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diff --git a/include/llvm/CodeGen/SwitchLoweringUtils.h b/include/llvm/CodeGen/SwitchLoweringUtils.h
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+++ b/include/llvm/CodeGen/SwitchLoweringUtils.h
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+//===- SwitchLoweringUtils.h - Switch Lowering ------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_SWITCHLOWERINGUTILS_H
+#define LLVM_CODEGEN_SWITCHLOWERINGUTILS_H
+
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/CodeGen/SelectionDAGNodes.h"
+#include "llvm/CodeGen/TargetLowering.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/Support/BranchProbability.h"
+
+namespace llvm {
+
+class FunctionLoweringInfo;
+class MachineBasicBlock;
+
+namespace SwitchCG {
+
+enum CaseClusterKind {
+  /// A cluster of adjacent case labels with the same destination, or just one
+  /// case.
+  CC_Range,
+  /// A cluster of cases suitable for jump table lowering.
+  CC_JumpTable,
+  /// A cluster of cases suitable for bit test lowering.
+  CC_BitTests
+};
+
+/// A cluster of case labels.
+struct CaseCluster {
+  CaseClusterKind Kind;
+  const ConstantInt *Low, *High;
+  union {
+    MachineBasicBlock *MBB;
+    unsigned JTCasesIndex;
+    unsigned BTCasesIndex;
+  };
+  BranchProbability Prob;
+
+  static CaseCluster range(const ConstantInt *Low, const ConstantInt *High,
+                           MachineBasicBlock *MBB, BranchProbability Prob) {
+    CaseCluster C;
+    C.Kind = CC_Range;
+    C.Low = Low;
+    C.High = High;
+    C.MBB = MBB;
+    C.Prob = Prob;
+    return C;
+  }
+
+  static CaseCluster jumpTable(const ConstantInt *Low, const ConstantInt *High,
+                               unsigned JTCasesIndex, BranchProbability Prob) {
+    CaseCluster C;
+    C.Kind = CC_JumpTable;
+    C.Low = Low;
+    C.High = High;
+    C.JTCasesIndex = JTCasesIndex;
+    C.Prob = Prob;
+    return C;
+  }
+
+  static CaseCluster bitTests(const ConstantInt *Low, const ConstantInt *High,
+                              unsigned BTCasesIndex, BranchProbability Prob) {
+    CaseCluster C;
+    C.Kind = CC_BitTests;
+    C.Low = Low;
+    C.High = High;
+    C.BTCasesIndex = BTCasesIndex;
+    C.Prob = Prob;
+    return C;
+  }
+};
+
+using CaseClusterVector = std::vector<CaseCluster>;
+using CaseClusterIt = CaseClusterVector::iterator;
+
+/// Sort Clusters and merge adjacent cases.
+void sortAndRangeify(CaseClusterVector &Clusters);
+
+struct CaseBits {
+  uint64_t Mask = 0;
+  MachineBasicBlock *BB = nullptr;
+  unsigned Bits = 0;
+  BranchProbability ExtraProb;
+
+  CaseBits() = default;
+  CaseBits(uint64_t mask, MachineBasicBlock *bb, unsigned bits,
+           BranchProbability Prob)
+      : Mask(mask), BB(bb), Bits(bits), ExtraProb(Prob) {}
+};
+
+using CaseBitsVector = std::vector<CaseBits>;
+
+/// This structure is used to communicate between SelectionDAGBuilder and
+/// SDISel for the code generation of additional basic blocks needed by
+/// multi-case switch statements.
+struct CaseBlock {
+  // For the GISel interface.
+  struct PredInfoPair {
+    CmpInst::Predicate Pred;
+    // Set when no comparison should be emitted.
+    bool NoCmp;
+  };
+  union {
+    // The condition code to use for the case block's setcc node.
+    // Besides the integer condition codes, this can also be SETTRUE, in which
+    // case no comparison gets emitted.
+    ISD::CondCode CC;
+    struct PredInfoPair PredInfo;
+  };
+
+  // The LHS/MHS/RHS of the comparison to emit.
