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. |
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 | |
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 | /// \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 | |