[Polly][NFC][ScopBuilder] Move RecordedAssumptions vector to ScopBuilder.

[domada]

Summary

Scope of changes:

1. Moved RecordedAssumptions vector to ScopBuilder. RecordedAssumptions are used only for Scop constructions.
2. Moved definition of RecordedAssumptionsTy to ScopHelper. It is required both by ScopBuilder and SCEVAffinator.
3. Add new function recordAssumption to ScopHelper. One of its argument is a reference to RecordedAssumption vector. This function is used by ScopBuilder and SCEVAffinator.
4. All RecordedAssumptions are created by ScopBuilder. isl::pw_aff objects for corresponding SCEVs are created inside ScopBuilder. Scop functions do not record any assumptions. Scop can use isl::pw_aff objects which were created by ScopBuilder.
5. Removed functions for handling RecordedAssumptions from Scop class.
6. Removed constness from getScopArrayInfo functions.
7. Replaced SCEVVisitor struct from SCEVAffinator with taylored version, which allow to pass pointer to RecordedAssumptions as function argument.

[Meinersbur]

Nice one.

polly/lib/Analysis/ScopBuilder.cpp

1494–1495

[style] llvm::reverse(RecordedAssumptions) should work as well.

1525

[suggestion] Now that RecordedAssumptions is part of ScopBuilder, it will be freed together with ScopBuilder, so explicitly clearing it should not be necessary.

polly/lib/Analysis/ScopInfo.cpp

699–700

Nice to have this moved out of MemoryAccess

1351

Is this an intentional change? Depending on the iteration order over basic blocks, the value might be used before its write is seem, in which case we'd need getOrCreateScopArrayInfo.

1693

The RecordedAssumptions stored inside ScopBuilder has a shorter lifetime than the Affinator stored inside this Scop object. Meaning that any use of Affinator after the destruction of ScopBuilder will lead to a use-after-free error. It should not happen since adding an assumption after the Scop has been constructed will have no effect. Now new assumptions should be detectable using Valgrind/AddressSanitizer, which might be a good thing, but the potential memory corruption worries me.

Do you have any plans how to ensure no use-after-free happens? E.g. set the RecordedAssumption to nullptr after the Scop has been built. We might even work on even moving the Affinator into ScopBuilder. I would at least appreciate a comment in the code explaining this.

polly/lib/Support/ScopHelper.cpp

155–162

[serious] The comment above applies to simplifyRegion, not recordAssumption.

[domada]

polly/lib/Analysis/ScopInfo.cpp

1807

This function is still used in polly/lib/CodeGen/PPCGCodeGeneration.cpp file. That's why I haven't moved it to ScopBuilder.

[domada]

polly/lib/Analysis/ScopInfo.cpp

1351

Yes, it was an intentional change. I wanted to move getOrCreateScopArrayInfo to ScopBuilder. Currently this function is used in lib/CodeGen/PPCGCodeGeneration.cpp and in ScopBuilder. That's why I haven't moved it in this patch. I need to rethink this change.

1693

Thank you for your comment. Initially I will set RecordedAssumption to nullptr. Finally I will try to move Affinator into ScopBuilder. I think that it should be the most elegant way.

[domada]

1. Reworked mechanism of collecting assumptions. All assumptions are now taken inside ScopBuilder.
2. Internal functions of Scop class do not record any assumption. They use cached isl::pw_aff objects which are created by ScopBuilder.

[domada]

polly/lib/Analysis/ScopInfo.cpp

1693

Initial change is reverted.

[Meinersbur]

Could you upload the nest diff with context (git diff -U999999)?

polly/include/polly/ScopBuilder.h

74

[style] RecordedAssumptionsTy RecordedAssumptions = nullptr preferable over initializer in the ctor.

polly/lib/Analysis/ScopBuilder.cpp

3230

[style] No Almost Always Auto: for (const SCEV *Size: Access->Sizes)

[style] Variable start with upper cases.

3241

[style] No Almost Always Auto: for (const SCEV *Subscript : Access->Subscripts)

[suggestion] Access using a getter might be preferable

3799

[suggestion] Clearing may not be necessary.

polly/lib/Support/SCEVAffinator.cpp

120

[serious] Assigning the field in one of the methods instead of in the ctor makes the lifetime issue even worse. Is there a reason not to pass RecordedAssumptions by function arguments?

