsigned CountDecimalDigit64_fast(uint64_t n) {
static const uint64_t powers_of_10[] = {
0,
10,
100,
1000,
10000,
100000,
1000000,
10000000,
100000000,
1000000000,
10000000000,
100000000000,
1000000000000,
10000000000000,
100000000000000,
1000000000000000,
10000000000000000,
100000000000000000,
1000000000000000000,
10000000000000000000U
};
unsigned long i = 0;
// uint32_t t = (32 - __builtin_clz(n | 1)) * 1233 >> 12;
#if _M_IX86
uint64_t m = n | 1;
if (_BitScanReverse(&i, m >> 32))
i += 32;
else
_BitScanReverse(&i, m & 0xFFFFFFFF);
#elif _M_X64
_BitScanReverse64(&i, n | 1);
#else
#error
#endif
uint32_t t = (i + 1) * 1233 >> 12;
return t - (n < powers_of_10[t]) + 1;
}
#if 0
// Exhaustive, very slow
TEST_F(Misc, CountDecimalDigit_Verify) {
unsigned i = 0;
do {
if (i % (65536 * 256) == 0)
printf("%u\n", i);
ASSERT_EQ(CountDecimalDigit_enroll4(i), CountDecimalDigit_fast(i));
i++;
} while (i != 0);
}
static const unsigned kDigits10Trial = 1000000000u;
TEST_F(Misc, CountDecimalDigit_naive) {
unsigned sum = 0;
for (unsigned i = 0; i < kDigits10Trial; i++)
sum += CountDecimalDigit_naive(i);
printf("%u\n", sum);
}
TEST_F(Misc, CountDecimalDigit_enroll4) {
unsigned sum = 0;
for (unsigned i = 0; i < kDigits10Trial; i++)
sum += CountDecimalDigit_enroll4(i);
printf("%u\n", sum);
}
TEST_F(Misc, CountDecimalDigit_fast) {
unsigned sum = 0;
for (unsigned i = 0; i < kDigits10Trial; i++)
sum += CountDecimalDigit_fast(i);
printf("%u\n", sum);
}
#endif
TEST_F(Misc, CountDecimalDigit64_VerifyFast) {
uint64_t i = 1, j;
do {
printf("%" PRIu64 "\n", i);
ASSERT_EQ(CountDecimalDigit64_enroll4(i), CountDecimalDigit64_fast(i));
j = i;
i *= 3;
} while (j < i);
}
////////////////////////////////////////////////////////////////////////////////
// integer-to-string conversion
// https://gist.github.com/anonymous/7179097
static const int randval[] ={
936116, 369532, 453755, -72860, 209713, 268347, 435278, -360266, -416287, -182064,
@ -185,6 +342,13 @@ static const int randval[] ={
static const size_t randvalCount = sizeof(randval) / sizeof(randval[0]);
static const size_t kItoaTrialCount = 10000;
static const char digits[201] =
"0001020304050607080910111213141516171819"
"2021222324252627282930313233343536373839"
"4041424344454647484950515253545556575859"
"6061626364656667686970717273747576777879"
"8081828384858687888990919293949596979899";
// Prevent code being optimized out
#define OUTPUT_LENGTH(length) printf("", length)
//#define OUTPUT_LENGTH(length) printf("%d\n", length)
@ -250,12 +414,22 @@ private:
OutputStream* os_;
};
static const char digits[201] =
"0001020304050607080910111213141516171819"
"2021222324252627282930313233343536373839"
"4041424344454647484950515253545556575859"
"6061626364656667686970717273747576777879"
"8081828384858687888990919293949596979899";
template<>
inline bool Writer1<rapidjson::StringBuffer>::WriteUint(unsigned u) {
char buffer[10];
char* p = buffer;
do {
*p++ = char(u % 10) + '0';
u /= 10;
} while (u > 0);
