LLVM  9.0.0svn
MCAsmLayout.h
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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 
15 namespace llvm {
16 class MCAssembler;
17 class MCFragment;
18 class MCSection;
19 class 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.
28 class MCAsmLayout {
29  MCAssembler &Assembler;
30 
31  /// List of sections in layout order.
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 
46 public:
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.
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 
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
Instances of this class represent a uniqued identifier for a section in the current translation unit...
Definition: MCSection.h:38
This class represents lattice values for constants.
Definition: AllocatorList.h:23
uint64_t getSectionAddressSize(const MCSection *Sec) const
Get the address space size of the given section, as it effects layout.
Definition: MCFragment.cpp:175
MCSymbol - Instances of this class represent a symbol name in the MC file, and MCSymbols are created ...
Definition: MCSymbol.h:41
F(f)
const llvm::SmallVectorImpl< MCSection * > & getSectionOrder() const
Definition: MCAsmLayout.h:66
Encapsulates the layout of an assembly file at a particular point in time.
Definition: MCAsmLayout.h:28
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
Definition: APFloat.h:41
MCAssembler & getAssembler() const
Get the assembler object this is a layout for.
Definition: MCAsmLayout.h:50
void layoutFragment(MCFragment *Fragment)
Perform layout for a single fragment, assuming that the previous fragment has already been laid out c...
MCAsmLayout(MCAssembler &Assembler)
Definition: MCFragment.cpp:32
void invalidateFragmentsFrom(MCFragment *F)
Invalidate the fragments starting with F because it has been resized.
Definition: MCFragment.cpp:51
bool getSymbolOffset(const MCSymbol &S, uint64_t &Val) const
Get the offset of the given symbol, as computed in the current layout.
Definition: MCFragment.cpp:129
llvm::SmallVectorImpl< MCSection * > & getSectionOrder()
Definition: MCAsmLayout.h:65
uint64_t getFragmentOffset(const MCFragment *F) const
Get the offset of the given fragment inside its containing section.
Definition: MCFragment.cpp:77
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:841
uint64_t getSectionFileSize(const MCSection *Sec) const
Get the data size of the given section, as emitted to the object file.
Definition: MCFragment.cpp:181
const MCSymbol * getBaseSymbol(const MCSymbol &Symbol) const
If this symbol is equivalent to A + Constant, return A.
Definition: MCFragment.cpp:139