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 MCSection;
20class MCSymbol;
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 {
30  MCAssembler &Assembler;
31
32  /// List of sections in layout order.
33  llvm::SmallVector<MCSection *, 16> SectionOrder;
34
35  /// The last fragment which was laid out, or 0 if nothing has been laid
36  /// out. Fragments are always laid out in order, so all fragments with a
37  /// lower ordinal will be valid.
38  mutable DenseMap<const MCSection *, MCFragment *> LastValidFragment;
39
40  /// \brief Make sure that the layout for the given fragment is valid, lazily
41  /// computing it if necessary.
42  void ensureValid(const MCFragment *F) const;
43
44  /// \brief Is the layout for this fragment valid?
45  bool isFragmentValid(const MCFragment *F) const;
46
47public:
48  MCAsmLayout(MCAssembler &Assembler);
49
50  /// Get the assembler object this is a layout for.
51  MCAssembler &getAssembler() const { return Assembler; }
52
53  /// \brief Invalidate the fragments starting with F because it has been
54  /// resized. The fragment's size should have already been updated, but
55  /// its bundle padding will be recomputed.
56  void invalidateFragmentsFrom(MCFragment *F);
57
58  /// \brief Perform layout for a single fragment, assuming that the previous
59  /// fragment has already been laid out correctly, and the parent section has
60  /// been initialized.
61  void layoutFragment(MCFragment *Fragment);
62
63  /// \name Section Access (in layout order)
64  /// @{
65
66  llvm::SmallVectorImpl<MCSection *> &getSectionOrder() { return SectionOrder; }
67  const llvm::SmallVectorImpl<MCSection *> &getSectionOrder() const {
68    return SectionOrder;
69  }
70
71  /// @}
72  /// \name Fragment Layout Data
73  /// @{
74
75  /// \brief Get the offset of the given fragment inside its containing section.
76  uint64_t getFragmentOffset(const MCFragment *F) const;
77
78  /// @}
79  /// \name Utility Functions
80  /// @{
81
82  /// \brief Get the address space size of the given section, as it effects
83  /// layout. This may differ from the size reported by \see getSectionSize() by
84  /// not including section tail padding.
85  uint64_t getSectionAddressSize(const MCSection *Sec) const;
86
87  /// \brief Get the data size of the given section, as emitted to the object
88  /// file. This may include additional padding, or be 0 for virtual sections.
89  uint64_t getSectionFileSize(const MCSection *Sec) const;
90
91  /// \brief Get the offset of the given symbol, as computed in the current
92  /// layout.
93  /// \return True on success.
94  bool getSymbolOffset(const MCSymbol &S, uint64_t &Val) const;
95
96  /// \brief Variant that reports a fatal error if the offset is not computable.
97  uint64_t getSymbolOffset(const MCSymbol &S) const;
98
99  /// \brief If this symbol is equivalent to A + Constant, return A.
100  const MCSymbol *getBaseSymbol(const MCSymbol &Symbol) const;
101
102  /// @}
103};
104
105} // end namespace llvm
106
107#endif
108