Update prebuilt Clang to r353983e.HEADq10.0

clang 9.0.5 (based on r353983e) from build 5696680.

Bug: http://b/135931688
Bug: http://b/136008926
Test: N/A
Change-Id: I922d17410047d2e2df4625615352c588ee71b203

1 files changed, 770 insertions, 0 deletions

diff --git a/clang-r353983e/include/llvm/Analysis/ScalarEvolutionExpressions.h b/clang-r353983e/include/llvm/Analysis/ScalarEvolutionExpressions.h
new file mode 100644
index 00000000..e187a962
--- /dev/null
+++ b/clang-r353983e/include/llvm/Analysis/ScalarEvolutionExpressions.h
@@ -0,0 +1,770 @@
+//===- llvm/Analysis/ScalarEvolutionExpressions.h - SCEV Exprs --*- 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 file defines the classes used to represent and build scalar expressions.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ANALYSIS_SCALAREVOLUTIONEXPRESSIONS_H
+#define LLVM_ANALYSIS_SCALAREVOLUTIONEXPRESSIONS_H
+
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/FoldingSet.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/iterator_range.h"
+#include "llvm/Analysis/ScalarEvolution.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Value.h"
+#include "llvm/IR/ValueHandle.h"
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/ErrorHandling.h"
+#include <cassert>
+#include <cstddef>
+
+namespace llvm {
+
+class APInt;
+class Constant;
+class ConstantRange;
+class Loop;
+class Type;
+
+  enum SCEVTypes {
+    // These should be ordered in terms of increasing complexity to make the
+    // folders simpler.
+    scConstant, scTruncate, scZeroExtend, scSignExtend, scAddExpr, scMulExpr,
+    scUDivExpr, scAddRecExpr, scUMaxExpr, scSMaxExpr,
+    scUnknown, scCouldNotCompute
+  };
+
+  /// This class represents a constant integer value.
+  class SCEVConstant : public SCEV {
+    friend class ScalarEvolution;
+
+    ConstantInt *V;
+
+    SCEVConstant(const FoldingSetNodeIDRef ID, ConstantInt *v) :
+      SCEV(ID, scConstant, 1), V(v) {}
+
+  public:
+    ConstantInt *getValue() const { return V; }
+    const APInt &getAPInt() const { return getValue()->getValue(); }
+
+    Type *getType() const { return V->getType(); }
+
+    /// Methods for support type inquiry through isa, cast, and dyn_cast:
+    static bool classof(const SCEV *S) {
+      return S->getSCEVType() == scConstant;
+    }
+  };
+
+  static unsigned short computeExpressionSize(ArrayRef<const SCEV *> Args) {
+    APInt Size(16, 1);
+    for (auto *Arg : Args)
+      Size = Size.uadd_sat(APInt(16, Arg->getExpressionSize()));
+    return (unsigned short)Size.getZExtValue();
+  }
+
+  /// This is the base class for unary cast operator classes.
+  class SCEVCastExpr : public SCEV {
+  protected:
+    const SCEV *Op;
+    Type *Ty;
+
+    SCEVCastExpr(const FoldingSetNodeIDRef ID,
+                 unsigned SCEVTy, const SCEV *op, Type *ty);
+
+  public:
+    const SCEV *getOperand() const { return Op; }
+    Type *getType() const { return Ty; }
+
+    /// Methods for support type inquiry through isa, cast, and dyn_cast:
+    static bool classof(const SCEV *S) {
+      return S->getSCEVType() == scTruncate ||
+             S->getSCEVType() == scZeroExtend ||
+             S->getSCEVType() == scSignExtend;
+    }
+  };
+
+  /// This class represents a truncation of an integer value to a
+  /// smaller integer value.
