1 files changed, 434 insertions, 358 deletions

diff --git a/contrib/llvm-project/llvm/include/llvm/Transforms/Utils/ScalarEvolutionExpander.h b/contrib/llvm-project/llvm/include/llvm/Transforms/Utils/ScalarEvolutionExpander.h
index 0c88f9f79e76..547245cfb963 100644
--- a/contrib/llvm-project/llvm/include/llvm/Transforms/Utils/ScalarEvolutionExpander.h
+++ b/contrib/llvm-project/llvm/include/llvm/Transforms/Utils/ScalarEvolutionExpander.h
@@ -26,410 +26,486 @@
 #include "llvm/Support/CommandLine.h"
 
 namespace llvm {
-  extern cl::opt<unsigned> SCEVCheapExpansionBudget;
+extern cl::opt<unsigned> SCEVCheapExpansionBudget;
+
+/// Return true if the given expression is safe to expand in the sense that
+/// all materialized values are safe to speculate anywhere their operands are
+/// defined.
+bool isSafeToExpand(const SCEV *S, ScalarEvolution &SE);
+
+/// Return true if the given expression is safe to expand in the sense that
+/// all materialized values are defined and safe to speculate at the specified
+/// location and their operands are defined at this location.
+bool isSafeToExpandAt(const SCEV *S, const Instruction *InsertionPoint,
+                      ScalarEvolution &SE);
+
+/// struct for holding enough information to help calculate the cost of the
+/// given SCEV when expanded into IR.
+struct SCEVOperand {
+  explicit SCEVOperand(unsigned Opc, int Idx, const SCEV *S) :
+    ParentOpcode(Opc), OperandIdx(Idx), S(S) { }
+  /// LLVM instruction opcode that uses the operand.
+  unsigned ParentOpcode;
+  /// The use index of an expanded instruction.
+  int OperandIdx;
+  /// The SCEV operand to be costed.
+  const SCEV* S;
+};
+
+/// This class uses information about analyze scalars to rewrite expressions
+/// in canonical form.
+///
+/// Clients should create an instance of this class when rewriting is needed,
+/// and destroy it when finished to allow the release of the associated
+/// memory.
+class SCEVExpander : public SCEVVisitor<SCEVExpander, Value *> {
+  ScalarEvolution &SE;
+  const DataLayout &DL;
+
+  // New instructions receive a name to identify them with the current pass.
+  const char *IVName;
+
+  /// Indicates whether LCSSA phis should be created for inserted values.
+  bool PreserveLCSSA;
+
+  // InsertedExpressions caches Values for reuse, so must track RAUW.
+  DenseMap<std::pair<const SCEV *, Instruction *>, TrackingVH<Value>>
+      InsertedExpressions;
+
+  // InsertedValues only flags inserted instructions so needs no RAUW.
+  DenseSet<AssertingVH<Value>> InsertedValues;
+  DenseSet<AssertingVH<Value>> InsertedPostIncValues;
+
+  /// Keep track of the existing IR values re-used during expansion.
+  /// FIXME: Ideally re-used instructions would not be added to
+  /// InsertedValues/InsertedPostIncValues.
+  SmallPtrSet<Value *, 16> ReusedValues;
+
+  /// A memoization of the "relevant" loop for a given SCEV.
+  DenseMap<const SCEV *, const Loop *> RelevantLoops;
+
+  /// Addrecs referring to any of the given loops are expanded in post-inc
+  /// mode. For example, expanding {1,+,1}<L> in post-inc mode returns the add
+  /// instruction that adds one to the phi for {0,+,1}<L>, as opposed to a new
+  /// phi starting at 1. This is only supported in non-canonical mode.
+  PostIncLoopSet PostIncLoops;
+
+  /// When this is non-null, addrecs expanded in the loop it indicates should
+  /// be inserted with increments at IVIncInsertPos.
+  const Loop *IVIncInsertLoop;
+
+  /// When expanding addrecs in the IVIncInsertLoop loop, insert the IV
+  /// increment at this position.
+  Instruction *IVIncInsertPos;
+
+  /// Phis that complete an IV chain. Reuse
+  DenseSet<AssertingVH<PHINode>> ChainedPhis;
+
+  /// When true, SCEVExpander tries to expand expressions in "canonical" form.
+  /// When false, expressions are expanded in a more literal form.
+  ///
+  /// In "canonical" form addrecs are expanded as arithmetic based on a
+  /// canonical induction variable. Note that CanonicalMode doesn't guarantee
+  /// that all expressions are expanded in "canonical" form. For some
+  /// expressions literal mode can be preferred.
+  bool CanonicalMode;
+
+  /// When invoked from LSR, the expander is in "strength reduction" mode. The
+  /// only difference is that phi's are only reused if they are already in
+  /// "expanded" form.
+  bool LSRMode;
+
+  typedef IRBuilder<TargetFolder, IRBuilderCallbackInserter> BuilderType;
+  BuilderType Builder;
+
+  // RAII object that stores the current insertion point and restores it when
+  // the object is destroyed. This includes the debug location.  Duplicated
+  // from InsertPointGuard to add SetInsertPoint() which is used to updated
+  // InsertPointGuards stack when insert points are moved during SCEV
+  // expansion.
+  class SCEVInsertPointGuard {
+    IRBuilderBase &Builder;
+    AssertingVH<BasicBlock> Block;
+    BasicBlock::iterator Point;
+    DebugLoc DbgLoc;
+    SCEVExpander *SE;
+
+    SCEVInsertPointGuard(const SCEVInsertPointGuard &) = delete;
+    SCEVInsertPointGuard &operator=(const SCEVInsertPointGuard &) = delete;
 
