MappedScop::Reduction: drop redundant reductionDim

The reduction band member is always the one immediately following
the coincident band members, so there is no need to store
its position separately.

Author: Sven Verdoolaege

tc/core/polyhedral/cuda/mapped_scop.cc

@@ -239,7 +239,7 @@ bool MappedScop::detectReductions(detail::ScheduleTree* tree) {
   if (!inits.is_empty()) {
     orderBefore(scop_->scheduleRoot(), tree, inits);
   }
-  reductionBandUpdates_.emplace(tree, Reduction(updateIds, reductionDim));
+  reductionBandUpdates_.emplace(tree, Reduction(updateIds));
   return true;
 }
 
@@ -261,11 +261,9 @@ isl::multi_union_pw_aff MappedScop::reductionMapSchedule(
   // mapped to threads.
   auto reductionSchedule = reductionBand->mupa_;
   auto nMember = reductionBand->nMember();
-  auto reductionDim = reductionBandUpdates_.at(st).reductionDim;
-  auto nMappedThreads =
-      std::min(numThreads.view.size(), reductionBand->nOuterCoincident() + 1);
+  auto reductionDim = reductionBand->nOuterCoincident();
+  auto nMappedThreads = std::min(numThreads.view.size(), reductionDim + 1);
   CHECK_GE(nMember, reductionDim);
-  CHECK_GE(reductionDim + 1, nMappedThreads);
   reductionSchedule = reductionSchedule.drop_dims(
       isl::dim_type::set, reductionDim + 1, nMember - (reductionDim + 1));
   reductionSchedule = reductionSchedule.drop_dims(

tc/core/polyhedral/cuda/mapped_scop.h

@@ -187,14 +187,11 @@ class MappedScop {
   // Information about a detected reduction that can potentially
   // be mapped to a library call.
   struct Reduction {
-    Reduction(std::vector<isl::id> ids, size_t index)
-        : ids(ids), separated(false), reductionDim(index) {}
+    Reduction(std::vector<isl::id> ids) : ids(ids), separated(false) {}
     // The statement identifiers of the reduction update statements.
     std::vector<isl::id> ids;
     // Has the reduction been separated out as a full block?
     bool separated;
-    // Index of the band member in which the reduction was detected.
-    size_t reductionDim;
   };
   // Map isolated innermost reduction band members to information
   // about the detected reduction.