[domada]

Uploaded the same changes with the more context: git format-patch -U999999 HEAD~1

[domada]

polly/lib/Support/SCEVAffinator.cpp

120

Some RecordedAssumptions are added inside visit and other visit_type_of_scev functions functions (for example visitTruncateExpr ). visit function and other visit_type_of_scev functions are part of` llvm::SCEVVisitor` struct. I cannot modify number of parameters for these functions, because they are part of LLVM infrastructure.

That's why I am trying to add pointer of RecordedAssumption vector to SCEVAffinator. This pointer is visible inside all functions inside SCEVAffinator class and I don't need to pass it as function argument.

I am wondering if it is worth to split SCEVAffinator into two classes? The first class will be responsible only for delivering PWACtx, and the second will be responsible for recording assumptions. The class for collecting assumptions will be instantiated only in ScopBuilder so the problem with object lifetime will be solved. The drawback of this approach is duplicated traversing of some SCEVs.

[Meinersbur]

LGTM. Please consider the [style] remarks as well before committing.

Thanks for the effort.

polly/lib/Support/SCEVAffinator.cpp

120

I see, thanks for the explanation.

For the [[ https://github.com/llvm/llvm-project/blob/master/polly/lib/Transform/ScheduleTreeTransform.cpp#L25 | ScheduleTreeVisitor ]] my solution was to implement visitor methods with variadic arguments, so you actually can pass additional parameters.

But I also think any workaround will be overkill for now and we just use the solution already done for BB.

[domada]

This patch implements individual version of SCEVVisitor. Taylored version of SCEVVisitor is required to pass pointer to RecordedAssumptions to visit_type_scev functions.

Please let me know if you prefer this solution or the previous one.

Before commit I will also fix style remarks.

[domada]

polly/lib/Support/SCEVAffinator.cpp

120

I have implemented something similar to ScheduleTreeVisitor, please look at function visitSCEV and please express your opinion.

On one hand implementation of own SCEVVisitor resolves problem of lifetime issue, but on the other hand I have created more code which is to some extent redundant to LLVM code.

polly/include/polly/ScopBuilder.h

   // The Scop
   std::unique_ptr<Scop> scop;
 
+  /// Collection to hold taken assumptions.
+  ///
+  /// There are two reasons why we want to record assumptions first before we
+  /// add them to the assumed/invalid context:
+  ///   1) If the SCoP is not profitable or otherwise invalid without the
+  ///      assumed/invalid context we do not have to compute it.
+  ///   2) Information about the context are gathered rather late in the SCoP
+  ///      construction (basically after we know all parameters), thus the user
+  ///      might see overly complicated assumptions to be taken while they will
+  ///      only be simplified later on.
+  RecordedAssumptionsTy RecordedAssumptions;
+
   // Methods for pattern matching against Fortran code generated by dragonegg.
   // @{
 

polly/include/polly/ScopInfo.h

 
 #include "polly/ScopDetection.h"
 #include "polly/Support/SCEVAffinator.h"
+#include "polly/Support/ScopHelper.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/MapVector.h"
 #include "llvm/ADT/SetVector.h"

 // are also unlikely to result in good code.
 extern int const MaxDisjunctsInDomain;
 
-/// Enumeration of assumptions Polly can take.
-enum AssumptionKind {
-  ALIASING,
-  INBOUNDS,
-  WRAPPING,
-  UNSIGNED,
-  PROFITABLE,
-  ERRORBLOCK,
-  COMPLEXITY,
-  INFINITELOOP,
-  INVARIANTLOAD,
-  DELINEARIZATION,
-};
-
-/// Enum to distinguish between assumptions and restrictions.
-enum AssumptionSign { AS_ASSUMPTION, AS_RESTRICTION };
-
 /// The different memory kinds used in Polly.
 ///
 /// We distinguish between arrays and various scalar memory objects. We use

 
   isl::basic_map createBasicAccessMap(ScopStmt *Statement);
 
-  void assumeNoOutOfBound();
+  isl::set assumeNoOutOfBound();
 
