[Polly] Migrate -polly-mse to the new pass manager.

This patch implements the `MaximalStaticExpansion` and its printer in NPM.

Reviewed By: Meinersbur

Differential Revision: https://reviews.llvm.org/D125870

polly/include/polly/LinkAllPasses.h

@@ -162,7 +162,7 @@ void initializeManagedMemoryRewritePassPass(llvm::PassRegistry &);
 #endif
 void initializeIslScheduleOptimizerWrapperPassPass(llvm::PassRegistry &);
 void initializeIslScheduleOptimizerPrinterLegacyPassPass(llvm::PassRegistry &);
-void initializeMaximalStaticExpanderPass(llvm::PassRegistry &);
+void initializeMaximalStaticExpanderWrapperPassPass(llvm::PassRegistry &);
 void initializePollyCanonicalizePass(llvm::PassRegistry &);
 void initializeFlattenSchedulePass(llvm::PassRegistry &);
 void initializeFlattenSchedulePrinterLegacyPassPass(llvm::PassRegistry &);

polly/include/polly/MaximalStaticExpansion.h

@@ -0,0 +1,42 @@
+//===- polly/MaximalStaticExpansion.h - expand memory access -*- C++ -*-======//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass fully expand the memory accesses of a Scop to get rid of
+// dependencies.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef POLLY_MAXIMALSTATICEXPANSION_H
+#define POLLY_MAXIMALSTATICEXPANSION_H
+
+#include "polly/ScopPass.h"
+#include "llvm/IR/PassManager.h"
+
+namespace polly {
+
+class MaximalStaticExpansionPass
+    : public llvm::PassInfoMixin<MaximalStaticExpansionPass> {
+public:
+  llvm::PreservedAnalyses run(Scop &, ScopAnalysisManager &,
+                              ScopStandardAnalysisResults &, SPMUpdater &);
+};
+
+struct MaximalStaticExpansionPrinterPass
+    : llvm::PassInfoMixin<MaximalStaticExpansionPrinterPass> {
+  MaximalStaticExpansionPrinterPass(raw_ostream &OS) : OS(OS) {}
+
+  PreservedAnalyses run(Scop &S, ScopAnalysisManager &,
+                        ScopStandardAnalysisResults &SAR, SPMUpdater &);
+
+private:
+  llvm::raw_ostream &OS;
+};
+
+} // namespace polly
+
+#endif /* POLLY_MAXIMALSTATICEXPANSION_H */

polly/lib/Support/PollyPasses.def

@@ -43,4 +43,6 @@ SCOP_PASS("polly-prune-unprofitable", PruneUnprofitablePass())
 SCOP_PASS("polly-opt-isl", IslScheduleOptimizerPass())
 SCOP_PASS("print<polly-opt-isl>", IslScheduleOptimizerPrinterPass(llvm::outs()))
 SCOP_PASS("polly-dce", DeadCodeElimPass())
+SCOP_PASS("polly-mse", MaximalStaticExpansionPass())
+SCOP_PASS("print<polly-mse>", MaximalStaticExpansionPrinterPass(llvm::outs()))
 #undef SCOP_PASS

polly/lib/Support/RegisterPasses.cpp

@@ -30,6 +30,7 @@
 #include "polly/ForwardOpTree.h"
 #include "polly/JSONExporter.h"
 #include "polly/LinkAllPasses.h"
+#include "polly/MaximalStaticExpansion.h"
 #include "polly/PolyhedralInfo.h"
 #include "polly/PruneUnprofitable.h"
 #include "polly/ScheduleOptimizer.h"
@@ -263,7 +264,7 @@ void initializePollyPasses(llvm::PassRegistry &Registry) {
   initializeJSONExporterPass(Registry);
   initializeJSONImporterPass(Registry);
   initializeJSONImporterPrinterLegacyPassPass(Registry);
-  initializeMaximalStaticExpanderPass(Registry);
+  initializeMaximalStaticExpanderWrapperPassPass(Registry);
   initializeIslAstInfoWrapperPassPass(Registry);
   initializeIslAstInfoPrinterLegacyPassPass(Registry);
   initializeIslScheduleOptimizerWrapperPassPass(Registry);

polly/lib/Transform/MaximalStaticExpansion.cpp

@@ -11,6 +11,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "polly/MaximalStaticExpansion.h"
 #include "polly/DependenceInfo.h"
 #include "polly/LinkAllPasses.h"
 #include "polly/ScopInfo.h"
@@ -34,13 +35,13 @@ using namespace polly;
 
 namespace {
 
-class MaximalStaticExpander final : public ScopPass {
+class MaximalStaticExpanderWrapperPass final : public ScopPass {
 public:
   static char ID;
 
-  explicit MaximalStaticExpander() : ScopPass(ID) {}
+  explicit MaximalStaticExpanderWrapperPass() : ScopPass(ID) {}
 
-  ~MaximalStaticExpander() override = default;
+  ~MaximalStaticExpanderWrapperPass() override = default;
 
   /// Expand the accesses of the SCoP.
   ///
@@ -55,63 +56,7 @@ public:
 
