fix(mgb/ops): immutable tensor support empty storage

GitOrigin-RevId: 2851498fce49d2c0801e1ef11cead37fbfddb974

src/opr/impl/io.cpp

@@ -100,7 +100,7 @@ void intl::HostIONodeBase::init_output_static_infer_desc() {
 
     if (fill_in_static_infer(nullptr)) {
         auto infer_val = [this](DeviceTensorND& dest, const InpVal&) -> bool {
-            if (fill_in_static_infer(&dest) && !dest.empty()) {
+            if (fill_in_static_infer(&dest) && dest.shape_valid()) {
                 return true;
             }
             return false;
@@ -423,8 +423,8 @@ void ImmutableTensor::Value::setup(CompNode cn, const HostTensorND& val) {
 
 DeviceTensorND& ImmutableTensor::Value::static_infer() {
     MGB_LOCK_GUARD(m_mtx);
-    if (m_static_infer.empty()) {
-        mgb_assert(!m_dev.empty());
+    if (!m_static_infer.shape_valid()) {
+        mgb_assert(m_dev.shape_valid());
         m_static_infer.comp_node(CompNode::default_cpu()).copy_from(m_dev);
     }
     return m_static_infer;