MCAsmLayout.h revision 47b3ec4daa12019b98468e8f646501ec285bbb59 
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 layed out, or 0 if nothing has been layed
40  /// out. Fragments are always layed out in order, so all fragments with a
41  /// lower ordinal will be up to date.
42  mutable 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 isSectionUpToDate(const MCSectionData *SD) const;
49  bool isFragmentUpToDate(const MCFragment *F) const;
50
51public:
52  MCAsmLayout(MCAssembler &_Assembler);
53
54  /// Get the assembler object this is a layout for.
55  MCAssembler &getAssembler() const { return Assembler; }
56
57  /// \brief Update the layout because a fragment has been resized. The
58  /// fragments size should have already been updated, the \arg SlideAmount is
59  /// the delta from the old size.
60  void UpdateForSlide(MCFragment *F, int SlideAmount);
61
62  /// \brief Update the layout because a fragment has been replaced.
63  void FragmentReplaced(MCFragment *Src, MCFragment *Dst);
64
65  /// \brief Perform a full layout.
66  void LayoutFile();
67
68  /// \brief Perform layout for a single fragment, assuming that the previous
69  /// fragment has already been layed out correctly, and the parent section has
70  /// been initialized.
71  void LayoutFragment(MCFragment *Fragment);
72
73  /// \brief Performs initial layout for a single section, assuming that the
74  /// previous section (including its fragments) has already been layed out
75  /// correctly.
76  void LayoutSection(MCSectionData *SD);
77
78  /// @name Section Access (in layout order)
79  /// @{
80
81  llvm::SmallVectorImpl<MCSectionData*> &getSectionOrder() {
82    return SectionOrder;
83  }
84  const llvm::SmallVectorImpl<MCSectionData*> &getSectionOrder() const {
85    return SectionOrder;
86  }
87
88  /// @}
89  /// @name Fragment Layout Data
90  /// @{
91
92  /// \brief Get the effective size of the given fragment, as computed in the
93  /// current layout.
94  uint64_t getFragmentEffectiveSize(const MCFragment *F) const;
95
96  /// \brief Get the offset of the given fragment inside its containing section.
97  uint64_t getFragmentOffset(const MCFragment *F) const;
98
99  /// @}
100  /// @name Section Layout Data
101  /// @{
102
103  /// \brief Get the computed address of the given section.
104  uint64_t getSectionAddress(const MCSectionData *SD) const;
105
106  /// @}
107  /// @name Utility Functions
108  /// @{
109
110  /// \brief Get the address of the given fragment, as computed in the current
111  /// layout.
112  uint64_t getFragmentAddress(const MCFragment *F) const;
113
114  /// \brief Get the address space size of the given section, as it effects
115  /// layout. This may differ from the size reported by \see getSectionSize() by
116  /// not including section tail padding.
117  uint64_t getSectionAddressSize(const MCSectionData *SD) const;
118
119  /// \brief Get the data size of the given section, as emitted to the object
120  /// file. This may include additional padding, or be 0 for virtual sections.
121  uint64_t getSectionFileSize(const MCSectionData *SD) const;
122
123  /// \brief Get the logical data size of the given section.
124  uint64_t getSectionSize(const MCSectionData *SD) const;
125
126  /// \brief Get the address of the given symbol, as computed in the current
127  /// layout.
128  uint64_t getSymbolAddress(const MCSymbolData *SD) const;
129
130  /// @}
131};
132
133} // end namespace llvm
134
135#endif
136