+  class SCEVTruncateExpr : public SCEVCastExpr {
+    friend class ScalarEvolution;
+
+    SCEVTruncateExpr(const FoldingSetNodeIDRef ID,
+                     const SCEV *op, Type *ty);
+
+  public:
+    /// Methods for support type inquiry through isa, cast, and dyn_cast:
+    static bool classof(const SCEV *S) {
+      return S->getSCEVType() == scTruncate;
+    }
+  };
+
+  /// This class represents a zero extension of a small integer value
+  /// to a larger integer value.
+  class SCEVZeroExtendExpr : public SCEVCastExpr {
+    friend class ScalarEvolution;
+
+    SCEVZeroExtendExpr(const FoldingSetNodeIDRef ID,
+                       const SCEV *op, Type *ty);
+
+  public:
+    /// Methods for support type inquiry through isa, cast, and dyn_cast:
+    static bool classof(const SCEV *S) {
+      return S->getSCEVType() == scZeroExtend;
+    }
+  };
+
+  /// This class represents a sign extension of a small integer value
+  /// to a larger integer value.
+  class SCEVSignExtendExpr : public SCEVCastExpr {
+    friend class ScalarEvolution;
+
+    SCEVSignExtendExpr(const FoldingSetNodeIDRef ID,
+                       const SCEV *op, Type *ty);
+
+  public:
+    /// Methods for support type inquiry through isa, cast, and dyn_cast:
+    static bool classof(const SCEV *S) {
+      return S->getSCEVType() == scSignExtend;
+    }
+  };
+
+  /// This node is a base class providing common functionality for
+  /// n'ary operators.
+  class SCEVNAryExpr : public SCEV {
+  protected:
+    // Since SCEVs are immutable, ScalarEvolution allocates operand
+    // arrays with its SCEVAllocator, so this class just needs a simple
+    // pointer rather than a more elaborate vector-like data structure.
+    // This also avoids the need for a non-trivial destructor.
+    const SCEV *const *Operands;
+    size_t NumOperands;
+
+    SCEVNAryExpr(const FoldingSetNodeIDRef ID, enum SCEVTypes T,
+                 const SCEV *const *O, size_t N)
+        : SCEV(ID, T, computeExpressionSize(makeArrayRef(O, N))), Operands(O),
+          NumOperands(N) {}
+
+  public:
+    size_t getNumOperands() const { return NumOperands; }
+
+    const SCEV *getOperand(unsigned i) const {
+      assert(i < NumOperands && "Operand index out of range!");
+      return Operands[i];
+    }
+
+    using op_iterator = const SCEV *const *;
+    using op_range = iterator_range<op_iterator>;
+
+    op_iterator op_begin() const { return Operands; }
+    op_iterator op_end() const { return Operands + NumOperands; }
+    op_range operands() const {
+      return make_range(op_begin(), op_end());
+    }
+
+    Type *getType() const { return getOperand(0)->getType(); }
+
+    NoWrapFlags getNoWrapFlags(NoWrapFlags Mask = NoWrapMask) const {
+      return (NoWrapFlags)(SubclassData & Mask);
+    }
+
+    bool hasNoUnsignedWrap() const {
+      return getNoWrapFlags(FlagNUW) != FlagAnyWrap;
+    }
+
+    bool hasNoSignedWrap() const {
+      return getNoWrapFlags(FlagNSW) != FlagAnyWrap;
+    }
+
+    bool hasNoSelfWrap() const {
+      return getNoWrapFlags(FlagNW) != FlagAnyWrap;
+    }
+
+    /// Methods for support type inquiry through isa, cast, and dyn_cast:
+    static bool classof(const SCEV *S) {
+      return S->getSCEVType() == scAddExpr ||
+             S->getSCEVType() == scMulExpr ||
+             S->getSCEVType() == scSMaxExpr ||
+             S->getSCEVType() == scUMaxExpr ||
+             S->getSCEVType() == scAddRecExpr;
+    }
+  };
+
+  /// This node is the base class for n'ary commutative operators.
