Local state tracing instrumentation

src/Compilers/CSharp/Portable/Binder/Binder.cs

@@ -882,7 +882,7 @@ internal BoundStatement WrapWithVariablesAndLocalFunctionsIfAny(CSharpSyntaxNode
                 return statement;
             }
 
-            return new BoundBlock(statement.Syntax, locals, localFunctions, hasUnsafeModifier: false,
+            return new BoundBlock(statement.Syntax, locals, localFunctions, hasUnsafeModifier: false, instrumentation: null,
                                   ImmutableArray.Create(statement))
             { WasCompilerGenerated = true };
         }

src/Compilers/CSharp/Portable/Binder/Binder_Statements.cs

@@ -1889,6 +1889,7 @@ private BoundBlock FinishBindBlockParts(CSharpSyntaxNode node, ImmutableArray<Bo
                 locals,
                 GetDeclaredLocalFunctionsForScope(node),
                 hasUnsafeModifier: node.Parent?.Kind() == SyntaxKind.UnsafeStatement,
+                instrumentation: null,
                 boundStatements);
         }
 

src/Compilers/CSharp/Portable/BoundTree/BoundNode.cs

@@ -498,9 +498,26 @@ private void CheckDeclared(LocalSymbol local)
 
             public override BoundNode? VisitBlock(BoundBlock node)
             {
+                if (node.Instrumentation != null)
+                {
+                    var added = DeclaredLocals.Add(node.Instrumentation.Local);
+                    Debug.Assert(added);
+
+                    _ = Visit(node.Instrumentation.Prologue);
+                }
+
                 AddAll(node.Locals);
                 base.VisitBlock(node);
                 RemoveAll(node.Locals);
+
+                if (node.Instrumentation != null)
+                {
+                    _ = Visit(node.Instrumentation.Epilogue);
+
+                    var removed = DeclaredLocals.Remove(node.Instrumentation.Local);
+                    Debug.Assert(removed);
+                }
+
                 return null;
             }
 

src/Compilers/CSharp/Portable/BoundTree/BoundNodes.xml

@@ -699,15 +699,48 @@
   <Node Name="BoundTypeOfOperator" Base="BoundTypeOf">
     <Field Name="SourceType" Type="BoundTypeExpression"/>
   </Node>
+
+  <!-- Instrumentation info attached to BoundBlock -->
+  <Node Name="BoundBlockInstrumentation" Base="BoundNode">
+    <Field Name="Local" Type="LocalSymbol" Null="disallow"/>
+    <Field Name="Prologue" Type="BoundStatement" Null="disallow"/>
+    <Field Name="Epilogue" Type="BoundStatement" Null="disallow"/>
+  </Node>
 
-   <!-- Represents the raw metadata token index value for a method definition.
-        Used by dynamic instrumentation to index into tables or arrays of per-method information. -->
+  <!-- Represents the raw metadata RowId value for a method definition.
+       Used by dynamic instrumentation to index into tables or arrays of per-method information. -->
   <Node Name="BoundMethodDefIndex" Base="BoundExpression">
     <!-- Non-null type is required for this node kind -->
     <Field Name="Type" Type="TypeSymbol" Override="true" Null="disallow"/>
     <Field Name="Method" Type="MethodSymbol"/>
   </Node>
 
