Smaller minor optimizations

Solver/Crafty/ActionSet.cs

@@ -1,5 +1,4 @@
 using Craftimizer.Simulator.Actions;
-using System;
 using System.Diagnostics.Contracts;
 using System.Numerics;
 using System.Runtime.CompilerServices;
@@ -52,11 +51,9 @@ public struct ActionSet
     public readonly bool IsEmpty => bits == 0;
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    //public readonly ActionType SelectRandom(Random random) => ElementAt(random.Next(Count));
+    public readonly ActionType SelectRandom(Random random) => ElementAt(random.Next(Count));
-    public readonly ActionType SelectRandom(Random random) => First();
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    //public ActionType? PopRandom(Random random) => PopFirst();
     public ActionType? PopRandom(Random random)
     {
         uint snapshot;
@@ -84,22 +81,16 @@ public struct ActionSet
         uint snapshot;
         uint newValue;
         ActionType action;
-        int i = 0;
         do
         {
-            ++i;
             snapshot = bits;
             if (snapshot == 0)
                 return null;
 
-            var index = 0;
+            action = ToAction(Intrinsics.NthBitSet(snapshot, 0) - 1);
-
-            action = ToAction(Intrinsics.NthBitSet(snapshot, index) - 1);
             newValue = snapshot & ~ToMask(action);
         }
         while (Interlocked.CompareExchange(ref bits, newValue, snapshot) != snapshot);
-        //if (i != 1)
-            //Console.WriteLine($"Retried {i-1} times");
         return action;
     }
 

Solver/Crafty/ArenaNode.cs

@@ -30,9 +30,9 @@ public sealed class ArenaNode<T> where T : struct
             if (Data == null)
                 Interlocked.CompareExchange(ref Data, new ArenaNode<T>[BatchCount][], null);
 
-            var index = Interlocked.Increment(ref this.index) - 1;
+            var idx = Interlocked.Increment(ref this.index) - 1;
 
-            var (arrayIdx, subIdx) = GetArrayIndex(index);
+            var (arrayIdx, subIdx) = GetArrayIndex(idx);
 
             if (Data[arrayIdx] == null)
                 Interlocked.CompareExchange(ref Data[arrayIdx], new ArenaNode<T>[BatchSize], null);

Solver/Crafty/NodeScores.cs

@@ -7,12 +7,12 @@ public struct NodeScores
 {
     public float ScoreSum;
     public float MaxScore;
-    public float Visits;
+    public int Visits;
 
     public void Visit(float score)
     {
-        ScoreSum += score;
+        Intrinsics.CASAdd(ref ScoreSum, score);
-        MaxScore = Math.Max(MaxScore, score);
+        Intrinsics.CASMax(ref MaxScore, score);
-        Visits++;
+        Interlocked.Increment(ref Visits);
     }
 }

Solver/Crafty/Solver.cs

@@ -96,7 +96,7 @@ public sealed class Solver
 
     [Pure]
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    private Node? EvalBestChild(float parentVisits, ref Node.ChildBuffer children)
+    private Node? EvalBestChild(int parentVisits, ref Node.ChildBuffer children)
     {
         if (parentVisits == 0)
             return null;
@@ -110,7 +110,7 @@ public sealed class Solver
         var CVector = new Vector<float>(C);
 
         Span<float> scoreSums = stackalloc float[vecLength];
-        Span<float> visits = stackalloc float[vecLength];
+        Span<int> visits = stackalloc int[vecLength];
         Span<float> maxScores = stackalloc float[vecLength];
 
         var max = (0, 0);
@@ -130,8 +130,9 @@ public sealed class Solver
 
             var s = new Vector<float>(scoreSums);
             var m = new Vector<float>(maxScores);
-            var v = new Vector<float>(visits);
+            var vInt = new Vector<int>(visits);
-            v = Vector.Max(v, Vector<float>.One);
+            vInt = Vector.Max(vInt, Vector<int>.One);
+            var v = Vector.ConvertToSingle(vInt);
             var exploitation = (W * (s / v)) + (w * m);
             var exploration = CVector * Intrinsics.ReciprocalSqrt(v);
             var evalScores = exploitation + exploration;