From fdf7062b630b1b6f92b6acdafef3d7a3db0f90d3 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Fri, 24 Oct 2025 14:35:34 +0000
Subject: [PATCH 1/2] Initial plan


From edc28f5f562c0436fe4ce9479b8fe4f4c8bce379 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Fri, 24 Oct 2025 15:00:13 +0000
Subject: [PATCH 2/2] Fix issue 121066: Update HelperCallProperties for
 INITCLASS and add test case

Co-authored-by: EgorBo <523221+EgorBo@users.noreply.github.com>
---
 src/coreclr/jit/utils.cpp                     |   2 +-
 .../JitBlue/Runtime_121066/Runtime_121066.cs  | 100 ++++++++++++++++++
 .../Runtime_121066/Runtime_121066.csproj      |  12 +++
 3 files changed, 113 insertions(+), 1 deletion(-)
 create mode 100644 src/tests/JIT/Regression/JitBlue/Runtime_121066/Runtime_121066.cs
 create mode 100644 src/tests/JIT/Regression/JitBlue/Runtime_121066/Runtime_121066.csproj

diff --git a/src/coreclr/jit/utils.cpp b/src/coreclr/jit/utils.cpp
index ac7674d70ca7d9..98e11c71ff371b 100644
--- a/src/coreclr/jit/utils.cpp
+++ b/src/coreclr/jit/utils.cpp
@@ -1727,7 +1727,7 @@ void HelperCallProperties::init()
 
             case CORINFO_HELP_INITCLASS:
             case CORINFO_HELP_INITINSTCLASS:
-                isPure      = true;
+                mutatesHeap = true;
                 mayRunCctor = true;
                 break;
 
diff --git a/src/tests/JIT/Regression/JitBlue/Runtime_121066/Runtime_121066.cs b/src/tests/JIT/Regression/JitBlue/Runtime_121066/Runtime_121066.cs
new file mode 100644
index 00000000000000..5b8426c2e0ea80
--- /dev/null
+++ b/src/tests/JIT/Regression/JitBlue/Runtime_121066/Runtime_121066.cs
@@ -0,0 +1,100 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Runtime.CompilerServices;
+using Xunit;
+
+public class Runtime_121066
+{
+    public static int preciseInitCctorsRun = 0;
+
+    class MyPreciseInitClass<T>
+    {
+        static MyPreciseInitClass()
+        {
+            preciseInitCctorsRun++;
+        }
+
+        public static void TriggerCctorClass()
+        {
+        }
+
+        public static void TriggerCctorMethod<U>()
+        { }
+    }
+
+    class MyClass<T>
+    {
+        static Type staticVarType = typeof(MyClass<T>);
+        public Type GetTypeOf()
+        {
+            return typeof(MyClass<T>);
+        }
+        public static Type GetTypeOfStatic()
+        {
+            return typeof(MyClass<T>);
+        }
+
+        public static Type GetTypeThroughStaticVar()
+        {
+            return staticVarType;
+        }
+    }
+
+    [Fact]
+    public static void TestEntryPoint()
+    {
+        Assert.True(TestPreciseInitCctors());
+    }
+
+    public static bool TestPreciseInitCctors()
+    {
+        if (preciseInitCctorsRun != 0)
+        {
+            Console.WriteLine("preciseInitCctorsRun should be 0, but is {0}", preciseInitCctorsRun);
+            return false;
+        }
+        MyPreciseInitClass<int>.TriggerCctorClass();
+        if (preciseInitCctorsRun != 1)
+        {
+            Console.WriteLine("preciseInitCctorsRun should be 1, but is {0}", preciseInitCctorsRun);
+            return false;
+        }
+        MyPreciseInitClass<short>.TriggerCctorMethod<int>();
+        if (preciseInitCctorsRun != 2)
+        {
+            Console.WriteLine("TriggerCctorClass should return 2, but is {0}", preciseInitCctorsRun);
+            return false;
+        }
+
+        object o = new MyPreciseInitClass<double>();
+        if (preciseInitCctorsRun != 3)
+        {
+            Console.WriteLine("TriggerCctorClass should return 3, but is {0}", preciseInitCctorsRun);
+            return false;
+        }
+
+        MyPreciseInitClass<object>.TriggerCctorClass();
+        if (preciseInitCctorsRun != 4)
+        {
+            Console.WriteLine("preciseInitCctorsRun should be 4 but is {0}", preciseInitCctorsRun);
+            return false;
+        }
+        MyPreciseInitClass<string>.TriggerCctorMethod<object>();
+        if (preciseInitCctorsRun != 5)
+        {
+            Console.WriteLine("TriggerCctorClass should return 5, but is {0}", preciseInitCctorsRun);
+            return false;
+        }
+
+        o = new MyPreciseInitClass<Type>();
+        if (preciseInitCctorsRun != 6)
+        {
+            Console.WriteLine("TriggerCctorClass should return 6,  but is {0}", preciseInitCctorsRun);
+            return false;
+        }
+
+        return true;
+    }
+}
diff --git a/src/tests/JIT/Regression/JitBlue/Runtime_121066/Runtime_121066.csproj b/src/tests/JIT/Regression/JitBlue/Runtime_121066/Runtime_121066.csproj
new file mode 100644
index 00000000000000..7488f34a9b11ac
--- /dev/null
+++ b/src/tests/JIT/Regression/JitBlue/Runtime_121066/Runtime_121066.csproj
@@ -0,0 +1,12 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <DebugType>None</DebugType>
+    <Optimize>True</Optimize>
+    <!-- Needed for CLRTestEnvironmentVariable -->
+    <RequiresProcessIsolation>true</RequiresProcessIsolation>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="$(MSBuildProjectName).cs" />
+    <CLRTestEnvironmentVariable Include="DOTNET_TieredCompilation" Value="0" />
+  </ItemGroup>
+</Project>