schedule_isl_conversion.cc: extendChild: extract out insertChild

extendChild moves down in both the original tree and
the result of the conversion.  Sometimes, however, it can be useful
to only move down in the original tree without moving
in the converted tree, e.g., when no corresponding node
is introduced in the converted tree.
This will be used for the thread specific marker nodes
added in the next commit.

Author: Sven Verdoolaege

tc/core/polyhedral/schedule_isl_conversion.cc

@@ -51,6 +51,7 @@ constexpr std::initializer_list<detail::ScheduleTreeType>
 
 namespace {
 
+isl::schedule_node insertChild(isl::schedule_node node, const ScheduleTree* st);
 isl::schedule_node extendChild(isl::schedule_node node, const ScheduleTree* st);
 
 /*
@@ -210,17 +211,27 @@ isl::schedule_node insert(isl::schedule_node node, const ScheduleTree* st) {
 
 /*
  * Recursively add nodes corresponding to the descendants of "st"
- * underneath "node".
+ * at "node".
  * If "st" does not have any children, then no descendants need to be added.
  */
-isl::schedule_node extendChild(
+isl::schedule_node insertChild(
     isl::schedule_node node,
     const ScheduleTree* st) {
   if (st->numChildren() == 0) {
     return node;
   }
 
-  return insert(node.child(0), st->child({0})).parent();
+  return insert(node, st->child({0}));
+}
+
+/*
+ * Recursively add nodes corresponding to the descendants of "st"
+ * underneath "node".
+ */
+isl::schedule_node extendChild(
+    isl::schedule_node node,
+    const ScheduleTree* st) {
+  return insertChild(node.child(0), st).parent();
 }
 } // namespace