MCAsmLayout.h revision 7a2bdde0a0eebcd2125055e0eacaca040f0b766c 
1//===- MCAsmLayout.h - Assembly Layout Object -------------------*- 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#ifndef LLVM_MC_MCASMLAYOUT_H
11#define LLVM_MC_MCASMLAYOUT_H
12
13#include "llvm/ADT/SmallVector.h"
14
15namespace llvm {
16class MCAssembler;
17class MCFragment;
18class MCSectionData;
19class MCSymbolData;
20
21/// Encapsulates the layout of an assembly file at a particular point in time.
22///
23/// Assembly may requiring compute multiple layouts for a particular assembly
24/// file as part of the relaxation process. This class encapsulates the layout
25/// at a single point in time in such a way that it is always possible to
26/// efficiently compute the exact addresses of any symbol in the assembly file,
27/// even during the relaxation process.
28class MCAsmLayout {
29public:
30  typedef llvm::SmallVectorImpl<MCSectionData*>::const_iterator const_iterator;
31  typedef llvm::SmallVectorImpl<MCSectionData*>::iterator iterator;
32
33private:
34  MCAssembler &Assembler;
35
36  /// List of sections in layout order.
37  llvm::SmallVector<MCSectionData*, 16> SectionOrder;
38
39  /// The last fragment which was laid out, or 0 if nothing has been laid
40  /// out. Fragments are always laid out in order, so all fragments with a
41  /// lower ordinal will be up to date.
42  mutable DenseMap<const MCSectionData*, MCFragment *> LastValidFragment;
43
44  /// \brief Make sure that the layout for the given fragment is valid, lazily
45  /// computing it if necessary.
46  void EnsureValid(const MCFragment *F) const;
47
48  bool isFragmentUpToDate(const MCFragment *F) const;
49
50public:
51  MCAsmLayout(MCAssembler &_Assembler);
52
53  /// Get the assembler object this is a layout for.
54  MCAssembler &getAssembler() const { return Assembler; }
55
56  /// \brief Invalidate all following fragments because a fragment has been
57  /// resized. The fragments size should have already been updated.
58  void Invalidate(MCFragment *F);
59
60  /// \brief Perform layout for a single fragment, assuming that the previous
61  /// fragment has already been laid out correctly, and the parent section has
62  /// been initialized.
63  void LayoutFragment(MCFragment *Fragment);
64
65  /// @name Section Access (in layout order)
66  /// @{
67
68  llvm::SmallVectorImpl<MCSectionData*> &getSectionOrder() {
69    return SectionOrder;
70  }
71  const llvm::SmallVectorImpl<MCSectionData*> &getSectionOrder() const {
72    return SectionOrder;
73  }
74
75  /// @}
76  /// @name Fragment Layout Data
77  /// @{
78
79  /// \brief Get the offset of the given fragment inside its containing section.
80  uint64_t getFragmentOffset(const MCFragment *F) const;
81
82  /// @}
83  /// @name Utility Functions
84  /// @{
85
86  /// \brief Get the address space size of the given section, as it effects
87  /// layout. This may differ from the size reported by \see getSectionSize() by
88  /// not including section tail padding.
89  uint64_t getSectionAddressSize(const MCSectionData *SD) const;
90
91  /// \brief Get the data size of the given section, as emitted to the object
92  /// file. This may include additional padding, or be 0 for virtual sections.
93  uint64_t getSectionFileSize(const MCSectionData *SD) const;
94
95  /// \brief Get the offset of the given symbol, as computed in the current
96  /// layout.
97  uint64_t getSymbolOffset(const MCSymbolData *SD) const;
98
99  /// @}
100};
101
102} // end namespace llvm
103
104#endif
105