+  class SCEVCommutativeExpr : public SCEVNAryExpr {
+  protected:
+    SCEVCommutativeExpr(const FoldingSetNodeIDRef ID,
+                        enum SCEVTypes T, const SCEV *const *O, size_t N)
+      : SCEVNAryExpr(ID, T, O, N) {}
+
+  public:
+    /// Methods for support type inquiry through isa, cast, and dyn_cast:
+    static bool classof(const SCEV *S) {
+      return S->getSCEVType() == scAddExpr ||
+             S->getSCEVType() == scMulExpr ||
+             S->getSCEVType() == scSMaxExpr ||
+             S->getSCEVType() == scUMaxExpr;
+    }
+
+    /// Set flags for a non-recurrence without clearing previously set flags.
+    void setNoWrapFlags(NoWrapFlags Flags) {
+      SubclassData |= Flags;
+    }
+  };
+
+  /// This node represents an addition of some number of SCEVs.
+  class SCEVAddExpr : public SCEVCommutativeExpr {
+    friend class ScalarEvolution;
+
+    SCEVAddExpr(const FoldingSetNodeIDRef ID,
+                const SCEV *const *O, size_t N)
+      : SCEVCommutativeExpr(ID, scAddExpr, O, N) {}
+
+  public:
+    Type *getType() const {
+      // Use the type of the last operand, which is likely to be a pointer
+      // type, if there is one. This doesn't usually matter, but it can help
+      // reduce casts when the expressions are expanded.
+      return getOperand(getNumOperands() - 1)->getType();
+    }
+
+    /// Methods for support type inquiry through isa, cast, and dyn_cast:
+    static bool classof(const SCEV *S) {
+      return S->getSCEVType() == scAddExpr;
+    }
+  };
+
+  /// This node represents multiplication of some number of SCEVs.
+  class SCEVMulExpr : public SCEVCommutativeExpr {
+    friend class ScalarEvolution;
+
+    SCEVMulExpr(const FoldingSetNodeIDRef ID,
+                const SCEV *const *O, size_t N)
+      : SCEVCommutativeExpr(ID, scMulExpr, O, N) {}
+
+  public:
+    /// Methods for support type inquiry through isa, cast, and dyn_cast:
+    static bool classof(const SCEV *S) {
+      return S->getSCEVType() == scMulExpr;
+    }
+  };
+
+  /// This class represents a binary unsigned division operation.
+  class SCEVUDivExpr : public SCEV {
+    friend class ScalarEvolution;
+
+    const SCEV *LHS;
+    const SCEV *RHS;
+
+    SCEVUDivExpr(const FoldingSetNodeIDRef ID, const SCEV *lhs, const SCEV *rhs)
+        : SCEV(ID, scUDivExpr, computeExpressionSize({lhs, rhs})), LHS(lhs),
+          RHS(rhs) {}
+
+  public:
+    const SCEV *getLHS() const { return LHS; }
+    const SCEV *getRHS() const { return RHS; }
+
+    Type *getType() const {
+      // In most cases the types of LHS and RHS will be the same, but in some
+      // crazy cases one or the other may be a pointer. ScalarEvolution doesn't
+      // depend on the type for correctness, but handling types carefully can
+      // avoid extra casts in the SCEVExpander. The LHS is more likely to be
+      // a pointer type than the RHS, so use the RHS' type here.
+      return getRHS()->getType();
+    }
+
+    /// Methods for support type inquiry through isa, cast, and dyn_cast:
+    static bool classof(const SCEV *S) {
+      return S->getSCEVType() == scUDivExpr;
+    }
+  };
+
+  /// This node represents a polynomial recurrence on the trip count
+  /// of the specified loop.  This is the primary focus of the
+  /// ScalarEvolution framework; all the other SCEV subclasses are
+  /// mostly just supporting infrastructure to allow SCEVAddRecExpr
+  /// expressions to be created and analyzed.
+  ///
+  /// All operands of an AddRec are required to be loop invariant.