+  <!-- Represents local id - a unique int value that represents local variable.-->
+  <Node Name="BoundLocalId" Base="BoundExpression">
+    <!-- Non-null type is required for this node kind -->
+    <Field Name="Type" Type="TypeSymbol" Override="true" Null="disallow"/>
+    <!-- Local symbol representing the variable. -->
+    <Field Name="Local" Type="LocalSymbol" Null="disallow"/>
+    <!-- Field symbol representing the variable if it has been lifted. -->
+    <Field Name="HoistedField" Type="FieldSymbol?" Null="allow"/>
+  </Node>
+
+  <!-- Represents parameter id - a unique int value that represents parameter.-->
+  <Node Name="BoundParameterId" Base="BoundExpression">
+    <!-- Non-null type is required for this node kind -->
+    <Field Name="Type" Type="TypeSymbol" Override="true" Null="disallow"/>
+    <!-- Local symbol representing the variable. -->
+    <Field Name="Parameter" Type="ParameterSymbol" Null="disallow"/>
+    <!-- Field symbol representing the parameter if it has been lifted. -->
+    <Field Name="HoistedField" Type="FieldSymbol?" Null="allow"/>
+  </Node>
+
+  <!-- Represents state machine instance id - a unique ulong value that represents an instance of a state machine.-->
+  <Node Name="BoundStateMachineInstanceId" Base="BoundExpression">
+    <!-- Non-null type is required for this node kind -->
+    <Field Name="Type" Type="TypeSymbol" Override="true" Null="disallow"/>
+  </Node>
+
   <!-- Represents the maximum raw metadata token index value for any method definition in the current module. -->
   <Node Name="BoundMaximumMethodDefIndex" Base="BoundExpression">
     <!-- Non-null type is required for this node kind -->
@@ -974,6 +1007,9 @@
     <Field Name="Locals" Type="ImmutableArray&lt;LocalSymbol&gt;"/>
     <Field Name="LocalFunctions" Type="ImmutableArray&lt;LocalFunctionSymbol&gt;"/>
     <Field Name="HasUnsafeModifier" Type="bool" Null="NotApplicable"/>
+
+    <!-- Optional block-level instrumentation info -->
+    <Field Name="Instrumentation" Type="BoundBlockInstrumentation?" Null="allow" />
   </Node>
 
   <!--

src/Compilers/CSharp/Portable/BoundTree/Constructors.cs

@@ -595,7 +595,8 @@ public BoundGotoStatement(SyntaxNode syntax, LabelSymbol label, bool hasErrors =
 
     internal partial class BoundBlock
     {
-        public BoundBlock(SyntaxNode syntax, ImmutableArray<LocalSymbol> locals, ImmutableArray<BoundStatement> statements, bool hasErrors = false) : this(syntax, locals, ImmutableArray<LocalFunctionSymbol>.Empty, hasUnsafeModifier: false, statements, hasErrors)
+        public BoundBlock(SyntaxNode syntax, ImmutableArray<LocalSymbol> locals, ImmutableArray<BoundStatement> statements, bool hasErrors = false)
+            : this(syntax, locals, ImmutableArray<LocalFunctionSymbol>.Empty, hasUnsafeModifier: false, instrumentation: null, statements, hasErrors)
         {
         }
 

src/Compilers/CSharp/Portable/CodeGen/CodeGenerator.cs

@@ -348,12 +348,14 @@ private void EmitSymbolToken(TypeSymbol symbol, SyntaxNode syntaxNode)
 
         private void EmitSymbolToken(MethodSymbol method, SyntaxNode syntaxNode, BoundArgListOperator optArgList, bool encodeAsRawDefinitionToken = false)
         {
-            _builder.EmitToken(_module.Translate(method, syntaxNode, _diagnostics.DiagnosticBag, optArgList, needDeclaration: encodeAsRawDefinitionToken), syntaxNode, _diagnostics.DiagnosticBag, encodeAsRawDefinitionToken);
+            var methodRef = _module.Translate(method, syntaxNode, _diagnostics.DiagnosticBag, optArgList, needDeclaration: encodeAsRawDefinitionToken);
+            _builder.EmitToken(methodRef, syntaxNode, _diagnostics.DiagnosticBag, encodeAsRawDefinitionToken ? Cci.MetadataWriter.RawTokenEncoding.RowId : 0);
         }
 
         private void EmitSymbolToken(FieldSymbol symbol, SyntaxNode syntaxNode)
         {
-            _builder.EmitToken(_module.Translate(symbol, syntaxNode, _diagnostics.DiagnosticBag), syntaxNode, _diagnostics.DiagnosticBag);
+            var fieldRef = _module.Translate(symbol, syntaxNode, _diagnostics.DiagnosticBag);
+            _builder.EmitToken(fieldRef, syntaxNode, _diagnostics.DiagnosticBag);
         }
 
         private void EmitSignatureToken(FunctionPointerTypeSymbol symbol, SyntaxNode syntaxNode)

src/Compilers/CSharp/Portable/CodeGen/EmitExpression.cs

@@ -257,6 +257,16 @@ private void EmitExpressionCore(BoundExpression expression, bool used)
                     EmitSourceDocumentIndex((BoundSourceDocumentIndex)expression);
                     break;
 
