MachineJumpTableInfo.h revision 193323 
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 <iosfwd>
25#include <cassert>
26
27namespace llvm {
28
29class MachineBasicBlock;
30class TargetData;
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 {
43  unsigned EntrySize;
44  unsigned Alignment;
45  std::vector<MachineJumpTableEntry> JumpTables;
46public:
47  MachineJumpTableInfo(unsigned Size, unsigned Align)
48  : EntrySize(Size), Alignment(Align) {}
49
50  /// getJumpTableIndex - Create a new jump table or return an existing one.
51  ///
52  unsigned getJumpTableIndex(const std::vector<MachineBasicBlock*> &DestBBs);
53
54  /// isEmpty - Return true if there are no jump tables.
55  ///
56  bool isEmpty() const { return JumpTables.empty(); }
57
58  const std::vector<MachineJumpTableEntry> &getJumpTables() const {
59    return JumpTables;
60  }
61
62  /// RemoveJumpTable - Mark the specific index as being dead.  This will cause
63  /// it to not be emitted.
64  void RemoveJumpTable(unsigned Idx) {
65    JumpTables[Idx].MBBs.clear();
66  }
67
68  /// ReplaceMBBInJumpTables - If Old is the target of any jump tables, update
69  /// the jump tables to branch to New instead.
70  bool ReplaceMBBInJumpTables(MachineBasicBlock *Old, MachineBasicBlock *New);
71
72  /// getEntrySize - Returns the size of an individual field in a jump table.
73  ///
74  unsigned getEntrySize() const { return EntrySize; }
75
76  /// getAlignment - returns the target's preferred alignment for jump tables
77  unsigned getAlignment() const { return Alignment; }
78
79  /// print - Used by the MachineFunction printer to print information about
80  /// jump tables.  Implemented in MachineFunction.cpp
81  ///
82  void print(std::ostream &OS) const;
83  void print(std::ostream *OS) const { if (OS) print(*OS); }
84
85  /// dump - Call print(std::cerr) to be called from the debugger.
86  ///
87  void dump() const;
88};
89
90} // End llvm namespace
91
92#endif
93