merge ScopedFootprint::footprint into TensorReferenceGroup::approximateFootprint

ScopedFootprint::footprint has only one call site and requires the
domain to be communicated from TensorReferenceGroup.  Arguably, only the
footprint of the entire group ever needs to be computed.  Merge the code
of ScopedFootprint::footprint into
TensorReferenceGroup::approximateFootprint.  This prepares for inclusion
of stride information.

Author: ftynse

tc/core/polyhedral/memory_promotion.cc

@@ -77,16 +77,17 @@ std::unique_ptr<TensorReferenceGroup> TensorReferenceGroup::makeSingleton(
   return group;
 }
 
-isl::set ScopedFootprint::footprint(isl::set domain) const {
-  auto space = box.get_space();
-  auto accessed = isl::map::universe(space).intersect_domain(domain);
+isl::set TensorReferenceGroup::approximateFootprint() const {
+  auto scopedDomain = scopedAccesses().domain();
+  auto space = approximation.box.get_space();
+  auto accessed = isl::map::universe(space).intersect_domain(scopedDomain);
   auto lspace = isl::local_space(accessed.get_space().range());
 
-  for (size_t i = 0; i < dim(); ++i) {
-    auto dimLowerBound = lowerBound(i);
+  for (size_t i = 0; i < approximation.dim(); ++i) {
+    auto dimLowerBound = approximation.lowerBound(i);
     auto rhs = isl::aff(lspace, isl::dim_type::set, i);
     isl::map partial = (isl::aff_map(dimLowerBound) <= rhs) &
-        (isl::aff_map(dimLowerBound + size(i)) > rhs);
+        (isl::aff_map(dimLowerBound + approximation.size(i)) > rhs);
     accessed = accessed & partial;
   }
   return accessed.range();

tc/core/polyhedral/memory_promotion.h

@@ -49,7 +49,6 @@ struct ScopedFootprint {
     return box.get_offset().get_aff(pos);
   }
   isl::fixed_box box;
-  isl::set footprint(isl::set domain) const;
   isl::multi_aff lowerBounds() const;
 };
 
@@ -131,9 +130,7 @@ class TensorReferenceGroup {
 
   // Rectangular overapproximation of the set of tensor elements accessed below
   // the scoping point.
-  isl::set approximateFootprint() const {
-    return approximation.footprint(scopedAccesses().domain());
-  }
+  isl::set approximateFootprint() const;
 
   isl::multi_aff promotion() const;
   isl::set promotedFootprint() const;