+                case BoundKind.LocalId:
+                    Debug.Assert(used);
+                    EmitLocalIdExpression((BoundLocalId)expression);
+                    break;
+
+                case BoundKind.ParameterId:
+                    Debug.Assert(used);
+                    EmitParameterIdExpression((BoundParameterId)expression);
+                    break;
+
                 case BoundKind.MethodInfo:
                     if (used)
                     {
@@ -3310,6 +3320,43 @@ private void EmitMethodDefIndexExpression(BoundMethodDefIndex node)
             EmitSymbolToken(symbol, node.Syntax, null, encodeAsRawDefinitionToken: true);
         }
 
+        private void EmitLocalIdExpression(BoundLocalId node)
+        {
+            Debug.Assert(node.Type.SpecialType == SpecialType.System_Int32);
+
+            if (node.HoistedField is null)
+            {
+                _builder.EmitIntConstant(GetLocal(node.Local).SlotIndex);
+            }
+            else
+            {
+                EmitHoistedVariableId(node.HoistedField, node.Syntax);
+            }
+        }
+
+        private void EmitParameterIdExpression(BoundParameterId node)
+        {
+            Debug.Assert(node.Type.SpecialType == SpecialType.System_Int32);
+
+            if (node.HoistedField is null)
+            {
+                _builder.EmitIntConstant(node.Parameter.Ordinal);
+            }
+            else
+            {
+                EmitHoistedVariableId(node.HoistedField, node.Syntax);
+            }
+        }
+
+        private void EmitHoistedVariableId(FieldSymbol field, SyntaxNode syntax)
+        {
+            Debug.Assert(field.IsDefinition);
+            var fieldRef = _module.Translate(field, syntax, _diagnostics.DiagnosticBag, needDeclaration: true);
+
+            _builder.EmitOpCode(ILOpCode.Ldtoken);
+            _builder.EmitToken(fieldRef, syntax, _diagnostics.DiagnosticBag, Cci.MetadataWriter.RawTokenEncoding.LiftedVariableId);
+        }
+
         private void EmitMaximumMethodDefIndexExpression(BoundMaximumMethodDefIndex node)
         {
             Debug.Assert(node.Type.SpecialType == SpecialType.System_Int32);

src/Compilers/CSharp/Portable/CodeGen/EmitStatement.cs

@@ -622,6 +622,54 @@ private bool IsLastBlockInMethod(BoundBlock block)
         }
 
         private void EmitBlock(BoundBlock block)
+        {
+            if (block.Instrumentation is not null)
+            {
+                EmitInstrumentedBlock(block.Instrumentation, block);
+            }
+            else
+            {
+                EmitUninstrumentedBlock(block);
+            }
+        }
+
+        private void EmitInstrumentedBlock(BoundBlockInstrumentation instrumentation, BoundBlock block)
+        {
+            _builder.OpenLocalScope();
+            DefineLocal(instrumentation.Local, block.Syntax);
+
+            if (_emitPdbSequencePoints)
+            {
+                EmitHiddenSequencePoint();
+            }
+
+            EmitStatement(instrumentation.Prologue);
+
+            _builder.AssertStackEmpty();
+
+            _builder.OpenLocalScope(ScopeType.TryCatchFinally);
+
+            _builder.OpenLocalScope(ScopeType.Try);
+            EmitUninstrumentedBlock(block);
+            _builder.CloseLocalScope(); // try
+
+            _builder.OpenLocalScope(ScopeType.Finally);
+
+            if (_emitPdbSequencePoints)
+            {
+                EmitHiddenSequencePoint();
+            }
+
+            EmitStatement(instrumentation.Epilogue);
+            _builder.CloseLocalScope(); // finally
+
+            _builder.CloseLocalScope(); // try-finally
+
+            FreeLocal(instrumentation.Local);
+            _builder.CloseLocalScope();
+        }
+
+        private void EmitUninstrumentedBlock(BoundBlock block)
         {
             var hasLocals = !block.Locals.IsEmpty;
 