   /// Compute bounds on an over approximated  access relation.
   ///

 /// Print ScopStmt S to raw_ostream OS.
 raw_ostream &operator<<(raw_ostream &OS, const ScopStmt &S);
 
-/// Helper struct to remember assumptions.
-struct Assumption {
-  /// The kind of the assumption (e.g., WRAPPING).
-  AssumptionKind Kind;
-
-  /// Flag to distinguish assumptions and restrictions.
-  AssumptionSign Sign;
-
-  /// The valid/invalid context if this is an assumption/restriction.
-  isl::set Set;
-
-  /// The location that caused this assumption.
-  DebugLoc Loc;
-
-  /// An optional block whose domain can simplify the assumption.
-  BasicBlock *BB;
-};
-
 /// Build the conditions sets for the branch condition @p Condition in
 /// the @p Domain.
 ///

   /// need to be "false". Otherwise they behave the same.
   isl::set InvalidContext;
 
-  using RecordedAssumptionsTy = SmallVector<Assumption, 8>;
-  /// Collection to hold taken assumptions.
-  ///
-  /// There are two reasons why we want to record assumptions first before we
-  /// add them to the assumed/invalid context:
-  ///   1) If the SCoP is not profitable or otherwise invalid without the
-  ///      assumed/invalid context we do not have to compute it.
-  ///   2) Information about the context are gathered rather late in the SCoP
-  ///      construction (basically after we know all parameters), thus the user
-  ///      might see overly complicated assumptions to be taken while they will
-  ///      only be simplified later on.
-  RecordedAssumptionsTy RecordedAssumptions;
-
   /// The schedule of the SCoP
   ///
   /// The schedule of the SCoP describes the execution order of the statements

                       InvariantEquivClasses.end());
   }
 
-  /// Return an iterator range containing hold assumptions.
-  iterator_range<RecordedAssumptionsTy::const_iterator>
-  recorded_assumptions() const {
-    return make_range(RecordedAssumptions.begin(), RecordedAssumptions.end());
-  }
-
   /// Return an iterator range containing all the MemoryAccess objects of the
   /// Scop.
   iterator_range<AccFuncVector::iterator> access_functions() {

   /// @returns True if the optimized SCoP can be executed.
   bool hasFeasibleRuntimeContext() const;
 
-  /// Clear assumptions which have been already processed.
-  void clearRecordedAssumptions() { return RecordedAssumptions.clear(); }
-
   /// Check if the assumption in @p Set is trivial or not.
   ///
   /// @param Set  The relations between parameters that are assumed to hold.

   void addAssumption(AssumptionKind Kind, isl::set Set, DebugLoc Loc,
                      AssumptionSign Sign, BasicBlock *BB);
 
-  /// Record an assumption for later addition to the assumed context.
-  ///
-  /// This function will add the assumption to the RecordedAssumptions. This
-  /// collection will be added (@see addAssumption) to the assumed context once
-  /// all paramaters are known and the context is fully built.
-  ///
-  /// @param Kind The assumption kind describing the underlying cause.
-  /// @param Set  The relations between parameters that are assumed to hold.
-  /// @param Loc  The location in the source that caused this assumption.
-  /// @param Sign Enum to indicate if the assumptions in @p Set are positive
-  ///             (needed/assumptions) or negative (invalid/restrictions).
-  /// @param BB   The block in which this assumption was taken. If it is
-  ///             set, the domain of that block will be used to simplify the
-  ///             actual assumption in @p Set once it is added. This is useful
-  ///             if the assumption was created prior to the domain.
-  void recordAssumption(AssumptionKind Kind, isl::set Set, DebugLoc Loc,
-                        AssumptionSign Sign, BasicBlock *BB = nullptr);
-
   /// Mark the scop as invalid.
   ///
   /// This method adds an assumption to the scop that is always invalid. As a

   ///
   /// @returns The ScopArrayInfo pointer or NULL if no such pointer is
   ///          available.
-  const ScopArrayInfo *getScopArrayInfoOrNull(Value *BasePtr, MemoryKind Kind);
+  ScopArrayInfo *getScopArrayInfoOrNull(Value *BasePtr, MemoryKind Kind);
 
