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z3/xxhash_extended_benchmark.cpp

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#include <iostream>
#include <chrono>
#include <vector>
#include <string>
#include <random>
#include <cassert>
#include <iomanip>
// Test both hash implementations directly
#include <cstring>
#include <cstdint>
// Bob Jenkins hash (original Z3)
#define mix(a,b,c) \
{ \
a -= b; a -= c; a ^= (c>>13); \
b -= c; b -= a; b ^= (a<<8); \
c -= a; c -= b; c ^= (b>>13); \
a -= b; a -= c; a ^= (c>>12); \
b -= c; b -= a; b ^= (a<<16); \
c -= a; c -= b; c ^= (b>>5); \
a -= b; a -= c; a ^= (c>>3); \
b -= c; b -= a; b ^= (a<<10); \
c -= a; c -= b; c ^= (b>>15); \
}
static unsigned read_unsigned(const char *s) {
unsigned n;
memcpy(&n, s, sizeof(unsigned));
return n;
}
unsigned jenkins_hash(const char * str, unsigned length, unsigned init_value) {
unsigned a, b, c, len;
len = length;
a = b = 0x9e3779b9;
c = init_value;
while (len >= 12) {
a += read_unsigned(str);
b += read_unsigned(str+4);
c += read_unsigned(str+8);
mix(a,b,c);
str += 12; len -= 12;
}
c += length;
switch(len) {
case 11: c+=((unsigned)str[10]<<24);
case 10: c+=((unsigned)str[9]<<16);
case 9 : c+=((unsigned)str[8]<<8);
case 8 : b+=((unsigned)str[7]<<24);
case 7 : b+=((unsigned)str[6]<<16);
case 6 : b+=((unsigned)str[5]<<8);
case 5 : b+=str[4];
case 4 : a+=((unsigned)str[3]<<24);
case 3 : a+=((unsigned)str[2]<<16);
case 2 : a+=((unsigned)str[1]<<8);
case 1 : a+=str[0];
break;
}
mix(a,b,c);
return c;
}
// xxHash32 implementation
static const uint32_t XXHASH_PRIME1 = 0x9E3779B1U;
static const uint32_t XXHASH_PRIME2 = 0x85EBCA77U;
static const uint32_t XXHASH_PRIME3 = 0xC2B2AE3DU;
static const uint32_t XXHASH_PRIME4 = 0x27D4EB2FU;
static const uint32_t XXHASH_PRIME5 = 0x165667B1U;
static inline uint32_t xxhash_rotl32(uint32_t x, int r) {
return (x << r) | (x >> (32 - r));
}
static inline uint32_t xxhash_read32le(const void* ptr) {
uint32_t val;
memcpy(&val, ptr, sizeof(val));
return val;
}
unsigned xxhash32(const char* data, unsigned len, unsigned seed) {
const uint8_t* p = (const uint8_t*)data;
const uint8_t* const bEnd = p + len;
uint32_t h32;
if (len >= 16) {
const uint8_t* const limit = bEnd - 16;
uint32_t v1 = seed + XXHASH_PRIME1 + XXHASH_PRIME2;
uint32_t v2 = seed + XXHASH_PRIME2;
uint32_t v3 = seed + 0;
uint32_t v4 = seed - XXHASH_PRIME1;
do {
v1 = xxhash_rotl32(v1 + xxhash_read32le(p) * XXHASH_PRIME2, 13) * XXHASH_PRIME1;
p += 4;
v2 = xxhash_rotl32(v2 + xxhash_read32le(p) * XXHASH_PRIME2, 13) * XXHASH_PRIME1;
p += 4;
v3 = xxhash_rotl32(v3 + xxhash_read32le(p) * XXHASH_PRIME2, 13) * XXHASH_PRIME1;
p += 4;
v4 = xxhash_rotl32(v4 + xxhash_read32le(p) * XXHASH_PRIME2, 13) * XXHASH_PRIME1;
p += 4;
} while (p <= limit);
h32 = xxhash_rotl32(v1, 1) + xxhash_rotl32(v2, 7) + xxhash_rotl32(v3, 12) + xxhash_rotl32(v4, 18);
} else {
h32 = seed + XXHASH_PRIME5;
}
h32 += (uint32_t) len;
while (p + 4 <= bEnd) {
h32 += xxhash_read32le(p) * XXHASH_PRIME3;
h32 = xxhash_rotl32(h32, 17) * XXHASH_PRIME4;
p += 4;
}
while (p < bEnd) {
h32 += (*p) * XXHASH_PRIME5;
h32 = xxhash_rotl32(h32, 11) * XXHASH_PRIME1;
p++;
}
h32 ^= h32 >> 15;
h32 *= XXHASH_PRIME2;
h32 ^= h32 >> 13;
h32 *= XXHASH_PRIME3;
h32 ^= h32 >> 16;
return h32;
}
// Generate test data with different size categories
std::vector<std::string> generate_test_data() {
std::vector<std::string> data;
std::mt19937 rng(42);
// Small strings (typical variable names, operators)
std::uniform_int_distribution<> small_len(4, 16);
for (int i = 0; i < 10000; ++i) {
int len = small_len(rng);
std::string s = "var_" + std::to_string(i);
while (s.length() < len) s += "_x";
s.resize(len);
data.push_back(s);
}
// Medium strings (expressions, terms)
std::uniform_int_distribution<> med_len(32, 128);
for (int i = 0; i < 5000; ++i) {
int len = med_len(rng);
std::string s = "(assert (and ";
while (s.length() < len) {
s += "(> x_" + std::to_string(i % 100) + " " + std::to_string(i % 10) + ") ";
}
s.resize(len - 2);
s += "))";
data.push_back(s);
}
