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// Copyright 2017 The Wuffs Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ----------------
// This file contains a hand-written C implementation of the Adler32 hash
// function, based on the code generated by the Wuffs std/zlib implementation.
// Its purpose is to benchmark different compilers, or different versions of
// the same compiler family.
//
// For example, on a Debian Testing system as of November 2017:
//
// $ clang-5.0 -O3 adler32-standalone.c; ./a.out
// 2311 MiB/s, clang 5.0.0 (tags/RELEASE_500/rc2)
// $ gcc -O3 adler32-standalone.c; ./a.out
// 3052 MiB/s, gcc 7.2.1 20171025
//
// which suggest that clang's code performs at about 76% the throughput of
// gcc's. This is filed as https://bugs.llvm.org/show_bug.cgi?id=35567
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <sys/time.h>
#define BUFFER_SIZE (1024 * 1024)
#define ONE_MIBIBYTE (1024 * 1024)
// The order matters here. Clang also defines "__GNUC__".
#if defined(__clang__)
const char* cc = "clang";
const char* cc_version = __clang_version__;
#elif defined(__GNUC__)
const char* cc = "gcc";
const char* cc_version = __VERSION__;
#elif defined(_MSC_VER)
const char* cc = "cl";
const char* cc_version = "???";
#else
const char* cc = "cc";
const char* cc_version = "???";
#endif
static uint32_t calculate_hash(uint8_t* x_ptr, size_t x_len) {
uint32_t s1 = 1;
uint32_t s2 = 0;
while (x_len > 0) {
uint8_t* prefix_ptr;
size_t prefix_len;
if (x_len > 5552) {
prefix_ptr = x_ptr;
prefix_len = 5552;
x_ptr = x_ptr + 5552;
x_len = x_len - 5552;
} else {
prefix_ptr = x_ptr;
prefix_len = x_len;
x_ptr = NULL;
x_len = 0;
}
uint8_t* p = prefix_ptr;
uint8_t* end0 = prefix_ptr + (prefix_len / 8) * 8;
while (p < end0) {
s1 += ((uint32_t)(*p));
s2 += s1;
p++;
s1 += ((uint32_t)(*p));
s2 += s1;
p++;
s1 += ((uint32_t)(*p));
s2 += s1;
p++;
s1 += ((uint32_t)(*p));
s2 += s1;
p++;
s1 += ((uint32_t)(*p));
s2 += s1;
p++;
s1 += ((uint32_t)(*p));
s2 += s1;
p++;
s1 += ((uint32_t)(*p));
s2 += s1;
p++;
s1 += ((uint32_t)(*p));
s2 += s1;
p++;
}
uint8_t* end1 = prefix_ptr + prefix_len;
while (p < end1) {
s1 += ((uint32_t)(*p));
s2 += s1;
p++;
}
s1 %= 65521;
s2 %= 65521;
}
return (s2 << 16) | s1;
}
uint8_t buffer[BUFFER_SIZE] = {0};
int main(int argc, char** argv) {
bool nocheck = false;
int i;
for (i = 0; i < argc; i++) {
if (!strcmp(argv[i], "-nocheck")) {
nocheck = true;
}
}
struct timeval bench_start_tv;
gettimeofday(&bench_start_tv, NULL);
const int num_reps = 1000;
// If changing BUFFER_SIZE, re-calculate this expected value with
// https://play.golang.org/p/IU2T58P00C
const uint32_t expected_hash_of_1mib_of_zeroes = 0x00f00001UL;
int num_bad = 0;
for (i = 0; i < num_reps; i++) {
uint32_t actual_hash = calculate_hash(buffer, BUFFER_SIZE);
if (!nocheck && (actual_hash != expected_hash_of_1mib_of_zeroes)) {
num_bad++;
}
}
if (num_bad) {
printf("num_bad: %d\n", num_bad);
return 1;
}
struct timeval bench_finish_tv;
gettimeofday(&bench_finish_tv, NULL);
int64_t micros =
(int64_t)(bench_finish_tv.tv_sec - bench_start_tv.tv_sec) * 1000000 +
(int64_t)(bench_finish_tv.tv_usec - bench_start_tv.tv_usec);
int64_t numer = ((int64_t)num_reps) * BUFFER_SIZE * 1000000;
int64_t denom = micros * ONE_MIBIBYTE;
int64_t mib_per_s = denom ? numer / denom : 0;
printf("%8d MiB/s, %s %s\n", (int)mib_per_s, cc, cc_version);
return 0;
}