+/// \brief Holds information about the memory runtime legality checks to verify
+/// that a group of pointers do not overlap.
+class RuntimePointerChecking {
+public:
+ struct PointerInfo {
+ /// Holds the pointer value that we need to check.
+ TrackingVH<Value> PointerValue;
+ /// Holds the pointer value at the beginning of the loop.
+ const SCEV *Start;
+ /// Holds the pointer value at the end of the loop.
+ const SCEV *End;
+ /// Holds the information if this pointer is used for writing to memory.
+ bool IsWritePtr;
+ /// Holds the id of the set of pointers that could be dependent because of a
+ /// shared underlying object.
+ unsigned DependencySetId;
+ /// Holds the id of the disjoint alias set to which this pointer belongs.
+ unsigned AliasSetId;
+ /// SCEV for the access.
+ const SCEV *Expr;
+
+ PointerInfo(Value *PointerValue, const SCEV *Start, const SCEV *End,
+ bool IsWritePtr, unsigned DependencySetId, unsigned AliasSetId,
+ const SCEV *Expr)
+ : PointerValue(PointerValue), Start(Start), End(End),
+ IsWritePtr(IsWritePtr), DependencySetId(DependencySetId),
+ AliasSetId(AliasSetId), Expr(Expr) {}
+ };
+
+ RuntimePointerChecking(ScalarEvolution *SE) : Need(false), SE(SE) {}
+
+ /// Reset the state of the pointer runtime information.
+ void reset() {
+ Need = false;
+ Pointers.clear();
+ Checks.clear();
+ }
+
+ /// Insert a pointer and calculate the start and end SCEVs.
+ void insert(Loop *Lp, Value *Ptr, bool WritePtr, unsigned DepSetId,
+ unsigned ASId, const ValueToValueMap &Strides);
+
+ /// \brief No run-time memory checking is necessary.
+ bool empty() const { return Pointers.empty(); }
+
+ /// A grouping of pointers. A single memcheck is required between
+ /// two groups.
+ struct CheckingPtrGroup {
+ /// \brief Create a new pointer checking group containing a single
+ /// pointer, with index \p Index in RtCheck.
+ CheckingPtrGroup(unsigned Index, RuntimePointerChecking &RtCheck)
+ : RtCheck(RtCheck), High(RtCheck.Pointers[Index].End),
+ Low(RtCheck.Pointers[Index].Start) {
+ Members.push_back(Index);
+ }
+
+ /// \brief Tries to add the pointer recorded in RtCheck at index
+ /// \p Index to this pointer checking group. We can only add a pointer
+ /// to a checking group if we will still be able to get
+ /// the upper and lower bounds of the check. Returns true in case
+ /// of success, false otherwise.
+ bool addPointer(unsigned Index);
+
+ /// Constitutes the context of this pointer checking group. For each
+ /// pointer that is a member of this group we will retain the index
+ /// at which it appears in RtCheck.
+ RuntimePointerChecking &RtCheck;
+ /// The SCEV expression which represents the upper bound of all the
+ /// pointers in this group.
+ const SCEV *High;
+ /// The SCEV expression which represents the lower bound of all the
+ /// pointers in this group.
+ const SCEV *Low;
+ /// Indices of all the pointers that constitute this grouping.
+ SmallVector<unsigned, 2> Members;
+ };
+
+ /// \brief A memcheck which made up of a pair of grouped pointers.
+ ///
+ /// These *have* to be const for now, since checks are generated from
+ /// CheckingPtrGroups in LAI::addRuntimeChecks which is a const member
+ /// function. FIXME: once check-generation is moved inside this class (after
+ /// the PtrPartition hack is removed), we could drop const.
+ typedef std::pair<const CheckingPtrGroup *, const CheckingPtrGroup *>
+ PointerCheck;
+
+ /// \brief Generate the checks and store it. This also performs the grouping
+ /// of pointers to reduce the number of memchecks necessary.
+ void generateChecks(MemoryDepChecker::DepCandidates &DepCands,
+ bool UseDependencies);
+
+ /// \brief Returns the checks that generateChecks created.
+ const SmallVector<PointerCheck, 4> &getChecks() const { return Checks; }
+
+ /// \brief Decide if we need to add a check between two groups of pointers,
+ /// according to needsChecking.
+ bool needsChecking(const CheckingPtrGroup &M,
+ const CheckingPtrGroup &N) const;
+
+ /// \brief Returns the number of run-time checks required according to
+ /// needsChecking.
+ unsigned getNumberOfChecks() const { return Checks.size(); }
+
+ /// \brief Print the list run-time memory checks necessary.
+ void print(raw_ostream &OS, unsigned Depth = 0) const;
+
+ /// Print \p Checks.
+ void printChecks(raw_ostream &OS, const SmallVectorImpl<PointerCheck> &Checks,
+ unsigned Depth = 0) const;
+
+ /// This flag indicates if we need to add the runtime check.
+ bool Need;
+
+ /// Information about the pointers that may require checking.
+ SmallVector<PointerInfo, 2> Pointers;
+
+ /// Holds a partitioning of pointers into "check groups".
+ SmallVector<CheckingPtrGroup, 2> CheckingGroups;
+
+ /// \brief Check if pointers are in the same partition
+ ///
+ /// \p PtrToPartition contains the partition number for pointers (-1 if the
+ /// pointer belongs to multiple partitions).
+ static bool
+ arePointersInSamePartition(const SmallVectorImpl<int> &PtrToPartition,
+ unsigned PtrIdx1, unsigned PtrIdx2);
+
+ /// \brief Decide whether we need to issue a run-time check for pointer at
+ /// index \p I and \p J to prove their independence.
+ bool needsChecking(unsigned I, unsigned J) const;
+
+private:
+ /// \brief Groups pointers such that a single memcheck is required
+ /// between two different groups. This will clear the CheckingGroups vector
+ /// and re-compute it. We will only group dependecies if \p UseDependencies
+ /// is true, otherwise we will create a separate group for each pointer.
+ void groupChecks(MemoryDepChecker::DepCandidates &DepCands,
+ bool UseDependencies);
+
+ /// Generate the checks and return them.
+ SmallVector<PointerCheck, 4>
+ generateChecks() const;
+
+ /// Holds a pointer to the ScalarEvolution analysis.
+ ScalarEvolution *SE;
+
+ /// \brief Set of run-time checks required to establish independence of
+ /// otherwise may-aliasing pointers in the loop.
+ SmallVector<PointerCheck, 4> Checks;
+};
+