-  /// Return true if the given expression is safe to expand in the sense that
-  /// all materialized values are safe to speculate anywhere their operands are
-  /// defined.
-  bool isSafeToExpand(const SCEV *S, ScalarEvolution &SE);
+  public:
+    SCEVInsertPointGuard(IRBuilderBase &B, SCEVExpander *SE)
+        : Builder(B), Block(B.GetInsertBlock()), Point(B.GetInsertPoint()),
+          DbgLoc(B.getCurrentDebugLocation()), SE(SE) {
+      SE->InsertPointGuards.push_back(this);
+    }
 
-  /// Return true if the given expression is safe to expand in the sense that
-  /// all materialized values are defined and safe to speculate at the specified
-  /// location and their operands are defined at this location.
-  bool isSafeToExpandAt(const SCEV *S, const Instruction *InsertionPoint,
-                        ScalarEvolution &SE);
+    ~SCEVInsertPointGuard() {
+      // These guards should always created/destroyed in FIFO order since they
+      // are used to guard lexically scoped blocks of code in
+      // ScalarEvolutionExpander.
+      assert(SE->InsertPointGuards.back() == this);
+      SE->InsertPointGuards.pop_back();
+      Builder.restoreIP(IRBuilderBase::InsertPoint(Block, Point));
+      Builder.SetCurrentDebugLocation(DbgLoc);
+    }
 
-  /// This class uses information about analyze scalars to rewrite expressions
-  /// in canonical form.
-  ///
-  /// Clients should create an instance of this class when rewriting is needed,
-  /// and destroy it when finished to allow the release of the associated
-  /// memory.
-  class SCEVExpander : public SCEVVisitor<SCEVExpander, Value*> {
-    ScalarEvolution &SE;
-    const DataLayout &DL;
-
-    // New instructions receive a name to identify them with the current pass.
-    const char* IVName;
-
-    // InsertedExpressions caches Values for reuse, so must track RAUW.
-    DenseMap<std::pair<const SCEV *, Instruction *>, TrackingVH<Value>>
-        InsertedExpressions;
-
-    // InsertedValues only flags inserted instructions so needs no RAUW.
-    DenseSet<AssertingVH<Value>> InsertedValues;
-    DenseSet<AssertingVH<Value>> InsertedPostIncValues;
-
-    /// A memoization of the "relevant" loop for a given SCEV.
-    DenseMap<const SCEV *, const Loop *> RelevantLoops;
-
-    /// Addrecs referring to any of the given loops are expanded in post-inc
-    /// mode. For example, expanding {1,+,1}<L> in post-inc mode returns the add
-    /// instruction that adds one to the phi for {0,+,1}<L>, as opposed to a new
-    /// phi starting at 1. This is only supported in non-canonical mode.
-    PostIncLoopSet PostIncLoops;
-
-    /// When this is non-null, addrecs expanded in the loop it indicates should
-    /// be inserted with increments at IVIncInsertPos.
-    const Loop *IVIncInsertLoop;
-
-    /// When expanding addrecs in the IVIncInsertLoop loop, insert the IV
-    /// increment at this position.
-    Instruction *IVIncInsertPos;
-
-    /// Phis that complete an IV chain. Reuse
-    DenseSet<AssertingVH<PHINode>> ChainedPhis;
-
-    /// When true, SCEVExpander tries to expand expressions in "canonical" form.
-    /// When false, expressions are expanded in a more literal form.
-    ///
-    /// In "canonical" form addrecs are expanded as arithmetic based on a
-    /// canonical induction variable. Note that CanonicalMode doesn't guarantee
-    /// that all expressions are expanded in "canonical" form. For some
-    /// expressions literal mode can be preferred.
-    bool CanonicalMode;
-
-    /// When invoked from LSR, the expander is in "strength reduction" mode. The
-    /// only difference is that phi's are only reused if they are already in
-    /// "expanded" form.
-    bool LSRMode;
-
-    typedef IRBuilder<TargetFolder> BuilderType;
-    BuilderType Builder;
-
-    // RAII object that stores the current insertion point and restores it when
-    // the object is destroyed. This includes the debug location.  Duplicated
-    // from InsertPointGuard to add SetInsertPoint() which is used to updated
-    // InsertPointGuards stack when insert points are moved during SCEV
-    // expansion.
-    class SCEVInsertPointGuard {
-      IRBuilderBase &Builder;
-      AssertingVH<BasicBlock> Block;
-      BasicBlock::iterator Point;
-      DebugLoc DbgLoc;
-      SCEVExpander *SE;
-
-      SCEVInsertPointGuard(const SCEVInsertPointGuard &) = delete;
-      SCEVInsertPointGuard &operator=(const SCEVInsertPointGuard &) = delete;
-
-    public:
-      SCEVInsertPointGuard(IRBuilderBase &B, SCEVExpander *SE)
-          : Builder(B), Block(B.GetInsertBlock()), Point(B.GetInsertPoint()),
-            DbgLoc(B.getCurrentDebugLocation()), SE(SE) {
-        SE->InsertPointGuards.push_back(this);
-      }
-
-      ~SCEVInsertPointGuard() {
-        // These guards should always created/destroyed in FIFO order since they
-        // are used to guard lexically scoped blocks of code in
-        // ScalarEvolutionExpander.
-        assert(SE->InsertPointGuards.back() == this);
-        SE->InsertPointGuards.pop_back();
-        Builder.restoreIP(IRBuilderBase::InsertPoint(Block, Point));
-        Builder.SetCurrentDebugLocation(DbgLoc);
-      }
-
-      BasicBlock::iterator GetInsertPoint() const { return Point; }
-      void SetInsertPoint(BasicBlock::iterator I) { Point = I; }
-    };
-
-    /// Stack of pointers to saved insert points, used to keep insert points
-    /// consistent when instructions are moved.
-    SmallVector<SCEVInsertPointGuard *, 8> InsertPointGuards;
+    BasicBlock::iterator GetInsertPoint() const { return Point; }
+    void SetInsertPoint(BasicBlock::iterator I) { Point = I; }
+  };
+
+  /// Stack of pointers to saved insert points, used to keep insert points
+  /// consistent when instructions are moved.
+  SmallVector<SCEVInsertPointGuard *, 8> InsertPointGuards;
 
