feat(mgb/opr): let Indexing(Set)MultiAxisVec support empty input

GitOrigin-RevId: f15b1d45a1f8ea9b51ccfe1fc4e42414de496fe2

src/opr/impl/indexing.cpp

@@ -291,8 +291,10 @@ template<class Opr>
 cg::OperatorNodeBase::NodeProp*
 IndexingMultiAxisVecBase<Opr>::do_make_node_prop() const {
     auto prop = Super::do_make_node_prop();
+    using DT = NodeProp::DepType;
     // TODO: should also allow input shape is empty if any
     // indexer's shape is empty
+    prop->add_dep_type_existing_var(input(0), DT::VALUE_ALLOW_EMPTY);
     for (auto i: m_input2idxonly_axis_indexer) {
         if (i) {
             prop->add_dep_type_existing_var(
@@ -415,7 +417,7 @@ void intl::IndexingModifyMultiAxisVecHelper<Opr>::scn_do_execute() {
     auto inp = this->fancy_indexing_get_tensors_for_modify_in_scn_do_execute();
     auto index_desc = this->make_megdnn_index_desc(
             inp.first.layout().ndim, ShouldWarnOnScalarIndexer<Opr>::val);
-    if (index_desc.second){
+    if (inp.first.shape().is_empty() || index_desc.second){
         mgb_assert(inp.second.shape().is_empty());
         return;
     }
@@ -476,10 +478,19 @@ MGB_IMPL_FANCY_INDEXING_OPR_GET(
         output(0)->add_flag(VarNode::Flag::ALLOW_EMPTY_SHAPE);
         );
 MGB_IMPL_FANCY_INDEXING_OPR_MODIFY(
-        IndexingSetMultiAxisVec, "indexing_set_multi_axis_vec", false);
+        IndexingSetMultiAxisVec, "indexing_set_multi_axis_vec", false,
+        output(0)->add_flag(VarNode::Flag::ALLOW_EMPTY_SHAPE);
+        );
 MGB_IMPL_FANCY_INDEXING_OPR_MODIFY(
         IndexingIncrMultiAxisVec, "indexing_incr_multi_axis_vec", false);
 
+IndexingSetMultiAxisVec::NodeProp* IndexingSetMultiAxisVec::do_make_node_prop() const {
+    auto prop = Super::do_make_node_prop();
+    prop->add_dep_type_existing_var(input(0),
+            NodeProp::DepType::VALUE_ALLOW_EMPTY);
+    return prop;
+}
+
 #if MGB_ENABLE_GRAD
 MGB_IMPL_OPR_GRAD(IndexingMultiAxisVec) {
     if (wrt_idx)

src/opr/include/megbrain/opr/indexing.h

@@ -132,11 +132,11 @@ namespace intl {
 
         void init_output_static_infer_desc() override final;
         void scn_do_execute() override final;
-        NodeProp* do_make_node_prop() const override;
         void add_input_layout_constraint() override final;
 
     protected:
         using Super::Super;
+        NodeProp* do_make_node_prop() const override;
     };
 } // namespace intl
 
@@ -158,6 +158,7 @@ public:
 MGB_DEFINE_OPR_CLASS(IndexingSetMultiAxisVec,
         intl::IndexingModifyMultiAxisVecHelper<megdnn::IndexingSetMultiAxisVec>
         ) // {
+        NodeProp* do_make_node_prop() const override;
 
     public:
         MGB_DECL_FANCY_INDEXING_OPR_MODIFY(IndexingSetMultiAxisVec);

src/opr/include/megbrain/opr/internal/indexing_helper.h

@@ -241,13 +241,15 @@ MGB_DYN_TYPE_OBJ_FINAL_IMPL(_opr)
             const OperatorNodeConfig &config = {}, \
             const InputTensorReplacer &input_tensor_replacer = {})
 
-#define MGB_IMPL_FANCY_INDEXING_OPR_MODIFY(_opr, _name, _require_scalar_index) \
+#define MGB_IMPL_FANCY_INDEXING_OPR_MODIFY(_opr, _name, _require_scalar_index, \
+    ctor_body...) \
 _opr::_opr(VarNode *inp, VarNode *value, const IndexDesc &desc, \
         const OperatorNodeConfig &config, \
         const InputTensorReplacer &input_tensor_replacer): \
     Super({inp->owner_graph(), config, _name, {inp, value}}, \
             inp, value, desc, _require_scalar_index, input_tensor_replacer) \
 { \
+    ctor_body; \
 } \
 SymbolVar _opr::make(SymbolVar inp, SymbolVar value, const IndexDesc &desc, \
         const OperatorNodeConfig &config, \