[RFC] use templated isl types makeParameterContext

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

@@ -866,7 +866,8 @@ void MappedScop::insertMappingContext() {
   auto space = scop.domain().get_space();
   auto mappingContext = makeParameterContext(
       space, mappingIdsWithSizes.begin(), mappingIdsWithSizes.end());
-  updateTopLevelContext(scop.scheduleRoot(), mappingContext.from_params());
+  updateTopLevelContext(
+      scop.scheduleRoot(), mappingContext.from_params<Prefix>());
 }
 
 namespace {

tc/external/detail/islpp.h

@@ -303,17 +303,17 @@ isl::multi_val makeMultiVal(isl::space s, const std::vector<T>& vals) {
 // 2. each new parameter dimension p(i) is bounded to be in [0, e(i) - 1]
 // 3. if e (i) == 0 then no constraint is set on the corresponding id(i)
 template <typename IterPair>
-inline isl::set makeParameterContext(
-    isl::space paramSpace,
+inline isl::Set<> makeParameterContext(
+    isl::Space<> paramSpace,
     const IterPair begin,
     const IterPair end) {
   for (auto it = begin; it != end; ++it) {
     paramSpace = paramSpace.add_param(it->first);
   }
-  isl::set res(isl::set::universe(paramSpace));
+  auto res(isl::Set<>::universe(paramSpace));
   for (auto it = begin; it != end; ++it) {
-    isl::aff a(isl::aff::param_on_domain_space(paramSpace, it->first));
-    res = res & (isl::aff_set(a) >= 0) & (isl::aff_set(a) < it->second);
+    auto a(isl::AffOn<>::param_on_domain_space(paramSpace, it->first));
+    res = res & isl::PwAffOn<>(a).nonneg_set() & isl::PwAffOn<>(it->second - a).pos_set();
   }
   return res;
 }