+  ///
+  class SCEVAddRecExpr : public SCEVNAryExpr {
+    friend class ScalarEvolution;
+
+    const Loop *L;
+
+    SCEVAddRecExpr(const FoldingSetNodeIDRef ID,
+                   const SCEV *const *O, size_t N, const Loop *l)
+      : SCEVNAryExpr(ID, scAddRecExpr, O, N), L(l) {}
+
+  public:
+    const SCEV *getStart() const { return Operands[0]; }
+    const Loop *getLoop() const { return L; }
+
+    /// Constructs and returns the recurrence indicating how much this
+    /// expression steps by.  If this is a polynomial of degree N, it
+    /// returns a chrec of degree N-1.  We cannot determine whether
+    /// the step recurrence has self-wraparound.
+    const SCEV *getStepRecurrence(ScalarEvolution &SE) const {
+      if (isAffine()) return getOperand(1);
+      return SE.getAddRecExpr(SmallVector<const SCEV *, 3>(op_begin()+1,
+                                                           op_end()),
+                              getLoop(), FlagAnyWrap);
+    }
+
+    /// Return true if this represents an expression A + B*x where A
+    /// and B are loop invariant values.
+    bool isAffine() const {
+      // We know that the start value is invariant.  This expression is thus
+      // affine iff the step is also invariant.
+      return getNumOperands() == 2;
+    }
+
+    /// Return true if this represents an expression A + B*x + C*x^2
+    /// where A, B and C are loop invariant values.  This corresponds
+    /// to an addrec of the form {L,+,M,+,N}
+    bool isQuadratic() const {
+      return getNumOperands() == 3;
+    }
+
+    /// Set flags for a recurrence without clearing any previously set flags.
+    /// For AddRec, either NUW or NSW implies NW. Keep track of this fact here
+    /// to make it easier to propagate flags.
+    void setNoWrapFlags(NoWrapFlags Flags) {
+      if (Flags & (FlagNUW | FlagNSW))
+        Flags = ScalarEvolution::setFlags(Flags, FlagNW);
+      SubclassData |= Flags;
+    }
+
+    /// Return the value of this chain of recurrences at the specified
+    /// iteration number.
+    const SCEV *evaluateAtIteration(const SCEV *It, ScalarEvolution &SE) const;
+
+    /// Return the number of iterations of this loop that produce
+    /// values in the specified constant range.  Another way of
+    /// looking at this is that it returns the first iteration number
+    /// where the value is not in the condition, thus computing the
+    /// exit count.  If the iteration count can't be computed, an
+    /// instance of SCEVCouldNotCompute is returned.
+    const SCEV *getNumIterationsInRange(const ConstantRange &Range,
+                                        ScalarEvolution &SE) const;
+
+    /// Return an expression representing the value of this expression
+    /// one iteration of the loop ahead.
+    const SCEVAddRecExpr *getPostIncExpr(ScalarEvolution &SE) const;
+
+    /// Methods for support type inquiry through isa, cast, and dyn_cast:
+    static bool classof(const SCEV *S) {
+      return S->getSCEVType() == scAddRecExpr;
+    }
+  };
+
+  /// This class represents a signed maximum selection.
+  class SCEVSMaxExpr : public SCEVCommutativeExpr {
+    friend class ScalarEvolution;
+
+    SCEVSMaxExpr(const FoldingSetNodeIDRef ID,
+                 const SCEV *const *O, size_t N)
+      : SCEVCommutativeExpr(ID, scSMaxExpr, O, N) {
+      // Max never overflows.
+      setNoWrapFlags((NoWrapFlags)(FlagNUW | FlagNSW));
+    }
+
+  public:
+    /// Methods for support type inquiry through isa, cast, and dyn_cast:
+    static bool classof(const SCEV *S) {
+      return S->getSCEVType() == scSMaxExpr;
+    }
+  };
+
+  /// This class represents an unsigned maximum selection.