   /// Register all analyses and transformations required.
   void getAnalysisUsage(AnalysisUsage &AU) const override;
-
-private:
-  /// OptimizationRemarkEmitter object for displaying diagnostic remarks.
-  OptimizationRemarkEmitter *ORE;
-
-  /// Emit remark
-  void emitRemark(StringRef Msg, Instruction *Inst);
-
-  /// Return true if the SAI in parameter is expandable.
-  ///
-  /// @param SAI the SAI that need to be checked.
-  /// @param Writes A set that will contains all the write accesses.
-  /// @param Reads A set that will contains all the read accesses.
-  /// @param S The SCop in which the SAI is in.
-  /// @param Dependences The RAW dependences of the SCop.
-  bool isExpandable(const ScopArrayInfo *SAI,
-                    SmallPtrSetImpl<MemoryAccess *> &Writes,
-                    SmallPtrSetImpl<MemoryAccess *> &Reads, Scop &S,
-                    const isl::union_map &Dependences);
-
-  /// Expand the MemoryAccess according to its domain.
-  ///
-  /// @param S The SCop in which the memory access appears in.
-  /// @param MA The memory access that need to be expanded.
-  ScopArrayInfo *expandAccess(Scop &S, MemoryAccess *MA);
-
-  /// Filter the dependences to have only one related to current memory access.
-  ///
-  /// @param S The SCop in which the memory access appears in.
-  /// @param MapDependences The dependences to filter.
-  /// @param MA The memory access that need to be expanded.
-  isl::union_map filterDependences(Scop &S,
-                                   const isl::union_map &MapDependences,
-                                   MemoryAccess *MA);
-
-  /// Expand the MemoryAccess according to Dependences and already expanded
-  /// MemoryAccesses.
-  ///
-  /// @param The SCop in which the memory access appears in.
-  /// @param The memory access that need to be expanded.
-  /// @param Dependences The RAW dependences of the SCop.
-  /// @param ExpandedSAI The expanded SAI created during write expansion.
-  /// @param Reverse if true, the Dependences union_map is reversed before
-  /// intersection.
-  void mapAccess(Scop &S, SmallPtrSetImpl<MemoryAccess *> &Accesses,
-                 const isl::union_map &Dependences, ScopArrayInfo *ExpandedSAI,
-                 bool Reverse);
-
-  /// Expand PHI memory accesses.
-  ///
-  /// @param The SCop in which the memory access appears in.
-  /// @param The ScopArrayInfo representing the PHI accesses to expand.
-  /// @param Dependences The RAW dependences of the SCop.
-  void expandPhi(Scop &S, const ScopArrayInfo *SAI,
-                 const isl::union_map &Dependences);
 };
-} // namespace
 
 #ifndef NDEBUG
 /// Whether a dimension of a set is bounded (lower and upper) by a constant,
@@ -128,360 +73,482 @@ static bool isDimBoundedByConstant(isl::set Set, unsigned dim) {
 }
 #endif
 
-char MaximalStaticExpander::ID = 0;
+class MaximalStaticExpansionImpl {
+  OptimizationRemarkEmitter &ORE;
+  Scop &S;
+  isl::union_map &Dependences;
 
-isl::union_map MaximalStaticExpander::filterDependences(
-    Scop &S, const isl::union_map &Dependences, MemoryAccess *MA) {
-  auto SAI = MA->getLatestScopArrayInfo();
-
-  auto AccessDomainSet = MA->getAccessRelation().domain();
-  auto AccessDomainId = AccessDomainSet.get_tuple_id();
-
-  isl::union_map MapDependences = isl::union_map::empty(S.getIslCtx());
-
-  for (isl::map Map : Dependences.get_map_list()) {
-    // Filter out Statement to Statement dependences.
-    if (!Map.can_curry())
-      continue;
-
-    // Intersect with the relevant SAI.
-    auto TmpMapDomainId =
-        Map.get_space().domain().unwrap().range().get_tuple_id(isl::dim::set);
-
-    ScopArrayInfo *UserSAI =
-        static_cast<ScopArrayInfo *>(TmpMapDomainId.get_user());
-
-    if (SAI != UserSAI)
-      continue;
-
-    // Get the correct S1[] -> S2[] dependence.
-    auto NewMap = Map.factor_domain();
-    auto NewMapDomainId = NewMap.domain().get_tuple_id();
-
-    if (AccessDomainId.get() != NewMapDomainId.get())
-      continue;
-
-    // Add the corresponding map to MapDependences.
-    MapDependences = MapDependences.unite(NewMap);
+  /// Emit remark
+  void emitRemark(StringRef Msg, Instruction *Inst) {
+    ORE.emit(OptimizationRemarkAnalysis(DEBUG_TYPE, "ExpansionRejection", Inst)
+             << Msg);
   }
 
-  return MapDependences;
-}
+  /// Filter the dependences to have only one related to current memory access.
+  ///
+  /// @param S The SCop in which the memory access appears in.
+  /// @param MapDependences The dependences to filter.
+  /// @param MA The memory access that need to be expanded.
+  isl::union_map filterDependences(const isl::union_map &Dependences,
+                                   MemoryAccess *MA) {
+    auto SAI = MA->getLatestScopArrayInfo();
 
-bool MaximalStaticExpander::isExpandable(
-    const ScopArrayInfo *SAI, SmallPtrSetImpl<MemoryAccess *> &Writes,
-    SmallPtrSetImpl<MemoryAccess *> &Reads, Scop &S,
-    const isl::union_map &Dependences) {
-  if (SAI->isValueKind()) {
-    Writes.insert(S.getValueDef(SAI));
-    for (auto MA : S.getValueUses(SAI))
-      Reads.insert(MA);
-    return true;
-  } else if (SAI->isPHIKind()) {
-    auto Read = S.getPHIRead(SAI);
+    auto AccessDomainSet = MA->getAccessRelation().domain();
+    auto AccessDomainId = AccessDomainSet.get_tuple_id();
 
-    auto StmtDomain = isl::union_set(Read->getStatement()->getDomain());
+    isl::union_map MapDependences = isl::union_map::empty(S.getIslCtx());
 
-    auto Writes = S.getPHIIncomings(SAI);
+    for (isl::map Map : Dependences.get_map_list()) {
+      // Filter out Statement to Statement dependences.
+      if (!Map.can_curry())
+        continue;
 
-    // Get the domain where all the writes are writing to.
-    auto WriteDomain = isl::union_set::empty(S.getIslCtx());
+      // Intersect with the relevant SAI.
+      auto TmpMapDomainId =
+          Map.get_space().domain().unwrap().range().get_tuple_id(isl::dim::set);
 
-    for (auto Write : Writes) {
-      auto MapDeps = filterDependences(S, Dependences, Write);
-      for (isl::map Map : MapDeps.get_map_list())
-        WriteDomain = WriteDomain.unite(Map.range());
+      ScopArrayInfo *UserSAI =
+          static_cast<ScopArrayInfo *>(TmpMapDomainId.get_user());
+
+      if (SAI != UserSAI)
+        continue;
+
+      // Get the correct S1[] -> S2[] dependence.
+      auto NewMap = Map.factor_domain();
+      auto NewMapDomainId = NewMap.domain().get_tuple_id();
+
+      if (AccessDomainId.get() != NewMapDomainId.get())
+        continue;
+
+      // Add the corresponding map to MapDependences.
+      MapDependences = MapDependences.unite(NewMap);
     }
 
