Optimize VM hot paths and add targeted benchmarks

benchmarks/Neo.VM.Benchmarks/Benchmarks.VMHotPaths.cs

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+// Copyright (C) 2015-2025 The Neo Project.
+//
+// Benchmarks.VMHotPaths.cs file belongs to the neo project and is free
+// software distributed under the MIT software license, see the
+// accompanying file LICENSE in the main directory of the
+// repository or http://www.opensource.org/licenses/mit-license.php
+// for more details.
+//
+// Redistribution and use in source and binary forms with or without
+// modifications are permitted.
+
+using BenchmarkDotNet.Attributes;
+using Neo.VM;
+using Neo.VM.Benchmark.OpCode;
+using VMOpCode = Neo.VM.OpCode;
+
+namespace Neo.VM.Benchmark
+{
+    /// <summary>
+    /// Benchmarks covering hot VM paths that were optimised (instruction decoding and frame returns).
+    /// </summary>
+    [MemoryDiagnoser]
+    public class Benchmarks_VMHotPaths
+    {
+        private byte[] _scriptBytes = null!;
+        private Script _cachedScript = null!;
+
+        [Params(32, 256, 1024)]
+        public int PushCount { get; set; }
+
+        [GlobalSetup]
+        public void Setup()
+        {
+            using ScriptBuilder builder = new(initialCapacity: PushCount * 4 + 8);
+            for (int i = 0; i < PushCount; i++)
+                builder.Emit(VMOpCode.PUSH1);
+            builder.Emit(VMOpCode.RET);
+            _scriptBytes = builder.ToArray();
+            _cachedScript = new Script(_scriptBytes, strictMode: false);
+        }
+
+        /// <summary>
+        /// Measures the cost of strict-mode construction and validation using the cached decoder.
+        /// </summary>
+        [Benchmark]
+        public Script ConstructStrictScript()
+        {
+            return new Script(_scriptBytes, strictMode: true);
+        }
+
+        /// <summary>
+        /// Measures the steady-state cost of iterating through all instructions via <see cref="Script.GetInstruction"/>.
+        /// </summary>
+        [Benchmark]
+        public int IterateInstructions()
+        {
+            var script = _cachedScript;
+            int ip = 0;
+            int count = 0;
+            while (ip < script.Length)
+            {
+                var instruction = script.GetInstruction(ip);
+                ip += instruction.Size;
+                count++;
+            }
+            return count;
+        }
+
+        /// <summary>
+        /// Executes the generated script so the return path copies values into the result stack.
+        /// </summary>
+        [Benchmark]
+        public VMState ExecutePushAndReturn()
+        {
+            using BenchmarkEngine engine = new();
+            engine.LoadScript(_cachedScript, rvcount: PushCount);
+            return engine.Execute();
+        }
+    }
+}