Fix DynamicInvokeMethodThunk hash code collisions (#103274)

* Fix DynamicInvokeMethodThunk hash code collisions * Update src/coreclr/tools/Common/TypeSystem/IL/Stubs/DynamicInvokeMethodThunk.cs Co-authored-by: Jan Kotas <[email protected]> * Update comments --------- Co-authored-by: Jan Kotas <[email protected]>
dotnet · Jun 17, 2024 · 899c766 · 899c766
1 parent e34003c
commit 899c766
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diff --git a/src/coreclr/tools/Common/TypeSystem/Common/MethodDesc.cs b/src/coreclr/tools/Common/TypeSystem/Common/MethodDesc.cs
@@ -491,7 +491,8 @@ private int AcquireHashCode()
         }
 
         /// <summary>
-        /// Compute HashCode. Should only be overridden by a MethodDesc that represents an instantiated method.
+        /// Compute HashCode. This hashcode is persisted into the image.
+        /// The algorithm to compute it must be in sync with the one used at runtime.
         /// </summary>
         protected virtual int ComputeHashCode()
         {

diff --git a/src/coreclr/tools/Common/TypeSystem/IL/Stubs/DynamicInvokeMethodThunk.cs b/src/coreclr/tools/Common/TypeSystem/IL/Stubs/DynamicInvokeMethodThunk.cs
@@ -112,6 +112,13 @@ public override MethodSignature Signature
             }
         }
 
+        protected override int ComputeHashCode()
+        {
+            // The hashcode of DynamicInvoke thunks is not persisted. It allows us to override default and
+            // use a hashcode with good distribution to reduce hash table collisions.
+            return base.ComputeHashCode() ^ _targetSignature.GetHashCode();
+        }
+
         public override string Name => "DynamicInvoke";
 
         public override string DiagnosticName => "DynamicInvoke";