char* d = os_->Allocate(p - buffer);
do {
--p;
*d++ = *p;
} while (p != buffer);
return true;
}
// Using digits LUT to reduce divsion/modulo
template<typename OutputStream>
@ -337,8 +511,254 @@ private:
OutputStream* os_;
};
// First pass to count digits
template<typename OutputStream>
class Writer3 {
public:
Writer3() : os_() {}
Writer3(OutputStream& os) : os_(&os) {}
void Reset(OutputStream& os) {
os_ = &os;
}
bool WriteInt(int i) {
if (i < 0) {
os_->Put('-');
i = -i;
}
return WriteUint((unsigned)i);
}
bool WriteUint(unsigned u) {
char buffer[10];
char *p = buffer;
do {
*p++ = char(u % 10) + '0';
u /= 10;
} while (u > 0);
do {
--p;
os_->Put(*p);
} while (p != buffer);
return true;
}
bool WriteInt64(int64_t i64) {
if (i64 < 0) {
os_->Put('-');
i64 = -i64;
}
WriteUint64((uint64_t)i64);
return true;
}
bool WriteUint64(uint64_t u64) {
char buffer[20];
char *p = buffer;
do {
*p++ = char(u64 % 10) + '0';
u64 /= 10;
} while (u64 > 0);
do {
--p;
os_->Put(*p);
} while (p != buffer);
return true;
}
private:
void WriteUintReverse(char* d, unsigned u) {
do {
*--d = char(u % 10) + '0';
u /= 10;
} while (u > 0);
}
void WriteUint64Reverse(char* d, uint64_t u) {
do {
*--d = char(u % 10) + '0';
u /= 10;
} while (u > 0);
}
OutputStream* os_;
};
template<>
inline bool Writer3<rapidjson::StringBuffer>::WriteUint(unsigned u) {
unsigned digit = CountDecimalDigit_fast(u);
WriteUintReverse(os_->Allocate(digit) + digit, u);
return true;
}
template<>
inline bool Writer3<rapidjson::InsituStringStream>::WriteUint(unsigned u) {
unsigned digit = CountDecimalDigit_fast(u);
WriteUintReverse(os_->Allocate(digit) + digit, u);
return true;
}
template<>
inline bool Writer3<rapidjson::StringBuffer>::WriteUint64(uint64_t u) {
unsigned digit = CountDecimalDigit64_fast(u);
WriteUint64Reverse(os_->Allocate(digit) + digit, u);
return true;
}
template<>
inline bool Writer3<rapidjson::InsituStringStream>::WriteUint64(uint64_t u) {
unsigned digit = CountDecimalDigit64_fast(u);
WriteUint64Reverse(os_->Allocate(digit) + digit, u);
return true;
}
// Using digits LUT to reduce divsion/modulo, two passes
template<typename OutputStream>
class Writer4 {
public:
Writer4() : os_() {}
Writer4(OutputStream& os) : os_(&os) {}
void Reset(OutputStream& os) {
os_ = &os;
}
bool WriteInt(int i) {
if (i < 0) {
os_->Put('-');
i = -i;
}
return WriteUint((unsigned)i);
}
bool WriteUint(unsigned u) {
char buffer[10];
char* p = buffer;
while (u >= 100) {
const unsigned i = (u % 100) << 1;
u /= 100;
*p++ = digits[i + 1];
*p++ = digits[i];
}
if (u < 10)
*p++ = char(u) + '0';
else {
const unsigned i = u << 1;
*p++ = digits[i + 1];
*p++ = digits[i];
}
do {
--p;
os_->Put(*p);
} while (p != buffer);
return true;
}
bool WriteInt64(int64_t i64) {
if (i64 < 0) {
os_->Put('-');
i64 = -i64;
}
WriteUint64((uint64_t)i64);
return true;
}
bool WriteUint64(uint64_t u64) {
char buffer[20];
char* p = buffer;
while (u64 >= 100) {
const unsigned i = static_cast<unsigned>(u64 % 100) << 1;
