MachineJumpTableInfo.h revision 071c62fad0b25ad4131e7f984173a796c1e63f61
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 }; 65private: 66 JTEntryKind EntryKind; 67 std::vector<MachineJumpTableEntry> JumpTables; 68public: 69 MachineJumpTableInfo(JTEntryKind Kind): EntryKind(Kind) {} 70 71 JTEntryKind getEntryKind() const { return EntryKind; } 72 73 /// getEntrySize - Return the size of each entry in the jump table. 74 unsigned getEntrySize(const TargetData &TD) const; 75 /// getEntryAlignment - Return the alignment of each entry in the jump table. 76 unsigned getEntryAlignment(const TargetData &TD) const; 77 78 /// getJumpTableIndex - Create a new jump table or return an existing one. 79 /// 80 unsigned getJumpTableIndex(const std::vector<MachineBasicBlock*> &DestBBs); 81 82 /// isEmpty - Return true if there are no jump tables. 83 /// 84 bool isEmpty() const { return JumpTables.empty(); } 85 86 const std::vector<MachineJumpTableEntry> &getJumpTables() const { 87 return JumpTables; 88 } 89 90 /// RemoveJumpTable - Mark the specific index as being dead. This will 91 /// prevent it from being emitted. 92 void RemoveJumpTable(unsigned Idx) { 93 JumpTables[Idx].MBBs.clear(); 94 } 95 96 /// ReplaceMBBInJumpTables - If Old is the target of any jump tables, update 97 /// the jump tables to branch to New instead. 98 bool ReplaceMBBInJumpTables(MachineBasicBlock *Old, MachineBasicBlock *New); 99 100 /// ReplaceMBBInJumpTable - If Old is a target of the jump tables, update 101 /// the jump table to branch to New instead. 102 bool ReplaceMBBInJumpTable(unsigned Idx, MachineBasicBlock *Old, 103 MachineBasicBlock *New); 104 105 /// print - Used by the MachineFunction printer to print information about 106 /// jump tables. Implemented in MachineFunction.cpp 107 /// 108 void print(raw_ostream &OS) const; 109 110 /// dump - Call to stderr. 111 /// 112 void dump() const; 113}; 114 115} // End llvm namespace 116 117#endif 118