-    // For now, read from original scalar is not possible.
-    if (!StmtDomain.is_equal(WriteDomain)) {
-      emitRemark(SAI->getName() + " read from its original value.",
-                 Read->getAccessInstruction());
+    return MapDependences;
+  }
+
+  /// Return true if the SAI in parameter is expandable.
+  ///
+  /// @param SAI the SAI that need to be checked.
+  /// @param Writes A set that will contains all the write accesses.
+  /// @param Reads A set that will contains all the read accesses.
+  /// @param S The SCop in which the SAI is in.
+  /// @param Dependences The RAW dependences of the SCop.
+  bool isExpandable(const ScopArrayInfo *SAI,
+                    SmallPtrSetImpl<MemoryAccess *> &Writes,
+                    SmallPtrSetImpl<MemoryAccess *> &Reads, Scop &S) {
+    if (SAI->isValueKind()) {
+      Writes.insert(S.getValueDef(SAI));
+      for (auto MA : S.getValueUses(SAI))
+        Reads.insert(MA);
+      return true;
+    } else if (SAI->isPHIKind()) {
+      auto Read = S.getPHIRead(SAI);
+
+      auto StmtDomain = isl::union_set(Read->getStatement()->getDomain());
+
+      auto Writes = S.getPHIIncomings(SAI);
+
+      // Get the domain where all the writes are writing to.
+      auto WriteDomain = isl::union_set::empty(S.getIslCtx());
+
+      for (auto Write : Writes) {
+        auto MapDeps = filterDependences(Dependences, Write);
+        for (isl::map Map : MapDeps.get_map_list())
+          WriteDomain = WriteDomain.unite(Map.range());
+      }
+
+      // For now, read from original scalar is not possible.
+      if (!StmtDomain.is_equal(WriteDomain)) {
+        emitRemark(SAI->getName() + " read from its original value.",
+                   Read->getAccessInstruction());
+        return false;
+      }
+
+      return true;
+    } else if (SAI->isExitPHIKind()) {
+      // For now, we are not able to expand ExitPhi.
+      emitRemark(SAI->getName() + " is a ExitPhi node.",
+                 S.getEnteringBlock()->getFirstNonPHI());
+      return false;
+    }
+
+    int NumberWrites = 0;
+    for (ScopStmt &Stmt : S) {
+      auto StmtReads = isl::union_map::empty(S.getIslCtx());
+      auto StmtWrites = isl::union_map::empty(S.getIslCtx());
+
+      for (MemoryAccess *MA : Stmt) {
+        // Check if the current MemoryAccess involved the current SAI.
+        if (SAI != MA->getLatestScopArrayInfo())
+          continue;
+
+        // For now, we are not able to expand array where read come after write
+        // (to the same location) in a same statement.
+        auto AccRel = isl::union_map(MA->getAccessRelation());
+        if (MA->isRead()) {
+          // Reject load after store to same location.
+          if (!StmtWrites.is_disjoint(AccRel)) {
+            emitRemark(SAI->getName() + " has read after write to the same "
+                                        "element in same statement. The "
+                                        "dependences found during analysis may "
+                                        "be wrong because Polly is not able to "
+                                        "handle such case for now.",
+                       MA->getAccessInstruction());
+            return false;
+          }
+
+          StmtReads = StmtReads.unite(AccRel);
+        } else {
+          StmtWrites = StmtWrites.unite(AccRel);
+        }
+
+        // For now, we are not able to expand MayWrite.
+        if (MA->isMayWrite()) {
+          emitRemark(SAI->getName() + " has a maywrite access.",
+                     MA->getAccessInstruction());
+          return false;
+        }
+
+        // For now, we are not able to expand SAI with more than one write.
+        if (MA->isMustWrite()) {
+          Writes.insert(MA);
+          NumberWrites++;
+          if (NumberWrites > 1) {
+            emitRemark(SAI->getName() + " has more than 1 write access.",
+                       MA->getAccessInstruction());
+            return false;
+          }
+        }
+
+        // Check if it is possible to expand this read.
+        if (MA->isRead()) {
+          // Get the domain of the current ScopStmt.
+          auto StmtDomain = Stmt.getDomain();
+
+          // Get the domain of the future Read access.
+          auto ReadDomainSet = MA->getAccessRelation().domain();
+          auto ReadDomain = isl::union_set(ReadDomainSet);
+
+          // Get the dependences relevant for this MA
+          auto MapDependences = filterDependences(Dependences.reverse(), MA);
+          unsigned NumberElementMap = isl_union_map_n_map(MapDependences.get());
+
+          if (NumberElementMap == 0) {
+            emitRemark("The expansion of " + SAI->getName() +
+                           " would lead to a read from the original array.",
+                       MA->getAccessInstruction());
+            return false;
+          }
+
+          auto DepsDomain = MapDependences.domain();
+
+          // If there are multiple maps in the Deps, we cannot handle this case
+          // for now.
+          if (NumberElementMap != 1) {
+            emitRemark(SAI->getName() +
+                           " has too many dependences to be handle for now.",
+                       MA->getAccessInstruction());
+            return false;
+          }
+
+          auto DepsDomainSet = isl::set(DepsDomain);
+
+          // For now, read from the original array is not possible.
+          if (!StmtDomain.is_subset(DepsDomainSet)) {
+            emitRemark("The expansion of " + SAI->getName() +
+                           " would lead to a read from the original array.",
+                       MA->getAccessInstruction());
+            return false;
+          }
+
+          Reads.insert(MA);
+        }
+      }
+    }
+
+    // No need to expand SAI with no write.
+    if (NumberWrites == 0) {
+      emitRemark(SAI->getName() + " has 0 write access.",
+                 S.getEnteringBlock()->getFirstNonPHI());
       return false;
     }
 
     return true;
-  } else if (SAI->isExitPHIKind()) {
-    // For now, we are not able to expand ExitPhi.
-    emitRemark(SAI->getName() + " is a ExitPhi node.",
-               S.getEnteringBlock()->getFirstNonPHI());
-    return false;
   }
 
