sum.cs

gistfile1.txt

    public class BenchSum
    {
        private int[] _values;

        [GlobalSetup]
        public void Setup()
        {
            _values = new int[1024];
        }

        [Benchmark(Baseline = true)]
        public int Foreach()
        {
            var values = _values;
            int result = 0;

            foreach (var value in values)
            {
                result += value;
            }

            return result;
        }

        [Benchmark]
        public int For()
        {
            var values = _values;
            int result = 0;

            for (int i = 0; i < values.Length; i++)
            {
                result += values[i];
            }

            return result;
        }

        [Benchmark]
        public int For2Ports()
        {
            var values = _values;
            int result1 = 0;
            int result2 = 0;

            for (int i = 0; i < values.Length; i += 2)
            { 
                result1 += values[i];
                result2 += values[i + 1];
            }

            return result1 + result2;
        }

        [Benchmark]
        public unsafe int For2Ports_NoNullCheck()
        {
            var len = _values.Length;

            int result1 = 0;
            int result2 = 0;

            fixed (int* pin = _values)
            {
                int* values = pin;
                for (int i = 0; i < len; i += 2)
                {
                    result1 += values[i];
                    result2 += values[i + 1];
                    values += 2;
                }
            }

            return result1 + result2;
        }

        [Benchmark]
        public unsafe int For2Ports_NoZeroExtendAndNullChecks()
        {
            var len = _values.Length;

            int result1 = 0;
            int result2 = 0;

            fixed (int* pin = _values)
            {
                int* values = pin;
                for (int i = 0; i < len; i += 2)
                {
                    result1 += *values;
                    result2 += *(values + 1);
                    values += 2;
                }
            }

            return result1 + result2;
        }

        [Benchmark]
        public unsafe int For4Ports_NoZeroExtendAndNullChecks()
        {
            var len = _values.Length;

            int result1 = 0;
            int result2 = 0;
            int result3 = 0;
            int result4 = 0;

            fixed (int* pin = _values)
            {
                long* values = (long*)pin;
                for (int i = 0; i < len; i += 2)
                {
                    result1 += (int)(*values >> 32);
                    result2 += (int)(*values & 0xFFFFFFFF);
                    values++;

                    result3 += (int)(*values >> 32);
                    result4 += (int)(*values & 0xFFFFFFFF);
                    values++;
                }
            }

            return result1 + result2 + result3 + result4;
        }

        [Benchmark]
        public int LinqSum()
        {
            var values = _values;
            var result = values.Sum(x => x);
            return result;
        }
        
        [Benchmark]
        public int LinqAgg()
        {
            var values = _values;
            var result = values.Aggregate(0, (acc, x) => acc + x);
            return result;
        }

        [Benchmark]
        public int SIMD()
        {
            var values = _values;
            Vector<int> vsum = new Vector<int>(0);
            
            for (int i = 0; i < values.Length; i += Vector<int>.Count)
            {
                var value = new Vector<int>(values, i);
                vsum = vsum + (value);
            }

            int result = 0;
            for (int i = 0; i < Vector<double>.Count; i++)
            {
                result += vsum[i];
            }

            return result;
        }
    }