[cDAC] Implement DacDbi GetCollectibleTypeStaticAddress

docs/design/datacontracts/RuntimeTypeSystem.md

@@ -267,8 +267,8 @@ bool IsFieldDescThreadStatic(TargetPointer fieldDescPointer);
 bool IsFieldDescStatic(TargetPointer fieldDescPointer);
 uint GetFieldDescType(TargetPointer fieldDescPointer);
 uint GetFieldDescOffset(TargetPointer fieldDescPointer, FieldDefinition fieldDef);
-TargetPointer GetFieldDescStaticAddress(TargetPointer fieldDescPointer);
-TargetPointer GetFieldDescThreadStaticAddress(TargetPointer fieldDescPointer, TargetPointer thread);
+TargetPointer GetFieldDescStaticAddress(TargetPointer fieldDescPointer, bool unboxValueTypes = true);
+TargetPointer GetFieldDescThreadStaticAddress(TargetPointer fieldDescPointer, TargetPointer thread, bool unboxValueTypes = true);
 ```
 
 ### Other APIs
@@ -2046,17 +2046,20 @@ uint GetFieldDescOffset(TargetPointer fieldDescPointer)
     return DWord2 & (uint)FieldDescFlags2.OffsetMask;
 }
 
-TargetPointer GetFieldDescStaticAddress(TargetPointer fieldDescPointer)
+TargetPointer GetFieldDescStaticAddress(TargetPointer fieldDescPointer, bool unboxValueTypes = true)
 {
     // Resolves the base pointer (GC or non-GC statics) for the enclosing type,
     // then applies the field's metadata-based offset within that region.
     // Uses GetGCStaticsBasePointer / GetNonGCStaticsBasePointer depending on the field's CorElementType.
+    // When unboxValueTypes is true (default), value-type statics are dereferenced to the unboxed
+    // payload inside the boxed object. Pass false to obtain the address of the boxed reference itself.
 }
 
-TargetPointer GetFieldDescThreadStaticAddress(TargetPointer fieldDescPointer, TargetPointer thread)
+TargetPointer GetFieldDescThreadStaticAddress(TargetPointer fieldDescPointer, TargetPointer thread, bool unboxValueTypes = true)
 {
     // Like GetFieldDescStaticAddress, but resolves thread-local base pointers instead.
     // Uses GetGCThreadStaticsBasePointer / GetNonGCThreadStaticsBasePointer.
+    // The unboxValueTypes parameter behaves the same as in GetFieldDescStaticAddress.
 }
 ```
 

src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.cs

@@ -266,8 +266,8 @@ public interface IRuntimeTypeSystem : IContract
     CorElementType GetFieldDescType(TargetPointer fieldDescPointer) => throw new NotImplementedException();
     uint GetFieldDescOffset(TargetPointer fieldDescPointer, FieldDefinition fieldDef) => throw new NotImplementedException();
     TargetPointer GetFieldDescByName(TypeHandle typeHandle, string fieldName) => throw new NotImplementedException();
-    TargetPointer GetFieldDescStaticAddress(TargetPointer fieldDescPointer) => throw new NotImplementedException();
-    TargetPointer GetFieldDescThreadStaticAddress(TargetPointer fieldDescPointer, TargetPointer thread) => throw new NotImplementedException();
+    TargetPointer GetFieldDescStaticAddress(TargetPointer fieldDescPointer, bool unboxValueTypes = true) => throw new NotImplementedException();
+    TargetPointer GetFieldDescThreadStaticAddress(TargetPointer fieldDescPointer, TargetPointer thread, bool unboxValueTypes = true) => throw new NotImplementedException();
     #endregion FieldDesc inspection APIs
     #region Other APIs
     void GetCoreLibFieldDescAndDef(string typeNamespace, string typeName, string fieldName, out TargetPointer fieldDescAddr, out FieldDefinition fieldDef) => throw new NotImplementedException();

src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs

@@ -2084,7 +2084,7 @@ private TargetPointer GetStaticAddressHandle(TargetPointer @base, uint offset, b
         return new TargetPointer(@base + offset);
     }
 