-  int NumberWrites = 0;
-  for (ScopStmt &Stmt : S) {
-    auto StmtReads = isl::union_map::empty(S.getIslCtx());
-    auto StmtWrites = isl::union_map::empty(S.getIslCtx());
+  /// Expand the MemoryAccess according to Dependences and already expanded
+  /// MemoryAccesses.
+  ///
+  /// @param The SCop in which the memory access appears in.
+  /// @param The memory access that need to be expanded.
+  /// @param Dependences The RAW dependences of the SCop.
+  /// @param ExpandedSAI The expanded SAI created during write expansion.
+  /// @param Reverse if true, the Dependences union_map is reversed before
+  /// intersection.
+  void mapAccess(SmallPtrSetImpl<MemoryAccess *> &Accesses,
+                 const isl::union_map &Dependences, ScopArrayInfo *ExpandedSAI,
+                 bool Reverse) {
+    for (auto MA : Accesses) {
+      // Get the current AM.
+      auto CurrentAccessMap = MA->getAccessRelation();
 
-    for (MemoryAccess *MA : Stmt) {
-      // Check if the current MemoryAccess involved the current SAI.
-      if (SAI != MA->getLatestScopArrayInfo())
+      // Get RAW dependences for the current WA.
+      auto DomainSet = MA->getAccessRelation().domain();
+      auto Domain = isl::union_set(DomainSet);
+
+      // Get the dependences relevant for this MA.
+      isl::union_map MapDependences =
+          filterDependences(Reverse ? Dependences.reverse() : Dependences, MA);
+
+      // If no dependences, no need to modify anything.
+      if (MapDependences.is_empty())
+        return;
+
+      assert(isl_union_map_n_map(MapDependences.get()) == 1 &&
+             "There are more than one RAW dependencies in the union map.");
+      auto NewAccessMap = isl::map::from_union_map(MapDependences);
+
+      auto Id = ExpandedSAI->getBasePtrId();
+
+      // Replace the out tuple id with the one of the access array.
+      NewAccessMap = NewAccessMap.set_tuple_id(isl::dim::out, Id);
+
+      // Set the new access relation.
+      MA->setNewAccessRelation(NewAccessMap);
+    }
+  }
+
+  /// Expand the MemoryAccess according to its domain.
+  ///
+  /// @param S The SCop in which the memory access appears in.
+  /// @param MA The memory access that need to be expanded.
+  ScopArrayInfo *expandAccess(MemoryAccess *MA) {
+    // Get the current AM.
+    auto CurrentAccessMap = MA->getAccessRelation();
+
+    unsigned in_dimensions =
+        unsignedFromIslSize(CurrentAccessMap.domain_tuple_dim());
+
+    // Get domain from the current AM.
+    auto Domain = CurrentAccessMap.domain();
+
+    // Create a new AM from the domain.
+    auto NewAccessMap = isl::map::from_domain(Domain);
+
+    // Add dimensions to the new AM according to the current in_dim.
+    NewAccessMap = NewAccessMap.add_dims(isl::dim::out, in_dimensions);
+
+    // Create the string representing the name of the new SAI.
+    // One new SAI for each statement so that each write go to a different
+    // memory cell.
+    auto CurrentStmtDomain = MA->getStatement()->getDomain();
+    auto CurrentStmtName = CurrentStmtDomain.get_tuple_name();
+    auto CurrentOutId = CurrentAccessMap.get_tuple_id(isl::dim::out);
+    std::string CurrentOutIdString =
+        MA->getScopArrayInfo()->getName() + "_" + CurrentStmtName + "_expanded";
+
+    // Set the tuple id for the out dimension.
+    NewAccessMap = NewAccessMap.set_tuple_id(isl::dim::out, CurrentOutId);
+
+    // Create the size vector.
+    std::vector<unsigned> Sizes;
+    for (unsigned i = 0; i < in_dimensions; i++) {
+      assert(isDimBoundedByConstant(CurrentStmtDomain, i) &&
+             "Domain boundary are not constant.");
+      auto UpperBound = getConstant(CurrentStmtDomain.dim_max(i), true, false);
+      assert(!UpperBound.is_null() && UpperBound.is_pos() &&
+             !UpperBound.is_nan() &&
+             "The upper bound is not a positive integer.");
+      assert(UpperBound.le(isl::val(CurrentAccessMap.ctx(),
+                                    std::numeric_limits<int>::max() - 1)) &&
+             "The upper bound overflow a int.");
+      Sizes.push_back(UpperBound.get_num_si() + 1);
+    }
+
+    // Get the ElementType of the current SAI.
+    auto ElementType = MA->getLatestScopArrayInfo()->getElementType();
+
+    // Create (or get if already existing) the new expanded SAI.
+    auto ExpandedSAI =
+        S.createScopArrayInfo(ElementType, CurrentOutIdString, Sizes);
+    ExpandedSAI->setIsOnHeap(true);
+
+    // Get the out Id of the expanded Array.
+    auto NewOutId = ExpandedSAI->getBasePtrId();
+
+    // Set the out id of the new AM to the new SAI id.
+    NewAccessMap = NewAccessMap.set_tuple_id(isl::dim::out, NewOutId);
+
+    // Add constraints to linked output with input id.
+    auto SpaceMap = NewAccessMap.get_space();
+    auto ConstraintBasicMap = isl::basic_map::equal(
+        SpaceMap, unsignedFromIslSize(SpaceMap.dim(isl::dim::in)));
+    NewAccessMap = isl::map(ConstraintBasicMap);
+
+    // Set the new access relation map.
+    MA->setNewAccessRelation(NewAccessMap);
+
+    return ExpandedSAI;
+  }
+
+  /// Expand PHI memory accesses.
+  ///
+  /// @param The SCop in which the memory access appears in.
+  /// @param The ScopArrayInfo representing the PHI accesses to expand.
+  /// @param Dependences The RAW dependences of the SCop.
+  void expandPhi(Scop &S, const ScopArrayInfo *SAI,
+                 const isl::union_map &Dependences) {
+    SmallPtrSet<MemoryAccess *, 4> Writes;
+    for (auto MA : S.getPHIIncomings(SAI))
+      Writes.insert(MA);
+    auto Read = S.getPHIRead(SAI);
+    auto ExpandedSAI = expandAccess(Read);
+
+    mapAccess(Writes, Dependences, ExpandedSAI, false);
+  }
+
+public:
+  MaximalStaticExpansionImpl(Scop &S, isl::union_map &Dependences,
+                             OptimizationRemarkEmitter &ORE)
+      : S(S), ORE(ORE), Dependences(Dependences) {}
+
+  /// Expand the accesses of the SCoP
+  ///
+  /// @param S The SCoP that must be expanded
+  /// @param D The dependencies information of SCoP
+  void expand() {
+    SmallVector<ScopArrayInfo *, 4> CurrentSAI(S.arrays().begin(),
+                                               S.arrays().end());
+    for (auto SAI : CurrentSAI) {
+      SmallPtrSet<MemoryAccess *, 4> AllWrites;
+      SmallPtrSet<MemoryAccess *, 4> AllReads;
+      if (!isExpandable(SAI, AllWrites, AllReads, S))
         continue;
 
