[LoopVectorize] Split out RuntimePointerCheck from LoopVectorizationLegality

[anemet]

Summary

RuntimePointerCheck will be used through LoopAccessAnalysis in
LoopVectorizationLegality.

NFC. This is part of the patchset that splits out the memory dependence logic
from LoopVectorizationLegality into a new class LoopAccessAnalysis.
LoopAccessAnalysis will be used by the new Loop Distribution pass.

[hfinkel]

Where is this going to end up eventually? Making it a global type seems odd. Do you want to put it into an anonymous namespace?

[anemet]

Address Hal's comments

[hfinkel]

LGTM.

[anemet]

r227747

lib/Transforms/Vectorize/LoopVectorize.cpp

 
 /// \brief Propagate known metadata from one instruction to a vector of others.
 static void propagateMetadata(SmallVectorImpl<Value *> &To, const Instruction *From) {
   for (Value *V : To)
     if (Instruction *I = dyn_cast<Instruction>(V))
       propagateMetadata(I, From);
 }
 
+/// This struct holds information about the memory runtime legality
+/// check that a group of pointers do not overlap.
+struct RuntimePointerCheck {
+  RuntimePointerCheck() : Need(false) {}
+
+  /// Reset the state of the pointer runtime information.
+  void reset() {
+    Need = false;
+    Pointers.clear();
+    Starts.clear();
+    Ends.clear();
+    IsWritePtr.clear();
+    DependencySetId.clear();
+    AliasSetId.clear();
+  }
+
+  /// Insert a pointer and calculate the start and end SCEVs.
+  void insert(ScalarEvolution *SE, Loop *Lp, Value *Ptr, bool WritePtr,
+              unsigned DepSetId, unsigned ASId, ValueToValueMap &Strides);
+
+  /// This flag indicates if we need to add the runtime check.
+  bool Need;
+  /// Holds the pointers that we need to check.
+  SmallVector<TrackingVH<Value>, 2> Pointers;
+  /// Holds the pointer value at the beginning of the loop.
+  SmallVector<const SCEV*, 2> Starts;
+  /// Holds the pointer value at the end of the loop.
+  SmallVector<const SCEV*, 2> Ends;
+  /// Holds the information if this pointer is used for writing to memory.
+  SmallVector<bool, 2> IsWritePtr;
+  /// Holds the id of the set of pointers that could be dependent because of a
+  /// shared underlying object.
+  SmallVector<unsigned, 2> DependencySetId;
+  /// Holds the id of the disjoint alias set to which this pointer belongs.
+  SmallVector<unsigned, 2> AliasSetId;
+};
+
 /// LoopVectorizationLegality checks if it is legal to vectorize a loop, and
 /// to what vectorization factor.
 /// This class does not look at the profitability of vectorization, only the
 /// legality. This class has two main kinds of checks:
 /// * Memory checks - The code in canVectorizeMemory checks if vectorization
 ///   will change the order of memory accesses in a way that will change the
 ///   correctness of the program.
 /// * Scalars checks - The code in canVectorizeInstrs and canVectorizeMemory
struct ReductionInstDesc {
     bool IsReduction;
     // The last instruction in a min/max pattern (select of the select(icmp())
     // pattern), or the current reduction instruction otherwise.
     Instruction *PatternLastInst;
     // If this is a min/max pattern the comparison predicate.
     MinMaxReductionKind MinMaxKind;
   };
 
-  /// This struct holds information about the memory runtime legality
-  /// check that a group of pointers do not overlap.
-  struct RuntimePointerCheck {
-    RuntimePointerCheck() : Need(false) {}
-
-    /// Reset the state of the pointer runtime information.
-    void reset() {
-      Need = false;
-      Pointers.clear();
-      Starts.clear();
-      Ends.clear();
-      IsWritePtr.clear();
-      DependencySetId.clear();
-      AliasSetId.clear();
-    }
-
-    /// Insert a pointer and calculate the start and end SCEVs.
-    void insert(ScalarEvolution *SE, Loop *Lp, Value *Ptr, bool WritePtr,
-                unsigned DepSetId, unsigned ASId, ValueToValueMap &Strides);
-
-    /// This flag indicates if we need to add the runtime check.
-    bool Need;
-    /// Holds the pointers that we need to check.
-    SmallVector<TrackingVH<Value>, 2> Pointers;
-    /// Holds the pointer value at the beginning of the loop.
-    SmallVector<const SCEV*, 2> Starts;
-    /// Holds the pointer value at the end of the loop.
-    SmallVector<const SCEV*, 2> Ends;
-    /// Holds the information if this pointer is used for writing to memory.
-    SmallVector<bool, 2> IsWritePtr;
-    /// Holds the id of the set of pointers that could be dependent because of a
-    /// shared underlying object.
-    SmallVector<unsigned, 2> DependencySetId;
-    /// Holds the id of the disjoint alias set to which this pointer belongs.
-    SmallVector<unsigned, 2> AliasSetId;
-  };
-
   /// A struct for saving information about induction variables.
   struct InductionInfo {
     InductionInfo(Value *Start, InductionKind K) : StartValue(Start), IK(K) {}
     InductionInfo() : StartValue(nullptr), IK(IK_NoInduction) {}
     /// Start value.
     TrackingVH<Value> StartValue;
     /// Induction kind.
     InductionKind IK;
DEBUG(dbgs() << "LV: Replacing SCEV: " << *OrigSCEV << " by: " << *ByOne
                  << "\n");
     return ByOne;
   }
 
