Add BasicBlock.IsReachable property. (#25698)

src/Compilers/CSharp/Test/Semantic/IOperation/IOperationTests_IBranchOperation.cs

@@ -1050,7 +1050,7 @@ void M(bool x)
             Leaving: {R6} {R1}
 }
 
-Block[B5] - Block
+Block[B5] - Block [UnReachable]
     Predecessors (0)
     Statements (1)
         IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null) (Syntax: 'x = true;')

src/Compilers/CSharp/Test/Semantic/IOperation/IOperationTests_ICoalesceOperation.cs

@@ -622,7 +622,7 @@ void F(dynamic alternative, dynamic result)
             IFlowCaptureReferenceOperation: 1 (OperationKind.FlowCaptureReference, Type: null, Constant: null, IsImplicit) (Syntax: 'null')
 
     Next (Regular) Block[B2]
-Block[B2] - Block
+Block[B2] - Block [UnReachable]
     Predecessors: [B1]
     Statements (1)
         IFlowCaptureOperation: 2 (OperationKind.FlowCapture, Type: null, IsImplicit) (Syntax: 'null')
@@ -717,7 +717,7 @@ void F(int alternative, int result)
             IFlowCaptureReferenceOperation: 1 (OperationKind.FlowCaptureReference, Type: null, Constant: null, IsInvalid, IsImplicit) (Syntax: 'null')
 
     Next (Regular) Block[B2]
-Block[B2] - Block
+Block[B2] - Block [UnReachable]
     Predecessors: [B1]
     Statements (1)
         IFlowCaptureOperation: 2 (OperationKind.FlowCapture, Type: null, IsInvalid, IsImplicit) (Syntax: 'null')
@@ -810,7 +810,7 @@ void F(int? alternative, int? result)
             IFlowCaptureReferenceOperation: 1 (OperationKind.FlowCaptureReference, Type: null, Constant: null, IsImplicit) (Syntax: 'null')
 
     Next (Regular) Block[B2]
-Block[B2] - Block
+Block[B2] - Block [UnReachable]
     Predecessors: [B1]
     Statements (1)
         IFlowCaptureOperation: 2 (OperationKind.FlowCapture, Type: null, IsImplicit) (Syntax: 'null')
@@ -1203,7 +1203,7 @@ void F(object alternative, object result)
                 IFlowCaptureReferenceOperation: 1 (OperationKind.FlowCaptureReference, Type: System.String, Constant: ""a"", IsImplicit) (Syntax: 'input')
 
     Next (Regular) Block[B4]
-Block[B3] - Block
+Block[B3] - Block [UnReachable]
     Predecessors: [B1]
     Statements (1)
         IFlowCaptureOperation: 2 (OperationKind.FlowCapture, Type: null, IsImplicit) (Syntax: 'alternative')

src/Compilers/CSharp/Test/Semantic/IOperation/IOperationTests_IIfStatement.cs

@@ -1277,7 +1277,7 @@ void M()
 
         Next (Regular) Block[B3]
             Leaving: {R1}
-    Block[B2] - Block
+    Block[B2] - Block [UnReachable]
         Predecessors: [B1]
         Statements (1)
             IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null) (Syntax: 'condition = true;')

src/Compilers/CSharp/Test/Semantic/IOperation/IOperationTests_IReturnStatement.cs

@@ -223,7 +223,7 @@ void F(bool a)
 Block[B0] - Entry
     Statements (0)
     Next (Regular) Block[B2]
-Block[B1] - Block
+Block[B1] - Block [UnReachable]
     Predecessors (0)
     Statements (1)
         IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null) (Syntax: 'a = true;')
@@ -273,7 +273,7 @@ int F(bool a)
     Statements (0)
     Next (Return) Block[B3]
         ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 1) (Syntax: '1')
-Block[B2] - Block
+Block[B2] - Block [UnReachable]
     Predecessors (0)
     Statements (1)
         IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null) (Syntax: 'a = true;')
@@ -624,7 +624,7 @@ int F()
     Statements (0)
     Next (Return) Block[B3]
         ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 1) (Syntax: '1')
-Block[B2] - Block
+Block[B2] - Block [UnReachable]
     Predecessors (0)
     Statements (0)
     Next (Return) Block[B3]
@@ -1189,7 +1189,7 @@ System.Collections.Generic.IEnumerable<int> F(bool a)
 Block[B0] - Entry
     Statements (0)
     Next (Regular) Block[B2]
-Block[B1] - Block
+Block[B1] - Block [UnReachable]
     Predecessors (0)
     Statements (1)
         IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null) (Syntax: 'a = true;')