u64 /= 100;
*p++ = digits[i + 1];
*p++ = digits[i];
}
if (u64 < 10)
*p++ = char(u64) + '0';
else {
const unsigned i = static_cast<unsigned>(u64) << 1;
*p++ = digits[i + 1];
*p++ = digits[i];
}
do {
--p;
os_->Put(*p);
} while (p != buffer);
return true;
}
private:
void WriteUintReverse(char* d, unsigned u) {
while (u >= 100) {
const unsigned i = (u % 100) << 1;
u /= 100;
*--d = digits[i + 1];
*--d = digits[i];
}
if (u < 10) {
*--d = char(u) + '0';
}
else {
const unsigned i = u << 1;
*--d = digits[i + 1];
*--d = digits[i];
}
}
void WriteUint64Reverse(char* d, uint64_t u) {
while (u >= 100) {
const unsigned i = (u % 100) << 1;
u /= 100;
*--d = digits[i + 1];
*--d = digits[i];
}
if (u < 10) {
*--d = char(u) + '0';
}
else {
const unsigned i = u << 1;
*--d = digits[i + 1];
*--d = digits[i];
}
}
OutputStream* os_;
};
template<>
inline bool Writer4<rapidjson::StringBuffer>::WriteUint(unsigned u) {
unsigned digit = CountDecimalDigit_fast(u);
WriteUintReverse(os_->Allocate(digit) + digit, u);
return true;
}
template<>
inline bool Writer4<rapidjson::InsituStringStream>::WriteUint(unsigned u) {
unsigned digit = CountDecimalDigit_fast(u);
WriteUintReverse(os_->Allocate(digit) + digit, u);
return true;
}
template<>
inline bool Writer4<rapidjson::StringBuffer>::WriteUint64(uint64_t u) {
unsigned digit = CountDecimalDigit64_fast(u);
WriteUint64Reverse(os_->Allocate(digit) + digit, u);
return true;
}
template<>
inline bool Writer4<rapidjson::InsituStringStream>::WriteUint64(uint64_t u) {
unsigned digit = CountDecimalDigit64_fast(u);
WriteUint64Reverse(os_->Allocate(digit) + digit, u);
return true;
}
template <typename Writer>
void itoa_Writer_Verify() {
void itoa_Writer_StringBufferVerify() {
rapidjson::StringBuffer sb;
Writer writer(sb);
for (int j = 0; j < randvalCount; j++) {
@ -350,6 +770,23 @@ void itoa_Writer_Verify() {
}
}
template <typename Writer>
void itoa_Writer_InsituStringStreamVerify() {
Writer writer;
for (int j = 0; j < randvalCount; j++) {
char buffer[32];
sprintf(buffer, "%d", randval[j]);
char buffer2[32];
rapidjson::InsituStringStream ss(buffer2);
writer.Reset(ss);
char* begin = ss.PutBegin();
writer.WriteInt(randval[j]);
ss.Put('\0');
ss.PutEnd(begin);
ASSERT_STREQ(buffer, buffer2);
}
}
template <typename Writer>
void itoa_Writer_StringBuffer() {
size_t length = 0;
@ -386,7 +823,7 @@ void itoa_Writer_InsituStringStream() {
};
template <typename Writer>
void itoa64_Writer_Verify() {
void itoa64_Writer_StringBufferVerify() {
rapidjson::StringBuffer sb;
Writer writer(sb);
for (int j = 0; j < randvalCount; j++) {
@ -399,6 +836,24 @@ void itoa64_Writer_Verify() {
}
}
template <typename Writer>
void itoa64_Writer_InsituStringStreamVerify() {
Writer writer;
for (int j = 0; j < randvalCount; j++) {
char buffer[32];
int64_t x = randval[j] * randval[j];
sprintf(buffer, "%" PRIi64, x);
char buffer2[32];
rapidjson::InsituStringStream ss(buffer2);
writer.Reset(ss);
char* begin = ss.PutBegin();
writer.WriteInt64(x);