   /// Return the cached ScopArrayInfo object for @p BasePtr.
   ///

   ///
   /// @returns The ScopArrayInfo pointer (may assert if no such pointer is
   ///          available).
-  const ScopArrayInfo *getScopArrayInfo(Value *BasePtr, MemoryKind Kind);
+  ScopArrayInfo *getScopArrayInfo(Value *BasePtr, MemoryKind Kind);
 
   /// Invalidate ScopArrayInfo object for base address.
   ///

   /// a dummy value of appropriate dimension is returned. This allows to bail
   /// for complex cases without "error handling code" needed on the users side.
   PWACtx getPwAff(const SCEV *E, BasicBlock *BB = nullptr,
-                  bool NonNegative = false);
+                  bool NonNegative = false,
+                  RecordedAssumptionsTy *RecordedAssumptions = nullptr);
 
   /// Compute the isl representation for the SCEV @p E
   ///
   /// This function is like @see Scop::getPwAff() but strips away the invalid
   /// domain part associated with the piecewise affine function.
-  isl::pw_aff getPwAffOnly(const SCEV *E, BasicBlock *BB = nullptr);
+  isl::pw_aff
+  getPwAffOnly(const SCEV *E, BasicBlock *BB = nullptr,
+               RecordedAssumptionsTy *RecordedAssumptions = nullptr);
 
   /// Check if an <nsw> AddRec for the loop L is cached.
   bool hasNSWAddRecForLoop(Loop *L) { return Affinator.hasNSWAddRecForLoop(L); }

polly/include/polly/Support/SCEVAffinator.h

 #ifndef POLLY_SCEV_AFFINATOR_H
 #define POLLY_SCEV_AFFINATOR_H
 
+#include "polly/Support/ScopHelper.h"
 #include "llvm/Analysis/ScalarEvolutionExpressions.h"
 #include "isl/isl-noexceptions.h"
 

   /// @param BB The block in which @p E is executed.
   ///
   /// @returns The isl representation of the SCEV @p E in @p Domain.
-  PWACtx getPwAff(const llvm::SCEV *E, llvm::BasicBlock *BB = nullptr);
+  PWACtx getPwAff(const llvm::SCEV *E, llvm::BasicBlock *BB = nullptr,
+                  RecordedAssumptionsTy *RecordedAssumptions = nullptr);
 
   /// Take the assumption that @p PWAC is non-negative.
-  void takeNonNegativeAssumption(PWACtx &PWAC);
+  void takeNonNegativeAssumption(
+      PWACtx &PWAC, RecordedAssumptionsTy *RecordedAssumptions = nullptr);
 
   /// Interpret the PWA in @p PWAC as an unsigned value.
   void interpretAsUnsigned(PWACtx &PWAC, unsigned Width);

   llvm::ScalarEvolution &SE;
   llvm::LoopInfo &LI;
   llvm::BasicBlock *BB;
+  RecordedAssumptionsTy *RecordedAssumptions;
 
   /// Target data for element size computing.
   const llvm::DataLayout &TD;

polly/include/polly/Support/ScopHelper.h

 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/ValueHandle.h"
+#include "isl/isl-noexceptions.h"
 
 namespace llvm {
 class LoopInfo;

 class Scop;
 class ScopStmt;
 