-    private TargetPointer GetFieldDescStaticOrThreadStaticAddress(TargetPointer fieldDescPointer, TargetPointer? thread = null)
+    private TargetPointer GetFieldDescStaticOrThreadStaticAddress(TargetPointer fieldDescPointer, TargetPointer? thread = null, bool unboxValueTypes = true)
     {
         TargetPointer enclosingMT = ((IRuntimeTypeSystem)this).GetMTOfEnclosingClass(fieldDescPointer);
         TypeHandle ctx = GetTypeHandle(enclosingMT);
@@ -2127,7 +2127,7 @@ private TargetPointer GetFieldDescStaticOrThreadStaticAddress(TargetPointer fiel
         uint offset = ((IRuntimeTypeSystem)this).GetFieldDescOffset(fieldDescPointer, fieldDef);
         bool isRVA = IsFieldDescRVA(fieldDescPointer);
         TargetPointer handleAddr = GetStaticAddressHandle(@base, offset, isRVA, fieldDescPointer, moduleHandle);
-        if (type == CorElementType.ValueType && !isRVA)
+        if (unboxValueTypes && type == CorElementType.ValueType && !isRVA)
         {
             TargetPointer objRef = _target.ReadPointer(handleAddr);
             Data.Object obj = _target.ProcessedData.GetOrAdd<Data.Object>(objRef);
@@ -2136,9 +2136,9 @@ private TargetPointer GetFieldDescStaticOrThreadStaticAddress(TargetPointer fiel
         return handleAddr;
     }
 
-    TargetPointer IRuntimeTypeSystem.GetFieldDescStaticAddress(TargetPointer fieldDescPointer) => GetFieldDescStaticOrThreadStaticAddress(fieldDescPointer);
+    TargetPointer IRuntimeTypeSystem.GetFieldDescStaticAddress(TargetPointer fieldDescPointer, bool unboxValueTypes) => GetFieldDescStaticOrThreadStaticAddress(fieldDescPointer, null, unboxValueTypes);
 
-    TargetPointer IRuntimeTypeSystem.GetFieldDescThreadStaticAddress(TargetPointer fieldDescPointer, TargetPointer thread) => GetFieldDescStaticOrThreadStaticAddress(fieldDescPointer, thread);
+    TargetPointer IRuntimeTypeSystem.GetFieldDescThreadStaticAddress(TargetPointer fieldDescPointer, TargetPointer thread, bool unboxValueTypes) => GetFieldDescStaticOrThreadStaticAddress(fieldDescPointer, thread, unboxValueTypes);
 
     void IRuntimeTypeSystem.GetCoreLibFieldDescAndDef(string @namespace, string typeName, string fieldName, out TargetPointer fieldDescAddr, out FieldDefinition fieldDef)
     {

src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs

@@ -1513,7 +1513,31 @@ public int GetThreadStaticAddress(ulong vmField, ulong vmRuntimeThread, ulong* p
     }
 
     public int GetCollectibleTypeStaticAddress(ulong vmField, ulong* pRetVal)
-        => LegacyFallbackHelper.CanFallback() && _legacy is not null ? _legacy.GetCollectibleTypeStaticAddress(vmField, pRetVal) : HResults.E_NOTIMPL;
+    {
+        *pRetVal = 0;
+        int hr = HResults.S_OK;
+        try
+        {
+            Contracts.IRuntimeTypeSystem rts = _target.Contracts.RuntimeTypeSystem;
+            TargetPointer fd = new TargetPointer(vmField);
+            *pRetVal = rts.GetFieldDescStaticAddress(fd, unboxValueTypes: false).Value;
+        }
+        catch (System.Exception ex)
+        {
+            hr = ex.HResult;
+        }
+#if DEBUG
+        if (_legacy is not null)
+        {
+            ulong retValLocal;
+            int hrLocal = _legacy.GetCollectibleTypeStaticAddress(vmField, &retValLocal);
+            Debug.ValidateHResult(hr, hrLocal);
+            if (hr == HResults.S_OK)
+                Debug.Assert(*pRetVal == retValLocal, $"cDAC: {*pRetVal}, DAC: {retValLocal}");
+        }
+#endif
+        return hr;
+    }
 
     public int GetEnCHangingFieldInfo(nint pEnCFieldInfo, nint pFieldData, Interop.BOOL* pfStatic)
         => LegacyFallbackHelper.CanFallback() && _legacy is not null ? _legacy.GetEnCHangingFieldInfo(pEnCFieldInfo, pFieldData, pfStatic) : HResults.E_NOTIMPL;