 #ifndef NDEBUG
-    const char *DebugType;
+  const char *DebugType;
 #endif
 
-    friend struct SCEVVisitor<SCEVExpander, Value*>;
-
-  public:
-    /// Construct a SCEVExpander in "canonical" mode.
-    explicit SCEVExpander(ScalarEvolution &se, const DataLayout &DL,
-                          const char *name)
-        : SE(se), DL(DL), IVName(name), IVIncInsertLoop(nullptr),
-          IVIncInsertPos(nullptr), CanonicalMode(true), LSRMode(false),
-          Builder(se.getContext(), TargetFolder(DL)) {
+  friend struct SCEVVisitor<SCEVExpander, Value *>;
+
+public:
+  /// Construct a SCEVExpander in "canonical" mode.
+  explicit SCEVExpander(ScalarEvolution &se, const DataLayout &DL,
+                        const char *name, bool PreserveLCSSA = true)
+      : SE(se), DL(DL), IVName(name), PreserveLCSSA(PreserveLCSSA),
+        IVIncInsertLoop(nullptr), IVIncInsertPos(nullptr), CanonicalMode(true),
+        LSRMode(false),
+        Builder(se.getContext(), TargetFolder(DL),
+                IRBuilderCallbackInserter(
+                    [this](Instruction *I) { rememberInstruction(I); })) {
 #ifndef NDEBUG
-      DebugType = "";
+    DebugType = "";
 #endif
-    }
+  }
 
-    ~SCEVExpander() {
-      // Make sure the insert point guard stack is consistent.
-      assert(InsertPointGuards.empty());
-    }
+  ~SCEVExpander() {
+    // Make sure the insert point guard stack is consistent.
+    assert(InsertPointGuards.empty());
+  }
 
 #ifndef NDEBUG
-    void setDebugType(const char* s) { DebugType = s; }
+  void setDebugType(const char *s) { DebugType = s; }
 #endif
 
-    /// Erase the contents of the InsertedExpressions map so that users trying
-    /// to expand the same expression into multiple BasicBlocks or different
-    /// places within the same BasicBlock can do so.
-    void clear() {
-      InsertedExpressions.clear();
-      InsertedValues.clear();
-      InsertedPostIncValues.clear();
-      ChainedPhis.clear();
+  /// Erase the contents of the InsertedExpressions map so that users trying
+  /// to expand the same expression into multiple BasicBlocks or different
+  /// places within the same BasicBlock can do so.
+  void clear() {
+    InsertedExpressions.clear();
+    InsertedValues.clear();
+    InsertedPostIncValues.clear();
+    ReusedValues.clear();
+    ChainedPhis.clear();
+  }
+
+  /// Return a vector containing all instructions inserted during expansion.
+  SmallVector<Instruction *, 32> getAllInsertedInstructions() const {
+    SmallVector<Instruction *, 32> Result;
+    for (auto &VH : InsertedValues) {
+      Value *V = VH;
+      if (ReusedValues.contains(V))
+        continue;
+      if (auto *Inst = dyn_cast<Instruction>(V))
+        Result.push_back(Inst);
     }
-
-    /// Return true for expressions that can't be evaluated at runtime
-    /// within given \b Budget.
-    ///
-    /// At is a parameter which specifies point in code where user is going to
-    /// expand this expression. Sometimes this knowledge can lead to
-    /// a less pessimistic cost estimation.
-    bool isHighCostExpansion(const SCEV *Expr, Loop *L, unsigned Budget,
-                             const TargetTransformInfo *TTI,
-                             const Instruction *At) {
-      assert(TTI && "This function requires TTI to be provided.");
-      assert(At && "This function requires At instruction to be provided.");
-      if (!TTI)      // In assert-less builds, avoid crashing
-        return true; // by always claiming to be high-cost.
-      SmallVector<const SCEV *, 8> Worklist;
-      SmallPtrSet<const SCEV *, 8> Processed;
-      int BudgetRemaining = Budget * TargetTransformInfo::TCC_Basic;
-      Worklist.emplace_back(Expr);
-      while (!Worklist.empty()) {
-        const SCEV *S = Worklist.pop_back_val();
-        if (isHighCostExpansionHelper(S, L, *At, BudgetRemaining, *TTI,
-                                      Processed, Worklist))
-          return true;
-      }
-      assert(BudgetRemaining >= 0 && "Should have returned from inner loop.");
-      return false;
+    for (auto &VH : InsertedPostIncValues) {
+      Value *V = VH;
+      if (ReusedValues.contains(V))
+        continue;
+      if (auto *Inst = dyn_cast<Instruction>(V))
+        Result.push_back(Inst);
     }
 