+  class SCEVUMaxExpr : public SCEVCommutativeExpr {
+    friend class ScalarEvolution;
+
+    SCEVUMaxExpr(const FoldingSetNodeIDRef ID,
+                 const SCEV *const *O, size_t N)
+      : SCEVCommutativeExpr(ID, scUMaxExpr, O, N) {
+      // Max never overflows.
+      setNoWrapFlags((NoWrapFlags)(FlagNUW | FlagNSW));
+    }
+
+  public:
+    /// Methods for support type inquiry through isa, cast, and dyn_cast:
+    static bool classof(const SCEV *S) {
+      return S->getSCEVType() == scUMaxExpr;
+    }
+  };
+
+  /// This means that we are dealing with an entirely unknown SCEV
+  /// value, and only represent it as its LLVM Value.  This is the
+  /// "bottom" value for the analysis.
+  class SCEVUnknown final : public SCEV, private CallbackVH {
+    friend class ScalarEvolution;
+
+    /// The parent ScalarEvolution value. This is used to update the
+    /// parent's maps when the value associated with a SCEVUnknown is
+    /// deleted or RAUW'd.
+    ScalarEvolution *SE;
+
+    /// The next pointer in the linked list of all SCEVUnknown
+    /// instances owned by a ScalarEvolution.
+    SCEVUnknown *Next;
+
+    SCEVUnknown(const FoldingSetNodeIDRef ID, Value *V,
+                ScalarEvolution *se, SCEVUnknown *next) :
+      SCEV(ID, scUnknown, 1), CallbackVH(V), SE(se), Next(next) {}
+
+    // Implement CallbackVH.
+    void deleted() override;
+    void allUsesReplacedWith(Value *New) override;
+
+  public:
+    Value *getValue() const { return getValPtr(); }
+
+    /// @{
+    /// Test whether this is a special constant representing a type
+    /// size, alignment, or field offset in a target-independent
+    /// manner, and hasn't happened to have been folded with other
+    /// operations into something unrecognizable. This is mainly only
+    /// useful for pretty-printing and other situations where it isn't
+    /// absolutely required for these to succeed.
+    bool isSizeOf(Type *&AllocTy) const;
+    bool isAlignOf(Type *&AllocTy) const;
+    bool isOffsetOf(Type *&STy, Constant *&FieldNo) const;
+    /// @}
+
+    Type *getType() const { return getValPtr()->getType(); }
+
+    /// Methods for support type inquiry through isa, cast, and dyn_cast:
+    static bool classof(const SCEV *S) {
+      return S->getSCEVType() == scUnknown;
+    }
+  };
+
+  /// This class defines a simple visitor class that may be used for
+  /// various SCEV analysis purposes.
+  template<typename SC, typename RetVal=void>
+  struct SCEVVisitor {
+    RetVal visit(const SCEV *S) {
+      switch (S->getSCEVType()) {
+      case scConstant:
+        return ((SC*)this)->visitConstant((const SCEVConstant*)S);
+      case scTruncate:
+        return ((SC*)this)->visitTruncateExpr((const SCEVTruncateExpr*)S);
+      case scZeroExtend:
+        return ((SC*)this)->visitZeroExtendExpr((const SCEVZeroExtendExpr*)S);
+      case scSignExtend:
+        return ((SC*)this)->visitSignExtendExpr((const SCEVSignExtendExpr*)S);
+      case scAddExpr:
+        return ((SC*)this)->visitAddExpr((const SCEVAddExpr*)S);
+      case scMulExpr:
+        return ((SC*)this)->visitMulExpr((const SCEVMulExpr*)S);
+      case scUDivExpr:
+        return ((SC*)this)->visitUDivExpr((const SCEVUDivExpr*)S);
+      case scAddRecExpr:
+        return ((SC*)this)->visitAddRecExpr((const SCEVAddRecExpr*)S);
+      case scSMaxExpr:
+        return ((SC*)this)->visitSMaxExpr((const SCEVSMaxExpr*)S);
+      case scUMaxExpr:
+        return ((SC*)this)->visitUMaxExpr((const SCEVUMaxExpr*)S);
+      case scUnknown:
+        return ((SC*)this)->visitUnknown((const SCEVUnknown*)S);
+      case scCouldNotCompute:
+        return ((SC*)this)->visitCouldNotCompute((const SCEVCouldNotCompute*)S);
+      default:
+        llvm_unreachable("Unknown SCEV type!");
+      }
+    }
+
+    RetVal visitCouldNotCompute(const SCEVCouldNotCompute *S) {
+      llvm_unreachable("Invalid use of SCEVCouldNotCompute!");
+    }
+  };
+
+  /// Visit all nodes in the expression tree using worklist traversal.
