From acea06f1f54cb8a739ca493ead595d37c8611806 Mon Sep 17 00:00:00 2001
From: Andrew Au <andrewau@microsoft.com>
Date: Sat, 20 Jan 2024 15:25:14 -0800
Subject: [PATCH] Frozen objects should be identified as Gen2 in the handle
 table (#97109)

---
 src/coreclr/gc/env/common.h        |  1 +
 src/coreclr/gc/handletable.cpp     | 10 +++++++++-
 src/coreclr/gc/handletablepriv.h   | 12 ++++++++++++
 src/coreclr/gc/handletablescan.cpp |  6 +++---
 4 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/src/coreclr/gc/env/common.h b/src/coreclr/gc/env/common.h
index 02e142a23a602..78562ef0438b4 100644
--- a/src/coreclr/gc/env/common.h
+++ b/src/coreclr/gc/env/common.h
@@ -21,6 +21,7 @@
 #include <assert.h>
 #include <stdarg.h>
 #include <memory.h>
+#include <limits.h>
 
 #include <new>
 
diff --git a/src/coreclr/gc/handletable.cpp b/src/coreclr/gc/handletable.cpp
index ca8b1dbaa61cb..356b0e0bdc314 100644
--- a/src/coreclr/gc/handletable.cpp
+++ b/src/coreclr/gc/handletable.cpp
@@ -24,6 +24,14 @@
 DWORD g_dwHandles = 0;
 #endif // ENABLE_PERF_COUNTERS || FEATURE_EVENT_TRACE
 
+#ifndef DACCESS_COMPILE
+int GetConvertedGeneration(_UNCHECKED_OBJECTREF obj)
+{
+    int generation = g_theGCHeap->WhichGeneration(obj);
+    return generation == INT_MAX ? max_generation : generation;
+}
+#endif //DACCESS_COMPILE
+
 /****************************************************************************
  *
  * FORWARD DECLARATIONS
@@ -577,7 +585,7 @@ void HndWriteBarrierWorker(OBJECTHANDLE handle, _UNCHECKED_OBJECTREF value)
     if (*pClumpAge != 0) // Perf optimization: if clumpAge is 0, nothing more to do
     {
         // find out generation
-        int generation = g_theGCHeap->WhichGeneration(value);
+        int generation = GetConvertedGeneration(value);
         uint32_t uType = HandleFetchType(handle);
 
 #ifdef FEATURE_ASYNC_PINNED_HANDLES
diff --git a/src/coreclr/gc/handletablepriv.h b/src/coreclr/gc/handletablepriv.h
index 086ef2e018b6f..e09e89cecaaae 100644
--- a/src/coreclr/gc/handletablepriv.h
+++ b/src/coreclr/gc/handletablepriv.h
@@ -942,3 +942,15 @@ void CALLBACK BlockVerifyAgeMapForBlocks(PTR_TableSegment pSegment, uint32_t uBl
 PTR_TableSegment CALLBACK xxxAsyncSegmentIterator(PTR_HandleTable pTable, TableSegment *pPrevSegment, CrstHolderWithState *pCrstHolder);
 
 /*--------------------------------------------------------------------------*/
+
+#ifndef DACCESS_COMPILE
+
+/*
+ * GetConvertedGeneration
+ *
+ * Get the generation of an object, where a frozen object is regarded as max_generation
+ *
+ */
+int GetConvertedGeneration(_UNCHECKED_OBJECTREF obj);
+
+#endif //DACCESS_COMPILE
diff --git a/src/coreclr/gc/handletablescan.cpp b/src/coreclr/gc/handletablescan.cpp
index 171647501b4cb..7c0692ad5b8ff 100644
--- a/src/coreclr/gc/handletablescan.cpp
+++ b/src/coreclr/gc/handletablescan.cpp
@@ -811,7 +811,7 @@ void BlockResetAgeMapForBlocksWorker(uint32_t *pdwGen, uint32_t dwClumpMask, Sca
             {
                 if (!HndIsNullOrDestroyedHandle(*pValue))
                 {
-                    int thisAge = g_theGCHeap->WhichGeneration(*pValue);
+                    int thisAge = GetConvertedGeneration(*pValue);
                     if (minAge > thisAge)
                         minAge = thisAge;
 
@@ -820,7 +820,7 @@ void BlockResetAgeMapForBlocksWorker(uint32_t *pdwGen, uint32_t dwClumpMask, Sca
                         [](Object*, Object* to, void* ctx)
                         {
                             int* minAge = reinterpret_cast<int*>(ctx);
-                            int generation = g_theGCHeap->WhichGeneration(to);
+                            int generation = GetConvertedGeneration(to);
                             if (*minAge > generation)
                             {
                                 *minAge = generation;
@@ -903,7 +903,7 @@ static void VerifyObjectAndAge(_UNCHECKED_OBJECTREF from, _UNCHECKED_OBJECTREF o
 {
     VerifyObject(from, obj);
 
-    int thisAge = g_theGCHeap->WhichGeneration(obj);
+    int thisAge = GetConvertedGeneration(obj);
 
     //debugging code
     //if (minAge > thisAge && thisAge < g_theGCHeap->GetMaxGeneration())