Generalize attribute_as_atomic to obj attrs too

In preparation for adding some atomic store and atomic bind ops for
attributes.

src/6model/6model.h

@@ -388,11 +388,11 @@ struct MVMREPROps_Attribute {
         MVMint64 hint);
 
     /* Provided the attribute is a native integer of the architecture's atomic
-     * size, returns an AO_t * referencing it. This is only valid until the
-     * next safepoint. If rebless is called on the object, updates may be lost
-     * although memory safety must not be violated. */
+     * size or an object pointer, returns an AO_t * referencing it. This is only
+     * valid until the next safepoint. If rebless is called on the object,
+     * updates may be lost although memory safety must not be violated. */
     AO_t * (*attribute_as_atomic) (MVMThreadContext *tc, MVMSTable *st,
-        void *data, MVMObject *class_handle, MVMString *name);
+        void *data, MVMObject *class_handle, MVMString *name, MVMuint16 kind);
 };
 struct MVMREPROps_Boxing {
     /* Used with boxing. Sets an integer value, for representations that

src/6model/reprs.c

@@ -24,7 +24,7 @@ GCC_DIAG_OFF(return-type)
 MVMint64 MVM_REPR_DEFAULT_IS_ATTRIBUTE_INITIALIZED(MVMThreadContext *tc, MVMSTable *st, void *data, MVMObject *class_handle, MVMString *name, MVMint64 hint) {
     die_no_attrs(tc, st->REPR->name, MVM_6model_get_stable_debug_name(tc, st));
 }
-AO_t * MVM_REPR_DEFAULT_ATTRIBUTE_AS_ATOMIC(MVMThreadContext *tc, MVMSTable *st, void *data, MVMObject *class_handle, MVMString *name) {
+AO_t * MVM_REPR_DEFAULT_ATTRIBUTE_AS_ATOMIC(MVMThreadContext *tc, MVMSTable *st, void *data, MVMObject *class_handle, MVMString *name, MVMuint16 kind) {
     die_no_attrs(tc, st->REPR->name, MVM_6model_get_stable_debug_name(tc, st));
 }
 GCC_DIAG_ON(return-type)

src/6model/reprs.h

@@ -174,7 +174,7 @@ void MVM_REPR_DEFAULT_GET_ATTRIBUTE(MVMThreadContext *tc, MVMSTable *st, MVMObje
 void MVM_REPR_DEFAULT_BIND_ATTRIBUTE(MVMThreadContext *tc, MVMSTable *st, MVMObject *root, void *data, MVMObject *class_handle, MVMString *name, MVMint64 hint, MVMRegister value, MVMuint16 kind);
 MVMint64 MVM_REPR_DEFAULT_IS_ATTRIBUTE_INITIALIZED(MVMThreadContext *tc, MVMSTable *st, void *data, MVMObject *class_handle, MVMString *name, MVMint64 hint);
 MVMint64 MVM_REPR_DEFAULT_HINT_FOR(MVMThreadContext *tc, MVMSTable *st, MVMObject *class_handle, MVMString *name);
-AO_t * MVM_REPR_DEFAULT_ATTRIBUTE_AS_ATOMIC(MVMThreadContext *tc, MVMSTable *st, void *data, MVMObject *class_handle, MVMString *name);
+AO_t * MVM_REPR_DEFAULT_ATTRIBUTE_AS_ATOMIC(MVMThreadContext *tc, MVMSTable *st, void *data, MVMObject *class_handle, MVMString *name, MVMuint16 kind);
 
 /* Default boxing REPR function for a REPR that lacks it. */
 void MVM_REPR_DEFAULT_SET_INT(MVMThreadContext *tc, MVMSTable *st, MVMObject *root, void *data, MVMint64 value);

src/6model/reprs/NativeRef.c

@@ -592,7 +592,7 @@ AO_t * MVM_nativeref_as_atomic_attribute_i(MVMThreadContext *tc, MVMObject *ref_
     MVMNativeRef *ref = (MVMNativeRef *)ref_obj;
     MVMObject *obj = ref->body.u.attribute.obj;
     return REPR(obj)->attr_funcs.attribute_as_atomic(tc, STABLE(obj), OBJECT_BODY(obj),
-        ref->body.u.attribute.class_handle, ref->body.u.attribute.name);
+        ref->body.u.attribute.class_handle, ref->body.u.attribute.name, MVM_reg_int64);
 }
 AO_t * MVM_nativeref_as_atomic_positional_i(MVMThreadContext *tc, MVMObject *ref_obj) {
     MVMNativeRef *ref = (MVMNativeRef *)ref_obj;

src/6model/reprs/P6opaque.c

@@ -431,7 +431,8 @@ static MVMint64 hint_for(MVMThreadContext *tc, MVMSTable *st, MVMObject *class_k
 /* Gets an architecture atomic sized native integer attribute as an atomic
  * reference. */
 static AO_t * attribute_as_atomic(MVMThreadContext *tc, MVMSTable *st, void *data,
-                                  MVMObject *class_handle, MVMString *name) {
+                                  MVMObject *class_handle, MVMString *name,
+                                  MVMuint16 kind) {
     MVMP6opaqueREPRData *repr_data = (MVMP6opaqueREPRData *)st->REPR_data;
     MVMint64 slot;
     data = MVM_p6opaque_real_data(tc, data);
@@ -440,15 +441,24 @@ static AO_t * attribute_as_atomic(MVMThreadContext *tc, MVMSTable *st, void *dat
             "P6opaque: must compose %s before using get_attribute", MVM_6model_get_stable_debug_name(tc, st));
     slot = try_get_slot(tc, repr_data, class_handle, name);
     if (slot >= 0) {
-        MVMSTable *attr_st = repr_data->flattened_stables[slot];
-        if (attr_st) {
-            const MVMStorageSpec *ss = attr_st->REPR->get_storage_spec(tc, attr_st);
-            if (ss->inlineable && ss->boxed_primitive == MVM_STORAGE_SPEC_BP_INT &&
-                    ss->bits / 8 == sizeof(AO_t))
-                return (AO_t *)((char *)data + repr_data->attribute_offsets[slot]);
+        if (kind == MVM_reg_int64) {
+            MVMSTable *attr_st = repr_data->flattened_stables[slot];
+            if (attr_st) {
+                const MVMStorageSpec *ss = attr_st->REPR->get_storage_spec(tc, attr_st);
+                if (ss->inlineable && ss->boxed_primitive == MVM_STORAGE_SPEC_BP_INT &&
+                        ss->bits / 8 == sizeof(AO_t))
+                    return (AO_t *)((char *)data + repr_data->attribute_offsets[slot]);
+            }
+            MVM_exception_throw_adhoc(tc,
+                "Can only do an atomic integer operation on an atomicint attribute");
+        }
+        else if (kind == MVM_reg_obj) {
+            return (AO_t *)((char *)data + repr_data->attribute_offsets[slot]);
+        }
+        else {
+            MVM_exception_throw_adhoc(tc,
+                "Can only perform atomic operations on object or atomicint attributes");
         }
-        MVM_exception_throw_adhoc(tc,
-            "Can only do an atomic integer operation on an atomicint attribute");
     }
     else {
         no_such_attribute(tc, "get atomic reference to", class_handle, name, st);