SkipLocalsInitAttribute working on the method where it is directly ap…

…plied (#24723)

* SkipLocalsInitAttribute recognized as a WellKnownAttribute and properly working on method declarations

* ILVisualizer locals init depends onAreLocalsZeroed flag

* SkipLocalsInitAttribute on method tests added

* SerializeMethodBody cannot use body from cache if they don't have the same AreLocalsZeroed flag

* Packages updated

build/Targets/Packages.props

@@ -47,7 +47,7 @@
     <MicrosoftIdentityModelClientsActiveDirectoryVersion>3.13.8</MicrosoftIdentityModelClientsActiveDirectoryVersion>
     <MicrosoftInternalPerformanceCodeMarkersDesignTimeVersion>15.0.26730-alpha</MicrosoftInternalPerformanceCodeMarkersDesignTimeVersion>
     <MicrosoftInternalVisualStudioShellInterop140DesignTimeVersion>14.3.25407-alpha</MicrosoftInternalVisualStudioShellInterop140DesignTimeVersion>
-    <MicrosoftMetadataVisualizerVersion>1.0.0-beta1-61531-03</MicrosoftMetadataVisualizerVersion>
+    <MicrosoftMetadataVisualizerVersion>1.0.0-beta1-62621-03</MicrosoftMetadataVisualizerVersion>
     <MicrosoftMSXMLVersion>8.0.0.0-alpha</MicrosoftMSXMLVersion>
     <!-- Using a private build of Microsoft.Net.Test.SDK to work around issue https://github.com/Microsoft/vstest/issues/373 -->
     <MicrosoftNETTestSdkVersion>15.6.0-dev</MicrosoftNETTestSdkVersion>

src/Compilers/CSharp/Portable/Compiler/MethodCompiler.cs

@@ -1346,7 +1346,7 @@ private static MethodBody GenerateMethodBody(
             var localSlotManager = new LocalSlotManager(variableSlotAllocatorOpt);
             var optimizations = compilation.Options.OptimizationLevel;
 
-            ILBuilder builder = new ILBuilder(moduleBuilder, localSlotManager, optimizations);
+            ILBuilder builder = new ILBuilder(moduleBuilder, localSlotManager, optimizations, method.AreLocalsZeroed);
             DiagnosticBag diagnosticsForThisMethod = DiagnosticBag.GetInstance();
             try
             {
@@ -1460,6 +1460,7 @@ private static MethodBody GenerateMethodBody(
                     builder.RealizedSequencePoints,
                     debugDocumentProvider,
                     builder.RealizedExceptionHandlers,
+                    builder.AreLocalsZeroed,
                     builder.GetAllScopes(),
                     builder.HasDynamicLocal,
                     importScopeOpt,

src/Compilers/CSharp/Portable/Symbols/ErrorMethodSymbol.cs

@@ -230,6 +230,11 @@ public sealed override DllImportData GetDllImportData()
             return null;
         }
 
+        public override bool AreLocalsZeroed
+        {
+            get { throw ExceptionUtilities.Unreachable; }
+        }
+
         internal sealed override MarshalPseudoCustomAttributeData ReturnValueMarshallingInformation
         {
             get { return null; }

src/Compilers/CSharp/Portable/Symbols/Metadata/PE/PEMethodSymbol.cs

@@ -1153,6 +1153,11 @@ internal override void AddSynthesizedReturnTypeAttributes(PEModuleBuilder module
             throw ExceptionUtilities.Unreachable;
         }
 
+        public override bool AreLocalsZeroed
+        {
+            get { throw ExceptionUtilities.Unreachable; }
+        }
+
         // perf, not correctness
         internal override CSharpCompilation DeclaringCompilation => null;
 

src/Compilers/CSharp/Portable/Symbols/MethodSymbol.cs

@@ -1221,6 +1221,11 @@ public virtual bool IsTupleMethod
             }
         }
 
+        /// <summary>
+        /// Returns true if locals are to be initialized
+        /// </summary>
+        public abstract bool AreLocalsZeroed { get; }
+
         /// <summary>
         /// If this is a method of a tuple type, return corresponding underlying method from the
         /// tuple underlying type. Otherwise, null.

src/Compilers/CSharp/Portable/Symbols/ReducedExtensionMethodSymbol.cs

@@ -183,6 +183,11 @@ public override DllImportData GetDllImportData()
             return _reducedFrom.GetDllImportData();
         }
 
+        public override bool AreLocalsZeroed
+        {
+            get { throw ExceptionUtilities.Unreachable; }
+        }
+
         internal override MarshalPseudoCustomAttributeData ReturnValueMarshallingInformation
         {
             get { return _reducedFrom.ReturnValueMarshallingInformation; }

src/Compilers/CSharp/Portable/Symbols/SignatureOnlyMethodSymbol.cs

@@ -132,6 +132,8 @@ public SignatureOnlyMethodSymbol(
 
         public override bool IsExtern { get { throw ExceptionUtilities.Unreachable; } }
 
+        public override bool AreLocalsZeroed { get { throw ExceptionUtilities.Unreachable; } }
+
         public override AssemblySymbol ContainingAssembly { get { throw ExceptionUtilities.Unreachable; } }
 
         internal override ModuleSymbol ContainingModule { get { throw ExceptionUtilities.Unreachable; } }

src/Compilers/CSharp/Portable/Symbols/Source/LambdaSymbol.cs

@@ -136,6 +136,11 @@ public override DllImportData GetDllImportData()
             return null;
         }
 
