1 //===-- CodeGen/MachineJumpTableInfo.h - Abstract Jump Tables --*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // The MachineJumpTableInfo class keeps track of jump tables referenced by 11 // lowered switch instructions in the MachineFunction. 12 // 13 // Instructions reference the address of these jump tables through the use of 14 // MO_JumpTableIndex values. When emitting assembly or machine code, these 15 // virtual address references are converted to refer to the address of the 16 // function jump tables. 17 // 18 //===----------------------------------------------------------------------===// 19 20 #ifndef LLVM_CODEGEN_MACHINEJUMPTABLEINFO_H 21 #define LLVM_CODEGEN_MACHINEJUMPTABLEINFO_H 22 23 #include <cassert> 24 #include <vector> 25 26 namespace llvm { 27 28 class MachineBasicBlock; 29 class DataLayout; 30 class raw_ostream; 31 32 /// MachineJumpTableEntry - One jump table in the jump table info. 33 /// 34 struct MachineJumpTableEntry { 35 /// MBBs - The vector of basic blocks from which to create the jump table. 36 std::vector<MachineBasicBlock*> MBBs; 37 MachineJumpTableEntryMachineJumpTableEntry38 explicit MachineJumpTableEntry(const std::vector<MachineBasicBlock*> &M) 39 : MBBs(M) {} 40 }; 41 42 class MachineJumpTableInfo { 43 public: 44 /// JTEntryKind - This enum indicates how each entry of the jump table is 45 /// represented and emitted. 46 enum JTEntryKind { 47 /// EK_BlockAddress - Each entry is a plain address of block, e.g.: 48 /// .word LBB123 49 EK_BlockAddress, 50 51 /// EK_GPRel64BlockAddress - Each entry is an address of block, encoded 52 /// with a relocation as gp-relative, e.g.: 53 /// .gpdword LBB123 54 EK_GPRel64BlockAddress, 55 56 /// EK_GPRel32BlockAddress - Each entry is an address of block, encoded 57 /// with a relocation as gp-relative, e.g.: 58 /// .gprel32 LBB123 59 EK_GPRel32BlockAddress, 60 61 /// EK_LabelDifference32 - Each entry is the address of the block minus 62 /// the address of the jump table. This is used for PIC jump tables where 63 /// gprel32 is not supported. e.g.: 64 /// .word LBB123 - LJTI1_2 65 /// If the .set directive is supported, this is emitted as: 66 /// .set L4_5_set_123, LBB123 - LJTI1_2 67 /// .word L4_5_set_123 68 EK_LabelDifference32, 69 70 /// EK_Inline - Jump table entries are emitted inline at their point of 71 /// use. It is the responsibility of the target to emit the entries. 72 EK_Inline, 73 74 /// EK_Custom32 - Each entry is a 32-bit value that is custom lowered by the 75 /// TargetLowering::LowerCustomJumpTableEntry hook. 76 EK_Custom32 77 }; 78 private: 79 JTEntryKind EntryKind; 80 std::vector<MachineJumpTableEntry> JumpTables; 81 public: MachineJumpTableInfo(JTEntryKind Kind)82 explicit MachineJumpTableInfo(JTEntryKind Kind): EntryKind(Kind) {} 83 getEntryKind()84 JTEntryKind getEntryKind() const { return EntryKind; } 85 86 /// getEntrySize - Return the size of each entry in the jump table. 87 unsigned getEntrySize(const DataLayout &TD) const; 88 /// getEntryAlignment - Return the alignment of each entry in the jump table. 89 unsigned getEntryAlignment(const DataLayout &TD) const; 90 91 /// createJumpTableIndex - Create a new jump table. 92 /// 93 unsigned createJumpTableIndex(const std::vector<MachineBasicBlock*> &DestBBs); 94 95 /// isEmpty - Return true if there are no jump tables. 96 /// isEmpty()97 bool isEmpty() const { return JumpTables.empty(); } 98 getJumpTables()99 const std::vector<MachineJumpTableEntry> &getJumpTables() const { 100 return JumpTables; 101 } 102 103 /// RemoveJumpTable - Mark the specific index as being dead. This will 104 /// prevent it from being emitted. RemoveJumpTable(unsigned Idx)105 void RemoveJumpTable(unsigned Idx) { 106 JumpTables[Idx].MBBs.clear(); 107 } 108 109 /// ReplaceMBBInJumpTables - If Old is the target of any jump tables, update 110 /// the jump tables to branch to New instead. 111 bool ReplaceMBBInJumpTables(MachineBasicBlock *Old, MachineBasicBlock *New); 112 113 /// ReplaceMBBInJumpTable - If Old is a target of the jump tables, update 114 /// the jump table to branch to New instead. 115 bool ReplaceMBBInJumpTable(unsigned Idx, MachineBasicBlock *Old, 116 MachineBasicBlock *New); 117 118 /// print - Used by the MachineFunction printer to print information about 119 /// jump tables. Implemented in MachineFunction.cpp 120 /// 121 void print(raw_ostream &OS) const; 122 123 /// dump - Call to stderr. 124 /// 125 void dump() const; 126 }; 127 128 } // End llvm namespace 129 130 #endif 131