+/// Enumeration of assumptions Polly can take.
+enum AssumptionKind {
+  ALIASING,
+  INBOUNDS,
+  WRAPPING,
+  UNSIGNED,
+  PROFITABLE,
+  ERRORBLOCK,
+  COMPLEXITY,
+  INFINITELOOP,
+  INVARIANTLOAD,
+  DELINEARIZATION,
+};
+
+/// Enum to distinguish between assumptions and restrictions.
+enum AssumptionSign { AS_ASSUMPTION, AS_RESTRICTION };
+
+/// Helper struct to remember assumptions.
+struct Assumption {
+  /// The kind of the assumption (e.g., WRAPPING).
+  AssumptionKind Kind;
+
+  /// Flag to distinguish assumptions and restrictions.
+  AssumptionSign Sign;
+
+  /// The valid/invalid context if this is an assumption/restriction.
+  isl::set Set;
+
+  /// The location that caused this assumption.
+  llvm::DebugLoc Loc;
+
+  /// An optional block whose domain can simplify the assumption.
+  llvm::BasicBlock *BB;
+};
+
+using RecordedAssumptionsTy = llvm::SmallVector<Assumption, 8>;
+
+/// Record an assumption for later addition to the assumed context.
+///
+/// This function will add the assumption to the RecordedAssumptions. This
+/// collection will be added (@see addAssumption) to the assumed context once
+/// all paramaters are known and the context is fully built.
+///
+/// @param RecordedAssumption container which keeps all recorded assumptions.
+/// @param Kind The assumption kind describing the underlying cause.
+/// @param Set  The relations between parameters that are assumed to hold.
+/// @param Loc  The location in the source that caused this assumption.
+/// @param Sign Enum to indicate if the assumptions in @p Set are positive
+///             (needed/assumptions) or negative (invalid/restrictions).
+/// @param BB   The block in which this assumption was taken. If it is
+///             set, the domain of that block will be used to simplify the
+///             actual assumption in @p Set once it is added. This is useful
+///             if the assumption was created prior to the domain.
+void recordAssumption(RecordedAssumptionsTy *RecordedAssumptions,
+                      AssumptionKind Kind, isl::set Set, llvm::DebugLoc Loc,
+                      AssumptionSign Sign, llvm::BasicBlock *BB = nullptr);
+
 /// Type to remap values.
 using ValueMapT = llvm::DenseMap<llvm::AssertingVH<llvm::Value>,
                                  llvm::AssertingVH<llvm::Value>>;

polly/lib/Analysis/ScopBuilder.cpp

         " their loads. "),
     cl::Hidden, cl::init(false), cl::cat(PollyCategory));
 
+static cl::opt<bool>
+    PollyIgnoreInbounds("polly-ignore-inbounds",
+                        cl::desc("Do not take inbounds assumptions at all"),
+                        cl::Hidden, cl::init(false), cl::cat(PollyCategory));
+
 static cl::opt<unsigned> RunTimeChecksMaxArraysPerGroup(
     "polly-rtc-max-arrays-per-group",
     cl::desc("The maximal number of arrays to compare in each alias group."),

 ScopBuilder::getPwAff(BasicBlock *BB,
                       DenseMap<BasicBlock *, isl::set> &InvalidDomainMap,
                       const SCEV *E, bool NonNegative) {
-  PWACtx PWAC = scop->getPwAff(E, BB, NonNegative);
+  PWACtx PWAC = scop->getPwAff(E, BB, NonNegative, &RecordedAssumptions);
   InvalidDomainMap[BB] = InvalidDomainMap[BB].unite(PWAC.second);
   return PWAC.first.release();
 }

     return true;
 
   isl::set UnboundedCtx = Parts.first.params();
-  scop->recordAssumption(INFINITELOOP, UnboundedCtx,
-                         HeaderBB->getTerminator()->getDebugLoc(),
-                         AS_RESTRICTION);
+  recordAssumption(&RecordedAssumptions, INFINITELOOP, UnboundedCtx,
+                   HeaderBB->getTerminator()->getDebugLoc(), AS_RESTRICTION);
   return true;
 }
 

     } else {
       InvalidDomain = Domain;
       isl::set DomPar = Domain.params();
-      scop->recordAssumption(ERRORBLOCK, DomPar,
-                             BB->getTerminator()->getDebugLoc(),
-                             AS_RESTRICTION);
+      recordAssumption(&RecordedAssumptions, ERRORBLOCK, DomPar,
+                       BB->getTerminator()->getDebugLoc(), AS_RESTRICTION);
       Domain = isl::set::empty(Domain.get_space());
     }
 