-    /// This method returns the canonical induction variable of the specified
-    /// type for the specified loop (inserting one if there is none).  A
-    /// canonical induction variable starts at zero and steps by one on each
-    /// iteration.
-    PHINode *getOrInsertCanonicalInductionVariable(const Loop *L, Type *Ty);
-
-    /// Return the induction variable increment's IV operand.
-    Instruction *getIVIncOperand(Instruction *IncV, Instruction *InsertPos,
-                                 bool allowScale);
-
-    /// Utility for hoisting an IV increment.
-    bool hoistIVInc(Instruction *IncV, Instruction *InsertPos);
-
-    /// replace congruent phis with their most canonical representative. Return
-    /// the number of phis eliminated.
-    unsigned replaceCongruentIVs(Loop *L, const DominatorTree *DT,
-                                 SmallVectorImpl<WeakTrackingVH> &DeadInsts,
-                                 const TargetTransformInfo *TTI = nullptr);
-
-    /// Insert code to directly compute the specified SCEV expression into the
-    /// program.  The inserted code is inserted into the specified block.
-    Value *expandCodeFor(const SCEV *SH, Type *Ty, Instruction *I);
-
-    /// Insert code to directly compute the specified SCEV expression into the
-    /// program.  The inserted code is inserted into the SCEVExpander's current
-    /// insertion point. If a type is specified, the result will be expanded to
-    /// have that type, with a cast if necessary.
-    Value *expandCodeFor(const SCEV *SH, Type *Ty = nullptr);
-
-
-    /// Generates a code sequence that evaluates this predicate.  The inserted
-    /// instructions will be at position \p Loc.  The result will be of type i1
-    /// and will have a value of 0 when the predicate is false and 1 otherwise.
-    Value *expandCodeForPredicate(const SCEVPredicate *Pred, Instruction *Loc);
-
-    /// A specialized variant of expandCodeForPredicate, handling the case when
-    /// we are expanding code for a SCEVEqualPredicate.
-    Value *expandEqualPredicate(const SCEVEqualPredicate *Pred,
-                                Instruction *Loc);
-
-    /// Generates code that evaluates if the \p AR expression will overflow.
-    Value *generateOverflowCheck(const SCEVAddRecExpr *AR, Instruction *Loc,
-                                 bool Signed);
-
-    /// A specialized variant of expandCodeForPredicate, handling the case when
-    /// we are expanding code for a SCEVWrapPredicate.
-    Value *expandWrapPredicate(const SCEVWrapPredicate *P, Instruction *Loc);
-
-    /// A specialized variant of expandCodeForPredicate, handling the case when
-    /// we are expanding code for a SCEVUnionPredicate.
-    Value *expandUnionPredicate(const SCEVUnionPredicate *Pred,
-                                Instruction *Loc);
-
-    /// Set the current IV increment loop and position.
-    void setIVIncInsertPos(const Loop *L, Instruction *Pos) {
-      assert(!CanonicalMode &&
-             "IV increment positions are not supported in CanonicalMode");
-      IVIncInsertLoop = L;
-      IVIncInsertPos = Pos;
-    }
+    return Result;
+  }
 