+  ///
+  /// Visitor implements:
+  ///   // return true to follow this node.
+  ///   bool follow(const SCEV *S);
+  ///   // return true to terminate the search.
+  ///   bool isDone();
+  template<typename SV>
+  class SCEVTraversal {
+    SV &Visitor;
+    SmallVector<const SCEV *, 8> Worklist;
+    SmallPtrSet<const SCEV *, 8> Visited;
+
+    void push(const SCEV *S) {
+      if (Visited.insert(S).second && Visitor.follow(S))
+        Worklist.push_back(S);
+    }
+
+  public:
+    SCEVTraversal(SV& V): Visitor(V) {}
+
+    void visitAll(const SCEV *Root) {
+      push(Root);
+      while (!Worklist.empty() && !Visitor.isDone()) {
+        const SCEV *S = Worklist.pop_back_val();
+
+        switch (S->getSCEVType()) {
+        case scConstant:
+        case scUnknown:
+          break;
+        case scTruncate:
+        case scZeroExtend:
+        case scSignExtend:
+          push(cast<SCEVCastExpr>(S)->getOperand());
+          break;
+        case scAddExpr:
+        case scMulExpr:
+        case scSMaxExpr:
+        case scUMaxExpr:
+        case scAddRecExpr:
+          for (const auto *Op : cast<SCEVNAryExpr>(S)->operands())
+            push(Op);
+          break;
+        case scUDivExpr: {
+          const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S);
+          push(UDiv->getLHS());
+          push(UDiv->getRHS());
+          break;
+        }
+        case scCouldNotCompute:
+          llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!");
+        default:
+          llvm_unreachable("Unknown SCEV kind!");
+        }
+      }
+    }
+  };
+
+  /// Use SCEVTraversal to visit all nodes in the given expression tree.
+  template<typename SV>
+  void visitAll(const SCEV *Root, SV& Visitor) {
+    SCEVTraversal<SV> T(Visitor);
+    T.visitAll(Root);
+  }
+
+  /// Return true if any node in \p Root satisfies the predicate \p Pred.
+  template <typename PredTy>
+  bool SCEVExprContains(const SCEV *Root, PredTy Pred) {
+    struct FindClosure {
+      bool Found = false;
+      PredTy Pred;
+
+      FindClosure(PredTy Pred) : Pred(Pred) {}
+
+      bool follow(const SCEV *S) {
+        if (!Pred(S))
+          return true;
+
+        Found = true;
+        return false;
+      }
+
+      bool isDone() const { return Found; }
+    };
+
+    FindClosure FC(Pred);
+    visitAll(Root, FC);
+    return FC.Found;
+  }
+
+  /// This visitor recursively visits a SCEV expression and re-writes it.
+  /// The result from each visit is cached, so it will return the same
+  /// SCEV for the same input.
+  template<typename SC>
+  class SCEVRewriteVisitor : public SCEVVisitor<SC, const SCEV *> {
+  protected:
+    ScalarEvolution &SE;
+    // Memoize the result of each visit so that we only compute once for
+    // the same input SCEV. This is to avoid redundant computations when
+    // a SCEV is referenced by multiple SCEVs. Without memoization, this
+    // visit algorithm would have exponential time complexity in the worst
+    // case, causing the compiler to hang on certain tests.