src/Compilers/CSharp/Test/Semantic/IOperation/IOperationTests_IThrowOperation.cs

@@ -39,7 +39,7 @@ void F()
     Predecessors: [B0]
     Statements (0)
     Next (ReThrow) Block[null]
-Block[B2] - Exit
+Block[B2] - Exit [UnReachable]
     Predecessors (0)
     Statements (0)
 ";
@@ -88,7 +88,7 @@ void F(int x)
                 ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 1) (Syntax: '1')
 
     Next (ReThrow) Block[null]
-Block[B2] - Block
+Block[B2] - Block [UnReachable]
     Predecessors (0)
     Statements (1)
         IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null) (Syntax: 'x = 2;')
@@ -100,7 +100,7 @@ void F(int x)
                 ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 2) (Syntax: '2')
 
     Next (Regular) Block[B3]
-Block[B3] - Exit
+Block[B3] - Exit [UnReachable]
     Predecessors: [B2]
     Statements (0)
 ";
@@ -133,7 +133,7 @@ void F(System.Exception ex)
     Statements (0)
     Next (Throw) Block[null]
         IParameterReferenceOperation: ex (OperationKind.ParameterReference, Type: System.Exception) (Syntax: 'ex')
-Block[B2] - Exit
+Block[B2] - Exit [UnReachable]
     Predecessors (0)
     Statements (0)
 ";
@@ -186,7 +186,7 @@ void F(System.Exception ex)
 
         Next (Throw) Block[null]
             IParameterReferenceOperation: ex (OperationKind.ParameterReference, Type: System.Exception) (Syntax: 'ex')
-    Block[B2] - Block
+    Block[B2] - Block [UnReachable]
         Predecessors (0)
         Statements (1)
             IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null) (Syntax: 'x = 2;')
@@ -201,7 +201,7 @@ void F(System.Exception ex)
             Leaving: {R1}
 }
 
-Block[B3] - Exit
+Block[B3] - Exit [UnReachable]
     Predecessors: [B2]
     Statements (0)
 ";
@@ -249,7 +249,7 @@ void F(int x, System.Exception ex)
             IParameterReferenceOperation: ex (OperationKind.ParameterReference, Type: System.Exception, IsInvalid) (Syntax: 'ex')
           Right: 
             IParameterReferenceOperation: x (OperationKind.ParameterReference, Type: System.Int32, IsInvalid) (Syntax: 'x')
-Block[B2] - Block
+Block[B2] - Block [UnReachable]
     Predecessors (0)
     Statements (1)
         IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null, IsInvalid) (Syntax: 'x = throw ex + x;')
@@ -267,7 +267,7 @@ void F(int x, System.Exception ex)
                           IOperation:  (OperationKind.None, Type: null, IsInvalid, IsImplicit) (Syntax: 'throw ex + x')
 
     Next (Regular) Block[B3]
-Block[B3] - Exit
+Block[B3] - Exit [UnReachable]
     Predecessors: [B2]
     Statements (0)
 ";
@@ -308,7 +308,7 @@ void F(int x, System.Exception ex)
 
     Next (Throw) Block[null]
         IParameterReferenceOperation: ex (OperationKind.ParameterReference, Type: System.Exception) (Syntax: 'ex')
-Block[B2] - Block
+Block[B2] - Block [UnReachable]
     Predecessors (0)
     Statements (1)
         IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null, IsInvalid) (Syntax: 'x = (throw ex) + x;')
@@ -330,7 +330,7 @@ void F(int x, System.Exception ex)
                         IParameterReferenceOperation: x (OperationKind.ParameterReference, Type: System.Int32) (Syntax: 'x')
 