-    /// Enable post-inc expansion for addrecs referring to the given
-    /// loops. Post-inc expansion is only supported in non-canonical mode.
-    void setPostInc(const PostIncLoopSet &L) {
-      assert(!CanonicalMode &&
-             "Post-inc expansion is not supported in CanonicalMode");
-      PostIncLoops = L;
+  /// Return true for expressions that can't be evaluated at runtime
+  /// within given \b Budget.
+  ///
+  /// At is a parameter which specifies point in code where user is going to
+  /// expand this expression. Sometimes this knowledge can lead to
+  /// a less pessimistic cost estimation.
+  bool isHighCostExpansion(const SCEV *Expr, Loop *L, unsigned Budget,
+                           const TargetTransformInfo *TTI,
+                           const Instruction *At) {
+    assert(TTI && "This function requires TTI to be provided.");
+    assert(At && "This function requires At instruction to be provided.");
+    if (!TTI)      // In assert-less builds, avoid crashing
+      return true; // by always claiming to be high-cost.
+    SmallVector<SCEVOperand, 8> Worklist;
+    SmallPtrSet<const SCEV *, 8> Processed;
+    int BudgetRemaining = Budget * TargetTransformInfo::TCC_Basic;
+    Worklist.emplace_back(-1, -1, Expr);
+    while (!Worklist.empty()) {
+      const SCEVOperand WorkItem = Worklist.pop_back_val();
+      if (isHighCostExpansionHelper(WorkItem, L, *At, BudgetRemaining,
+                                    *TTI, Processed, Worklist))
+        return true;
     }
+    assert(BudgetRemaining >= 0 && "Should have returned from inner loop.");
+    return false;
+  }
+
+  /// Return the induction variable increment's IV operand.
+  Instruction *getIVIncOperand(Instruction *IncV, Instruction *InsertPos,
+                               bool allowScale);
+
+  /// Utility for hoisting an IV increment.
+  bool hoistIVInc(Instruction *IncV, Instruction *InsertPos);
+
+  /// replace congruent phis with their most canonical representative. Return
+  /// the number of phis eliminated.
+  unsigned replaceCongruentIVs(Loop *L, const DominatorTree *DT,
+                               SmallVectorImpl<WeakTrackingVH> &DeadInsts,
+                               const TargetTransformInfo *TTI = nullptr);
+
+  /// Insert code to directly compute the specified SCEV expression into the
+  /// program.  The code is inserted into the specified block.
+  Value *expandCodeFor(const SCEV *SH, Type *Ty, Instruction *I) {
+    return expandCodeForImpl(SH, Ty, I, true);
+  }
+
+  /// Insert code to directly compute the specified SCEV expression into the
+  /// program.  The code is inserted into the SCEVExpander's current
+  /// insertion point. If a type is specified, the result will be expanded to
+  /// have that type, with a cast if necessary.
+  Value *expandCodeFor(const SCEV *SH, Type *Ty = nullptr) {
+    return expandCodeForImpl(SH, Ty, true);
+  }
+
+  /// Generates a code sequence that evaluates this predicate.  The inserted
+  /// instructions will be at position \p Loc.  The result will be of type i1
+  /// and will have a value of 0 when the predicate is false and 1 otherwise.
+  Value *expandCodeForPredicate(const SCEVPredicate *Pred, Instruction *Loc);
+
+  /// A specialized variant of expandCodeForPredicate, handling the case when
+  /// we are expanding code for a SCEVEqualPredicate.
+  Value *expandEqualPredicate(const SCEVEqualPredicate *Pred, Instruction *Loc);
+
+  /// Generates code that evaluates if the \p AR expression will overflow.
+  Value *generateOverflowCheck(const SCEVAddRecExpr *AR, Instruction *Loc,
+                               bool Signed);
+
+  /// A specialized variant of expandCodeForPredicate, handling the case when
+  /// we are expanding code for a SCEVWrapPredicate.
+  Value *expandWrapPredicate(const SCEVWrapPredicate *P, Instruction *Loc);
+
+  /// A specialized variant of expandCodeForPredicate, handling the case when
+  /// we are expanding code for a SCEVUnionPredicate.
+  Value *expandUnionPredicate(const SCEVUnionPredicate *Pred, Instruction *Loc);
+
+  /// Set the current IV increment loop and position.
+  void setIVIncInsertPos(const Loop *L, Instruction *Pos) {
+    assert(!CanonicalMode &&
+           "IV increment positions are not supported in CanonicalMode");
+    IVIncInsertLoop = L;
+    IVIncInsertPos = Pos;
+  }
+
+  /// Enable post-inc expansion for addrecs referring to the given
+  /// loops. Post-inc expansion is only supported in non-canonical mode.
+  void setPostInc(const PostIncLoopSet &L) {
+    assert(!CanonicalMode &&
+           "Post-inc expansion is not supported in CanonicalMode");
+    PostIncLoops = L;
+  }
+
+  /// Disable all post-inc expansion.
+  void clearPostInc() {
+    PostIncLoops.clear();
+
+    // When we change the post-inc loop set, cached expansions may no
+    // longer be valid.
+    InsertedPostIncValues.clear();
+  }
+
+  /// Disable the behavior of expanding expressions in canonical form rather
+  /// than in a more literal form. Non-canonical mode is useful for late
+  /// optimization passes.
+  void disableCanonicalMode() { CanonicalMode = false; }
+
+  void enableLSRMode() { LSRMode = true; }
+
+  /// Set the current insertion point. This is useful if multiple calls to
+  /// expandCodeFor() are going to be made with the same insert point and the
+  /// insert point may be moved during one of the expansions (e.g. if the
+  /// insert point is not a block terminator).
+  void setInsertPoint(Instruction *IP) {
+    assert(IP);
+    Builder.SetInsertPoint(IP);
+  }
+
+  /// Clear the current insertion point. This is useful if the instruction
+  /// that had been serving as the insertion point may have been deleted.
+  void clearInsertPoint() { Builder.ClearInsertionPoint(); }
+
+  /// Set location information used by debugging information.
+  void SetCurrentDebugLocation(DebugLoc L) {
+    Builder.SetCurrentDebugLocation(std::move(L));
+  }
+
+  /// Get location information used by debugging information.
+  DebugLoc getCurrentDebugLocation() const {
+    return Builder.getCurrentDebugLocation();
+  }
+
+  /// Return true if the specified instruction was inserted by the code
+  /// rewriter.  If so, the client should not modify the instruction. Note that
+  /// this also includes instructions re-used during expansion.
+  bool isInsertedInstruction(Instruction *I) const {
+    return InsertedValues.count(I) || InsertedPostIncValues.count(I);
+  }
+
+  void setChainedPhi(PHINode *PN) { ChainedPhis.insert(PN); }
+
+  /// Try to find the ValueOffsetPair for S. The function is mainly used to
+  /// check whether S can be expanded cheaply.  If this returns a non-None
+  /// value, we know we can codegen the `ValueOffsetPair` into a suitable
+  /// expansion identical with S so that S can be expanded cheaply.
+  ///
+  /// L is a hint which tells in which loop to look for the suitable value.
+  /// On success return value which is equivalent to the expanded S at point
+  /// At. Return nullptr if value was not found.
+  ///
+  /// Note that this function does not perform an exhaustive search. I.e if it
+  /// didn't find any value it does not mean that there is no such value.
+  ///
+  Optional<ScalarEvolution::ValueOffsetPair>
+  getRelatedExistingExpansion(const SCEV *S, const Instruction *At, Loop *L);
 
