ScheduleTreeBand: hide copy constructor

ScheduleTree nodes are not supposed to be manipulated by-value, only via unique
pointers.  Make the copy constructor of ScheduleTreeBand private, similarly to
its main constructor, and provide a static member function to return copies
wrapped in a unique pointer.  Note that unlike the conventional copy
constructor, this static function takes a pointer to the tree rather than a
reference.  This keeps the API consistent as all other functions manipulate
with pointers to the tree nodes rather than references.

Author: ftynse

tc/core/polyhedral/schedule_tree.cc

@@ -137,7 +137,7 @@ static std::unique_ptr<ScheduleTree> makeElem(const ScheduleTree& st) {
   if (st.type_ == detail::ScheduleTreeType::None) {
     LOG(FATAL) << "Hit Error node!";
   }
-  ELEM_MAKE_CASE(ScheduleTreeBand)
+  ELEM_MAKE_CASE_CSTR(ScheduleTreeBand)
   ELEM_MAKE_CASE_CSTR(ScheduleTreeContext)
   ELEM_MAKE_CASE_CSTR(ScheduleTreeDomain)
   ELEM_MAKE_CASE_CSTR(ScheduleTreeExtension)

tc/core/polyhedral/schedule_tree_elem.cc

@@ -201,6 +201,14 @@ std::unique_ptr<ScheduleTreeBand> ScheduleTreeBand::make(
   return band;
 }
 
+std::unique_ptr<ScheduleTreeBand> ScheduleTreeBand::make(
+    const ScheduleTreeBand* tree,
+    std::vector<ScheduleTreeUPtr>&& children) {
+  auto res = std::unique_ptr<ScheduleTreeBand>(new ScheduleTreeBand(*tree));
+  res->appendChildren(std::move(children));
+  return res;
+}
+
 // Return the number of scheduling dimensions in the band
 size_t ScheduleTreeBand::nMember() const {
   size_t res = mupa_.size();

tc/core/polyhedral/schedule_tree_elem.h

@@ -261,17 +261,17 @@ struct ScheduleTreeSet : public ScheduleTree {
 struct ScheduleTreeBand : public ScheduleTree {
  private:
   explicit ScheduleTreeBand(isl::ctx ctx) : ScheduleTree(ctx, {}, NodeType) {}
-
- public:
-  static constexpr detail::ScheduleTreeType NodeType =
-      detail::ScheduleTreeType::Band;
-
   ScheduleTreeBand(const ScheduleTreeBand& eb)
       : ScheduleTree(eb),
         permutable_(eb.permutable_),
         mupa_(eb.mupa_),
         coincident_(eb.coincident_),
         unroll_(eb.unroll_) {}
+
+ public:
+  static constexpr detail::ScheduleTreeType NodeType =
+      detail::ScheduleTreeType::Band;
+
   virtual ~ScheduleTreeBand() override {}
 
   bool operator==(const ScheduleTreeBand& other) const;
@@ -290,6 +290,9 @@ struct ScheduleTreeBand : public ScheduleTree {
       std::vector<bool> coincident,
       std::vector<bool> unroll,
       std::vector<ScheduleTreeUPtr>&& children = {});
+  static std::unique_ptr<ScheduleTreeBand> make(
+      const ScheduleTreeBand* tree,
+      std::vector<ScheduleTreeUPtr>&& children = {});
 
   // Return the number of scheduling dimensions in the band
   size_t nMember() const;