fix

Author: bitfaster

BitFaster.Caching.Benchmarks/Lfu/SketchIncrement.cs

@@ -1,5 +1,6 @@
 
 using System.Collections.Generic;
+using Benchly;
 using BenchmarkDotNet.Attributes;
 using BenchmarkDotNet.Jobs;
 using BitFaster.Caching.Lfu;
@@ -9,6 +10,7 @@ namespace BitFaster.Caching.Benchmarks.Lfu
     [SimpleJob(RuntimeMoniker.Net60)]
     [MemoryDiagnoser(displayGenColumns: false)]
     [HideColumns("Job", "Median", "RatioSD", "Alloc Ratio")]
+    [ColumnChart(Title = "Sketch Increment ({JOB})")]
     public class SketchIncrement
     {
         const int iterations = 1_048_576;

BitFaster.Caching.UnitTests/Intrinsics.cs

@@ -14,14 +14,13 @@ public static class Intrinsics
         public static void SkipAvxIfNotSupported<I>()
         {
 #if NETCOREAPP3_1_OR_GREATER
-#if NET6_0_OR_GREATER
-            // when we are trying to test Avx2, skip the test if it's not supported
+    #if NET6_0_OR_GREATER
+            // when we are trying to test Avx2/Arm64, skip the test if it's not supported
             Skip.If(typeof(I) == typeof(DetectIsa) && !(Avx2.IsSupported || AdvSimd.Arm64.IsSupported));
-#else
-// when we are trying to test Avx2, skip the test if it's not supported
+    #else
+            // when we are trying to test Avx2, skip the test if it's not supported
             Skip.If(typeof(I) == typeof(DetectIsa) && !Avx2.IsSupported);
-#endif
-
+    #endif
 
 #else
             Skip.If(true);

BitFaster.Caching.UnitTests/Lfu/CmSketchTests.cs

@@ -6,12 +6,12 @@
 
 namespace BitFaster.Caching.UnitTests.Lfu
 {
-    // Test with AVX2 or ARM64 if it is supported
-    public class CMSketchAvx2Tests : CmSketchTestBase<DetectIsa>
+    // Test with AVX2/ARM64 if it is supported
+    public class CMSketchIntrinsicsTests : CmSketchTestBase<DetectIsa>
     {
     }
 
-    // Test with AVX2 disabled
+    // Test with AVX2/ARM64 disabled
     public class CmSketchTests : CmSketchTestBase<DisableHardwareIntrinsics>
     {
     }
@@ -29,14 +29,23 @@ public CmSketchTestBase()
         public void Repro()
         {
             sketch = new CmSketchCore<int, I>(1_048_576, EqualityComparer<int>.Default);
+            var baseline = new CmSketchCore<int, DisableHardwareIntrinsics>(1_048_576, EqualityComparer<int>.Default);
 
             for (int i = 0; i < 1_048_576; i++)
             {
                 if (i % 3 == 0)
                 {
                     sketch.Increment(i);
+                    baseline.Increment(i);
                 }
             }
+
+            baseline.Size.Should().Be(sketch.Size);
+
+            for (int i = 0; i < 1_048_576; i++)
+            {
+                sketch.EstimateFrequency(i).Should().Be(baseline.EstimateFrequency(i));
+            }
         }
 
 

BitFaster.Caching/Lfu/CmSketchCore.cs

@@ -473,12 +473,15 @@ private unsafe int EstimateFrequencyArm(T value)
                 a = AdvSimd.And(a, fifteen);
                 b = AdvSimd.And(b, fifteen);
 
-                var minA = AdvSimd.Arm64.MinAcross(a.AsInt32());
-                var minB = AdvSimd.Arm64.MinAcross(b.AsInt32());
-                minA = AdvSimd.Arm64.InsertSelectedScalar(minA, 1, minB, 0);
-                var min = AdvSimd.Arm64.MinAcross(minA.AsInt16());
+                // TODO: VectorTableLookup
+                Vector128<int> x = AdvSimd.Arm64.InsertSelectedScalar(Vector128<int>.Zero, 0, a.AsInt32(), 0);
+                x = AdvSimd.Arm64.InsertSelectedScalar(x, 1, a.AsInt32(), 2);
+                x = AdvSimd.Arm64.InsertSelectedScalar(x, 2, b.AsInt32(), 0);
+                x = AdvSimd.Arm64.InsertSelectedScalar(x, 3, b.AsInt32(), 2);
+
+                var minA = AdvSimd.Arm64.MinAcross(x);
 
-                return min.ToScalar();
+                return minA.ToScalar();
             }
         }
 #endif