-    /// Disable all post-inc expansion.
-    void clearPostInc() {
-      PostIncLoops.clear();
+  /// Returns a suitable insert point after \p I, that dominates \p
+  /// MustDominate. Skips instructions inserted by the expander.
+  BasicBlock::iterator findInsertPointAfter(Instruction *I,
+                                            Instruction *MustDominate);
 
-      // When we change the post-inc loop set, cached expansions may no
-      // longer be valid.
-      InsertedPostIncValues.clear();
-    }
+private:
+  LLVMContext &getContext() const { return SE.getContext(); }
 
-    /// Disable the behavior of expanding expressions in canonical form rather
-    /// than in a more literal form. Non-canonical mode is useful for late
-    /// optimization passes.
-    void disableCanonicalMode() { CanonicalMode = false; }
+  /// Insert code to directly compute the specified SCEV expression into the
+  /// program. The code is inserted into the SCEVExpander's current
+  /// insertion point. If a type is specified, the result will be expanded to
+  /// have that type, with a cast if necessary. If \p Root is true, this
+  /// indicates that \p SH is the top-level expression to expand passed from
+  /// an external client call.
+  Value *expandCodeForImpl(const SCEV *SH, Type *Ty, bool Root);
 
-    void enableLSRMode() { LSRMode = true; }
+  /// Insert code to directly compute the specified SCEV expression into the
+  /// program. The code is inserted into the specified block. If \p
+  /// Root is true, this indicates that \p SH is the top-level expression to
+  /// expand passed from an external client call.
+  Value *expandCodeForImpl(const SCEV *SH, Type *Ty, Instruction *I, bool Root);
 
-    /// Set the current insertion point. This is useful if multiple calls to
-    /// expandCodeFor() are going to be made with the same insert point and the
-    /// insert point may be moved during one of the expansions (e.g. if the
-    /// insert point is not a block terminator).
-    void setInsertPoint(Instruction *IP) {
-      assert(IP);
-      Builder.SetInsertPoint(IP);
-    }
+  /// Recursive helper function for isHighCostExpansion.
+  bool isHighCostExpansionHelper(
+    const SCEVOperand &WorkItem, Loop *L, const Instruction &At,
+    int &BudgetRemaining, const TargetTransformInfo &TTI,
+    SmallPtrSetImpl<const SCEV *> &Processed,
+    SmallVectorImpl<SCEVOperand> &Worklist);
 
-    /// Clear the current insertion point. This is useful if the instruction
-    /// that had been serving as the insertion point may have been deleted.
-    void clearInsertPoint() { Builder.ClearInsertionPoint(); }
+  /// Insert the specified binary operator, doing a small amount of work to
+  /// avoid inserting an obviously redundant operation, and hoisting to an
+  /// outer loop when the opportunity is there and it is safe.
+  Value *InsertBinop(Instruction::BinaryOps Opcode, Value *LHS, Value *RHS,
+                     SCEV::NoWrapFlags Flags, bool IsSafeToHoist);
 
