1//===-- JumpInstrTableInfo.h: Info for Jump-Instruction Tables --*- C++ -*-===//
2//
3// This file is distributed under the University of Illinois Open Source
4// License. See LICENSE.TXT for details.
5//
6//===----------------------------------------------------------------------===//
7///
8/// \file
9/// \brief Information about jump-instruction tables that have been created by
10/// JumpInstrTables pass.
11///
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_ANALYSIS_JUMPINSTRTABLEINFO_H
15#define LLVM_ANALYSIS_JUMPINSTRTABLEINFO_H
16
17#include "llvm/ADT/DenseMap.h"
18#include "llvm/Pass.h"
19#include <vector>
20
21namespace llvm {
22class Function;
23class FunctionType;
24
25/// This class stores information about jump-instruction tables created by the
26/// JumpInstrTables pass (in lib/CodeGen/JumpInstrTables.cpp). Each table is a
27/// map from a function type to a vector of pairs. The first element of each
28/// pair is the function that has the jumptable annotation. The second element
29/// is a function that was declared by JumpInstrTables and used to replace all
30/// address-taking sites for the original function.
31///
32/// The information in this pass is used in AsmPrinter
33/// (lib/CodeGen/AsmPrinter/AsmPrinter.cpp) to generate the required assembly
34/// for the jump-instruction tables.
35class JumpInstrTableInfo : public ImmutablePass {
36public:
37  static char ID;
38
39  /// The default byte alignment for jump tables is 16, which is large but
40  /// usually safe.
41  JumpInstrTableInfo(uint64_t ByteAlign = 16);
42  ~JumpInstrTableInfo() override;
43  const char *getPassName() const override {
44    return "Jump-Instruction Table Info";
45  }
46
47  typedef std::pair<Function *, Function *> JumpPair;
48  typedef DenseMap<FunctionType *, std::vector<JumpPair> > JumpTables;
49
50  /// Inserts an entry in a table, adding the table if it doesn't exist.
51  void insertEntry(FunctionType *TableFunTy, Function *Target, Function *Jump);
52
53  /// Gets the tables.
54  const JumpTables &getTables() const { return Tables; }
55
56  /// Gets the alignment in bytes of a jumptable entry.
57  uint64_t entryByteAlignment() const { return ByteAlignment; }
58private:
59  JumpTables Tables;
60
61  /// A power-of-two alignment of a jumptable entry.
62  uint64_t ByteAlignment;
63};
64
65/// Creates a JumpInstrTableInfo pass with the given bound on entry size. This
66/// bound specifies the maximum number of bytes needed to represent an
67/// unconditional jump or a trap instruction in the back end currently in use.
68ModulePass *createJumpInstrTableInfoPass(unsigned Bound);
69}
70
71#endif /* LLVM_ANALYSIS_JUMPINSTRTABLEINFO_H */
72