1//===- MCAsmLayout.h - Assembly Layout Object -------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef LLVM_MC_MCASMLAYOUT_H
10#define LLVM_MC_MCASMLAYOUT_H
11
12#include "llvm/ADT/DenseMap.h"
13#include "llvm/ADT/SmallVector.h"
14
15namespace llvm {
16class MCAssembler;
17class MCFragment;
18class MCSection;
19class MCSymbol;
20
21/// Encapsulates the layout of an assembly file at a particular point in time.
22///
23/// Assembly may require computing 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 address of any symbol in the assembly file,
27/// even during the relaxation process.
28class MCAsmLayout {
29  MCAssembler &Assembler;
30
31  /// List of sections in layout order.
32  llvm::SmallVector<MCSection *, 16> SectionOrder;
33
34  /// The last fragment which was laid out, or 0 if nothing has been laid
35  /// out. Fragments are always laid out in order, so all fragments with a
36  /// lower ordinal will be valid.
37  mutable DenseMap<const MCSection *, MCFragment *> LastValidFragment;
38
39  /// Make sure that the layout for the given fragment is valid, lazily
40  /// computing it if necessary.
41  void ensureValid(const MCFragment *F) const;
42
43  /// Is the layout for this fragment valid?
44  bool isFragmentValid(const MCFragment *F) const;
45
46public:
47  MCAsmLayout(MCAssembler &Assembler);
48
49  /// Get the assembler object this is a layout for.
50  MCAssembler &getAssembler() const { return Assembler; }
51
52  /// Invalidate the fragments starting with F because it has been
53  /// resized. The fragment's size should have already been updated, but
54  /// its bundle padding will be recomputed.
55  void invalidateFragmentsFrom(MCFragment *F);
56
57  /// Perform layout for a single fragment, assuming that the previous
58  /// fragment has already been laid out correctly, and the parent section has
59  /// been initialized.
60  void layoutFragment(MCFragment *Fragment);
61
62  /// \name Section Access (in layout order)
63  /// @{
64
65  llvm::SmallVectorImpl<MCSection *> &getSectionOrder() { return SectionOrder; }
66  const llvm::SmallVectorImpl<MCSection *> &getSectionOrder() const {
67    return SectionOrder;
68  }
69
70  /// @}
71  /// \name Fragment Layout Data
72  /// @{
73
74  /// Get the offset of the given fragment inside its containing section.
75  uint64_t getFragmentOffset(const MCFragment *F) const;
76
77  /// @}
78  /// \name Utility Functions
79  /// @{
80
81  /// Get the address space size of the given section, as it effects
82  /// layout. This may differ from the size reported by \see getSectionSize() by
83  /// not including section tail padding.
84  uint64_t getSectionAddressSize(const MCSection *Sec) const;
85
86  /// Get the data size of the given section, as emitted to the object
87  /// file. This may include additional padding, or be 0 for virtual sections.
88  uint64_t getSectionFileSize(const MCSection *Sec) const;
89
90  /// Get the offset of the given symbol, as computed in the current
91  /// layout.
92  /// \return True on success.
93  bool getSymbolOffset(const MCSymbol &S, uint64_t &Val) const;
94
95  /// Variant that reports a fatal error if the offset is not computable.
96  uint64_t getSymbolOffset(const MCSymbol &S) const;
97
98  /// If this symbol is equivalent to A + Constant, return A.
99  const MCSymbol *getBaseSymbol(const MCSymbol &Symbol) const;
100
101  /// @}
102};
103
104} // end namespace llvm
105
106#endif
107