+    DenseMap<const SCEV *, const SCEV *> RewriteResults;
+
+  public:
+    SCEVRewriteVisitor(ScalarEvolution &SE) : SE(SE) {}
+
+    const SCEV *visit(const SCEV *S) {
+      auto It = RewriteResults.find(S);
+      if (It != RewriteResults.end())
+        return It->second;
+      auto* Visited = SCEVVisitor<SC, const SCEV *>::visit(S);
+      auto Result = RewriteResults.try_emplace(S, Visited);
+      assert(Result.second && "Should insert a new entry");
+      return Result.first->second;
+    }
+
+    const SCEV *visitConstant(const SCEVConstant *Constant) {
+      return Constant;
+    }
+
+    const SCEV *visitTruncateExpr(const SCEVTruncateExpr *Expr) {
+      const SCEV *Operand = ((SC*)this)->visit(Expr->getOperand());
+      return Operand == Expr->getOperand()
+                 ? Expr
+                 : SE.getTruncateExpr(Operand, Expr->getType());
+    }
+
+    const SCEV *visitZeroExtendExpr(const SCEVZeroExtendExpr *Expr) {
+      const SCEV *Operand = ((SC*)this)->visit(Expr->getOperand());
+      return Operand == Expr->getOperand()
+                 ? Expr
+                 : SE.getZeroExtendExpr(Operand, Expr->getType());
+    }
+
+    const SCEV *visitSignExtendExpr(const SCEVSignExtendExpr *Expr) {
+      const SCEV *Operand = ((SC*)this)->visit(Expr->getOperand());
+      return Operand == Expr->getOperand()
+                 ? Expr
+                 : SE.getSignExtendExpr(Operand, Expr->getType());
+    }
+
+    const SCEV *visitAddExpr(const SCEVAddExpr *Expr) {
+      SmallVector<const SCEV *, 2> Operands;
+      bool Changed = false;
+      for (auto *Op : Expr->operands()) {
+        Operands.push_back(((SC*)this)->visit(Op));
+        Changed |= Op != Operands.back();
+      }
+      return !Changed ? Expr : SE.getAddExpr(Operands);
+    }
+
+    const SCEV *visitMulExpr(const SCEVMulExpr *Expr) {
+      SmallVector<const SCEV *, 2> Operands;
+      bool Changed = false;
+      for (auto *Op : Expr->operands()) {
+        Operands.push_back(((SC*)this)->visit(Op));
+        Changed |= Op != Operands.back();
+      }
+      return !Changed ? Expr : SE.getMulExpr(Operands);
+    }
+
+    const SCEV *visitUDivExpr(const SCEVUDivExpr *Expr) {
+      auto *LHS = ((SC *)this)->visit(Expr->getLHS());
+      auto *RHS = ((SC *)this)->visit(Expr->getRHS());
+      bool Changed = LHS != Expr->getLHS() || RHS != Expr->getRHS();
+      return !Changed ? Expr : SE.getUDivExpr(LHS, RHS);
+    }
+
+    const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
+      SmallVector<const SCEV *, 2> Operands;
+      bool Changed = false;
+      for (auto *Op : Expr->operands()) {
+        Operands.push_back(((SC*)this)->visit(Op));
+        Changed |= Op != Operands.back();
+      }
+      return !Changed ? Expr
+                      : SE.getAddRecExpr(Operands, Expr->getLoop(),
+                                         Expr->getNoWrapFlags());
+    }
+
+    const SCEV *visitSMaxExpr(const SCEVSMaxExpr *Expr) {
+      SmallVector<const SCEV *, 2> Operands;
+      bool Changed = false;
+      for (auto *Op : Expr->operands()) {
+        Operands.push_back(((SC *)this)->visit(Op));
+        Changed |= Op != Operands.back();
+      }
+      return !Changed ? Expr : SE.getSMaxExpr(Operands);
+    }
+
+    const SCEV *visitUMaxExpr(const SCEVUMaxExpr *Expr) {
+      SmallVector<const SCEV *, 2> Operands;
+      bool Changed = false;
+      for (auto *Op : Expr->operands()) {
+        Operands.push_back(((SC*)this)->visit(Op));
+        Changed |= Op != Operands.back();
+      }
+      return !Changed ? Expr : SE.getUMaxExpr(Operands);
+    }
+
+    const SCEV *visitUnknown(const SCEVUnknown *Expr) {
+      return Expr;
+    }
+
+    const SCEV *visitCouldNotCompute(const SCEVCouldNotCompute *Expr) {
+      return Expr;
+    }
+  };
+
+  using ValueToValueMap = DenseMap<const Value *, Value *>;
+
+  /// The SCEVParameterRewriter takes a scalar evolution expression and updates
+  /// the SCEVUnknown components following the Map (Value -> Value).
