From e823ed9966ac5ac8972a84d77bc5102e5d1c5c85 Mon Sep 17 00:00:00 2001
From: Siegfried Pammer <siegfriedpammer@gmail.com>
Date: Fri, 31 Dec 2021 01:54:54 +0100
Subject: [PATCH] #2594: Cache LoadedAssembly.GetTargetFrameworkIdAsync,
 LoadedAssembly.GetRuntimePackAsync, PEFile.Name, PEFile.FullName to improve
 performance of assembly resolving. This improves performance of the analysis
 by a factor of 2.

---
 ICSharpCode.Decompiler/Metadata/PEFile.cs | 42 +++++++++++++++++------
 ILSpy/LoadedAssembly.cs                   | 34 +++++++++++++-----
 2 files changed, 58 insertions(+), 18 deletions(-)

diff --git a/ICSharpCode.Decompiler/Metadata/PEFile.cs b/ICSharpCode.Decompiler/Metadata/PEFile.cs
index f2a57ab0f..8368c67ce 100644
--- a/ICSharpCode.Decompiler/Metadata/PEFile.cs
+++ b/ICSharpCode.Decompiler/Metadata/PEFile.cs
@@ -72,8 +72,38 @@ namespace ICSharpCode.Decompiler.Metadata
 		}
 
 		public bool IsAssembly => Metadata.IsAssembly;
-		public string Name => GetName();
-		public string FullName => IsAssembly ? Metadata.GetFullAssemblyName() : Name;
+
+		string? name;
+
+		public string Name {
+			get {
+				var value = LazyInit.VolatileRead(ref name);
+				if (value == null)
+				{
+					var metadata = Metadata;
+					value = metadata.IsAssembly
+						? metadata.GetString(metadata.GetAssemblyDefinition().Name)
+						: metadata.GetString(metadata.GetModuleDefinition().Name);
+					value = LazyInit.GetOrSet(ref name, value);
+				}
+				return value;
+			}
+		}
+
+		string? fullName;
+
+		public string FullName {
+			get {
+				var value = LazyInit.VolatileRead(ref fullName);
+				if (value == null)
+				{
+					var metadata = Metadata;
+					value = metadata.IsAssembly ? metadata.GetFullAssemblyName() : Name;
+					value = LazyInit.GetOrSet(ref fullName, value);
+				}
+				return value;
+			}
+		}
 
 		public TargetRuntime GetRuntime()
 		{
@@ -98,14 +128,6 @@ namespace ICSharpCode.Decompiler.Metadata
 			}
 		}
 
-		string GetName()
-		{
-			var metadata = Metadata;
-			if (metadata.IsAssembly)
-				return metadata.GetString(metadata.GetAssemblyDefinition().Name);
-			return metadata.GetString(metadata.GetModuleDefinition().Name);
-		}
-
 		public ImmutableArray<AssemblyReference> AssemblyReferences => Metadata.AssemblyReferences.Select(r => new AssemblyReference(this, r)).ToImmutableArray();
 		public ImmutableArray<Resource> Resources => GetResources().ToImmutableArray();
 
diff --git a/ILSpy/LoadedAssembly.cs b/ILSpy/LoadedAssembly.cs
index 320a7f581..cad1fb69f 100644
--- a/ILSpy/LoadedAssembly.cs
+++ b/ILSpy/LoadedAssembly.cs
@@ -107,22 +107,41 @@ namespace ICSharpCode.ILSpy
 			this.ParentBundle = bundle;
 		}
 
+		string? targetFrameworkId;
+
 		/// <summary>
 		/// Returns a target framework identifier in the form '&lt;framework&gt;Version=v&lt;version&gt;'.
-		/// Returns an empty string if no TargetFrameworkAttribute was found or the file doesn't contain an assembly header, i.e., is only a module.
+		/// Returns an empty string if no TargetFrameworkAttribute was found
+		/// or the file doesn't contain an assembly header, i.e., is only a module.
 		/// 
 		/// Throws an exception if the file does not contain any .NET metadata (e.g. file of unknown format).
 		/// </summary>
 		public async Task<string> GetTargetFrameworkIdAsync()
 		{
-			var assembly = await GetPEFileAsync().ConfigureAwait(false);
-			return assembly.DetectTargetFrameworkId() ?? string.Empty;
+			var value = LazyInit.VolatileRead(ref targetFrameworkId);
+			if (value == null)
+			{
+				var assembly = await GetPEFileAsync().ConfigureAwait(false);
+				value = assembly.DetectTargetFrameworkId() ?? string.Empty;
+				value = LazyInit.GetOrSet(ref targetFrameworkId, value);
+			}
+
+			return value;
 		}
 
+		string? runtimePack;
+
 		public async Task<string> GetRuntimePackAsync()
 		{
-			var assembly = await GetPEFileAsync().ConfigureAwait(false);
-			return assembly.DetectRuntimePack() ?? string.Empty;
+			var value = LazyInit.VolatileRead(ref runtimePack);
+			if (value == null)
+			{
+				var assembly = await GetPEFileAsync().ConfigureAwait(false);
+				value = assembly.DetectRuntimePack() ?? string.Empty;
+				value = LazyInit.GetOrSet(ref runtimePack, value);
+			}
+
+			return value;
 		}
 
 		public ReferenceLoadInfo LoadedAssemblyReferencesInfo { get; } = new ReferenceLoadInfo();
@@ -588,10 +607,9 @@ namespace ICSharpCode.ILSpy
 						var reader = module.Metadata;
 						if (reader == null || !reader.IsAssembly)
 							continue;
-						var asmDef = reader.GetAssemblyDefinition();
-						string tfm = await loaded.GetTargetFrameworkIdAsync();
+						string tfm = await loaded.GetTargetFrameworkIdAsync().ConfigureAwait(false);
 						string key = tfm + ";"
-							+ (shortNames ? reader.GetString(asmDef.Name) : reader.GetFullAssemblyName());
+							+ (shortNames ? module.Name : module.FullName);
 						if (!result.ContainsKey(key))
 						{
 							result.Add(key, module);