     Next (Regular) Block[B3]
-Block[B3] - Exit
+Block[B3] - Exit [UnReachable]
     Predecessors: [B2]
     Statements (0)
 ";
@@ -375,7 +375,7 @@ void F(int x, System.Exception ex)
 
     Next (Throw) Block[null]
         IParameterReferenceOperation: ex (OperationKind.ParameterReference, Type: System.Exception, IsInvalid) (Syntax: 'ex')
-Block[B2] - Block
+Block[B2] - Block [UnReachable]
     Predecessors (0)
     Statements (1)
         IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null, IsInvalid) (Syntax: 'x = x + throw ex;')
@@ -397,7 +397,7 @@ void F(int x, System.Exception ex)
                               IOperation:  (OperationKind.None, Type: null, IsInvalid, IsImplicit) (Syntax: 'throw ex')
 
     Next (Regular) Block[B3]
-Block[B3] - Exit
+Block[B3] - Exit [UnReachable]
     Predecessors: [B2]
     Statements (0)
 ";
@@ -442,7 +442,7 @@ void F(int x, System.Exception ex)
 
     Next (Throw) Block[null]
         IParameterReferenceOperation: ex (OperationKind.ParameterReference, Type: System.Exception) (Syntax: 'ex')
-Block[B2] - Block
+Block[B2] - Block [UnReachable]
     Predecessors (0)
     Statements (1)
         IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null, IsInvalid) (Syntax: 'x = x + (throw ex);')
@@ -464,7 +464,7 @@ void F(int x, System.Exception ex)
                               IOperation:  (OperationKind.None, Type: null, IsInvalid, IsImplicit) (Syntax: 'throw ex')
 
     Next (Regular) Block[B3]
-Block[B3] - Exit
+Block[B3] - Exit [UnReachable]
     Predecessors: [B2]
     Statements (0)
 ";
@@ -522,7 +522,7 @@ void F(object x, object y, System.Exception ex)
     Statements (0)
     Next (Throw) Block[null]
         IParameterReferenceOperation: ex (OperationKind.ParameterReference, Type: System.Exception) (Syntax: 'ex')
-Block[B4] - Block
+Block[B4] - Block [UnReachable]
     Predecessors (0)
     Statements (1)
         IFlowCaptureOperation: 2 (OperationKind.FlowCapture, Type: null, IsImplicit) (Syntax: 'throw ex')
@@ -606,7 +606,7 @@ void F(object x, object y, object z, System.Exception ex)
     Statements (0)
     Next (Throw) Block[null]
         IParameterReferenceOperation: ex (OperationKind.ParameterReference, Type: System.Exception) (Syntax: 'ex')
-Block[B4] - Block
+Block[B4] - Block [UnReachable]
     Predecessors (0)
     Statements (1)
         IFlowCaptureOperation: 2 (OperationKind.FlowCapture, Type: null, IsImplicit) (Syntax: 'throw ex')
@@ -779,7 +779,7 @@ void F(int u)
                     ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 2) (Syntax: '2')
 
         Next (ReThrow) Block[null]
-    Block[B3] - Block
+    Block[B3] - Block [UnReachable]
         Predecessors (0)
         Statements (1)
             IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null) (Syntax: 'u = 3;')
@@ -885,7 +885,7 @@ void F(object x, object y, object z, int u)
         Next (Throw) Block[null]
             IInvalidOperation (OperationKind.Invalid, Type: null, IsInvalid) (Syntax: '')
               Children(0)
-    Block[B5] - Block
+    Block[B5] - Block [UnReachable]
         Predecessors (0)
         Statements (1)
             IFlowCaptureOperation: 1 (OperationKind.FlowCapture, Type: null, IsInvalid, IsImplicit) (Syntax: 'throw')
@@ -958,7 +958,7 @@ void F(System.Exception ex)
 
