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
23 #include "llvm/Support/Printable.h"
29 class MachineBasicBlock;
33 /// MachineJumpTableEntry - One jump table in the jump table info.
35 struct MachineJumpTableEntry {
36 /// MBBs - The vector of basic blocks from which to create the jump table.
37 std::vector<MachineBasicBlock*> MBBs;
39 explicit MachineJumpTableEntry(const std::vector<MachineBasicBlock*> &M)
43 class MachineJumpTableInfo {
45 /// JTEntryKind - This enum indicates how each entry of the jump table is
46 /// represented and emitted.
48 /// EK_BlockAddress - Each entry is a plain address of block, e.g.:
52 /// EK_GPRel64BlockAddress - Each entry is an address of block, encoded
53 /// with a relocation as gp-relative, e.g.:
55 EK_GPRel64BlockAddress,
57 /// EK_GPRel32BlockAddress - Each entry is an address of block, encoded
58 /// with a relocation as gp-relative, e.g.:
60 EK_GPRel32BlockAddress,
62 /// EK_LabelDifference32 - Each entry is the address of the block minus
63 /// the address of the jump table. This is used for PIC jump tables where
64 /// gprel32 is not supported. e.g.:
65 /// .word LBB123 - LJTI1_2
66 /// If the .set directive is supported, this is emitted as:
67 /// .set L4_5_set_123, LBB123 - LJTI1_2
68 /// .word L4_5_set_123
71 /// EK_Inline - Jump table entries are emitted inline at their point of
72 /// use. It is the responsibility of the target to emit the entries.
75 /// EK_Custom32 - Each entry is a 32-bit value that is custom lowered by the
76 /// TargetLowering::LowerCustomJumpTableEntry hook.
80 JTEntryKind EntryKind;
81 std::vector<MachineJumpTableEntry> JumpTables;
83 explicit MachineJumpTableInfo(JTEntryKind Kind): EntryKind(Kind) {}
85 JTEntryKind getEntryKind() const { return EntryKind; }
87 /// getEntrySize - Return the size of each entry in the jump table.
88 unsigned getEntrySize(const DataLayout &TD) const;
89 /// getEntryAlignment - Return the alignment of each entry in the jump table.
90 unsigned getEntryAlignment(const DataLayout &TD) const;
92 /// createJumpTableIndex - Create a new jump table.
94 unsigned createJumpTableIndex(const std::vector<MachineBasicBlock*> &DestBBs);
96 /// isEmpty - Return true if there are no jump tables.
98 bool isEmpty() const { return JumpTables.empty(); }
100 const std::vector<MachineJumpTableEntry> &getJumpTables() const {
104 /// RemoveJumpTable - Mark the specific index as being dead. This will
105 /// prevent it from being emitted.
106 void RemoveJumpTable(unsigned Idx) {
107 JumpTables[Idx].MBBs.clear();
110 /// ReplaceMBBInJumpTables - If Old is the target of any jump tables, update
111 /// the jump tables to branch to New instead.
112 bool ReplaceMBBInJumpTables(MachineBasicBlock *Old, MachineBasicBlock *New);
114 /// ReplaceMBBInJumpTable - If Old is a target of the jump tables, update
115 /// the jump table to branch to New instead.
116 bool ReplaceMBBInJumpTable(unsigned Idx, MachineBasicBlock *Old,
117 MachineBasicBlock *New);
119 /// print - Used by the MachineFunction printer to print information about
120 /// jump tables. Implemented in MachineFunction.cpp
122 void print(raw_ostream &OS) const;
124 /// dump - Call to stderr.
130 /// Prints a jump table entry reference.
133 /// %jump-table.5 - a jump table entry with index == 5.
135 /// Usage: OS << printJumpTableEntryReference(Idx) << '\n';
136 Printable printJumpTableEntryReference(unsigned Idx);
138 } // End llvm namespace