 }
 
 void ScopBuilder::addRecordedAssumptions() {
-  for (auto &AS : llvm::reverse(scop->recorded_assumptions())) {
+  for (auto &AS : llvm::reverse(RecordedAssumptions)) {
 
     if (!AS.BB) {
       scop->addAssumption(AS.Kind, AS.Set, AS.Loc, AS.Sign,

 
     scop->addAssumption(AS.Kind, isl::manage(S), AS.Loc, AS_RESTRICTION, AS.BB);
   }
-  scop->clearRecordedAssumptions();
 }
 
 void ScopBuilder::addUserAssumptions(

 }
 
 void ScopBuilder::assumeNoOutOfBounds() {
+  if (PollyIgnoreInbounds)
+    return;
   for (auto &Stmt : *scop)
-    for (auto &Access : Stmt)
-      Access->assumeNoOutOfBound();
+    for (auto &Access : Stmt) {
+      isl::set Outside = Access->assumeNoOutOfBound();
+      const auto &Loc = Access->getAccessInstruction()
+                            ? Access->getAccessInstruction()->getDebugLoc()
+                            : DebugLoc();
+      recordAssumption(&RecordedAssumptions, INBOUNDS, Outside, Loc,
+                       AS_ASSUMPTION);
+    }
 }
 
 void ScopBuilder::ensureValueWrite(Instruction *Inst) {

     else
       Ty = MemoryKind::Array;
 
+    // Create isl::pw_aff for SCEVs which describe sizes. Collect all
+    // assumptions which are taken. isl::pw_aff objects are cached internally and
+    // they are used later by scop.
+    for (auto &size : Access->Sizes) {
+      if (!size)
+        continue;
+      scop->getPwAff(size, nullptr, false, &RecordedAssumptions);
+    }
     auto *SAI = scop->getOrCreateScopArrayInfo(Access->getOriginalBaseAddr(),
                                                ElementType, Access->Sizes, Ty);
+
+    // Create isl::pw_aff for SCEVs which describe subscripts. Collect all
+    // assumptions which are taken. isl::pw_aff objects are cached internally and
+    // they are used later by scop.
+    for (auto &subscript : Access->Subscripts) {
+      if (!Access->isAffine() || !subscript)
+        continue;
+      scop->getPwAff(subscript, Stmt.getEntryBlock(), false,
+                     &RecordedAssumptions);
+    }
     Access->buildAccessRelation(SAI);
     scop->addAccessData(Access);
   }

     InfeasibleScops++;
     Msg = "SCoP ends here but was dismissed.";
     LLVM_DEBUG(dbgs() << "SCoP detected but dismissed\n");
+    RecordedAssumptions.clear();
     scop.reset();
   } else {
     Msg = "SCoP ends here.";

polly/lib/Analysis/ScopInfo.cpp

     cl::desc("Take more precise inbounds assumptions (do not scale well)"),
     cl::Hidden, cl::init(false), cl::cat(PollyCategory));
 
-static cl::opt<bool>
-    PollyIgnoreInbounds("polly-ignore-inbounds",
-                        cl::desc("Do not take inbounds assumptions at all"),
-                        cl::Hidden, cl::init(false), cl::cat(PollyCategory));
-
 static cl::opt<bool> PollyIgnoreParamBounds(
     "polly-ignore-parameter-bounds",
     cl::desc(

 // possibly yield out of bound memory accesses. The complement of these
 // constraints is the set of constraints that needs to be assumed to ensure such
 // statement instances are never executed.
-void MemoryAccess::assumeNoOutOfBound() {
-  if (PollyIgnoreInbounds)
-    return;
+isl::set MemoryAccess::assumeNoOutOfBound() {
   auto *SAI = getScopArrayInfo();
   isl::space Space = getOriginalAccessRelationSpace().range();
   isl::set Outside = isl::set::empty(Space);

   // bail out more often than strictly necessary.
   Outside = Outside.remove_divs();
   Outside = Outside.complement();
-  const auto &Loc = getAccessInstruction()
-                        ? getAccessInstruction()->getDebugLoc()
-                        : DebugLoc();
+
   if (!PollyPreciseInbounds)
     Outside = Outside.gist_params(Statement->getDomain().params());
-  Statement->getParent()->recordAssumption(INBOUNDS, Outside, Loc,
-                                           AS_ASSUMPTION);
+  return Outside;
 }
 
 void MemoryAccess::buildMemIntrinsicAccessRelation() {

   return SAI;
 }
 
-const ScopArrayInfo *Scop::getScopArrayInfoOrNull(Value *BasePtr,
-                                                  MemoryKind Kind) {
+ScopArrayInfo *Scop::getScopArrayInfoOrNull(Value *BasePtr, MemoryKind Kind) {
   auto *SAI = ScopArrayInfoMap[std::make_pair(BasePtr, Kind)].get();
   return SAI;
 }
 