-    /// Set location information used by debugging information.
-    void SetCurrentDebugLocation(DebugLoc L) {
-      Builder.SetCurrentDebugLocation(std::move(L));
-    }
+  /// Arrange for there to be a cast of V to Ty at IP, reusing an existing
+  /// cast if a suitable one exists, moving an existing cast if a suitable one
+  /// exists but isn't in the right place, or creating a new one.
+  Value *ReuseOrCreateCast(Value *V, Type *Ty, Instruction::CastOps Op,
+                           BasicBlock::iterator IP);
 
-    /// Get location information used by debugging information.
-    const DebugLoc &getCurrentDebugLocation() const {
-      return Builder.getCurrentDebugLocation();
-    }
+  /// Insert a cast of V to the specified type, which must be possible with a
+  /// noop cast, doing what we can to share the casts.
+  Value *InsertNoopCastOfTo(Value *V, Type *Ty);
 
-    /// Return true if the specified instruction was inserted by the code
-    /// rewriter.  If so, the client should not modify the instruction.
-    bool isInsertedInstruction(Instruction *I) const {
-      return InsertedValues.count(I) || InsertedPostIncValues.count(I);
-    }
+  /// Expand a SCEVAddExpr with a pointer type into a GEP instead of using
+  /// ptrtoint+arithmetic+inttoptr.
+  Value *expandAddToGEP(const SCEV *const *op_begin, const SCEV *const *op_end,
+                        PointerType *PTy, Type *Ty, Value *V);
+  Value *expandAddToGEP(const SCEV *Op, PointerType *PTy, Type *Ty, Value *V);
 
-    void setChainedPhi(PHINode *PN) { ChainedPhis.insert(PN); }
-
-    /// Try to find existing LLVM IR value for S available at the point At.
-    Value *getExactExistingExpansion(const SCEV *S, const Instruction *At,
-                                     Loop *L);
-
-    /// Try to find the ValueOffsetPair for S. The function is mainly used to
-    /// check whether S can be expanded cheaply.  If this returns a non-None
-    /// value, we know we can codegen the `ValueOffsetPair` into a suitable
-    /// expansion identical with S so that S can be expanded cheaply.
-    ///
-    /// L is a hint which tells in which loop to look for the suitable value.
-    /// On success return value which is equivalent to the expanded S at point
-    /// At. Return nullptr if value was not found.
-    ///
-    /// Note that this function does not perform an exhaustive search. I.e if it
-    /// didn't find any value it does not mean that there is no such value.
-    ///
-    Optional<ScalarEvolution::ValueOffsetPair>
-    getRelatedExistingExpansion(const SCEV *S, const Instruction *At, Loop *L);
-
-  private:
-    LLVMContext &getContext() const { return SE.getContext(); }
-
-    /// Recursive helper function for isHighCostExpansion.
-    bool isHighCostExpansionHelper(const SCEV *S, Loop *L,
-                                   const Instruction &At, int &BudgetRemaining,
-                                   const TargetTransformInfo &TTI,
-                                   SmallPtrSetImpl<const SCEV *> &Processed,
-                                   SmallVectorImpl<const SCEV *> &Worklist);
-
-    /// Insert the specified binary operator, doing a small amount of work to
-    /// avoid inserting an obviously redundant operation, and hoisting to an
-    /// outer loop when the opportunity is there and it is safe.
-    Value *InsertBinop(Instruction::BinaryOps Opcode, Value *LHS, Value *RHS,
-                       SCEV::NoWrapFlags Flags, bool IsSafeToHoist);
-
-    /// Arrange for there to be a cast of V to Ty at IP, reusing an existing
-    /// cast if a suitable one exists, moving an existing cast if a suitable one
-    /// exists but isn't in the right place, or creating a new one.
-    Value *ReuseOrCreateCast(Value *V, Type *Ty,
-                             Instruction::CastOps Op,
-                             BasicBlock::iterator IP);
-
-    /// Insert a cast of V to the specified type, which must be possible with a
-    /// noop cast, doing what we can to share the casts.
-    Value *InsertNoopCastOfTo(Value *V, Type *Ty);
-
-    /// Expand a SCEVAddExpr with a pointer type into a GEP instead of using
-    /// ptrtoint+arithmetic+inttoptr.
-    Value *expandAddToGEP(const SCEV *const *op_begin,
-                          const SCEV *const *op_end,
-                          PointerType *PTy, Type *Ty, Value *V);
-    Value *expandAddToGEP(const SCEV *Op, PointerType *PTy, Type *Ty, Value *V);
-
-    /// Find a previous Value in ExprValueMap for expand.
-    ScalarEvolution::ValueOffsetPair
-    FindValueInExprValueMap(const SCEV *S, const Instruction *InsertPt);
-
-    Value *expand(const SCEV *S);
-
-    /// Determine the most "relevant" loop for the given SCEV.
-    const Loop *getRelevantLoop(const SCEV *);
-
-    Value *visitConstant(const SCEVConstant *S) {
-      return S->getValue();
-    }
+  /// Find a previous Value in ExprValueMap for expand.
+  ScalarEvolution::ValueOffsetPair
+  FindValueInExprValueMap(const SCEV *S, const Instruction *InsertPt);
 
-    Value *visitTruncateExpr(const SCEVTruncateExpr *S);
+  Value *expand(const SCEV *S);
 