     Next (Throw) Block[null]
         IParameterReferenceOperation: ex (OperationKind.ParameterReference, Type: System.Exception) (Syntax: 'ex')
-Block[B2] - Exit
+Block[B2] - Exit [UnReachable]
     Predecessors (0)
     Statements (0)
 ";
@@ -1072,7 +1072,7 @@ void F(System.Exception ex, bool a)
     Statements (0)
     Next (Throw) Block[null]
         IParameterReferenceOperation: ex (OperationKind.ParameterReference, Type: System.Exception) (Syntax: 'ex')
-Block[B3] - Exit
+Block[B3] - Exit [UnReachable]
     Predecessors (0)
     Statements (0)
 ";
@@ -1195,7 +1195,7 @@ void F(System.Exception ex)
     Statements (0)
     Next (Throw) Block[null]
         IParameterReferenceOperation: ex (OperationKind.ParameterReference, Type: System.Exception) (Syntax: 'ex')
-Block[B3] - Exit
+Block[B3] - Exit [UnReachable]
     Predecessors (0)
     Statements (0)
 ";
@@ -1345,7 +1345,7 @@ void F(System.Exception ex, int x)
         Statements (0)
         Next (Throw) Block[null]
             IParameterReferenceOperation: ex (OperationKind.ParameterReference, Type: System.Exception) (Syntax: 'ex')
-    Block[B3] - Block
+    Block[B3] - Block [UnReachable]
         Predecessors (0)
         Statements (1)
             IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null) (Syntax: 'x = 2;')
@@ -1425,7 +1425,7 @@ void F(int x)
         Predecessors: [B3]
         Statements (0)
         Next (ReThrow) Block[null]
-    Block[B3] - Block
+    Block[B3] - Block [UnReachable]
         Predecessors (0)
         Statements (1)
             IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null) (Syntax: 'x = 2;')
@@ -1486,7 +1486,7 @@ int F(bool a, System.Exception ex1, System.Exception ex2)
     Statements (0)
     Next (Throw) Block[null]
         IParameterReferenceOperation: ex2 (OperationKind.ParameterReference, Type: System.Exception) (Syntax: 'ex2')
-Block[B3] - Exit
+Block[B3] - Exit [UnReachable]
     Predecessors (0)
     Statements (0)
 ";
@@ -1541,7 +1541,7 @@ void F(int x, System.Exception ex1, System.Exception ex2, bool a)
     Statements (0)
     Next (Throw) Block[null]
         IParameterReferenceOperation: ex2 (OperationKind.ParameterReference, Type: System.Exception) (Syntax: 'ex2')
-Block[B3] - Exit
+Block[B3] - Exit [UnReachable]
     Predecessors (0)
     Statements (0)
 ";
@@ -1843,7 +1843,7 @@ void F(int u)
         Next (ReThrow) Block[null]
 }
 
-Block[B3] - Exit
+Block[B3] - Exit [UnReachable]
     Predecessors: [B1]
     Statements (0)
 ";
@@ -1906,7 +1906,7 @@ void F(int u, System.Exception ex)
             IParameterReferenceOperation: ex (OperationKind.ParameterReference, Type: System.Exception) (Syntax: 'ex')
 }
 
-Block[B3] - Exit
+Block[B3] - Exit [UnReachable]
     Predecessors: [B1]
     Statements (0)
 ";

src/Compilers/Core/Portable/Operations/BasicBlock.cs

@@ -54,6 +54,8 @@ public BasicBlock(BasicBlockKind kind)
 
         public int Ordinal { get; internal set; } = -1;
 
+        public bool IsReachable { get; internal set; } = false;
+
         /// <summary>
         /// Enclosing region
         /// </summary>

src/Compilers/Core/Portable/Operations/ControlFlowGraph.Region.cs

@@ -190,6 +190,11 @@ public sealed class Region
                 }
 #endif
             }
+
+            internal bool ContainsBlock(int destinationOrdinal)
+            {
+                return FirstBlockOrdinal <= destinationOrdinal && LastBlockOrdinal >= destinationOrdinal;
+            }
         }
     }
 }