-const ScopArrayInfo *Scop::getScopArrayInfo(Value *BasePtr, MemoryKind Kind) {
+ScopArrayInfo *Scop::getScopArrayInfo(Value *BasePtr, MemoryKind Kind) {
   auto *SAI = getScopArrayInfoOrNull(BasePtr, Kind);
   assert(SAI && "No ScopArrayInfo available for this base pointer");
   return SAI;

     InvalidContext = InvalidContext.unite(Set).coalesce();
 }
 
-void Scop::recordAssumption(AssumptionKind Kind, isl::set Set, DebugLoc Loc,
-                            AssumptionSign Sign, BasicBlock *BB) {
-  assert((Set.is_params() || BB) &&
-         "Assumptions without a basic block must be parameter sets");
-  RecordedAssumptions.push_back({Kind, Sign, Set, Loc, BB});
-}
-
 void Scop::invalidate(AssumptionKind Kind, DebugLoc Loc, BasicBlock *BB) {
   LLVM_DEBUG(dbgs() << "Invalidate SCoP because of reason " << Kind << "\n");
   addAssumption(Kind, isl::set::empty(getParamSpace()), Loc, AS_ASSUMPTION, BB);

 isl::ctx Scop::getIslCtx() const { return IslCtx.get(); }
 
 __isl_give PWACtx Scop::getPwAff(const SCEV *E, BasicBlock *BB,
-                                 bool NonNegative) {
+                                 bool NonNegative,
+                                 RecordedAssumptionsTy *RecordedAssumptions) {
   // First try to use the SCEVAffinator to generate a piecewise defined
   // affine function from @p E in the context of @p BB. If that tasks becomes to
   // complex the affinator might return a nullptr. In such a case we invalidate
   // the SCoP and return a dummy value. This way we do not need to add error
   // handling code to all users of this function.
-  auto PWAC = Affinator.getPwAff(E, BB);
+  auto PWAC = Affinator.getPwAff(E, BB, RecordedAssumptions);
   if (PWAC.first) {
     // TODO: We could use a heuristic and either use:
     //         SCEVAffinator::takeNonNegativeAssumption

     //         SCEVAffinator::interpretAsUnsigned
     //       to deal with unsigned or "NonNegative" SCEVs.
     if (NonNegative)
-      Affinator.takeNonNegativeAssumption(PWAC);
+      Affinator.takeNonNegativeAssumption(PWAC, RecordedAssumptions);
     return PWAC;
   }
 
   auto DL = BB ? BB->getTerminator()->getDebugLoc() : DebugLoc();
   invalidate(COMPLEXITY, DL, BB);
-  return Affinator.getPwAff(SE->getZero(E->getType()), BB);
+  return Affinator.getPwAff(SE->getZero(E->getType()), BB, RecordedAssumptions);
 }
 
 isl::union_set Scop::getDomains() const {

   return isl::manage(Domain);
 }
 
-isl::pw_aff Scop::getPwAffOnly(const SCEV *E, BasicBlock *BB) {
-  PWACtx PWAC = getPwAff(E, BB);
+isl::pw_aff Scop::getPwAffOnly(const SCEV *E, BasicBlock *BB,
+                               RecordedAssumptionsTy *RecordedAssumptions) {
+  PWACtx PWAC = getPwAff(E, BB, RecordedAssumptions);
   return PWAC.first;
 }
 

polly/lib/Support/SCEVAffinator.cpp

 
 SCEVAffinator::SCEVAffinator(Scop *S, LoopInfo &LI)
     : S(S), Ctx(S->getIslCtx().get()), SE(*S->getSE()), LI(LI),
+      RecordedAssumptions(nullptr),
       TD(S->getFunction().getParent()->getDataLayout()) {}
 