+  // Emit by default LHS op RHS. MHS is used for range comparisons:
+  // If MHS is not null: (LHS <= MHS) and (MHS <= RHS).
+  const Value *CmpLHS, *CmpMHS, *CmpRHS;
+
+  // The block to branch to if the setcc is true/false.
+  MachineBasicBlock *TrueBB, *FalseBB;
+
+  // The block into which to emit the code for the setcc and branches.
+  MachineBasicBlock *ThisBB;
+
+  /// The debug location of the instruction this CaseBlock was
+  /// produced from.
+  SDLoc DL;
+  DebugLoc DbgLoc;
+
+  // Branch weights.
+  BranchProbability TrueProb, FalseProb;
+
+  // Constructor for SelectionDAG.
+  CaseBlock(ISD::CondCode cc, const Value *cmplhs, const Value *cmprhs,
+            const Value *cmpmiddle, MachineBasicBlock *truebb,
+            MachineBasicBlock *falsebb, MachineBasicBlock *me, SDLoc dl,
+            BranchProbability trueprob = BranchProbability::getUnknown(),
+            BranchProbability falseprob = BranchProbability::getUnknown())
+      : CC(cc), CmpLHS(cmplhs), CmpMHS(cmpmiddle), CmpRHS(cmprhs),
+        TrueBB(truebb), FalseBB(falsebb), ThisBB(me), DL(dl),
+        TrueProb(trueprob), FalseProb(falseprob) {}
+
+  // Constructor for GISel.
+  CaseBlock(CmpInst::Predicate pred, bool nocmp, const Value *cmplhs,
+            const Value *cmprhs, const Value *cmpmiddle,
+            MachineBasicBlock *truebb, MachineBasicBlock *falsebb,
+            MachineBasicBlock *me, DebugLoc dl,
+            BranchProbability trueprob = BranchProbability::getUnknown(),
+            BranchProbability falseprob = BranchProbability::getUnknown())
+      : PredInfo({pred, nocmp}), CmpLHS(cmplhs), CmpMHS(cmpmiddle),
+        CmpRHS(cmprhs), TrueBB(truebb), FalseBB(falsebb), ThisBB(me),
+        DbgLoc(dl), TrueProb(trueprob), FalseProb(falseprob) {}
+};
+
+struct JumpTable {
+  /// The virtual register containing the index of the jump table entry
+  /// to jump to.
+  unsigned Reg;
+  /// The JumpTableIndex for this jump table in the function.
+  unsigned JTI;
+  /// The MBB into which to emit the code for the indirect jump.
+  MachineBasicBlock *MBB;
+  /// The MBB of the default bb, which is a successor of the range
+  /// check MBB.  This is when updating PHI nodes in successors.
+  MachineBasicBlock *Default;
+
+  JumpTable(unsigned R, unsigned J, MachineBasicBlock *M, MachineBasicBlock *D)
+      : Reg(R), JTI(J), MBB(M), Default(D) {}
+};
+struct JumpTableHeader {
+  APInt First;
+  APInt Last;
+  const Value *SValue;
+  MachineBasicBlock *HeaderBB;
+  bool Emitted;
+  bool OmitRangeCheck;
+
+  JumpTableHeader(APInt F, APInt L, const Value *SV, MachineBasicBlock *H,
+                  bool E = false)
+      : First(std::move(F)), Last(std::move(L)), SValue(SV), HeaderBB(H),
+        Emitted(E), OmitRangeCheck(false) {}
+};
+using JumpTableBlock = std::pair<JumpTableHeader, JumpTable>;
+
+struct BitTestCase {
+  uint64_t Mask;
+  MachineBasicBlock *ThisBB;
+  MachineBasicBlock *TargetBB;
+  BranchProbability ExtraProb;
+
+  BitTestCase(uint64_t M, MachineBasicBlock *T, MachineBasicBlock *Tr,
+              BranchProbability Prob)
+      : Mask(M), ThisBB(T), TargetBB(Tr), ExtraProb(Prob) {}
+};
+
+using BitTestInfo = SmallVector<BitTestCase, 3>;
+
+struct BitTestBlock {
+  APInt First;
+  APInt Range;
+  const Value *SValue;
+  unsigned Reg;
+  MVT RegVT;
+  bool Emitted;
+  bool ContiguousRange;
+  MachineBasicBlock *Parent;
+  MachineBasicBlock *Default;
+  BitTestInfo Cases;
+  BranchProbability Prob;
+  BranchProbability DefaultProb;
+
+  BitTestBlock(APInt F, APInt R, const Value *SV, unsigned Rg, MVT RgVT, bool E,
+               bool CR, MachineBasicBlock *P, MachineBasicBlock *D,
+               BitTestInfo C, BranchProbability Pr)
+      : First(std::move(F)), Range(std::move(R)), SValue(SV), Reg(Rg),
+        RegVT(RgVT), Emitted(E), ContiguousRange(CR), Parent(P), Default(D),
+        Cases(std::move(C)), Prob(Pr) {}
+};
+
+/// Return the range of value within a range.
