introduce MappedScop::blockMappingSchedule

By analogy with MappedScop::threadMappingSchedule, this function
constructs the mapping of domain elements to blocks as
multi_union_pw_aff.  It will be used in the subsequent commits.

Author: ftynse

tc/core/polyhedral/cuda/mapped_scop.cc

@@ -461,6 +461,8 @@ bool hasOuterSequentialMember(
   return false;
 }
 
+// Name of the space of blocks inside the grid
+constexpr auto kGrid = "grid";
 // Name of the space of threads inside a block
 constexpr auto kBlock = "block";
 // Name of the space of warps
@@ -510,6 +512,16 @@ isl::multi_union_pw_aff MappedScop::threadMappingSchedule(
   return extractDomainToIds(tree, ids, tupleId);
 }
 
+isl::multi_union_pw_aff MappedScop::blockMappingSchedule(
+    const detail::ScheduleTree* tree) const {
+  std::vector<mapping::MappingId> ids;
+  for (size_t i = 0; i < numBlocks.view.size(); ++i) {
+    ids.emplace_back(mapping::BlockId::makeId(i));
+  }
+  auto tupleId = isl::id(tree->ctx_, kGrid);
+  return extractDomainToIds(scop_->scheduleRoot(), tree, ids, tupleId);
+}
+
 Scop::SyncLevel MappedScop::findBestSync(
     detail::ScheduleTree* st1,
     detail::ScheduleTree* st2,

tc/core/polyhedral/cuda/mapped_scop.h

@@ -193,6 +193,13 @@ class MappedScop {
   isl::multi_union_pw_aff threadMappingSchedule(
       const detail::ScheduleTree* tree) const;
 
+  // Extract a mapping from the domain elements active at "tree"
+  // to the block identifiers, where all branches in "tree"
+  // are assumed to have been mapped to block identifiers.
+  // The result lives in a space of the form grid[x, ...].
+  isl::multi_union_pw_aff blockMappingSchedule(
+      const detail::ScheduleTree* tree) const;
+
  private:
   // Insert the optimal combination of synchronizations in the sequence
   void insertBestSyncInSeq(detail::ScheduleTree* seq);