MCAsmLayout.h revision f43e3fdb4ffddff6f71b5597c813c43e1e206564 
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 up to date.
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  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 Invalidate the fragments after F because it has been resized.
58  /// The fragment's size should have already been updated.
59  void invalidateFragmentsAfter(MCFragment *F);
60
61  /// \brief Perform layout for a single fragment, assuming that the previous
62  /// fragment has already been laid out correctly, and the parent section has
63  /// been initialized.
64  void LayoutFragment(MCFragment *Fragment);
65
66  /// @name Section Access (in layout order)
67  /// @{
68
69  llvm::SmallVectorImpl<MCSectionData*> &getSectionOrder() {
70    return SectionOrder;
71  }
72  const llvm::SmallVectorImpl<MCSectionData*> &getSectionOrder() const {
73    return SectionOrder;
74  }
75
76  /// @}
77  /// @name Fragment Layout Data
78  /// @{
79
80  /// \brief Get the offset of the given fragment inside its containing section.
81  uint64_t getFragmentOffset(const MCFragment *F) const;
82
83  /// @}
84  /// @name Utility Functions
85  /// @{
86
87  /// \brief Get the address space size of the given section, as it effects
88  /// layout. This may differ from the size reported by \see getSectionSize() by
89  /// not including section tail padding.
90  uint64_t getSectionAddressSize(const MCSectionData *SD) const;
91
92  /// \brief Get the data size of the given section, as emitted to the object
93  /// file. This may include additional padding, or be 0 for virtual sections.
94  uint64_t getSectionFileSize(const MCSectionData *SD) const;
95
96  /// \brief Get the offset of the given symbol, as computed in the current
97  /// layout.
98  uint64_t getSymbolOffset(const MCSymbolData *SD) const;
99
100  /// @}
101};
102
103} // end namespace llvm
104
105#endif
106