+uint64_t getJumpTableRange(const CaseClusterVector &Clusters, unsigned First,
+                           unsigned Last);
+
+/// Return the number of cases within a range.
+uint64_t getJumpTableNumCases(const SmallVectorImpl<unsigned> &TotalCases,
+                              unsigned First, unsigned Last);
+
+struct SwitchWorkListItem {
+  MachineBasicBlock *MBB;
+  CaseClusterIt FirstCluster;
+  CaseClusterIt LastCluster;
+  const ConstantInt *GE;
+  const ConstantInt *LT;
+  BranchProbability DefaultProb;
+};
+using SwitchWorkList = SmallVector<SwitchWorkListItem, 4>;
+
+class SwitchLowering {
+public:
+  SwitchLowering(FunctionLoweringInfo &funcinfo) : FuncInfo(funcinfo) {}
+
+  void init(const TargetLowering &tli, const TargetMachine &tm,
+            const DataLayout &dl) {
+    TLI = &tli;
+    TM = &tm;
+    DL = &dl;
+  }
+
+  /// Vector of CaseBlock structures used to communicate SwitchInst code
+  /// generation information.
+  std::vector<CaseBlock> SwitchCases;
+
+  /// Vector of JumpTable structures used to communicate SwitchInst code
+  /// generation information.
+  std::vector<JumpTableBlock> JTCases;
+
+  /// Vector of BitTestBlock structures used to communicate SwitchInst code
+  /// generation information.
+  std::vector<BitTestBlock> BitTestCases;
+
+  void findJumpTables(CaseClusterVector &Clusters, const SwitchInst *SI,
+                      MachineBasicBlock *DefaultMBB);
+
+  bool buildJumpTable(const CaseClusterVector &Clusters, unsigned First,
+                      unsigned Last, const SwitchInst *SI,
+                      MachineBasicBlock *DefaultMBB, CaseCluster &JTCluster);
+
+
+  void findBitTestClusters(CaseClusterVector &Clusters, const SwitchInst *SI);
+
+  /// Build a bit test cluster from Clusters[First..Last]. Returns false if it
+  /// decides it's not a good idea.
+  bool buildBitTests(CaseClusterVector &Clusters, unsigned First, unsigned Last,
+                     const SwitchInst *SI, CaseCluster &BTCluster);
+
+  virtual void addSuccessorWithProb(
+      MachineBasicBlock *Src, MachineBasicBlock *Dst,
+      BranchProbability Prob = BranchProbability::getUnknown()) = 0;
+
+  virtual ~SwitchLowering() = default;
+
+private:
+  const TargetLowering *TLI;
+  const TargetMachine *TM;
+  const DataLayout *DL;
+  FunctionLoweringInfo &FuncInfo;
+};
+
+} // namespace SwitchCG
+} // namespace llvm
+
+#endif // LLVM_CODEGEN_SWITCHLOWERINGUTILS_H
+