src/Compilers/Core/Portable/PublicAPI.Unshipped.txt

@@ -32,6 +32,7 @@ Microsoft.CodeAnalysis.Operations.BasicBlock.BranchKind.Return = 2 -> Microsoft.
 Microsoft.CodeAnalysis.Operations.BasicBlock.BranchKind.StructuredExceptionHandling = 3 -> Microsoft.CodeAnalysis.Operations.BasicBlock.BranchKind
 Microsoft.CodeAnalysis.Operations.BasicBlock.BranchKind.Throw = 5 -> Microsoft.CodeAnalysis.Operations.BasicBlock.BranchKind
 Microsoft.CodeAnalysis.Operations.BasicBlock.Conditional.get -> (Microsoft.CodeAnalysis.IOperation Condition, bool JumpIfTrue, Microsoft.CodeAnalysis.Operations.BasicBlock.Branch Branch)
+Microsoft.CodeAnalysis.Operations.BasicBlock.IsReachable.get -> bool
 Microsoft.CodeAnalysis.Operations.BasicBlock.Kind.get -> Microsoft.CodeAnalysis.Operations.BasicBlockKind
 Microsoft.CodeAnalysis.Operations.BasicBlock.Next.get -> (Microsoft.CodeAnalysis.IOperation Value, Microsoft.CodeAnalysis.Operations.BasicBlock.Branch Branch)
 Microsoft.CodeAnalysis.Operations.BasicBlock.Ordinal.get -> int

src/Compilers/VisualBasic/Test/Semantic/IOperation/IOperationTests_ICoalesceOperation.vb

@@ -659,7 +659,7 @@ Block[B1] - Block
             IFlowCaptureReferenceOperation: 1 (OperationKind.FlowCaptureReference, Type: null, Constant: null, IsImplicit) (Syntax: 'Nothing')
 
     Next (Regular) Block[B2]
-Block[B2] - Block
+Block[B2] - Block [UnReachable]
     Predecessors: [B1]
     Statements (1)
         IFlowCaptureOperation: 2 (OperationKind.FlowCapture, Type: null, IsImplicit) (Syntax: 'Nothing')
@@ -755,7 +755,7 @@ Block[B1] - Block
             IFlowCaptureReferenceOperation: 1 (OperationKind.FlowCaptureReference, Type: null, Constant: null, IsImplicit) (Syntax: 'Nothing')
 
     Next (Regular) Block[B2]
-Block[B2] - Block
+Block[B2] - Block [UnReachable]
     Predecessors: [B1]
     Statements (1)
         IFlowCaptureOperation: 2 (OperationKind.FlowCapture, Type: null, IsImplicit) (Syntax: 'Nothing')
@@ -851,7 +851,7 @@ Block[B1] - Block
             IFlowCaptureReferenceOperation: 1 (OperationKind.FlowCaptureReference, Type: null, Constant: null, IsImplicit) (Syntax: 'Nothing')
 
     Next (Regular) Block[B2]
-Block[B2] - Block
+Block[B2] - Block [UnReachable]
     Predecessors: [B1]
     Statements (1)
         IFlowCaptureOperation: 2 (OperationKind.FlowCapture, Type: null, IsImplicit) (Syntax: 'Nothing')

src/Compilers/VisualBasic/Test/Semantic/IOperation/IOperationTests_IEndOperation.vb

@@ -28,7 +28,7 @@ Block[B1] - Block
     Predecessors: [B0]
     Statements (0)
     Next (ProgramTermination) Block[null]
-Block[B2] - Exit
+Block[B2] - Exit [UnReachable]
     Predecessors (0)
     Statements (0)
 ]]>.Value
@@ -69,7 +69,7 @@ Block[B1] - Block
                 ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 1) (Syntax: '1')
 
     Next (ProgramTermination) Block[null]
-Block[B2] - Block
+Block[B2] - Block [UnReachable]
     Predecessors (0)
     Statements (1)
         IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null) (Syntax: 'x = 2')
@@ -81,7 +81,7 @@ Block[B2] - Block
                 ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 2) (Syntax: '2')
 
     Next (Regular) Block[B3]
-Block[B3] - Exit
+Block[B3] - Exit [UnReachable]
     Predecessors: [B2]
     Statements (0)
 ]]>.Value
@@ -139,7 +139,7 @@ Block[B0] - Entry
         Next (ProgramTermination) Block[null]
 }
 
-Block[B3] - Exit
+Block[B3] - Exit [UnReachable]
     Predecessors: [B1]
     Statements (0)
 ]]>.Value
@@ -182,7 +182,7 @@ Block[B1] - Block
                 ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 1) (Syntax: '1')
 