 Loop *SCEVAffinator::getScope() { return BB ? LI.getLoopFor(BB) : nullptr; }

       NonNegPWA, isl_pw_aff_add(PWAC.first.release(), ExpPWA)));
 }
 
-void SCEVAffinator::takeNonNegativeAssumption(PWACtx &PWAC) {
+void SCEVAffinator::takeNonNegativeAssumption(
+    PWACtx &PWAC, RecordedAssumptionsTy *RecordedAssumptions) {
+  this->RecordedAssumptions = RecordedAssumptions;
+
   auto *NegPWA = isl_pw_aff_neg(PWAC.first.copy());
   auto *NegDom = isl_pw_aff_pos_set(NegPWA);
   PWAC.second =
       isl::manage(isl_set_union(PWAC.second.release(), isl_set_copy(NegDom)));
   auto *Restriction = BB ? NegDom : isl_set_params(NegDom);
   auto DL = BB ? BB->getTerminator()->getDebugLoc() : DebugLoc();
-  S->recordAssumption(UNSIGNED, isl::manage(Restriction), DL, AS_RESTRICTION,
-                      BB);
+  recordAssumption(RecordedAssumptions, UNSIGNED, isl::manage(Restriction), DL,
+                   AS_RESTRICTION, BB);
 }
 
 PWACtx SCEVAffinator::getPWACtxFromPWA(isl::pw_aff PWA) {
   return std::make_pair(PWA, isl::set::empty(isl::space(Ctx, 0, NumIterators)));
 }
 
-PWACtx SCEVAffinator::getPwAff(const SCEV *Expr, BasicBlock *BB) {
+PWACtx SCEVAffinator::getPwAff(const SCEV *Expr, BasicBlock *BB,
+                               RecordedAssumptionsTy *RecordedAssumptions) {
   this->BB = BB;
+  this->RecordedAssumptions = RecordedAssumptions;
 
   if (BB) {
     auto *DC = S->getDomainConditions(BB).release();

   NotEqualSet = NotEqualSet.coalesce();
 
   if (!NotEqualSet.is_empty())
-    S->recordAssumption(WRAPPING, NotEqualSet, Loc, AS_RESTRICTION, BB);
+    recordAssumption(RecordedAssumptions, WRAPPING, NotEqualSet, Loc,
+                     AS_RESTRICTION, BB);
 
   return PWAC;
 }

     OutOfBoundsDom = isl_set_params(OutOfBoundsDom);
   }
 
-  S->recordAssumption(UNSIGNED, isl::manage(OutOfBoundsDom), DebugLoc(),
-                      AS_RESTRICTION, BB);
+  recordAssumption(RecordedAssumptions, UNSIGNED, isl::manage(OutOfBoundsDom),
+                   DebugLoc(), AS_RESTRICTION, BB);
 
   return OpPWAC;
 }

 
   // If the width is to big we assume the negative part does not occur.
   if (!computeModuloForExpr(Op)) {
-    takeNonNegativeAssumption(OpPWAC);
+    takeNonNegativeAssumption(OpPWAC, RecordedAssumptions);
     return OpPWAC;
   }
 

   //       precise but therefor a heuristic is needed.
 
   // Assume a non-negative dividend.
-  takeNonNegativeAssumption(DividendPWAC);
+  takeNonNegativeAssumption(DividendPWAC, RecordedAssumptions);
 
   DividendPWAC = combine(DividendPWAC, DivisorPWAC, isl_pw_aff_div);
   DividendPWAC.first = DividendPWAC.first.floor();

polly/lib/Support/ScopHelper.cpp

   polly::splitEntryBlockForAlloca(EntryBlock, DT, LI, RI);
 }
 
+void polly::recordAssumption(polly::RecordedAssumptionsTy *RecordedAssumptions,
+                             polly::AssumptionKind Kind, isl::set Set,
+                             DebugLoc Loc, polly::AssumptionSign Sign,
+                             BasicBlock *BB) {
+  assert((Set.is_params() || BB) &&
+         "Assumptions without a basic block must be parameter sets");
+  if (RecordedAssumptions)
+    RecordedAssumptions->push_back({Kind, Sign, Set, Loc, BB});
+}
+
 /// The SCEVExpander will __not__ generate any code for an existing SDiv/SRem
 /// instruction but just use it, if it is referenced as a SCEVUnknown. We want
 /// however to generate new code if the instruction is in the analyzed region