+  class SCEVParameterRewriter : public SCEVRewriteVisitor<SCEVParameterRewriter> {
+  public:
+    static const SCEV *rewrite(const SCEV *Scev, ScalarEvolution &SE,
+                               ValueToValueMap &Map,
+                               bool InterpretConsts = false) {
+      SCEVParameterRewriter Rewriter(SE, Map, InterpretConsts);
+      return Rewriter.visit(Scev);
+    }
+
+    SCEVParameterRewriter(ScalarEvolution &SE, ValueToValueMap &M, bool C)
+      : SCEVRewriteVisitor(SE), Map(M), InterpretConsts(C) {}
+
+    const SCEV *visitUnknown(const SCEVUnknown *Expr) {
+      Value *V = Expr->getValue();
+      if (Map.count(V)) {
+        Value *NV = Map[V];
+        if (InterpretConsts && isa<ConstantInt>(NV))
+          return SE.getConstant(cast<ConstantInt>(NV));
+        return SE.getUnknown(NV);
+      }
+      return Expr;
+    }
+
+  private:
+    ValueToValueMap &Map;
+    bool InterpretConsts;
+  };
+
+  using LoopToScevMapT = DenseMap<const Loop *, const SCEV *>;
+
+  /// The SCEVLoopAddRecRewriter takes a scalar evolution expression and applies
+  /// the Map (Loop -> SCEV) to all AddRecExprs.
+  class SCEVLoopAddRecRewriter
+      : public SCEVRewriteVisitor<SCEVLoopAddRecRewriter> {
+  public:
+    SCEVLoopAddRecRewriter(ScalarEvolution &SE, LoopToScevMapT &M)
+        : SCEVRewriteVisitor(SE), Map(M) {}
+
+    static const SCEV *rewrite(const SCEV *Scev, LoopToScevMapT &Map,
+                               ScalarEvolution &SE) {
+      SCEVLoopAddRecRewriter Rewriter(SE, Map);
+      return Rewriter.visit(Scev);
+    }
+
+    const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
+      SmallVector<const SCEV *, 2> Operands;
+      for (const SCEV *Op : Expr->operands())
+        Operands.push_back(visit(Op));
+
+      const Loop *L = Expr->getLoop();
+      const SCEV *Res = SE.getAddRecExpr(Operands, L, Expr->getNoWrapFlags());
+
+      if (0 == Map.count(L))
+        return Res;
+
+      const SCEVAddRecExpr *Rec = cast<SCEVAddRecExpr>(Res);
+      return Rec->evaluateAtIteration(Map[L], SE);
+    }
+
+  private:
+    LoopToScevMapT &Map;
+  };
+
+} // end namespace llvm
+
+#endif // LLVM_ANALYSIS_SCALAREVOLUTIONEXPRESSIONS_H