introduce a Kind of a promoted declaration

A kernel variable can be declared as shared or as automatic (register).

Author: ftynse

include/tc/core/polyhedral/scop.h

@@ -306,8 +306,11 @@ struct Scop {
   void promoteEverythingAt(std::vector<size_t> pos);
 
   struct PromotedDecl {
+    enum class Kind { SharedMem, Register };
+
     isl::id tensorId;
     std::vector<size_t> sizes;
+    Kind kind;
   };
 
   struct PromotionInfo {
@@ -356,7 +359,8 @@ struct Scop {
   // Assumes such argument exists.
   const Halide::OutputImageParam& findArgument(isl::id id) const;
 
-  // Promote a tensor reference group to shared memory, inserting the copy
+  // Promote a tensor reference group to a storage of a given "kind",
+  // inserting the copy
   // statements below the given node.  Inserts an Extension node below the give
   // node, unless there is already another Extension node which introduces
   // copies.  The Extension node has a unique Sequence child, whose children
@@ -368,7 +372,8 @@ struct Scop {
   // If "forceLastExtentOdd" is set, the last extent in the declaration is
   // incremented if it is even.  This serves as a simple heuristic to reduce
   // shared memory bank conflicts.
-  void promoteGroupToShared(
+  void promoteGroup(
+      PromotedDecl::Kind kind,
       isl::id tensorId,
       std::unique_ptr<TensorReferenceGroup>&& gr,
       detail::ScheduleTree* tree,

src/core/polyhedral/memory_promotion_heuristic.cc

@@ -530,7 +530,8 @@ void promoteToSharedGreedy(
           continue;
         }
 
-        scop.promoteGroupToShared(
+        scop.promoteGroup(
+            Scop::PromotedDecl::Kind::SharedMem,
             tensorId,
             std::move(group),
             bandNode,

src/core/polyhedral/scop.cc

@@ -179,7 +179,8 @@ void checkFiltersDisjointStatements(const ScheduleTree* root) {
 }
 } // namespace
 
-void Scop::promoteGroupToShared(
+void Scop::promoteGroup(
+    PromotedDecl::Kind kind,
     isl::id tensorId,
     std::unique_ptr<TensorReferenceGroup>&& gr,
     ScheduleTree* tree,
@@ -192,7 +193,7 @@ void Scop::promoteGroupToShared(
   if (sizes.size() > 0 && forceLastExtentOdd && (sizes.back() % 2) == 0) {
     sizes.back() += 1;
   }
-  promotedDecls_[groupId] = PromotedDecl{tensorId, sizes};
+  promotedDecls_[groupId] = PromotedDecl{tensorId, sizes, kind};
 
   auto group = std::shared_ptr<TensorReferenceGroup>(std::move(gr));
   for (const auto& id : activeStmts) {
@@ -248,7 +249,13 @@ void Scop::promoteEverythingAt(std::vector<size_t> pos) {
   auto groupMap = TensorReferenceGroup::accessedBySubtree(tree, *this);
   for (auto& p : groupMap) {
     for (auto& gr : p.second) {
-      promoteGroupToShared(p.first, std::move(gr), tree, activeStmts, schedule);
+      promoteGroup(
+          PromotedDecl::Kind::SharedMem,
+          p.first,
+          std::move(gr),
+          tree,
+          activeStmts,
+          schedule);
     }
   }
   insertSyncsAroundCopies(tree);