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 /// \returns whether the offset of fragment \p F can be obtained via
53 /// getFragmentOffset.
54 bool canGetFragmentOffset(const MCFragment *F) const;
55
56 /// Invalidate the fragments starting with F because it has been
57 /// resized. The fragment's size should have already been updated, but
58 /// its bundle padding will be recomputed.
59 void invalidateFragmentsFrom(MCFragment *F);
60
61 /// 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<MCSection *> &getSectionOrder() { return SectionOrder; }
70 const llvm::SmallVectorImpl<MCSection *> &getSectionOrder() const {
71 return SectionOrder;
72 }
73
74 /// @}
75 /// \name Fragment Layout Data
76 /// @{
77
78 /// Get the offset of the given fragment inside its containing section.
79 uint64_t getFragmentOffset(const MCFragment *F) const;
80
81 /// @}
82 /// \name Utility Functions
83 /// @{
84
85 /// Get the address space size of the given section, as it effects
86 /// layout. This may differ from the size reported by \see
87 /// getSectionFileSize() by not including section tail padding.
88 uint64_t getSectionAddressSize(const MCSection *Sec) const;
89
90 /// Get the data size of the given section, as emitted to the object
91 /// file. This may include additional padding, or be 0 for virtual sections.
92 uint64_t getSectionFileSize(const MCSection *Sec) const;
93
94 /// Get the offset of the given symbol, as computed in the current
95 /// layout.
96 /// \return True on success.
97 bool getSymbolOffset(const MCSymbol &S, uint64_t &Val) const;
98
99 /// Variant that reports a fatal error if the offset is not computable.
100 uint64_t getSymbolOffset(const MCSymbol &S) const;
101
102 /// If this symbol is equivalent to A + Constant, return A.
103 const MCSymbol *getBaseSymbol(const MCSymbol &Symbol) const;
104
105 /// @}
106};
107
108} // end namespace llvm
109
110#endif
111

source code of llvm/include/llvm/MC/MCAsmLayout.h