@@ -644,7 +692,15 @@ private void EmitBlock(BoundBlock block)
             if (_indirectReturnState == IndirectReturnState.Needed &&
                 IsLastBlockInMethod(block))
             {
-                HandleReturn();
+                if (block.Instrumentation != null)
+                {
+                    // jump out of try-finally
+                    _builder.EmitBranch(ILOpCode.Br, s_returnLabel);
+                }
+                else
+                {
+                    HandleReturn();
+                }
             }
 
             if (hasLocals)

src/Compilers/CSharp/Portable/CodeGen/Optimizer.cs

@@ -614,6 +614,11 @@ public override BoundNode VisitBlock(BoundBlock node)
         {
             Debug.Assert(EvalStackIsEmpty(), "entering blocks when evaluation stack is not empty?");
 
+            if (node.Instrumentation != null)
+            {
+                DeclareLocal(node.Instrumentation.Local, stack: 0);
+            }
+
             // normally we would not allow stack locals
             // when evaluation stack is not empty.
             DeclareLocals(node.Locals, 0);

src/Compilers/CSharp/Portable/Compilation/CSharpCompilation.cs

@@ -2791,7 +2791,6 @@ private void GetDiagnosticsForAllMethodBodies(BindingDiagnosticBag diagnostics,
                                                                        cancellationToken: cancellationToken)
                                                 : null,
                 emittingPdb: false,
-                emitTestCoverageData: false,
                 hasDeclarationErrors: false,
                 emitMethodBodies: false,
                 diagnostics: diagnostics,
@@ -2905,7 +2904,6 @@ void compileMethodBodiesAndDocComments(SyntaxTree? filterTree, TextSpan? filterS
                                 compilation: this,
                                 moduleBeingBuiltOpt: null,
                                 emittingPdb: false,
-                                emitTestCoverageData: false,
                                 hasDeclarationErrors: false,
                                 emitMethodBodies: false,
                                 diagnostics: bindingDiagnostics,
@@ -3191,12 +3189,12 @@ internal override StrongNameKeys StrongNameKeys
         internal override bool CompileMethods(
             CommonPEModuleBuilder moduleBuilder,
             bool emittingPdb,
-            bool emitMetadataOnly,
-            bool emitTestCoverageData,
             DiagnosticBag diagnostics,
             Predicate<ISymbolInternal>? filterOpt,
             CancellationToken cancellationToken)
         {
+            var emitMetadataOnly = moduleBuilder.EmitOptions.EmitMetadataOnly;
+
             // The diagnostics should include syntax and declaration errors. We insert these before calling Emitter.Emit, so that the emitter
             // does not attempt to emit if there are declaration errors (but we do insert all errors from method body binding...)
             PooledHashSet<int>? excludeDiagnostics = null;
@@ -3233,7 +3231,7 @@ internal override bool CompileMethods(
             }
             else
             {
-                if ((emittingPdb || emitTestCoverageData) &&
+                if ((emittingPdb || moduleBeingBuilt.EmitOptions.InstrumentationKinds.Contains(InstrumentationKind.TestCoverage)) &&
                     !CreateDebugDocuments(moduleBeingBuilt.DebugDocumentsBuilder, moduleBeingBuilt.EmbeddedTexts, diagnostics))
                 {
                     return false;
@@ -3251,7 +3249,6 @@ internal override bool CompileMethods(
                     this,
                     moduleBeingBuilt,
                     emittingPdb,
-                    emitTestCoverageData,
                     hasDeclarationErrors,
                     emitMethodBodies: true,
                     diagnostics: new BindingDiagnosticBag(methodBodyDiagnosticBag),