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 //===-- CodeGen/MachineJumpTableInfo.h - Abstract Jump Tables  --*- 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
 //
 //===----------------------------------------------------------------------===//
 //
 // The MachineJumpTableInfo class keeps track of jump tables referenced by
 // lowered switch instructions in the MachineFunction.
 //
 // Instructions reference the address of these jump tables through the use of
 // MO_JumpTableIndex values.  When emitting assembly or machine code, these
 // virtual address references are converted to refer to the address of the
 // function jump tables.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CODEGEN_MACHINEJUMPTABLEINFO_H
 #define LLVM_CODEGEN_MACHINEJUMPTABLEINFO_H
 
 #include "llvm/Support/Printable.h"
 #include <cassert>
 #include <vector>
 
 namespace llvm {
 
 class MachineBasicBlock;
 class DataLayout;
 class raw_ostream;
 enum class MachineFunctionDataHotness;
 
 /// MachineJumpTableEntry - One jump table in the jump table info.
 ///
 struct MachineJumpTableEntry {
   /// MBBs - The vector of basic blocks from which to create the jump table.
   std::vector<MachineBasicBlock*> MBBs;
 
   /// The hotness of MJTE is inferred from the hotness of the source basic
   /// block(s) that reference it.
   MachineFunctionDataHotness Hotness;
 
   explicit MachineJumpTableEntry(const std::vector<MachineBasicBlock *> &M);
 };
 
 class MachineJumpTableInfo {
 public:
   /// JTEntryKind - This enum indicates how each entry of the jump table is
   /// represented and emitted.
   enum JTEntryKind {
     /// EK_BlockAddress - Each entry is a plain address of block, e.g.:
     ///     .word LBB123
     EK_BlockAddress,
 
     /// EK_GPRel64BlockAddress - Each entry is an address of block, encoded
     /// with a relocation as gp-relative, e.g.:
     ///     .gpdword LBB123
     EK_GPRel64BlockAddress,
 
     /// EK_GPRel32BlockAddress - Each entry is an address of block, encoded
     /// with a relocation as gp-relative, e.g.:
     ///     .gprel32 LBB123
     EK_GPRel32BlockAddress,
 
     /// EK_LabelDifference32 - Each entry is the address of the block minus
     /// the address of the jump table.  This is used for PIC jump tables where
     /// gprel32 is not supported.  e.g.:
     ///      .word LBB123 - LJTI1_2
     /// If the .set directive is supported, this is emitted as:
     ///      .set L4_5_set_123, LBB123 - LJTI1_2
     ///      .word L4_5_set_123
     EK_LabelDifference32,
 
     /// EK_LabelDifference64 - Each entry is the address of the block minus
     /// the address of the jump table.  This is used for PIC jump tables where
     /// gprel64 is not supported.  e.g.:
     ///      .quad LBB123 - LJTI1_2
     EK_LabelDifference64,
 
     /// EK_Inline - Jump table entries are emitted inline at their point of
     /// use. It is the responsibility of the target to emit the entries.
     EK_Inline,
 
     /// EK_Custom32 - Each entry is a 32-bit value that is custom lowered by the
     /// TargetLowering::LowerCustomJumpTableEntry hook.
     EK_Custom32
   };
 
 private:
   JTEntryKind EntryKind;
   std::vector<MachineJumpTableEntry> JumpTables;
 public:
   explicit MachineJumpTableInfo(JTEntryKind Kind): EntryKind(Kind) {}
 
   JTEntryKind getEntryKind() const { return EntryKind; }
 
   /// getEntrySize - Return the size of each entry in the jump table.
   unsigned getEntrySize(const DataLayout &TD) const;
   /// getEntryAlignment - Return the alignment of each entry in the jump table.
   unsigned getEntryAlignment(const DataLayout &TD) const;
 
   /// createJumpTableIndex - Create a new jump table.
   ///
   unsigned createJumpTableIndex(const std::vector<MachineBasicBlock*> &DestBBs);
 
   /// isEmpty - Return true if there are no jump tables.
   ///
   bool isEmpty() const { return JumpTables.empty(); }
 
   const std::vector<MachineJumpTableEntry> &getJumpTables() const {
     return JumpTables;
   }
 
   // Update machine jump table entry's hotness. Return true if the hotness is
   // updated.
   bool updateJumpTableEntryHotness(size_t JTI,
                                    MachineFunctionDataHotness Hotness);
 
   /// RemoveJumpTable - Mark the specific index as being dead.  This will
   /// prevent it from being emitted.
   void RemoveJumpTable(unsigned Idx) {
     JumpTables[Idx].MBBs.clear();
   }
 
   /// RemoveMBBFromJumpTables - If MBB is present in any jump tables, remove it.
   bool RemoveMBBFromJumpTables(MachineBasicBlock *MBB);
 
   /// ReplaceMBBInJumpTables - If Old is the target of any jump tables, update
   /// the jump tables to branch to New instead.
   bool ReplaceMBBInJumpTables(MachineBasicBlock *Old, MachineBasicBlock *New);
 
   /// ReplaceMBBInJumpTable - If Old is a target of the jump tables, update
   /// the jump table to branch to New instead.
   bool ReplaceMBBInJumpTable(unsigned Idx, MachineBasicBlock *Old,
                              MachineBasicBlock *New);
 
   /// print - Used by the MachineFunction printer to print information about
   /// jump tables.  Implemented in MachineFunction.cpp
   ///
   void print(raw_ostream &OS) const;
 
   /// dump - Call to stderr.
   ///
   void dump() const;
 };
 
 
 /// Prints a jump table entry reference.
 ///
 /// The format is:
 ///   %jump-table.5       - a jump table entry with index == 5.
 ///
 /// Usage: OS << printJumpTableEntryReference(Idx) << '\n';
 Printable printJumpTableEntryReference(unsigned Idx);
 
 } // End llvm namespace
 
 #endif

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