-      // For now, we are not able to expand array where read come after write
-      // (to the same location) in a same statement.
-      auto AccRel = isl::union_map(MA->getAccessRelation());
-      if (MA->isRead()) {
-        // Reject load after store to same location.
-        if (!StmtWrites.is_disjoint(AccRel)) {
-          emitRemark(SAI->getName() + " has read after write to the same "
-                                      "element in same statement. The "
-                                      "dependences found during analysis may "
-                                      "be wrong because Polly is not able to "
-                                      "handle such case for now.",
-                     MA->getAccessInstruction());
-          return false;
-        }
+      if (SAI->isValueKind() || SAI->isArrayKind()) {
+        assert(AllWrites.size() == 1 || SAI->isValueKind());
 
-        StmtReads = StmtReads.unite(AccRel);
-      } else {
-        StmtWrites = StmtWrites.unite(AccRel);
-      }
+        auto TheWrite = *(AllWrites.begin());
+        ScopArrayInfo *ExpandedArray = expandAccess(TheWrite);
 
-      // For now, we are not able to expand MayWrite.
-      if (MA->isMayWrite()) {
-        emitRemark(SAI->getName() + " has a maywrite access.",
-                   MA->getAccessInstruction());
-        return false;
-      }
-
-      // For now, we are not able to expand SAI with more than one write.
-      if (MA->isMustWrite()) {
-        Writes.insert(MA);
-        NumberWrites++;
-        if (NumberWrites > 1) {
-          emitRemark(SAI->getName() + " has more than 1 write access.",
-                     MA->getAccessInstruction());
-          return false;
-        }
-      }
-
-      // Check if it is possible to expand this read.
-      if (MA->isRead()) {
-        // Get the domain of the current ScopStmt.
-        auto StmtDomain = Stmt.getDomain();
-
-        // Get the domain of the future Read access.
-        auto ReadDomainSet = MA->getAccessRelation().domain();
-        auto ReadDomain = isl::union_set(ReadDomainSet);
-
-        // Get the dependences relevant for this MA
-        auto MapDependences = filterDependences(S, Dependences.reverse(), MA);
-        unsigned NumberElementMap = isl_union_map_n_map(MapDependences.get());
-
-        if (NumberElementMap == 0) {
-          emitRemark("The expansion of " + SAI->getName() +
-                         " would lead to a read from the original array.",
-                     MA->getAccessInstruction());
-          return false;
-        }
-
-        auto DepsDomain = MapDependences.domain();
-
-        // If there are multiple maps in the Deps, we cannot handle this case
-        // for now.
-        if (NumberElementMap != 1) {
-          emitRemark(SAI->getName() +
-                         " has too many dependences to be handle for now.",
-                     MA->getAccessInstruction());
-          return false;
-        }
-
-        auto DepsDomainSet = isl::set(DepsDomain);
-
-        // For now, read from the original array is not possible.
-        if (!StmtDomain.is_subset(DepsDomainSet)) {
-          emitRemark("The expansion of " + SAI->getName() +
-                         " would lead to a read from the original array.",
-                     MA->getAccessInstruction());
-          return false;
-        }
-
-        Reads.insert(MA);
+        mapAccess(AllReads, Dependences, ExpandedArray, true);
+      } else if (SAI->isPHIKind()) {
+        expandPhi(S, SAI, Dependences);
       }
     }
   }
 
-  // No need to expand SAI with no write.
-  if (NumberWrites == 0) {
-    emitRemark(SAI->getName() + " has 0 write access.",
-               S.getEnteringBlock()->getFirstNonPHI());
-    return false;
+  /// Dump the internal information about a performed MSE to @p OS.
+  void print(llvm::raw_ostream &OS) {
+    OS << "After arrays {\n";
+
+    for (auto &Array : S.arrays())
+      Array->print(OS);
+
+    OS << "}\n";
+
+    OS << "After accesses {\n";
+    for (auto &Stmt : S) {
+      OS.indent(4) << Stmt.getBaseName() << "{\n";
+      for (auto *MA : Stmt)
+        MA->print(OS);
+      OS.indent(4) << "}\n";
+    }
+    OS << "}\n";
+  }
+};
+
+static std::unique_ptr<MaximalStaticExpansionImpl>
+runMaximalStaticExpansion(Scop &S, OptimizationRemarkEmitter &ORE,
+                          const Dependences &D) {
+  auto Dependences = D.getDependences(Dependences::TYPE_RAW);
+
+  std::unique_ptr<MaximalStaticExpansionImpl> Impl =
+      std::make_unique<MaximalStaticExpansionImpl>(S, Dependences, ORE);
+
+  Impl->expand();
+  return Impl;
+}
+
+static PreservedAnalyses runMSEUsingNPM(Scop &S, ScopAnalysisManager &SAM,
+                                        ScopStandardAnalysisResults &SAR,
+                                        raw_ostream *OS) {
+  OptimizationRemarkEmitter ORE(&S.getFunction());
+
+  auto &DI = SAM.getResult<DependenceAnalysis>(S, SAR);
+  auto &D = DI.getDependences(Dependences::AL_Reference);
+
+  std::unique_ptr<MaximalStaticExpansionImpl> Impl =
+      runMaximalStaticExpansion(S, ORE, D);
+
+  if (OS) {
+    *OS << "Printing analysis 'Polly - Maximal static expansion of SCoP' for "
+           "region: '"
+        << S.getName() << "' in function '" << S.getFunction().getName()
+        << "':\n";
+
+    if (Impl) {
+      *OS << "MSE result:\n";
+      Impl->print(*OS);
+    }
   }
 
