1 files changed, 48 insertions, 3 deletions

diff --git a/src/vm/siginfo.cpp b/src/vm/siginfo.cpp
index 9adfb4998c..b9955eca68 100644
--- a/src/vm/siginfo.cpp
+++ b/src/vm/siginfo.cpp
@@ -4953,10 +4953,52 @@ void PromoteCarefully(promote_func   fn,
     (*fn) (ppObj, sc, flags);
 }
 
+void ReportByRefPointersFromByRefLikeObject(promote_func *fn, ScanContext *sc, PTR_MethodTable pMT, PTR_VOID pSrc)
+{
+    WRAPPER_NO_CONTRACT;
+
+    _ASSERTE(pMT->IsByRefLike());
+
+    // TODO: TypedReference should ideally be implemented as a by-ref-like struct containing a ByReference<T> field,
+    // in which case the check for g_TypedReferenceMT below would not be necessary
+    if (pMT == g_TypedReferenceMT || pMT->HasSameTypeDefAs(g_pByReferenceClass))
+    {
+        (*fn)(dac_cast<PTR_PTR_Object>(pSrc), sc, GC_CALL_INTERIOR);
+        return;
+    }
+
+    ApproxFieldDescIterator fieldIterator(pMT, ApproxFieldDescIterator::INSTANCE_FIELDS);
+    for (FieldDesc *pFD = fieldIterator.Next(); pFD != NULL; pFD = fieldIterator.Next())
+    {
+        if (pFD->GetFieldType() != ELEMENT_TYPE_VALUETYPE)
+        {
+            continue;
+        }
+
+        // TODO: GetApproxFieldTypeHandleThrowing may throw. This is a potential stress problem for fragile NGen of non-CoreLib
+        // assemblies. It won’t ever throw for CoreCLR with R2R. Figure out if anything needs to be done to deal with the
+        // exception.
+        PTR_MethodTable pFieldMT = pFD->GetApproxFieldTypeHandleThrowing().AsMethodTable();
+        if (!pFieldMT->IsByRefLike())
+        {
+            continue;
+        }
+
+        int fieldStartIndex = pFD->GetOffset() / sizeof(void *);
+        PTR_PTR_Object fieldRef = dac_cast<PTR_PTR_Object>(PTR_BYTE(pSrc) + fieldStartIndex);
+        ReportByRefPointersFromByRefLikeObject(fn, sc, pFieldMT, fieldRef);
+    }
+}
+
 void ReportPointersFromValueType(promote_func *fn, ScanContext *sc, PTR_MethodTable pMT, PTR_VOID pSrc)
 {
     WRAPPER_NO_CONTRACT;
-    
+
+    if (pMT->IsByRefLike())
+    {
+        ReportByRefPointersFromByRefLikeObject(fn, sc, pMT, pSrc);
+    }
+
     if (!pMT->ContainsPointers())
         return;
     
@@ -4985,9 +5027,12 @@ void ReportPointersFromValueType(promote_func *fn, ScanContext *sc, PTR_MethodTa
 void ReportPointersFromValueTypeArg(promote_func *fn, ScanContext *sc, PTR_MethodTable pMT, ArgDestination *pSrc)
 {
     WRAPPER_NO_CONTRACT;
-    
-    if (!pMT->ContainsPointers())
+
+    if (!pMT->ContainsPointers() && !pMT->IsByRefLike())
+    {
         return;
+    }
+
 #if defined(UNIX_AMD64_ABI) && defined(FEATURE_UNIX_AMD64_STRUCT_PASSING)    
     if (pSrc->IsStructPassedInRegs())
     {