-    Value *visitZeroExtendExpr(const SCEVZeroExtendExpr *S);
+  /// Determine the most "relevant" loop for the given SCEV.
+  const Loop *getRelevantLoop(const SCEV *);
 
-    Value *visitSignExtendExpr(const SCEVSignExtendExpr *S);
+  Value *visitConstant(const SCEVConstant *S) { return S->getValue(); }
 
-    Value *visitAddExpr(const SCEVAddExpr *S);
+  Value *visitPtrToIntExpr(const SCEVPtrToIntExpr *S);
 
-    Value *visitMulExpr(const SCEVMulExpr *S);
+  Value *visitTruncateExpr(const SCEVTruncateExpr *S);
 
-    Value *visitUDivExpr(const SCEVUDivExpr *S);
+  Value *visitZeroExtendExpr(const SCEVZeroExtendExpr *S);
 
-    Value *visitAddRecExpr(const SCEVAddRecExpr *S);
+  Value *visitSignExtendExpr(const SCEVSignExtendExpr *S);
 
-    Value *visitSMaxExpr(const SCEVSMaxExpr *S);
+  Value *visitAddExpr(const SCEVAddExpr *S);
 
-    Value *visitUMaxExpr(const SCEVUMaxExpr *S);
+  Value *visitMulExpr(const SCEVMulExpr *S);
 
-    Value *visitSMinExpr(const SCEVSMinExpr *S);
+  Value *visitUDivExpr(const SCEVUDivExpr *S);
 
-    Value *visitUMinExpr(const SCEVUMinExpr *S);
+  Value *visitAddRecExpr(const SCEVAddRecExpr *S);
 
-    Value *visitUnknown(const SCEVUnknown *S) {
-      return S->getValue();
-    }
+  Value *visitSMaxExpr(const SCEVSMaxExpr *S);
 
-    void rememberInstruction(Value *I);
+  Value *visitUMaxExpr(const SCEVUMaxExpr *S);
 
-    bool isNormalAddRecExprPHI(PHINode *PN, Instruction *IncV, const Loop *L);
+  Value *visitSMinExpr(const SCEVSMinExpr *S);
 
-    bool isExpandedAddRecExprPHI(PHINode *PN, Instruction *IncV, const Loop *L);
+  Value *visitUMinExpr(const SCEVUMinExpr *S);
 
-    Value *expandAddRecExprLiterally(const SCEVAddRecExpr *);
-    PHINode *getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized,
-                                       const Loop *L,
-                                       Type *ExpandTy,
-                                       Type *IntTy,
-                                       Type *&TruncTy,
-                                       bool &InvertStep);
-    Value *expandIVInc(PHINode *PN, Value *StepV, const Loop *L,
-                       Type *ExpandTy, Type *IntTy, bool useSubtract);
+  Value *visitUnknown(const SCEVUnknown *S) { return S->getValue(); }
 
-    void hoistBeforePos(DominatorTree *DT, Instruction *InstToHoist,
-                        Instruction *Pos, PHINode *LoopPhi);
+  void rememberInstruction(Value *I);
 
-    void fixupInsertPoints(Instruction *I);
-  };
-}
+  bool isNormalAddRecExprPHI(PHINode *PN, Instruction *IncV, const Loop *L);
+
+  bool isExpandedAddRecExprPHI(PHINode *PN, Instruction *IncV, const Loop *L);
+
+  Value *expandAddRecExprLiterally(const SCEVAddRecExpr *);
+  PHINode *getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized,
+                                     const Loop *L, Type *ExpandTy, Type *IntTy,
+                                     Type *&TruncTy, bool &InvertStep);
+  Value *expandIVInc(PHINode *PN, Value *StepV, const Loop *L, Type *ExpandTy,
+                     Type *IntTy, bool useSubtract);
+
+  void hoistBeforePos(DominatorTree *DT, Instruction *InstToHoist,
+                      Instruction *Pos, PHINode *LoopPhi);
+
+  void fixupInsertPoints(Instruction *I);
+
+  /// If required, create LCSSA PHIs for \p Users' operand \p OpIdx. If new
+  /// LCSSA PHIs have been created, return the LCSSA PHI available at \p User.
+  /// If no PHIs have been created, return the unchanged operand \p OpIdx.
+  Value *fixupLCSSAFormFor(Instruction *User, unsigned OpIdx);
+};
+
+/// Helper to remove instructions inserted during SCEV expansion, unless they
+/// are marked as used.
+class SCEVExpanderCleaner {
+  SCEVExpander &Expander;
+
+  DominatorTree &DT;
+
+  /// Indicates whether the result of the expansion is used. If false, the
+  /// instructions added during expansion are removed.
+  bool ResultUsed;
+
+public:
+  SCEVExpanderCleaner(SCEVExpander &Expander, DominatorTree &DT)
+      : Expander(Expander), DT(DT), ResultUsed(false) {}
+
+  ~SCEVExpanderCleaner();
+
+  /// Indicate that the result of the expansion is used.
+  void markResultUsed() { ResultUsed = true; }
+};
+} // namespace llvm
 
 #endif