1 files changed, 169 insertions, 0 deletions
diff --git a/tests/src/JIT/Performance/CodeQuality/BenchF/Romber/Romber.cs b/tests/src/JIT/Performance/CodeQuality/BenchF/Romber/Romber.cs
new file mode 100644
index 0000000000..5824cd43cc
--- /dev/null
+++ b/tests/src/JIT/Performance/CodeQuality/BenchF/Romber/Romber.cs
@@ -0,0 +1,169 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+//
+// Integration by romberg method adapted from Conte and de Boor
+
+using Microsoft.Xunit.Performance;
+using System;
+using System.Runtime.CompilerServices;
+using Xunit;
+
+[assembly: OptimizeForBenchmarks]
+[assembly: MeasureInstructionsRetired]
+
+public static class Romber
+{
+#if DEBUG
+    public const int Iterations = 1;
+#else
+    public const int Iterations = 640000;
+#endif
+
+    private static T[][] AllocArray<T>(int n1, int n2)
+    {
+        T[][] a = new T[n1][];
+        for (int i = 0; i < n1; ++i)
+        {
+            a[i] = new T[n2];
+        }
+        return a;
+    }
+
+    [MethodImpl(MethodImplOptions.NoInlining)]
+    private static bool Bench()
+    {
+        double[][] r = AllocArray<double>(11, 11);
+        double[][] t = AllocArray<double>(11, 11);
+
+        int idbg, m, n, i, kmax, fourj, j, kmaxm2, l, k, mm1;
+        double sum, ratio, t1, h, a, b;
+
+        for (l = 1; l <= Iterations; l++)
+        {
+            idbg = 0;
+            m = 2;
+            kmax = 6;
+            a = 0;
+            b = 1;
+            h = (b - a) / (m);
+            sum = (F(a) + F(b)) / 2;
+
+            mm1 = m - 1;
+            if (mm1 < 0)
+            {
+                goto L40;
+            }
+            if (mm1 == 0)
+            {
+                goto L10;
+            }
+            for (i = 1; i <= mm1; i++)
+            {
+                t1 = a + i * h;
+                sum = sum + F(t1);
+            }
+
+        L10:
+            t[1][1] = sum * h;
+            if (idbg != 0)
+            {
+                System.Console.WriteLine(" romberg t-table \n");
+                System.Console.WriteLine("{0}\n", t[1][1]);
+            }
+
+            for (k = 2; k <= kmax; k++)
+            {
+                h = h / 2;
+                n = m * 2;
+                sum = 0;
+                for (i = 1; i <= n / 2; i++)
+                {
+                    r[k][1] = r[k - 1][1] * System.Math.Sqrt(b * mm1);
+                    t1 = a + i * h;
+                    sum = sum + F(t1);
+                }
+
+                t[k][1] = t[k - 1][1] / 2 + sum * h;
+                fourj = 1;
+                for (j = 2; j <= k; j++)
+                {
+                    fourj = fourj * 4;
+                    t[k - 1][j - 1] = t[k][j - 1] - t[k - 1][j - 1];
+                    t[k][j] = t[k][j - 1] + t[k - 1][j - 1] / (fourj - 1);
+                }
+
+                if (idbg != 0)
+                {
+                    j = 1;
+                    System.Console.WriteLine("{0} {1} {2}d\n", t[k][j], j, k);
+                }
+            }
+
+            kmaxm2 = kmax - 2;
+            if (kmaxm2 <= 0)
+            {
+                goto L40;
+            }
+
+            if (idbg != 0)
+            {
+                System.Console.WriteLine(" table of ratios \n");
+            }
+
+            for (k = 1; k <= kmaxm2; k++)
+            {
+                for (j = 1; j <= k; j++)
+                {
+                    ratio = 0;
+                    if (System.Math.Abs(t[k + 1][j]) > 0)
+                    {
+                        ratio = t[k][j] / t[k + 1][j];
+                    }
+                    t[k][j] = ratio;
+                }
+            }
+
+            if (idbg != 0)
+            {
+                j = 1;
+                System.Console.WriteLine("{0} {1} {2}\n", t[k][j], j, k);
+            }
+
+        L40:
+            {
+            }
+        }
+
+        return true;
+    }
+
+    private static double F(double x)
+    {
+        return (System.Math.Exp((-(x)) * (x)));
+    }
+
+    [Benchmark]
+    public static void Test()
+    {
+        foreach (var iteration in Benchmark.Iterations)
+        {
+            using (iteration.StartMeasurement())
+            {
+                Bench();
+            }
+        }
+    }
+
+    private static bool TestBase()
+    {
+        bool result = Bench();
+        return result;
+    }
+
+    public static int Main()
+    {
+        bool result = TestBase();
+        return (result ? 100 : -1);
+    }
+}