1 files changed, 148 insertions, 0 deletions
diff --git a/tests/src/JIT/Performance/CodeQuality/Inlining/InlineGCStruct.cs b/tests/src/JIT/Performance/CodeQuality/Inlining/InlineGCStruct.cs
new file mode 100644
index 0000000000..660627cc72
--- /dev/null
+++ b/tests/src/JIT/Performance/CodeQuality/Inlining/InlineGCStruct.cs
@@ -0,0 +1,148 @@
+// 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.
+
+// In CoreCLR String.Format(ref, ref) is small and readily inlined.
+// The inline introduces a System.Parms GC struct local which is
+// untracked and must be zero initialized in the prolog. When the
+// inlined callsite is in a cold path, the inline hurts performance.
+//
+// There are two test methods below, one of which calls String.Format
+// on a cold path and the other which has similar structure but
+// does not call String.Format. Expectation is that they will have
+// similar performance.
+//
+// See https://github.com/dotnet/coreclr/issues/7569 for context.
+
+using Microsoft.Xunit.Performance;
+using System;
+using System.Runtime.CompilerServices;
+using Xunit;
+
+[assembly: OptimizeForBenchmarks]
+[assembly: MeasureInstructionsRetired]
+
+namespace Inlining
+{
+public class InlineGCStruct
+{
+#if DEBUG
+    public const int Iterations = 1;
+#else
+    public const int Iterations = 2500000;
+#endif
+
+    [MethodImpl(MethodImplOptions.NoInlining)]
+    public static int FastFunctionNotCallingStringFormat(int param)
+    {
+        if (param < 0)
+        {
+            throw new Exception(String.Format("We do not like the value {0:N0}.", param));
+        }
+
+        if (param == int.MaxValue)
+        {
+            throw new Exception(String.Format("{0:N0} is maxed out.", param));
+        }
+
+        if (param > int.MaxValue / 2)
+        {
+            throw new Exception(String.Format("We do not like the value {0:N0} either.", param));
+        }
+
+        return param * 2;
+    }
+
+    [MethodImpl(MethodImplOptions.NoInlining)]
+    public static int FastFunctionNotHavingStringFormat(int param)
+    {
+        if (param < 0)
+        {
+            throw new ArgumentOutOfRangeException("param", "We do not like this value.");
+        }
+
+        if (param == int.MaxValue)
+        {
+            throw new ArgumentOutOfRangeException("param", "Maxed out.");
+        }
+
+        if (param > int.MaxValue / 2)
+        {
+            throw new ArgumentOutOfRangeException("param", "We do not like this value either.");
+        }
+
+        return param * 2;
+    }
+
+    [Benchmark]
+    public static bool WithFormat()
+    {
+        int result = 0;
+
+        foreach (var iteration in Benchmark.Iterations)
+        {
+            using (iteration.StartMeasurement())
+            {
+                for (int i = 0; i < Iterations; i++)
+                {
+                    result |= FastFunctionNotCallingStringFormat(11);
+                }
+            }
+        }
+
+        return (result == 22);
+    }
+
+    [Benchmark]
+    public static bool WithoutFormat()
+    {
+        int result = 0;
+
+        foreach (var iteration in Benchmark.Iterations)
+        {
+            using (iteration.StartMeasurement())
+            {
+                for (int i = 0; i < Iterations; i++)
+                {
+                    result |= FastFunctionNotHavingStringFormat(11);
+                }
+            }
+        }
+
+        return (result == 22);
+    }
+
+    public static bool WithoutFormatBase()
+    {
+        int result = 0;
+
+        for (int i = 0; i < Iterations; i++)
+        {
+            result |= FastFunctionNotHavingStringFormat(11);
+        }
+
+        return (result == 22);
+    }
+
+    public static bool WithFormatBase()
+    {
+        int result = 0;
+
+        for (int i = 0; i < Iterations; i++)
+        {
+            result |= FastFunctionNotCallingStringFormat(11);
+        }
+
+        return (result == 22);
+    }
+
+    public static int Main()
+    {
+        bool withFormat = WithFormatBase();
+        bool withoutFormat = WithoutFormatBase();
+
+        return (withFormat && withoutFormat ? 100 : -1);
+    }
+}
+}
+