ss.Put('\0');
ss.PutEnd(begin);
ASSERT_STREQ(buffer, buffer2);
}
}
template <typename Writer>
void itoa64_Writer_StringBuffer() {
size_t length = 0;
@ -434,53 +889,39 @@ void itoa64_Writer_InsituStringStream() {
OUTPUT_LENGTH(length);
};
TEST_F(Misc, itoa_Writer1_Verify) {
itoa_Writer_Verify<Writer1<rapidjson::StringBuffer> >();
}
TEST_F(Misc, itoa_Writer1_StringBufferVerify) { itoa_Writer_StringBufferVerify<Writer1<rapidjson::StringBuffer> >(); }
TEST_F(Misc, itoa_Writer2_StringBufferVerify) { itoa_Writer_StringBufferVerify<Writer2<rapidjson::StringBuffer> >(); }
TEST_F(Misc, itoa_Writer3_StringBufferVerify) { itoa_Writer_StringBufferVerify<Writer3<rapidjson::StringBuffer> >(); }
TEST_F(Misc, itoa_Writer4_StringBufferVerify) { itoa_Writer_StringBufferVerify<Writer4<rapidjson::StringBuffer> >(); }
TEST_F(Misc, itoa_Writer1_InsituStringStreamVerify) { itoa_Writer_InsituStringStreamVerify<Writer1<rapidjson::InsituStringStream> >(); }
TEST_F(Misc, itoa_Writer2_InsituStringStreamVerify) { itoa_Writer_InsituStringStreamVerify<Writer2<rapidjson::InsituStringStream> >(); }
TEST_F(Misc, itoa_Writer3_InsituStringStreamVerify) { itoa_Writer_InsituStringStreamVerify<Writer3<rapidjson::InsituStringStream> >(); }
TEST_F(Misc, itoa_Writer4_InsituStringStreamVerify) { itoa_Writer_InsituStringStreamVerify<Writer4<rapidjson::InsituStringStream> >(); }
TEST_F(Misc, itoa_Writer1_StringBuffer) { itoa_Writer_StringBuffer<Writer1<rapidjson::StringBuffer> >(); }
TEST_F(Misc, itoa_Writer2_StringBuffer) { itoa_Writer_StringBuffer<Writer2<rapidjson::StringBuffer> >(); }
TEST_F(Misc, itoa_Writer3_StringBuffer) { itoa_Writer_StringBuffer<Writer3<rapidjson::StringBuffer> >(); }
TEST_F(Misc, itoa_Writer4_StringBuffer) { itoa_Writer_StringBuffer<Writer4<rapidjson::StringBuffer> >(); }
TEST_F(Misc, itoa_Writer1_InsituStringStream) { itoa_Writer_InsituStringStream<Writer1<rapidjson::InsituStringStream> >(); }
TEST_F(Misc, itoa_Writer2_InsituStringStream) { itoa_Writer_InsituStringStream<Writer2<rapidjson::InsituStringStream> >(); }
TEST_F(Misc, itoa_Writer3_InsituStringStream) { itoa_Writer_InsituStringStream<Writer3<rapidjson::InsituStringStream> >(); }
TEST_F(Misc, itoa_Writer4_InsituStringStream) { itoa_Writer_InsituStringStream<Writer4<rapidjson::InsituStringStream> >(); }
TEST_F(Misc, itoa_Writer2_Verify) {
itoa_Writer_Verify<Writer1<rapidjson::StringBuffer> >();
}
TEST_F(Misc, itoa_Writer1_StringBuffer) {
itoa_Writer_StringBuffer<Writer1<rapidjson::StringBuffer> >();
}
TEST_F(Misc, itoa_Writer1_InsituStringStream) {
itoa_Writer_InsituStringStream<Writer1<rapidjson::InsituStringStream> >();
}
TEST_F(Misc, itoa_Writer2_StringBuffer) {
itoa_Writer_StringBuffer<Writer2<rapidjson::StringBuffer> >();
}
TEST_F(Misc, itoa_Writer2_InsituStringStream) {
itoa_Writer_InsituStringStream<Writer2<rapidjson::InsituStringStream> >();
}
TEST_F(Misc, itoa64_Writer1_Verify) {
itoa64_Writer_Verify<Writer1<rapidjson::StringBuffer> >();
}
