MCAsmLayout.h revision 4766ef41b31e4f97bce1179c3b0398303bf65356 
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/DenseMap.h"
14#include "llvm/ADT/SmallVector.h"
15
16namespace llvm {
17class MCAssembler;
18class MCFragment;
19class MCSectionData;
20class MCSymbolData;
21
22/// Encapsulates the layout of an assembly file at a particular point in time.
23///
24/// Assembly may require computing multiple layouts for a particular assembly
25/// file as part of the relaxation process. This class encapsulates the layout
26/// at a single point in time in such a way that it is always possible to
27/// efficiently compute the exact address of any symbol in the assembly file,
28/// even during the relaxation process.
29class MCAsmLayout {
30public:
31  typedef llvm::SmallVectorImpl<MCSectionData*>::const_iterator const_iterator;
32  typedef llvm::SmallVectorImpl<MCSectionData*>::iterator iterator;
33
34private:
35  MCAssembler &Assembler;
36
37  /// List of sections in layout order.
38  llvm::SmallVector<MCSectionData*, 16> SectionOrder;
39
40  /// The last fragment which was laid out, or 0 if nothing has been laid
41  /// out. Fragments are always laid out in order, so all fragments with a
42  /// lower ordinal will be valid.
43  mutable DenseMap<const MCSectionData*, MCFragment*> LastValidFragment;
44
45  /// \brief Make sure that the layout for the given fragment is valid, lazily
46  /// computing it if necessary.
47  void ensureValid(const MCFragment *F) const;
48
49  /// \brief Is the layout for this fragment valid?
50  bool isFragmentValid(const MCFragment *F) const;
51
52  /// \brief Compute the amount of padding required before this fragment to
53  /// obey bundling restrictions.
54  uint64_t computeBundlePadding(const MCFragment *F,
55                                uint64_t FOffset, uint64_t FSize);
56
57public:
58  MCAsmLayout(MCAssembler &_Assembler);
59
60  /// Get the assembler object this is a layout for.
61  MCAssembler &getAssembler() const { return Assembler; }
62
63  /// \brief Invalidate the fragments after F because it has been resized.
64  /// The fragment's size should have already been updated.
65  void invalidateFragmentsAfter(MCFragment *F);
66
67  /// \brief Perform layout for a single fragment, assuming that the previous
68  /// fragment has already been laid out correctly, and the parent section has
69  /// been initialized.
70  void layoutFragment(MCFragment *Fragment);
71
72  /// @name Section Access (in layout order)
73  /// @{
74
75  llvm::SmallVectorImpl<MCSectionData*> &getSectionOrder() {
76    return SectionOrder;
77  }
78  const llvm::SmallVectorImpl<MCSectionData*> &getSectionOrder() const {
79    return SectionOrder;
80  }
81
82  /// @}
83  /// @name Fragment Layout Data
84  /// @{
85
86  /// \brief Get the offset of the given fragment inside its containing section.
87  uint64_t getFragmentOffset(const MCFragment *F) const;
88
89  /// @}
90  /// @name Utility Functions
91  /// @{
92
93  /// \brief Get the address space size of the given section, as it effects
94  /// layout. This may differ from the size reported by \see getSectionSize() by
95  /// not including section tail padding.
96  uint64_t getSectionAddressSize(const MCSectionData *SD) const;
97
98  /// \brief Get the data size of the given section, as emitted to the object
99  /// file. This may include additional padding, or be 0 for virtual sections.
100  uint64_t getSectionFileSize(const MCSectionData *SD) const;
101
102  /// \brief Get the offset of the given symbol, as computed in the current
103  /// layout.
104  uint64_t getSymbolOffset(const MCSymbolData *SD) const;
105
106  /// @}
107};
108
109} // end namespace llvm
110
111#endif
112