   // Otherwise, just return the SCEV of the original pointer.
   return SE->getSCEV(Ptr);
 }
 
-void LoopVectorizationLegality::RuntimePointerCheck::insert(
-    ScalarEvolution *SE, Loop *Lp, Value *Ptr, bool WritePtr, unsigned DepSetId,
+void RuntimePointerCheck::insert(ScalarEvolution *SE, Loop *Lp, Value *Ptr,
+                                 bool WritePtr, unsigned DepSetId,
                                  unsigned ASId, ValueToValueMap &Strides) {
   // Get the stride replaced scev.
   const SCEV *Sc = replaceSymbolicStrideSCEV(SE, Strides, Ptr);
   const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Sc);
   assert(AR && "Invalid addrec expression");
   const SCEV *Ex = SE->getBackedgeTakenCount(Lp);
   const SCEV *ScEnd = AR->evaluateAtIteration(Ex, *SE);
   Pointers.push_back(Ptr);
   Starts.push_back(AR->getStart());
InnerLoopVectorizer::addStrideCheck(Instruction *Loc) {
   ChkBuilder.Insert(TheCheck, "stride.not.one");
   FirstInst = getFirstInst(FirstInst, TheCheck, Loc);
 
   return std::make_pair(FirstInst, TheCheck);
 }
 
 std::pair<Instruction *, Instruction *>
 InnerLoopVectorizer::addRuntimeCheck(Instruction *Loc) {
-  LoopVectorizationLegality::RuntimePointerCheck *PtrRtCheck =
-  Legal->getRuntimePointerCheck();
+  RuntimePointerCheck *PtrRtCheck = Legal->getRuntimePointerCheck();
 
   Instruction *tnullptr = nullptr;
   if (!PtrRtCheck->Need)
     return std::pair<Instruction *, Instruction *>(tnullptr, tnullptr);
 
   unsigned NumPointers = PtrRtCheck->Pointers.size();
   SmallVector<TrackingVH<Value> , 2> Starts;
   SmallVector<TrackingVH<Value> , 2> Ends;
public:
   void addStore(AliasAnalysis::Location &Loc) {
     Value *Ptr = const_cast<Value*>(Loc.Ptr);
     AST.add(Ptr, AliasAnalysis::UnknownSize, Loc.AATags);
     Accesses.insert(MemAccessInfo(Ptr, true));
   }
 
   /// \brief Check whether we can check the pointers at runtime for
   /// non-intersection.
-  bool canCheckPtrAtRT(LoopVectorizationLegality::RuntimePointerCheck &RtCheck,
-                       unsigned &NumComparisons, ScalarEvolution *SE,
-                       Loop *TheLoop, ValueToValueMap &Strides,
+  bool canCheckPtrAtRT(RuntimePointerCheck &RtCheck, unsigned &NumComparisons,
+                       ScalarEvolution *SE, Loop *TheLoop,
+                       ValueToValueMap &Strides,
                        bool ShouldCheckStride = false);
 
   /// \brief Goes over all memory accesses, checks whether a RT check is needed
   /// and builds sets of dependent accesses.
   void buildDependenceSets() {
     processMemAccesses();
   }
 

 }
 
 /// \brief Check the stride of the pointer and ensure that it does not wrap in
 /// the address space.
 static int isStridedPtr(ScalarEvolution *SE, const DataLayout *DL, Value *Ptr,
                         const Loop *Lp, ValueToValueMap &StridesMap);
 
 bool AccessAnalysis::canCheckPtrAtRT(
-    LoopVectorizationLegality::RuntimePointerCheck &RtCheck,
+    RuntimePointerCheck &RtCheck,
     unsigned &NumComparisons, ScalarEvolution *SE, Loop *TheLoop,
     ValueToValueMap &StridesMap, bool ShouldCheckStride) {
   // Find pointers with computable bounds. We are going to use this information
   // to place a runtime bound check.
   bool CanDoRT = true;
 
   bool IsDepCheckNeeded = isDependencyCheckNeeded();
   NumComparisons = 0;