[ILVerify] Fix block re-verification possibly causing endless loop (#4575)

* Fixed block re-verification after stack merge possibly causing endless loop.

* Refactored BasicBlock.EndOffset to BasicBlock.ImportState.

1 files changed, 7 insertions, 1 deletions

diff --git a/src/ILCompiler.Compiler/src/IL/ILImporter.Scanner.cs b/src/ILCompiler.Compiler/src/IL/ILImporter.Scanner.cs
index 4a099c9a6..b30e9e7b4 100644
--- a/src/ILCompiler.Compiler/src/IL/ILImporter.Scanner.cs
+++ b/src/ILCompiler.Compiler/src/IL/ILImporter.Scanner.cs
@@ -34,10 +34,16 @@ namespace Internal.IL
         private class BasicBlock
         {
             // Common fields
+            public enum ImportState : byte
+            {
+                Unmarked,
+                IsPending
+            }
+
             public BasicBlock Next;
 
             public int StartOffset;
-            public int EndOffset;
+            public ImportState State = ImportState.Unmarked;
 
             public bool TryStart;
             public bool FilterStart;