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MachineJumpTableInfo.h
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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 <cassert>
24 #include <vector>
25 
26 namespace llvm {
27 
28 class MachineBasicBlock;
29 class DataLayout;
30 class raw_ostream;
31 
32 /// MachineJumpTableEntry - One jump table in the jump table info.
33 ///
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 
43 public:
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
50 
51  /// EK_GPRel64BlockAddress - Each entry is an address of block, encoded
52  /// with a relocation as gp-relative, e.g.:
53  /// .gpdword LBB123
55 
56  /// EK_GPRel32BlockAddress - Each entry is an address of block, encoded
57  /// with a relocation as gp-relative, e.g.:
58  /// .gprel32 LBB123
60 
61  /// EK_LabelDifference32 - Each entry is the address of the block minus
62  /// the address of the jump table. This is used for PIC jump tables where
63  /// gprel32 is not supported. e.g.:
64  /// .word LBB123 - LJTI1_2
65  /// If the .set directive is supported, this is emitted as:
66  /// .set L4_5_set_123, LBB123 - LJTI1_2
67  /// .word L4_5_set_123
69 
70  /// EK_Inline - Jump table entries are emitted inline at their point of
71  /// use. It is the responsibility of the target to emit the entries.
73 
74  /// EK_Custom32 - Each entry is a 32-bit value that is custom lowered by the
75  /// TargetLowering::LowerCustomJumpTableEntry hook.
76  EK_Custom32
77  };
78 private:
79  JTEntryKind EntryKind;
80  std::vector<MachineJumpTableEntry> JumpTables;
81 public:
82  explicit MachineJumpTableInfo(JTEntryKind Kind): EntryKind(Kind) {}
83 
84  JTEntryKind getEntryKind() const { return EntryKind; }
85 
86  /// getEntrySize - Return the size of each entry in the jump table.
87  unsigned getEntrySize(const DataLayout &TD) const;
88  /// getEntryAlignment - Return the alignment of each entry in the jump table.
89  unsigned getEntryAlignment(const DataLayout &TD) const;
90 
91  /// createJumpTableIndex - Create a new jump table.
92  ///
93  unsigned createJumpTableIndex(const std::vector<MachineBasicBlock*> &DestBBs);
94 
95  /// isEmpty - Return true if there are no jump tables.
96  ///
97  bool isEmpty() const { return JumpTables.empty(); }
98 
99  const std::vector<MachineJumpTableEntry> &getJumpTables() const {
100  return JumpTables;
101  }
102 
103  /// RemoveJumpTable - Mark the specific index as being dead. This will
104  /// prevent it from being emitted.
105  void RemoveJumpTable(unsigned Idx) {
106  JumpTables[Idx].MBBs.clear();
107  }
108 
109  /// ReplaceMBBInJumpTables - If Old is the target of any jump tables, update
110  /// the jump tables to branch to New instead.
111  bool ReplaceMBBInJumpTables(MachineBasicBlock *Old, MachineBasicBlock *New);
112 
113  /// ReplaceMBBInJumpTable - If Old is a target of the jump tables, update
114  /// the jump table to branch to New instead.
115  bool ReplaceMBBInJumpTable(unsigned Idx, MachineBasicBlock *Old,
116  MachineBasicBlock *New);
117 
118  /// print - Used by the MachineFunction printer to print information about
119  /// jump tables. Implemented in MachineFunction.cpp
120  ///
121  void print(raw_ostream &OS) const;
122 
123  /// dump - Call to stderr.
124  ///
125  void dump() const;
126 };
127 
128 } // End llvm namespace
129 
130 #endif
A parsed version of the target data layout string in and methods for querying it. ...
Definition: DataLayout.h:109
const std::vector< MachineJumpTableEntry > & getJumpTables() const
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
EK_Inline - Jump table entries are emitted inline at their point of use.
void RemoveJumpTable(unsigned Idx)
RemoveJumpTable - Mark the specific index as being dead.
JTEntryKind
JTEntryKind - This enum indicates how each entry of the jump table is represented and emitted...
EK_LabelDifference32 - Each entry is the address of the block minus the address of the jump table...
EK_BlockAddress - Each entry is a plain address of block, e.g.
EK_GPRel64BlockAddress - Each entry is an address of block, encoded with a relocation as gp-relative...
void dump(const SparseBitVector< ElementSize > &LHS, raw_ostream &out)
static void print(raw_ostream &Out, object::Archive::Kind Kind, T Val)
MachineJumpTableEntry(const std::vector< MachineBasicBlock *> &M)
std::vector< MachineBasicBlock * > MBBs
MBBs - The vector of basic blocks from which to create the jump table.
MachineJumpTableEntry - One jump table in the jump table info.
MachineJumpTableInfo(JTEntryKind Kind)
const unsigned Kind
bool isEmpty() const
isEmpty - Return true if there are no jump tables.
JTEntryKind getEntryKind() const
This class implements an extremely fast bulk output stream that can only output to a stream...
Definition: raw_ostream.h:44
EK_GPRel32BlockAddress - Each entry is an address of block, encoded with a relocation as gp-relative...