+        public override bool AreLocalsZeroed
+        {
+            get { throw ExceptionUtilities.Unreachable; }
+        }
+
         internal override MarshalPseudoCustomAttributeData ReturnValueMarshallingInformation
         {
             get { return null; }

src/Compilers/CSharp/Portable/Symbols/Source/LocalFunctionSymbol.cs

@@ -340,6 +340,8 @@ internal override TypeSymbol IteratorElementType
 
         public override DllImportData GetDllImportData() => null;
 
+        public override bool AreLocalsZeroed => throw ExceptionUtilities.Unreachable;
+
         internal override ImmutableArray<string> GetAppliedConditionalSymbols() => ImmutableArray<string>.Empty;
 
         internal override bool IsMetadataNewSlot(bool ignoreInterfaceImplementationChanges = false) => false;

src/Compilers/CSharp/Portable/Symbols/Source/SourceMemberMethodSymbol.cs

@@ -358,6 +358,15 @@ public override Symbol AssociatedSymbol
             }
         }
 
+        public override bool AreLocalsZeroed
+        {
+            get
+            {
+                var data = this.GetDecodedWellKnownAttributeData();
+                return data != null ? !data.HasSkipLocalsInitAttribute : true;
+            }
+        }
+
         #region Flags
 
         public override bool ReturnsVoid
@@ -1128,6 +1137,10 @@ private void DecodeWellKnownAttributeAppliedToMethod(ref DecodeWellKnownAttribut
                     arguments.Diagnostics.Add(ErrorCode.ERR_SecurityCriticalOrSecuritySafeCriticalOnAsync, arguments.AttributeSyntaxOpt.Location, arguments.AttributeSyntaxOpt.GetErrorDisplayName());
                 }
             }
+            else if (attribute.IsTargetAttribute(this, AttributeDescription.SkipLocalsInitAttribute))
+            {
+                arguments.GetOrCreateData<CommonMethodWellKnownAttributeData>().HasSkipLocalsInitAttribute = true;
+            }
             else
             {
                 var compilation = this.DeclaringCompilation;

src/Compilers/CSharp/Portable/Symbols/Synthesized/SynthesizedEntryPointSymbol.cs

@@ -241,6 +241,11 @@ public override DllImportData GetDllImportData()
             return null;
         }
 
+        public override bool AreLocalsZeroed
+        {
+            get { return true; }
+        }
+
         internal override MarshalPseudoCustomAttributeData ReturnValueMarshallingInformation
         {
             get { return null; }

src/Compilers/CSharp/Portable/Symbols/Synthesized/SynthesizedGlobalMethodSymbol.cs

@@ -116,6 +116,11 @@ public override DllImportData GetDllImportData()
             return null;
         }
 
+        public override bool AreLocalsZeroed
+        {
+            get { return true; }
+        }
+
         internal override MarshalPseudoCustomAttributeData ReturnValueMarshallingInformation
         {
             get { return null; }

src/Compilers/CSharp/Portable/Symbols/Synthesized/SynthesizedInstanceMethodSymbol.cs

@@ -30,6 +30,14 @@ public sealed override bool IsImplicitlyDeclared
             }
         }
 
+        public override bool AreLocalsZeroed
+        {
+            get
+            {
+                return true;
+            }
+        }
+
         internal override bool TryGetThisParameter(out ParameterSymbol thisParameter)
         {
             Debug.Assert(!IsStatic);

src/Compilers/CSharp/Portable/Symbols/Synthesized/SynthesizedIntrinsicOperatorSymbol.cs

@@ -163,6 +163,11 @@ public override DllImportData GetDllImportData()
             return null;
         }
 
+        public override bool AreLocalsZeroed
+        {
+            get { throw ExceptionUtilities.Unreachable; }
+        }
+
         internal override IEnumerable<Cci.SecurityAttribute> GetSecurityInformation()
         {
             return SpecializedCollections.EmptyEnumerable<Cci.SecurityAttribute>();

src/Compilers/CSharp/Portable/Symbols/Synthesized/SynthesizedStaticConstructor.cs

@@ -334,6 +334,11 @@ public override DllImportData GetDllImportData()
             return null;
         }
 
+        public override bool AreLocalsZeroed
+        {
+            get { return true; }
+        }
+
         internal override MarshalPseudoCustomAttributeData ReturnValueMarshallingInformation
         {
             get { return null; }

src/Compilers/CSharp/Portable/Symbols/Wrapped/WrappedMethodSymbol.cs

@@ -78,6 +78,14 @@ public override bool HidesBaseMethodsByName
             }
         }
 
+        public override bool AreLocalsZeroed
+        {
+            get
+            {
+                return UnderlyingMethod.AreLocalsZeroed;
+            }
+        }
+
         public override ImmutableArray<Location> Locations
         {
             get