-  return true;
+  return PreservedAnalyses::all();
 }
 
-void MaximalStaticExpander::mapAccess(Scop &S,
-                                      SmallPtrSetImpl<MemoryAccess *> &Accesses,
-                                      const isl::union_map &Dependences,
-                                      ScopArrayInfo *ExpandedSAI,
-                                      bool Reverse) {
-  for (auto MA : Accesses) {
-    // Get the current AM.
-    auto CurrentAccessMap = MA->getAccessRelation();
+} // namespace
 
-    // Get RAW dependences for the current WA.
-    auto DomainSet = MA->getAccessRelation().domain();
-    auto Domain = isl::union_set(DomainSet);
-
-    // Get the dependences relevant for this MA.
-    isl::union_map MapDependences =
-        filterDependences(S, Reverse ? Dependences.reverse() : Dependences, MA);
-
-    // If no dependences, no need to modify anything.
-    if (MapDependences.is_empty())
-      return;
-
-    assert(isl_union_map_n_map(MapDependences.get()) == 1 &&
-           "There are more than one RAW dependencies in the union map.");
-    auto NewAccessMap = isl::map::from_union_map(MapDependences);
-
-    auto Id = ExpandedSAI->getBasePtrId();
-
-    // Replace the out tuple id with the one of the access array.
-    NewAccessMap = NewAccessMap.set_tuple_id(isl::dim::out, Id);
-
-    // Set the new access relation.
-    MA->setNewAccessRelation(NewAccessMap);
-  }
+PreservedAnalyses
+MaximalStaticExpansionPass::run(Scop &S, ScopAnalysisManager &SAM,
+                                ScopStandardAnalysisResults &SAR,
+                                SPMUpdater &) {
+  return runMSEUsingNPM(S, SAM, SAR, nullptr);
 }
 
-ScopArrayInfo *MaximalStaticExpander::expandAccess(Scop &S, MemoryAccess *MA) {
-  // Get the current AM.
-  auto CurrentAccessMap = MA->getAccessRelation();
-
-  unsigned in_dimensions =
-      unsignedFromIslSize(CurrentAccessMap.domain_tuple_dim());
-
-  // Get domain from the current AM.
-  auto Domain = CurrentAccessMap.domain();
-
-  // Create a new AM from the domain.
-  auto NewAccessMap = isl::map::from_domain(Domain);
-
-  // Add dimensions to the new AM according to the current in_dim.
-  NewAccessMap = NewAccessMap.add_dims(isl::dim::out, in_dimensions);
-
-  // Create the string representing the name of the new SAI.
-  // One new SAI for each statement so that each write go to a different memory
-  // cell.
-  auto CurrentStmtDomain = MA->getStatement()->getDomain();
-  auto CurrentStmtName = CurrentStmtDomain.get_tuple_name();
-  auto CurrentOutId = CurrentAccessMap.get_tuple_id(isl::dim::out);
-  std::string CurrentOutIdString =
-      MA->getScopArrayInfo()->getName() + "_" + CurrentStmtName + "_expanded";
-
-  // Set the tuple id for the out dimension.
-  NewAccessMap = NewAccessMap.set_tuple_id(isl::dim::out, CurrentOutId);
-
-  // Create the size vector.
-  std::vector<unsigned> Sizes;
-  for (unsigned i = 0; i < in_dimensions; i++) {
-    assert(isDimBoundedByConstant(CurrentStmtDomain, i) &&
-           "Domain boundary are not constant.");
-    auto UpperBound = getConstant(CurrentStmtDomain.dim_max(i), true, false);
-    assert(!UpperBound.is_null() && UpperBound.is_pos() &&
-           !UpperBound.is_nan() &&
-           "The upper bound is not a positive integer.");
-    assert(UpperBound.le(isl::val(CurrentAccessMap.ctx(),
-                                  std::numeric_limits<int>::max() - 1)) &&
-           "The upper bound overflow a int.");
-    Sizes.push_back(UpperBound.get_num_si() + 1);
-  }
-
-  // Get the ElementType of the current SAI.
-  auto ElementType = MA->getLatestScopArrayInfo()->getElementType();
-
-  // Create (or get if already existing) the new expanded SAI.
-  auto ExpandedSAI =
-      S.createScopArrayInfo(ElementType, CurrentOutIdString, Sizes);
-  ExpandedSAI->setIsOnHeap(true);
-
-  // Get the out Id of the expanded Array.
-  auto NewOutId = ExpandedSAI->getBasePtrId();
-
-  // Set the out id of the new AM to the new SAI id.
-  NewAccessMap = NewAccessMap.set_tuple_id(isl::dim::out, NewOutId);
-
-  // Add constraints to linked output with input id.
-  auto SpaceMap = NewAccessMap.get_space();
-  auto ConstraintBasicMap = isl::basic_map::equal(
-      SpaceMap, unsignedFromIslSize(SpaceMap.dim(isl::dim::in)));
-  NewAccessMap = isl::map(ConstraintBasicMap);
-
-  // Set the new access relation map.
-  MA->setNewAccessRelation(NewAccessMap);
-
-  return ExpandedSAI;
+PreservedAnalyses
+MaximalStaticExpansionPrinterPass::run(Scop &S, ScopAnalysisManager &SAM,
+                                       ScopStandardAnalysisResults &SAR,
+                                       SPMUpdater &) {
+  return runMSEUsingNPM(S, SAM, SAR, &OS);
 }
 