TEST_F(Misc, itoa64_Writer2_Verify) {
itoa64_Writer_Verify<Writer1<rapidjson::StringBuffer> >();
}
TEST_F(Misc, itoa64_Writer1_StringBuffer) {
itoa64_Writer_StringBuffer<Writer1<rapidjson::StringBuffer> >();
}
TEST_F(Misc, itoa64_Writer1_InsituStringStream) {
itoa64_Writer_InsituStringStream<Writer1<rapidjson::InsituStringStream> >();
}
TEST_F(Misc, itoa64_Writer2_StringBuffer) {
itoa64_Writer_StringBuffer<Writer2<rapidjson::StringBuffer> >();
}
TEST_F(Misc, itoa64_Writer2_InsituStringStream) {
itoa64_Writer_InsituStringStream<Writer2<rapidjson::InsituStringStream> >();
}
TEST_F(Misc, itoa64_Writer1_StringBufferVerify) { itoa64_Writer_StringBufferVerify<Writer1<rapidjson::StringBuffer> >(); }
TEST_F(Misc, itoa64_Writer2_StringBufferVerify) { itoa64_Writer_StringBufferVerify<Writer2<rapidjson::StringBuffer> >(); }
TEST_F(Misc, itoa64_Writer3_StringBufferVerify) { itoa64_Writer_StringBufferVerify<Writer3<rapidjson::StringBuffer> >(); }
TEST_F(Misc, itoa64_Writer4_StringBufferVerify) { itoa64_Writer_StringBufferVerify<Writer4<rapidjson::StringBuffer> >(); }
TEST_F(Misc, itoa64_Writer1_InsituStringStreamVerify) { itoa64_Writer_InsituStringStreamVerify<Writer1<rapidjson::InsituStringStream> >(); }
TEST_F(Misc, itoa64_Writer2_InsituStringStreamVerify) { itoa64_Writer_InsituStringStreamVerify<Writer2<rapidjson::InsituStringStream> >(); }
TEST_F(Misc, itoa64_Writer3_InsituStringStreamVerify) { itoa64_Writer_InsituStringStreamVerify<Writer3<rapidjson::InsituStringStream> >(); }
TEST_F(Misc, itoa64_Writer4_InsituStringStreamVerify) { itoa64_Writer_InsituStringStreamVerify<Writer4<rapidjson::InsituStringStream> >(); }
TEST_F(Misc, itoa64_Writer1_StringBuffer) { itoa64_Writer_StringBuffer<Writer1<rapidjson::StringBuffer> >(); }
TEST_F(Misc, itoa64_Writer2_StringBuffer) { itoa64_Writer_StringBuffer<Writer2<rapidjson::StringBuffer> >(); }
TEST_F(Misc, itoa64_Writer3_StringBuffer) { itoa64_Writer_StringBuffer<Writer3<rapidjson::StringBuffer> >(); }
TEST_F(Misc, itoa64_Writer4_StringBuffer) { itoa64_Writer_StringBuffer<Writer4<rapidjson::StringBuffer> >(); }
TEST_F(Misc, itoa64_Writer1_InsituStringStream) { itoa64_Writer_InsituStringStream<Writer1<rapidjson::InsituStringStream> >(); }
TEST_F(Misc, itoa64_Writer2_InsituStringStream) { itoa64_Writer_InsituStringStream<Writer2<rapidjson::InsituStringStream> >(); }
TEST_F(Misc, itoa64_Writer3_InsituStringStream) { itoa64_Writer_InsituStringStream<Writer3<rapidjson::InsituStringStream> >(); }
TEST_F(Misc, itoa64_Writer4_InsituStringStream) { itoa64_Writer_InsituStringStream<Writer4<rapidjson::InsituStringStream> >(); }
TEST_F(Misc, itoa_sprintf) {
size_t length = 0;
@ -498,7 +939,8 @@ TEST_F(Misc, itoa64_sprintf) {
for (int i = 0; i < kItoaTrialCount; i++) {
for (int j = 0; j < randvalCount; j++) {
char buffer[32];
length += sprintf(buffer, "%" PRIi64, randval[j] * randval[j]);
int64_t x = randval[j] * randval[j];
length += sprintf(buffer, "%" PRIi64, x);
}
}
OUTPUT_LENGTH(length);