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// Copyright 2017 Global Phasing Ltd.
#include <cmath>
#include <cstdlib> // for rand
#include <benchmark/benchmark.h>
static double use_round(double x) { return std::round(x); }
static double use_floor(double x) { return std::floor(x + 0.5); }
static double use_nearbyint(double x) { return std::nearbyint(x); }
static double use_rint(double x) { return std::rint(x); }
static long use_lrint(double x) { return std::lrint(x); }
static long use2_round(double x) { return (long) std::round(x); }
static long use2_floor(double x) { return (long) std::floor(x + 0.5); }
static long use2_nearbyint(double x) { return (long) std::nearbyint(x); }
static long use2_rint(double x) { return (long) std::rint(x); }
double numbers[] = {
1.331, 6.3, 4, -4.5, 99341.4106,
0, -6.05823, 1e-9, 18.419, -12345.67
};
inline void run(benchmark::State& state, double(*func)(double)) {
for (double& x : numbers) { // otherwise it would be all optimized out
x = std::rand() % 10 == 0 ? -x : x;
}
for (auto _ : state)
for (double x : numbers)
benchmark::DoNotOptimize((*func)(x));
}
inline void run2(benchmark::State& state, long(*func)(double)) {
for (double& x : numbers) { // otherwise it would be all optimized out
x = std::rand() % 10 == 0 ? -x : x;
}
for (auto _ : state)
for (double x : numbers)
benchmark::DoNotOptimize((*func)(x));
}
BENCHMARK_CAPTURE(run, round, use_round);
BENCHMARK_CAPTURE(run, floor, use_floor);
BENCHMARK_CAPTURE(run, nearbyint, use_nearbyint);
BENCHMARK_CAPTURE(run, rint, use_rint);
BENCHMARK_CAPTURE(run2, lrint, use_lrint);
BENCHMARK_CAPTURE(run2, round, use2_round);
BENCHMARK_CAPTURE(run2, floor, use2_floor);
BENCHMARK_CAPTURE(run2, nearbyint, use2_nearbyint);
BENCHMARK_CAPTURE(run2, rint, use2_rint);
BENCHMARK_MAIN();
/*
-----------------------------------------------------
Benchmark Time CPU Iterations
-----------------------------------------------------
run/round 26 ns 26 ns 23927270
run/floor 18 ns 18 ns 37953966
run/nearbyint 18 ns 18 ns 38603220
run/rint 13 ns 13 ns 53661537
run2/lrint 18 ns 18 ns 38754555
run2/round 27 ns 27 ns 26094020
run2/floor 18 ns 18 ns 38176320
run2/nearbyint 16 ns 16 ns 43588313
run2/rint 13 ns 13 ns 53491145
*/
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