Common: Remove CityHash32 and CityHashCrc128 variants

In 64-bit systems, CityHash64 is always strictly better than CityHash32.
CityHashCrc128 requires SSE 4.2.
This commit is contained in:
Yuri Kunde Schlesner 2018-01-15 01:38:54 -08:00
parent f081388afe
commit 712e6ee960
2 changed files with 0 additions and 275 deletions

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@ -135,141 +135,6 @@ static const uint64 k0 = 0xc3a5c85c97cb3127ULL;
static const uint64 k1 = 0xb492b66fbe98f273ULL;
static const uint64 k2 = 0x9ae16a3b2f90404fULL;
// Magic numbers for 32-bit hashing. Copied from Murmur3.
static const uint32 c1 = 0xcc9e2d51;
static const uint32 c2 = 0x1b873593;
// A 32-bit to 32-bit integer hash copied from Murmur3.
static uint32 fmix(uint32 h) {
h ^= h >> 16;
h *= 0x85ebca6b;
h ^= h >> 13;
h *= 0xc2b2ae35;
h ^= h >> 16;
return h;
}
static uint32 Rotate32(uint32 val, int shift) {
// Avoid shifting by 32: doing so yields an undefined result.
return shift == 0 ? val : ((val >> shift) | (val << (32 - shift)));
}
#undef PERMUTE3
#define PERMUTE3(a, b, c) \
do { \
std::swap(a, b); \
std::swap(a, c); \
} while (0)
static uint32 Mur(uint32 a, uint32 h) {
// Helper from Murmur3 for combining two 32-bit values.
a *= c1;
a = Rotate32(a, 17);
a *= c2;
h ^= a;
h = Rotate32(h, 19);
return h * 5 + 0xe6546b64;
}
static uint32 Hash32Len13to24(const char* s, size_t len) {
uint32 a = Fetch32(s - 4 + (len >> 1));
uint32 b = Fetch32(s + 4);
uint32 c = Fetch32(s + len - 8);
uint32 d = Fetch32(s + (len >> 1));
uint32 e = Fetch32(s);
uint32 f = Fetch32(s + len - 4);
uint32 h = len;
return fmix(Mur(f, Mur(e, Mur(d, Mur(c, Mur(b, Mur(a, h)))))));
}
static uint32 Hash32Len0to4(const char* s, size_t len) {
uint32 b = 0;
uint32 c = 9;
for (size_t i = 0; i < len; i++) {
signed char v = s[i];
b = b * c1 + v;
c ^= b;
}
return fmix(Mur(b, Mur(len, c)));
}
static uint32 Hash32Len5to12(const char* s, size_t len) {
uint32 a = len, b = len * 5, c = 9, d = b;
a += Fetch32(s);
b += Fetch32(s + len - 4);
c += Fetch32(s + ((len >> 1) & 4));
return fmix(Mur(c, Mur(b, Mur(a, d))));
}
uint32 CityHash32(const char* s, size_t len) {
if (len <= 24) {
return len <= 12 ? (len <= 4 ? Hash32Len0to4(s, len) : Hash32Len5to12(s, len))
: Hash32Len13to24(s, len);
}
// len > 24
uint32 h = len, g = c1 * len, f = g;
uint32 a0 = Rotate32(Fetch32(s + len - 4) * c1, 17) * c2;
uint32 a1 = Rotate32(Fetch32(s + len - 8) * c1, 17) * c2;
uint32 a2 = Rotate32(Fetch32(s + len - 16) * c1, 17) * c2;
uint32 a3 = Rotate32(Fetch32(s + len - 12) * c1, 17) * c2;
uint32 a4 = Rotate32(Fetch32(s + len - 20) * c1, 17) * c2;
h ^= a0;
h = Rotate32(h, 19);
h = h * 5 + 0xe6546b64;
h ^= a2;
h = Rotate32(h, 19);
h = h * 5 + 0xe6546b64;
g ^= a1;
g = Rotate32(g, 19);
g = g * 5 + 0xe6546b64;
g ^= a3;
g = Rotate32(g, 19);
g = g * 5 + 0xe6546b64;
f += a4;
f = Rotate32(f, 19);
f = f * 5 + 0xe6546b64;
size_t iters = (len - 1) / 20;
do {
uint32 a0 = Rotate32(Fetch32(s) * c1, 17) * c2;
uint32 a1 = Fetch32(s + 4);
uint32 a2 = Rotate32(Fetch32(s + 8) * c1, 17) * c2;
uint32 a3 = Rotate32(Fetch32(s + 12) * c1, 17) * c2;
uint32 a4 = Fetch32(s + 16);
h ^= a0;
h = Rotate32(h, 18);
h = h * 5 + 0xe6546b64;
f += a1;
f = Rotate32(f, 19);
f = f * c1;
g += a2;
g = Rotate32(g, 18);
g = g * 5 + 0xe6546b64;
h ^= a3 + a1;
h = Rotate32(h, 19);
h = h * 5 + 0xe6546b64;
g ^= a4;
g = bswap_32(g) * 5;
h += a4 * 5;
h = bswap_32(h);
f += a0;
PERMUTE3(f, h, g);
s += 20;
} while (--iters != 0);
g = Rotate32(g, 11) * c1;
g = Rotate32(g, 17) * c1;
f = Rotate32(f, 11) * c1;
f = Rotate32(f, 17) * c1;
h = Rotate32(h + g, 19);
h = h * 5 + 0xe6546b64;
h = Rotate32(h, 17) * c1;
h = Rotate32(h + f, 19);
h = h * 5 + 0xe6546b64;
