MachineJumpTableInfo.h revision 210299
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 <vector> 24#include <cassert> 25 26namespace llvm { 27 28class MachineBasicBlock; 29class TargetData; 30class raw_ostream; 31 32/// MachineJumpTableEntry - One jump table in the jump table info. 33/// 34struct MachineJumpTableEntry { 35 /// MBBs - The vector of basic blocks from which to create the jump table. 36 std::vector<MachineBasicBlock*> MBBs; 37 38 explicit MachineJumpTableEntry(const std::vector<MachineBasicBlock*> &M) 39 : MBBs(M) {} 40}; 41 42class MachineJumpTableInfo { 43public: 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_GPRel32BlockAddress - Each entry is an address of block, encoded 52 /// with a relocation as gp-relative, e.g.: 53 /// .gprel32 LBB123 54 EK_GPRel32BlockAddress, 55 56 /// EK_LabelDifference32 - Each entry is the address of the block minus 57 /// the address of the jump table. This is used for PIC jump tables where 58 /// gprel32 is not supported. e.g.: 59 /// .word LBB123 - LJTI1_2 60 /// If the .set directive is supported, this is emitted as: 61 /// .set L4_5_set_123, LBB123 - LJTI1_2 62 /// .word L4_5_set_123 63 EK_LabelDifference32, 64 65 /// EK_Inline - Jump table entries are emitted inline at their point of 66 /// use. It is the responsibility of the target to emit the entries. 67 EK_Inline, 68 69 /// EK_Custom32 - Each entry is a 32-bit value that is custom lowered by the 70 /// TargetLowering::LowerCustomJumpTableEntry hook. 71 EK_Custom32 72 }; 73private: 74 JTEntryKind EntryKind; 75 std::vector<MachineJumpTableEntry> JumpTables; 76public: 77 explicit MachineJumpTableInfo(JTEntryKind Kind): EntryKind(Kind) {} 78 79 JTEntryKind getEntryKind() const { return EntryKind; } 80 81 /// getEntrySize - Return the size of each entry in the jump table. 82 unsigned getEntrySize(const TargetData &TD) const; 83 /// getEntryAlignment - Return the alignment of each entry in the jump table. 84 unsigned getEntryAlignment(const TargetData &TD) const; 85 86 /// createJumpTableIndex - Create a new jump table. 87 /// 88 unsigned createJumpTableIndex(const std::vector<MachineBasicBlock*> &DestBBs); 89 90 /// isEmpty - Return true if there are no jump tables. 91 /// 92 bool isEmpty() const { return JumpTables.empty(); } 93 94 const std::vector<MachineJumpTableEntry> &getJumpTables() const { 95 return JumpTables; 96 } 97 98 /// RemoveJumpTable - Mark the specific index as being dead. This will 99 /// prevent it from being emitted. 100 void RemoveJumpTable(unsigned Idx) { 101 JumpTables[Idx].MBBs.clear(); 102 } 103 104 /// ReplaceMBBInJumpTables - If Old is the target of any jump tables, update 105 /// the jump tables to branch to New instead. 106 bool ReplaceMBBInJumpTables(MachineBasicBlock *Old, MachineBasicBlock *New); 107 108 /// ReplaceMBBInJumpTable - If Old is a target of the jump tables, update 109 /// the jump table to branch to New instead. 110 bool ReplaceMBBInJumpTable(unsigned Idx, MachineBasicBlock *Old, 111 MachineBasicBlock *New); 112 113 /// print - Used by the MachineFunction printer to print information about 114 /// jump tables. Implemented in MachineFunction.cpp 115 /// 116 void print(raw_ostream &OS) const; 117 118 /// dump - Call to stderr. 119 /// 120 void dump() const; 121}; 122 123} // End llvm namespace 124 125#endif 126