Add static fields for generic types (#3218)

***NO_CI***

Author: josesimoes

src/CLR/Core/GarbageCollector.cpp

@@ -706,6 +706,17 @@ void CLR_RT_GarbageCollector::Assembly_Mark()
 
 #if !defined(NANOCLR_APPDOMAINS)
         CheckMultipleBlocks(pASSM->staticFields, pASSM->staticFieldsCount);
+
+        // Mark generic static fields for each TypeSpec
+        for (int i = 0; i < pASSM->tablesSize[TBL_TypeSpec]; i++)
+        {
+            CLR_RT_TypeSpec_CrossReference &ts = pASSM->crossReferenceTypeSpec[i];
+
+            if (ts.genericStaticFields != nullptr && ts.genericStaticFieldsCount > 0)
+            {
+                CheckMultipleBlocks(ts.genericStaticFields, ts.genericStaticFieldsCount);
+            }
+        }
 #endif
 
         CheckSingleBlock(&pASSM->file);

src/CLR/Core/Interpreter.cpp

@@ -2728,13 +2728,25 @@ HRESULT CLR_RT_Thread::Execute_IL(CLR_RT_StackFrame &stackArg)
                 {
                     FETCH_ARG_COMPRESSED_FIELDTOKEN(arg, ip);
 
-                    CLR_RT_FieldDef_Instance field;
+                    CLR_RT_FieldDef_Instance field{};
+                    CLR_RT_HeapBlock *ptr = nullptr;
+
+                    // resolve field token
                     if (field.ResolveToken(arg, assm, &stack->m_call) == false)
                     {
                         NANOCLR_SET_AND_LEAVE(CLR_E_WRONG_TYPE);
                     }
 
-                    CLR_RT_HeapBlock *ptr = CLR_RT_ExecutionEngine::AccessStaticField(field);
+                    if (field.genericType && NANOCLR_INDEX_IS_VALID(*field.genericType))
+                    {
+                        // access static field of a generic instance
+                        ptr = field.assembly->GetStaticFieldByFieldDef(field, field.genericType);
+                    }
+                    else
+                    {
+                        // static field of a non-generic class
+                        ptr = CLR_RT_ExecutionEngine::AccessStaticField(field);
+                    }
 
                     if (ptr == nullptr)
                     {
@@ -2756,13 +2768,25 @@ HRESULT CLR_RT_Thread::Execute_IL(CLR_RT_StackFrame &stackArg)
                 {
                     FETCH_ARG_COMPRESSED_FIELDTOKEN(arg, ip);
 
-                    CLR_RT_FieldDef_Instance field;
+                    CLR_RT_FieldDef_Instance field{};
+                    CLR_RT_HeapBlock *ptr = nullptr;
+
+                    // resolve field token
                     if (field.ResolveToken(arg, assm, &stack->m_call) == false)
                     {
                         NANOCLR_SET_AND_LEAVE(CLR_E_WRONG_TYPE);
                     }
 
-                    CLR_RT_HeapBlock *ptr = CLR_RT_ExecutionEngine::AccessStaticField(field);
+                    if (field.genericType && NANOCLR_INDEX_IS_VALID(*field.genericType))
+                    {
+                        // access static field of a generic instance
+                        ptr = field.assembly->GetStaticFieldByFieldDef(field, field.genericType);
+                    }
+                    else
+                    {
+                        // static field of a non-generic class
+                        ptr = CLR_RT_ExecutionEngine::AccessStaticField(field);
+                    }
 
                     if (ptr == nullptr)
                     {
@@ -2783,13 +2807,25 @@ HRESULT CLR_RT_Thread::Execute_IL(CLR_RT_StackFrame &stackArg)
                 {
                     FETCH_ARG_COMPRESSED_FIELDTOKEN(arg, ip);
 
-                    CLR_RT_FieldDef_Instance field;
+                    CLR_RT_FieldDef_Instance field{};
+                    CLR_RT_HeapBlock *ptr = nullptr;
+
+                    // resolve field token
                     if (field.ResolveToken(arg, assm, &stack->m_call) == false)
                     {
                         NANOCLR_SET_AND_LEAVE(CLR_E_WRONG_TYPE);
                     }
 
-                    CLR_RT_HeapBlock *ptr = CLR_RT_ExecutionEngine::AccessStaticField(field);
+                    if (field.genericType && NANOCLR_INDEX_IS_VALID(*field.genericType))
+                    {
+                        // access static field of a generic instance
+                        ptr = field.assembly->GetStaticFieldByFieldDef(field, field.genericType);
+                    }
+                    else
+                    {
+                        // static field of a non-generic class
+                        ptr = CLR_RT_ExecutionEngine::AccessStaticField(field);
+                    }
 
                     if (ptr == nullptr)
                     {