h = Rotate32(h, 17) * c1;
return h;
}
// Bitwise right rotate. Normally this will compile to a single
// instruction, especially if the shift is a manifest constant.
static uint64 Rotate(uint64 val, int shift) {
@ -518,141 +383,4 @@ uint128 CityHash128(const char* s, size_t len) {
: CityHash128WithSeed(s, len, uint128(k0, k1));
}
#ifdef __SSE4_2__
#include <citycrc.h>
#include <nmmintrin.h>
// Requires len >= 240.
static void CityHashCrc256Long(const char* s, size_t len, uint32 seed, uint64* result) {
uint64 a = Fetch64(s + 56) + k0;
uint64 b = Fetch64(s + 96) + k0;
uint64 c = result[0] = HashLen16(b, len);
uint64 d = result[1] = Fetch64(s + 120) * k0 + len;
uint64 e = Fetch64(s + 184) + seed;
uint64 f = 0;
uint64 g = 0;
uint64 h = c + d;
uint64 x = seed;
uint64 y = 0;
uint64 z = 0;
// 240 bytes of input per iter.
size_t iters = len / 240;
len -= iters * 240;
do {
#undef CHUNK
#define CHUNK(r) \
PERMUTE3(x, z, y); \
b += Fetch64(s); \
c += Fetch64(s + 8); \
d += Fetch64(s + 16); \
e += Fetch64(s + 24); \
f += Fetch64(s + 32); \
a += b; \
h += f; \
b += c; \
f += d; \
g += e; \
e += z; \
g += x; \
z = _mm_crc32_u64(z, b + g); \
y = _mm_crc32_u64(y, e + h); \
x = _mm_crc32_u64(x, f + a); \
e = Rotate(e, r); \
c += e; \
s += 40
CHUNK(0);
PERMUTE3(a, h, c);
CHUNK(33);
PERMUTE3(a, h, f);
CHUNK(0);
PERMUTE3(b, h, f);
CHUNK(42);
PERMUTE3(b, h, d);
CHUNK(0);
PERMUTE3(b, h, e);
CHUNK(33);
PERMUTE3(a, h, e);
} while (--iters > 0);
while (len >= 40) {
CHUNK(29);
e ^= Rotate(a, 20);
h += Rotate(b, 30);
g ^= Rotate(c, 40);
f += Rotate(d, 34);
PERMUTE3(c, h, g);
len -= 40;
}
if (len > 0) {
s = s + len - 40;
CHUNK(33);
e ^= Rotate(a, 43);
h += Rotate(b, 42);
g ^= Rotate(c, 41);
f += Rotate(d, 40);
}
result[0] ^= h;
result[1] ^= g;
g += h;
a = HashLen16(a, g + z);
x += y << 32;
b += x;
c = HashLen16(c, z) + h;
d = HashLen16(d, e + result[0]);
g += e;
h += HashLen16(x, f);
e = HashLen16(a, d) + g;
z = HashLen16(b, c) + a;
y = HashLen16(g, h) + c;
result[0] = e + z + y + x;
a = ShiftMix((a + y) * k0) * k0 + b;
result[1] += a + result[0];
a = ShiftMix(a * k0) * k0 + c;
result[2] = a + result[1];
a = ShiftMix((a + e) * k0) * k0;
result[3] = a + result[2];
}
// Requires len < 240.
static void CityHashCrc256Short(const char* s, size_t len, uint64* result) {
char buf[240];
memcpy(buf, s, len);
memset(buf + len, 0, 240 - len);
CityHashCrc256Long(buf, 240, ~static_cast<uint32>(len), result);
}
void CityHashCrc256(const char* s, size_t len, uint64* result) {
if (LIKELY(len >= 240)) {
CityHashCrc256Long(s, len, 0, result);
} else {
CityHashCrc256Short(s, len, result);
}
}
uint128 CityHashCrc128WithSeed(const char* s, size_t len, uint128 seed) {
if (len <= 900) {
return CityHash128WithSeed(s, len, seed);
} else {
uint64 result[4];
CityHashCrc256(s, len, result);
uint64 u = Uint128High64(seed) + result[0];
uint64 v = Uint128Low64(seed) + result[1];
return uint128(HashLen16(u, v + result[2]), HashLen16(Rotate(v, 32), u * k0 + result[3]));
}
}
uint128 CityHashCrc128(const char* s, size_t len) {
if (len <= 900) {
return CityHash128(s, len);
} else {
uint64 result[4];
CityHashCrc256(s, len, result);
return uint128(result[2], result[3]);
}
}
#endif
} // namespace Common

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@ -94,9 +94,6 @@ uint128 CityHash128(const char* s, size_t len);
// hashed into the result.
uint128 CityHash128WithSeed(const char* s, size_t len, uint128 seed);
// Hash function for a byte array. Most useful in 32-bit binaries.
uint32_t CityHash32(const char* buf, size_t len);
// Hash 128 input bits down to 64 bits of output.
// This is intended to be a reasonably good hash function.
inline uint64_t Hash128to64(const uint128& x) {