Add static fields for generic types

- TypeSpec cross reference now stores instances of static fields and field defs.
- Assembly now has GetGenericStaticField() and GetStaticFieldByFieldDef().
- TypeSpec instance now has a helper API IsClosedGenericType().
- Update handlers for stsfld, ldsfld and ldsflda to deal with static fields of closed generic types.

Author: josesimoes

src/CLR/Core/Interpreter.cpp

@@ -2728,13 +2728,33 @@ 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
+                        CLR_RT_FieldDef_Index genericField{};
+                        genericField.data = field.data;
+
+                        // find the assembly where the generic type is instantiated
+                        CLR_RT_Assembly *typeSpecAsm =
+                            g_CLR_RT_TypeSystem.m_assemblies[field.genericType->Assembly() - 1];
+
+                        // now access the generic static field
+                        ptr = typeSpecAsm->GetGenericStaticField(*field.genericType, genericField);
+                    }
+                    else
+                    {
+                        // static field of a non-generic class
+                        ptr = CLR_RT_ExecutionEngine::AccessStaticField(field);
+                    }
 
                     if (ptr == nullptr)
                     {
@@ -2756,13 +2776,33 @@ 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
+                        CLR_RT_FieldDef_Index genericField{};
+                        genericField.data = field.data;
+
+                        // find the assembly where the generic type is instantiated
+                        CLR_RT_Assembly *typeSpecAsm =
+                            g_CLR_RT_TypeSystem.m_assemblies[field.genericType->Assembly() - 1];
+
+                        // now access the generic static field
+                        ptr = typeSpecAsm->GetGenericStaticField(*field.genericType, genericField);
+                    }
+                    else
+                    {
+                        // static field of a non-generic class
+                        ptr = CLR_RT_ExecutionEngine::AccessStaticField(field);
+                    }
 
                     if (ptr == nullptr)
                     {
@@ -2783,13 +2823,33 @@ 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
+                        CLR_RT_FieldDef_Index genericField{};
+                        genericField.data = field.data;
+
+                        // find the assembly where the generic type is instantiated
+                        CLR_RT_Assembly *typeSpecAsm =
+                            g_CLR_RT_TypeSystem.m_assemblies[field.genericType->Assembly() - 1];
+
+                        // now access the generic static field
+                        ptr = typeSpecAsm->GetGenericStaticField(*field.genericType, genericField);
+                    }
+                    else
+                    {
+                        // static field of a non-generic class
+                        ptr = CLR_RT_ExecutionEngine::AccessStaticField(field);
+                    }
 
                     if (ptr == nullptr)
                     {