[RFC] use templated isl types reductionMapSchedule

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/polyhedral/cuda/mapped_scop.cc

@@ -319,8 +319,8 @@ bool MappedScop::needReductionSeparation(const ScheduleTree* st) {
   return !reductionBandUpdates_.at(st).separated;
 }
 
-isl::multi_union_pw_aff MappedScop::reductionMapSchedule(
-    const ScheduleTree* st) {
+isl::MultiUnionPwAff<Statement, ReductionSchedule>
+MappedScop::reductionMapSchedule(const ScheduleTree* st) {
   TC_CHECK(reductionBandUpdates_.count(st) == 1);
   auto reductionBand = st->as<ScheduleTreeBand>();
   TC_CHECK(reductionBand);
@@ -342,10 +342,10 @@ ScheduleTree* MappedScop::separateReduction(ScheduleTree* st) {
 
   auto root = scop_->scheduleRoot();
   auto domain = activeDomainPoints(root, st);
-  auto prefixSchedule = prefixScheduleMupa(root, st);
+  auto prefixSchedule = prefixScheduleMupa<Prefix>(root, st);
   auto reductionSchedule = reductionMapSchedule(st);
   auto space = reductionSchedule.get_space();
-  auto size = isl::multi_val::zero(space);
+  auto size = isl::MultiVal<ReductionSchedule>::zero(space);
   for (size_t i = 0; i < numThreads.view.size(); ++i) {
     auto pos = numThreads.view.size() - 1 - i;
     size = size.set_val(pos, isl::val(st->ctx_, numThreads.view[i]));

tc/core/polyhedral/cuda/mapped_scop.h

@@ -24,6 +24,7 @@
 #include "tc/core/cuda/cuda_mapping_options.h"
 #include "tc/core/polyhedral/cuda/mapping_types.h"
 #include "tc/core/polyhedral/cuda/memory_promotion_heuristic.h"
+#include "tc/core/polyhedral/domain_types.h"
 #include "tc/core/polyhedral/scop.h"
 #include "tc/core/tensor.h"
 #include "tc/external/isl.h"
@@ -171,7 +172,8 @@ class MappedScop {
   // Return the schedule that will be used by mapInnermostBandsToThreads
   // for mapping to thread identifiers, with the last function
   // corresponding to thread identifier x.
-  isl::multi_union_pw_aff reductionMapSchedule(const detail::ScheduleTree* st);
+  isl::MultiUnionPwAff<Statement, ReductionSchedule> reductionMapSchedule(
+      const detail::ScheduleTree* st);
   // Separate out reductions that can be mapped to an entire block.
   // The remaining parts, if any, are no longer considered for replacement
   // by a library call.