-void MaximalStaticExpander::expandPhi(Scop &S, const ScopArrayInfo *SAI,
-                                      const isl::union_map &Dependences) {
-  SmallPtrSet<MemoryAccess *, 4> Writes;
-  for (auto MA : S.getPHIIncomings(SAI))
-    Writes.insert(MA);
-  auto Read = S.getPHIRead(SAI);
-  auto ExpandedSAI = expandAccess(S, Read);
+char MaximalStaticExpanderWrapperPass::ID = 0;
 
-  mapAccess(S, Writes, Dependences, ExpandedSAI, false);
-}
-
-void MaximalStaticExpander::emitRemark(StringRef Msg, Instruction *Inst) {
-  ORE->emit(OptimizationRemarkAnalysis(DEBUG_TYPE, "ExpansionRejection", Inst)
-            << Msg);
-}
-
-bool MaximalStaticExpander::runOnScop(Scop &S) {
+bool MaximalStaticExpanderWrapperPass::runOnScop(Scop &S) {
   // Get the ORE from OptimizationRemarkEmitterWrapperPass.
-  ORE = &(getAnalysis<OptimizationRemarkEmitterWrapperPass>().getORE());
+  OptimizationRemarkEmitter *ORE =
+      &getAnalysis<OptimizationRemarkEmitterWrapperPass>().getORE();
 
   // Get the RAW Dependences.
   auto &DI = getAnalysis<DependenceInfo>();
   auto &D = DI.getDependences(Dependences::AL_Reference);
-  isl::union_map Dependences = D.getDependences(Dependences::TYPE_RAW);
 
-  SmallVector<ScopArrayInfo *, 4> CurrentSAI(S.arrays().begin(),
-                                             S.arrays().end());
-
-  for (auto SAI : CurrentSAI) {
-    SmallPtrSet<MemoryAccess *, 4> AllWrites;
-    SmallPtrSet<MemoryAccess *, 4> AllReads;
-    if (!isExpandable(SAI, AllWrites, AllReads, S, Dependences))
-      continue;
-
-    if (SAI->isValueKind() || SAI->isArrayKind()) {
-      assert(AllWrites.size() == 1 || SAI->isValueKind());
-
-      auto TheWrite = *(AllWrites.begin());
-      ScopArrayInfo *ExpandedArray = expandAccess(S, TheWrite);
-
-      mapAccess(S, AllReads, Dependences, ExpandedArray, true);
-    } else if (SAI->isPHIKind()) {
-      expandPhi(S, SAI, Dependences);
-    }
-  }
+  std::unique_ptr<MaximalStaticExpansionImpl> Impl =
+      runMaximalStaticExpansion(S, *ORE, D);
 
   return false;
 }
 
-void MaximalStaticExpander::printScop(raw_ostream &OS, Scop &S) const {
+void MaximalStaticExpanderWrapperPass::printScop(raw_ostream &OS,
+                                                 Scop &S) const {
   S.print(OS, false);
 }
 
-void MaximalStaticExpander::getAnalysisUsage(AnalysisUsage &AU) const {
+void MaximalStaticExpanderWrapperPass::getAnalysisUsage(
+    AnalysisUsage &AU) const {
   ScopPass::getAnalysisUsage(AU);
   AU.addRequired<DependenceInfo>();
   AU.addRequired<OptimizationRemarkEmitterWrapperPass>();
 }
 
 Pass *polly::createMaximalStaticExpansionPass() {
-  return new MaximalStaticExpander();
+  return new MaximalStaticExpanderWrapperPass();
 }
 
-INITIALIZE_PASS_BEGIN(MaximalStaticExpander, "polly-mse",
+INITIALIZE_PASS_BEGIN(MaximalStaticExpanderWrapperPass, "polly-mse",
                       "Polly - Maximal static expansion of SCoP", false, false);
 INITIALIZE_PASS_DEPENDENCY(DependenceInfo);
 INITIALIZE_PASS_DEPENDENCY(OptimizationRemarkEmitterWrapperPass);
-INITIALIZE_PASS_END(MaximalStaticExpander, "polly-mse",
+INITIALIZE_PASS_END(MaximalStaticExpanderWrapperPass, "polly-mse",
                     "Polly - Maximal static expansion of SCoP", false, false)

polly/test/MaximalStaticExpansion/load_after_store_same_statement.ll

@@ -1,5 +1,7 @@
 ; RUN: opt %loadPolly -polly-stmt-granularity=bb -polly-mse -polly-print-scops -disable-output < %s | FileCheck %s
+; RUN: opt %loadNPMPolly -polly-stmt-granularity=bb "-passes=scop(print<polly-mse>)" -disable-output < %s | FileCheck %s
 ; RUN: opt %loadPolly -polly-stmt-granularity=bb -polly-mse -polly-print-scops -pass-remarks-analysis="polly-mse" -disable-output < %s 2>&1| FileCheck %s --check-prefix=MSE
+; RUN: opt %loadNPMPolly -polly-stmt-granularity=bb "-passes=scop(print<polly-mse>)" -pass-remarks-analysis="polly-mse" -disable-output < %s 2>&1 | FileCheck %s --check-prefix=MSE
 ;
 ; Verify that the expansion of an array with load after store in a same statement is not done.
 ;

polly/test/MaximalStaticExpansion/read_from_original.ll

@@ -1,5 +1,7 @@
 ; RUN: opt %loadPolly -polly-mse -polly-print-scops -disable-output < %s | FileCheck %s
+; RUN: opt %loadNPMPolly "-passes=scop(print<polly-mse>)" -disable-output < %s | FileCheck %s
 ; RUN: opt %loadPolly -polly-mse -polly-print-scops -pass-remarks-analysis="polly-mse" -disable-output < %s 2>&1| FileCheck %s --check-prefix=MSE
+; RUN: opt %loadNPMPolly "-passes=scop(print<polly-mse>)" -pass-remarks-analysis="polly-mse" -disable-output < %s 2>&1 | FileCheck %s --check-prefix=MSE
 ;
 ; Verify that Polly detects problems and does not expand the array
 ;

