1 //===-- CodeGen/MachineJumpTableInfo.h - Abstract Jump Tables --*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // The MachineJumpTableInfo class keeps track of jump tables referenced by
11 // lowered switch instructions in the MachineFunction.
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.
18 //===----------------------------------------------------------------------===//
20 #ifndef LLVM_CODEGEN_MACHINEJUMPTABLEINFO_H
21 #define LLVM_CODEGEN_MACHINEJUMPTABLEINFO_H
28 class MachineBasicBlock;
32 /// MachineJumpTableEntry - One jump table in the jump table info.
34 struct MachineJumpTableEntry {
35 /// MBBs - The vector of basic blocks from which to create the jump table.
36 std::vector<MachineBasicBlock*> MBBs;
38 explicit MachineJumpTableEntry(const std::vector<MachineBasicBlock*> &M)
42 class MachineJumpTableInfo {
44 /// JTEntryKind - This enum indicates how each entry of the jump table is
45 /// represented and emitted.
47 /// EK_BlockAddress - Each entry is a plain address of block, e.g.:
51 /// EK_GPRel32BlockAddress - Each entry is an address of block, encoded
52 /// with a relocation as gp-relative, e.g.:
54 EK_GPRel32BlockAddress,
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
65 /// EK_Custom32 - Each entry is a 32-bit value that is custom lowered by the
66 /// TargetLowering::LowerCustomJumpTableEntry hook.
70 JTEntryKind EntryKind;
71 std::vector<MachineJumpTableEntry> JumpTables;
73 MachineJumpTableInfo(JTEntryKind Kind): EntryKind(Kind) {}
75 JTEntryKind getEntryKind() const { return EntryKind; }
77 /// getEntrySize - Return the size of each entry in the jump table.
78 unsigned getEntrySize(const TargetData &TD) const;
79 /// getEntryAlignment - Return the alignment of each entry in the jump table.
80 unsigned getEntryAlignment(const TargetData &TD) const;
82 /// getJumpTableIndex - Create a new jump table or return an existing one.
84 unsigned getJumpTableIndex(const std::vector<MachineBasicBlock*> &DestBBs);
86 /// isEmpty - Return true if there are no jump tables.
88 bool isEmpty() const { return JumpTables.empty(); }
90 const std::vector<MachineJumpTableEntry> &getJumpTables() const {
94 /// RemoveJumpTable - Mark the specific index as being dead. This will
95 /// prevent it from being emitted.
96 void RemoveJumpTable(unsigned Idx) {
97 JumpTables[Idx].MBBs.clear();
100 /// ReplaceMBBInJumpTables - If Old is the target of any jump tables, update
101 /// the jump tables to branch to New instead.
102 bool ReplaceMBBInJumpTables(MachineBasicBlock *Old, MachineBasicBlock *New);
104 /// ReplaceMBBInJumpTable - If Old is a target of the jump tables, update
105 /// the jump table to branch to New instead.
106 bool ReplaceMBBInJumpTable(unsigned Idx, MachineBasicBlock *Old,
107 MachineBasicBlock *New);
109 /// print - Used by the MachineFunction printer to print information about
110 /// jump tables. Implemented in MachineFunction.cpp
112 void print(raw_ostream &OS) const;
114 /// dump - Call to stderr.
119 } // End llvm namespace