// Large strings (complex formulas)
std::uniform_int_distribution<> large_len(256, 1024);
for (int i = 0; i < 1000; ++i) {
int len = large_len(rng);
std::string s = "(assert (or ";
while (s.length() < len) {
s += "(and (= term_" + std::to_string(i) + "_" + std::to_string(s.length() % 50);
s += " value_" + std::to_string(i % 20) + ") ";
s += "(> expr_" + std::to_string(i % 30) + " 0)) ";
}
s.resize(len - 2);
s += "))";
data.push_back(s);
}
// Very large strings (where xxHash should excel)
std::uniform_int_distribution<> xl_len(1024, 4096);
for (int i = 0; i < 500; ++i) {
int len = xl_len(rng);
std::string s;
s.reserve(len);
while (s.length() < len) {
s += "(assert (and (> variable_with_very_long_name_" + std::to_string(i);
s += "_component_" + std::to_string(s.length() % 100);
s += " constant_value_" + std::to_string(i % 50) + ") ";
s += "(< another_very_long_variable_name_" + std::to_string(i);
s += "_part_" + std::to_string(s.length() % 200);
s += " upper_bound_" + std::to_string(i % 25) + "))) ";
}
s.resize(len);
data.push_back(s);
}
return data;
}
template<typename HashFunc>
double benchmark_hash(const std::vector<std::string>& data, HashFunc hash_func, const std::string& name) {
const int iterations = 10000;
auto start = std::chrono::high_resolution_clock::now();
volatile unsigned result = 0;
for (int iter = 0; iter < iterations; ++iter) {
for (const auto& str : data) {
result += hash_func(str.c_str(), str.length(), 0);
}
}
auto end = std::chrono::high_resolution_clock::now();
auto duration = std::chrono::duration_cast<std::chrono::microseconds>(end - start);
if (result == 0xDEADBEEF) std::cout << "Impossible";
double ms = duration.count() / 1000.0;
// Calculate throughput
size_t total_bytes = 0;
for (const auto& str : data) total_bytes += str.length();
double mb_per_sec = (total_bytes * iterations) / (ms * 1024.0);
std::cout << name << ": " << std::fixed << std::setprecision(3)
<< ms << " ms (" << mb_per_sec << " MB/sec)" << std::endl;
return ms;
}
int main() {
std::cout << "=== Extended Hash Function Performance Benchmark ===" << std::endl;
std::cout << "Testing with comprehensive Z3-realistic workloads" << std::endl;
auto test_data = generate_test_data();
std::cout << "\nGenerated " << test_data.size() << " test strings" << std::endl;
// Calculate size distribution
size_t total_bytes = 0;
size_t small_count = 0, med_count = 0, large_count = 0, xl_count = 0;
for (const auto& str : test_data) {
total_bytes += str.length();
if (str.length() <= 16) small_count++;
else if (str.length() <= 128) med_count++;
else if (str.length() <= 1024) large_count++;
else xl_count++;
}
std::cout << "Distribution:" << std::endl;
std::cout << " Small (≤16): " << small_count << " strings" << std::endl;
std::cout << " Medium (≤128): " << med_count << " strings" << std::endl;
std::cout << " Large (≤1024): " << large_count << " strings" << std::endl;
std::cout << " XL (>1024): " << xl_count << " strings" << std::endl;
std::cout << " Total data: " << (total_bytes / 1024) << " KB" << std::endl;
std::cout << "\n--- Performance Comparison (100 iterations) ---" << std::endl;
double jenkins_time = benchmark_hash(test_data, jenkins_hash, "Bob Jenkins Hash");
double xxhash_time = benchmark_hash(test_data, xxhash32, "xxHash32 ");
std::cout << "\n=== Performance Summary ===" << std::endl;
std::cout << std::fixed << std::setprecision(3);
std::cout << "Jenkins time: " << jenkins_time << " ms" << std::endl;
std::cout << "xxHash time: " << xxhash_time << " ms" << std::endl;
if (xxhash_time < jenkins_time) {
double speedup = jenkins_time / xxhash_time;
double improvement = ((jenkins_time - xxhash_time) / jenkins_time) * 100;
std::cout << "Speedup: " << speedup << "x (" << improvement << "% faster)" << std::endl;
} else {
double slowdown = xxhash_time / jenkins_time;
double regression = ((xxhash_time - jenkins_time) / jenkins_time) * 100;
std::cout << "Slowdown: " << slowdown << "x (" << regression << "% slower)" << std::endl;
}
return 0;
}
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