[RFC] use templated isl types constructTensorTuple

Templated isl types require the user to specify the domain and range
universes of isl objects, allowing the compiler to check whether
it makes sense to combine pairs of objects.
This RFC only converts isPromotableToRegistersBelow and some related
functions to illustrate the effect.
The isPromotableToRegistersBelow was already applying operations
correctly, so the code itself did not require any changes.
However, one variable was reused to store different types
of intermediate result and this one had to be split up into
several variables because they now have different types.

Author: Sven Verdoolaege

tc/core/halide2isl.cc

@@ -258,7 +258,7 @@ isl::map extractAccess(
   // to the outer loop iterators) and then convert this set
   // into a map in terms of the iteration domain.
 
-  isl::space paramSpace = domain.paramSpace;
+  auto paramSpace = isl::Space<>(domain.paramSpace);
   isl::id tensorID(paramSpace.get_ctx(), tensor);
   auto tensorTuple = constructTensorTuple(paramSpace, tensorID, args.size());
   auto tensorSpace = tensorTuple.get_space();

tc/core/polyhedral/domain_types.h

@@ -0,0 +1,15 @@
+namespace tc {
+namespace polyhedral {
+
+struct Prefix;
+struct Reduction;
+struct ReductionSchedule;
+struct Scope;
+struct Statement;
+struct Tag;
+struct Tensor;
+struct Thread;
+struct Warp;
+
+} // namespace polyhedral
+} // namespace tc

tc/core/polyhedral/memory_promotion.cc

@@ -410,7 +410,7 @@ namespace {
 // context of the scop.
 isl::set tensorElementsSet(const Scop& scop, isl::id tensorId) {
   auto halideParameter = scop.findArgument(tensorId).parameter();
-  auto space = scop.domain().get_space();
+  auto space = isl::Space<>(scop.domain().get_space());
   auto nDim = halideParameter.dimensions();
   auto tensorTuple = constructTensorTuple(space, tensorId, nDim);
   auto tensorSpace = tensorTuple.get_space();

tc/core/polyhedral/utils.cc

@@ -15,6 +15,8 @@
  */
 #include "tc/core/polyhedral/utils.h"
 
+#include "tc/core/polyhedral/domain_types.h"
+
 namespace tc {
 namespace polyhedral {
 
@@ -24,15 +26,15 @@ namespace polyhedral {
  * of the user.
  * Since some names are required, use names of the form "__tc_tensor_arg*".
  */
-isl::multi_id
-constructTensorTuple(isl::space paramSpace, isl::id tensorId, size_t dim) {
-  auto tensorSpace = paramSpace.add_named_tuple_id_ui(tensorId, dim);
+isl::MultiId<Tensor>
+constructTensorTuple(isl::Space<> paramSpace, isl::id tensorId, size_t dim) {
+  auto tensorSpace = paramSpace.add_named_tuple_id_ui<Tensor>(tensorId, dim);
   isl::id_list tensorArgs(paramSpace.get_ctx(), 0);
   for (size_t i = 0; i < dim; ++i) {
     auto name = std::string("__tc_tensor_arg") + std::to_string(i);
     tensorArgs = tensorArgs.add(isl::id(paramSpace.get_ctx(), name));
   }
-  return isl::multi_id(tensorSpace, tensorArgs);
+  return isl::MultiId<Tensor>(tensorSpace, tensorArgs);
 }
 
 } // namespace polyhedral

tc/core/polyhedral/utils.h

@@ -15,6 +15,7 @@
  */
 #pragma once
 
+#include "tc/core/polyhedral/domain_types.h"
 #include "tc/external/isl.h"
 
 namespace tc {
@@ -24,8 +25,8 @@ namespace polyhedral {
  * dimension "dim" from the parameter space "paramSpace",
  * without any specific names for the indices.
  */
-isl::multi_id
-constructTensorTuple(isl::space paramSpace, isl::id tensorId, size_t dim);
+isl::MultiId<Tensor>
+constructTensorTuple(isl::Space<> paramSpace, isl::id tensorId, size_t dim);
 
 } // namespace polyhedral
 } // namespace tc