more filtering in enum conservatively (#95937)

Author: VSadov

src/coreclr/nativeaot/Runtime/gcrhenv.cpp

@@ -291,6 +291,7 @@ void MethodTable::InitializeAsGcFreeType()
 #endif // !DACCESS_COMPILE
 
 extern void GcEnumObject(PTR_OBJECTREF pObj, uint32_t flags, EnumGcRefCallbackFunc * fnGcEnumRef, EnumGcRefScanContext * pSc);
+extern void GcEnumObjectConservatively(PTR_PTR_Object ppObj, EnumGcRefCallbackFunc* fnGcEnumRef, EnumGcRefScanContext* pSc);
 extern void GcEnumObjectsConservatively(PTR_OBJECTREF pLowerBound, PTR_OBJECTREF pUpperBound, EnumGcRefCallbackFunc * fnGcEnumRef, EnumGcRefScanContext * pSc);
 extern void GcBulkEnumObjects(PTR_OBJECTREF pObjs, DWORD cObjs, EnumGcRefCallbackFunc * fnGcEnumRef, EnumGcRefScanContext * pSc);
 
@@ -356,7 +357,7 @@ void RedhawkGCInterface::EnumGcRef(PTR_RtuObjectRef pRef, GCRefKind kind, void *
 // static
 void RedhawkGCInterface::EnumGcRefConservatively(PTR_RtuObjectRef pRef, void* pfnEnumCallback, void* pvCallbackData)
 {
-    GcEnumObject((PTR_OBJECTREF)pRef, GC_CALL_INTERIOR | GC_CALL_PINNED, (EnumGcRefCallbackFunc*)pfnEnumCallback, (EnumGcRefScanContext*)pvCallbackData);
+    GcEnumObjectConservatively((PTR_OBJECTREF)pRef, (EnumGcRefCallbackFunc*)pfnEnumCallback, (EnumGcRefScanContext*)pvCallbackData);
 }
 
 #ifndef DACCESS_COMPILE

src/coreclr/nativeaot/Runtime/gcrhscan.cpp

@@ -156,7 +156,21 @@ void GcEnumObjectsConservatively(PTR_PTR_Object ppLowerBound, PTR_PTR_Object ppU
             // value is a GC heap reference but it's a cheap check that weeds out a lot of spurious values.
             PTR_Object pObj = *ppObj;
             if (((PTR_UInt8)pObj >= g_lowest_address) && ((PTR_UInt8)pObj <= g_highest_address))
-                fnGcEnumRef(ppObj, pSc, GC_CALL_INTERIOR|GC_CALL_PINNED);
+                PromoteCarefully(ppObj, GC_CALL_INTERIOR | GC_CALL_PINNED, fnGcEnumRef, pSc);
         }
     }
 }
+
+void GcEnumObjectConservatively(PTR_PTR_Object ppObj, EnumGcRefCallbackFunc* fnGcEnumRef, EnumGcRefScanContext* pSc)
+{
+    // Only report potential references in the promotion phase. Since we report everything as pinned there
+    // should be no work to do in the relocation phase.
+    if (pSc->promotion)
+    {
+        // Only report values that lie in the GC heap range. This doesn't conclusively guarantee that the
+        // value is a GC heap reference but it's a cheap check that weeds out a lot of spurious values.
+        PTR_Object pObj = *ppObj;
+        if (((PTR_UInt8)pObj >= g_lowest_address) && ((PTR_UInt8)pObj <= g_highest_address))
+            PromoteCarefully(ppObj, GC_CALL_INTERIOR | GC_CALL_PINNED, fnGcEnumRef, pSc);
+    }
+}