     Next (ProgramTermination) Block[null]
-Block[B2] - Exit
+Block[B2] - Exit [UnReachable]
     Predecessors (0)
     Statements (0)
 ]]>.Value
@@ -218,7 +218,7 @@ Block[B1] - Block
         IParameterReferenceOperation: x (OperationKind.ParameterReference, Type: System.Boolean) (Syntax: 'x')
 
     Next (ProgramTermination) Block[null]
-Block[B2] - Exit
+Block[B2] - Exit [UnReachable]
     Predecessors (0)
     Statements (0)
 ]]>.Value
@@ -276,7 +276,7 @@ Block[B3] - Block
     Predecessors: [B1] [B2]
     Statements (0)
     Next (ProgramTermination) Block[null]
-Block[B4] - Exit
+Block[B4] - Exit [UnReachable]
     Predecessors (0)
     Statements (0)
 ]]>.Value
@@ -324,7 +324,7 @@ Block[B1] - Block
         IParameterReferenceOperation: a (OperationKind.ParameterReference, Type: System.Boolean) (Syntax: 'a')
 
     Next (ProgramTermination) Block[null]
-Block[B2] - Exit
+Block[B2] - Exit [UnReachable]
     Predecessors (0)
     Statements (0)
 ]]>.Value
@@ -463,7 +463,7 @@ Block[B0] - Entry
 }
 .finally {R3}
 {
-    Block[B2] - Block
+    Block[B2] - Block [UnReachable]
         Predecessors (0)
         Statements (1)
             IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null) (Syntax: 'x = 1')
@@ -477,7 +477,7 @@ Block[B0] - Entry
         Next (StructuredExceptionHandling) Block[null]
 }
 
-Block[B3] - Exit
+Block[B3] - Exit [UnReachable]
     Predecessors (0)
     Statements (0)
 ]]>.Value

src/Test/Utilities/Portable/Compilation/ControlFlowGraphVerifier.cs

@@ -57,6 +57,7 @@ public static string GetFlowGraph(Compilation compilation, ControlFlowGraph grap
                         Assert.Null(currentRegion.ExceptionType);
                         Assert.Empty(currentRegion.Locals);
                         Assert.Equal(ControlFlowGraph.RegionKind.Root, currentRegion.Kind);
+                        Assert.True(block.IsReachable);
                         break;
 
                     case BasicBlockKind.Exit:
@@ -85,7 +86,7 @@ public static string GetFlowGraph(Compilation compilation, ControlFlowGraph grap
                     stringBuilder.AppendLine();
                 }
 
-                appendLine($"Block[B{i}] - {block.Kind}");
+                appendLine($"Block[B{i}] - {block.Kind}{(block.IsReachable ? "" : " [UnReachable]")}");
 
                 var predecessors = block.Predecessors;
 
@@ -130,6 +131,7 @@ public static string GetFlowGraph(Compilation compilation, ControlFlowGraph grap
                         Assert.Same(blocks[conditionalBranch.Destination.Ordinal], conditionalBranch.Destination);
                     }
 
+                    Assert.NotEqual(BasicBlock.BranchKind.StructuredExceptionHandling, conditionalBranch.Kind);
                     appendLine($"    Jump if {(block.Conditional.JumpIfTrue ? "True" : "False")} ({conditionalBranch.Kind}) to Block[{getDestinationString(ref conditionalBranch)}]");
 
                     IOperation value = block.Conditional.Condition;
@@ -153,6 +155,13 @@ public static string GetFlowGraph(Compilation compilation, ControlFlowGraph grap
                         Assert.Same(blocks[nextBranch.Destination.Ordinal], nextBranch.Destination);
                     }
 
+                    if (nextBranch.Kind == BasicBlock.BranchKind.StructuredExceptionHandling)
+                    {
+                        Assert.Null(nextBranch.Destination);
+                        Assert.Equal(block.Region.LastBlockOrdinal, block.Ordinal);
+                        Assert.True(block.Region.Kind == ControlFlowGraph.RegionKind.Filter || block.Region.Kind == ControlFlowGraph.RegionKind.Finally);
+                    }
+
                     appendLine($"    Next ({nextBranch.Kind}) Block[{getDestinationString(ref nextBranch)}]");
                     IOperation value = block.Next.Value;