polly/test/MaximalStaticExpansion/too_many_writes.ll

@@ -1,5 +1,7 @@
 ; RUN: opt %loadPolly -polly-mse -polly-print-scops -disable-output < %s | FileCheck %s
+; RUN: opt %loadNPMPolly "-passes=scop(print<polly-mse>)" -disable-output < %s | FileCheck %s
 ; RUN: opt %loadPolly -polly-mse -polly-print-scops -pass-remarks-analysis="polly-mse" -disable-output < %s 2>&1 | FileCheck %s --check-prefix=MSE
+; RUN: opt %loadNPMPolly "-passes=scop(print<polly-mse>)" -pass-remarks-analysis="polly-mse" -disable-output < %s 2>&1 | FileCheck %s --check-prefix=MSE
 ;
 ; Verify that Polly detects problems and does not expand the array
 ;

polly/test/MaximalStaticExpansion/working_deps_between_inners.ll

@@ -1,4 +1,5 @@
 ; RUN: opt %loadPolly -polly-mse -polly-print-scops -disable-output < %s | FileCheck %s
+; RUN: opt %loadNPMPolly "-passes=scop(print<polly-mse>)" -disable-output < %s | FileCheck %s
 ;
 ; Verify that the accesses are correctly expanded for MemoryKind::Array
 ;

polly/test/MaximalStaticExpansion/working_deps_between_inners_phi.ll

@@ -1,5 +1,7 @@
 ; RUN: opt %loadPolly -polly-mse -polly-print-scops -disable-output < %s | FileCheck %s
+; RUN: opt %loadNPMPolly "-passes=scop(print<polly-mse>)" -disable-output < %s | FileCheck %s
 ; RUN: opt %loadPolly -polly-mse -polly-print-scops -pass-remarks-analysis="polly-mse" -disable-output < %s 2>&1 | FileCheck %s --check-prefix=MSE
+; RUN: opt %loadNPMPolly -polly-stmt-granularity=bb "-passes=scop(print<polly-mse>)" -pass-remarks-analysis="polly-mse" -disable-output < %s 2>&1 | FileCheck %s --check-prefix=MSE
 ;
 ; Verify that the accesses are correctly expanded for MemoryKind::Array and MemoryKind::PHI.
 ; tmp_06_phi is not expanded because it need copy in.

polly/test/MaximalStaticExpansion/working_expansion.ll

@@ -1,4 +1,5 @@
 ; RUN: opt %loadPolly -polly-mse -polly-print-scops -disable-output < %s | FileCheck %s
+; RUN: opt %loadNPMPolly "-passes=scop(print<polly-mse>)" -disable-output < %s | FileCheck %s
 ;
 ; Verify that the accesses are correctly expanded for MemoryKind::Array
 ;

polly/test/MaximalStaticExpansion/working_expansion_multiple_dependences_per_statement.ll

@@ -1,4 +1,5 @@
 ; RUN: opt %loadPolly -polly-stmt-granularity=bb -polly-mse -polly-print-scops -disable-output < %s | FileCheck %s
+; RUN: opt %loadNPMPolly -polly-stmt-granularity=bb "-passes=scop(print<polly-mse>)" -disable-output < %s | FileCheck %s
 ;
 ; Verify that the accesses are correctly expanded
 ;

polly/test/MaximalStaticExpansion/working_expansion_multiple_instruction_per_statement.ll

@@ -1,4 +1,5 @@
 ; RUN: opt %loadPolly -polly-stmt-granularity=bb -polly-mse -polly-print-scops -disable-output < %s | FileCheck %s
+; RUN: opt %loadNPMPolly -polly-stmt-granularity=bb "-passes=scop(print<polly-mse>)" -disable-output < %s | FileCheck %s
 ;
 ; Verify that the accesses are correctly expanded
 ;

polly/test/MaximalStaticExpansion/working_phi_expansion.ll

@@ -1,5 +1,7 @@
 ; RUN: opt %loadPolly -polly-mse -polly-print-scops -disable-output < %s | FileCheck %s
+; RUN: opt %loadNPMPolly "-passes=scop(print<polly-mse>)" -disable-output < %s | FileCheck %s
 ; RUN: opt %loadPolly -polly-mse -polly-print-scops -pass-remarks-analysis="polly-mse" -disable-output < %s 2>&1 | FileCheck %s --check-prefix=MSE
+; RUN: opt %loadNPMPolly "-passes=scop(print<polly-mse>)" -pass-remarks-analysis="polly-mse" -disable-output < %s 2>&1 | FileCheck %s --check-prefix=MSE
 ;
 ; Verify that the accesses are correctly expanded for MemoryKind::PHI
 ; tmp_04 is not expanded because it need copy-in.

polly/test/MaximalStaticExpansion/working_phi_two_scalars.ll

@@ -1,5 +1,7 @@
 ; RUN: opt %loadPolly -polly-stmt-granularity=bb -polly-mse -polly-print-scops -disable-output < %s | FileCheck %s
+; RUN: opt %loadNPMPolly -polly-stmt-granularity=bb "-passes=scop(print<polly-mse>)" -disable-output < %s | FileCheck %s
 ; RUN: opt %loadPolly -polly-stmt-granularity=bb -polly-mse -polly-print-scops -pass-remarks-analysis="polly-mse" -disable-output < %s 2>&1 | FileCheck %s --check-prefix=MSE
+; RUN: opt %loadNPMPolly -polly-stmt-granularity=bb "-passes=scop(print<polly-mse>)" -pass-remarks-analysis="polly-mse" -disable-output < %s 2>&1 | FileCheck %s --check-prefix=MSE
 ;
 ; Verify that the accesses are correctly expanded for MemoryKind::PHI
 ; tmp_05 and tmp2_06 are not expanded because they need copy-in.

polly/test/MaximalStaticExpansion/working_value_expansion.ll

@@ -1,4 +1,5 @@
 ; RUN: opt %loadPolly -polly-mse -polly-print-scops -disable-output < %s | FileCheck %s
+; RUN: opt %loadNPMPolly "-passes=scop(print<polly-mse>)" -disable-output < %s | FileCheck %s
 ;
 ; Verify that the accesses are correctly expanded for MemoryKind::Value
 ;