1 | //===- MCSectionCOFF.h - COFF Machine Code Sections -------------*- 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 | // This file declares the MCSectionCOFF class. |
10 | // |
11 | //===----------------------------------------------------------------------===// |
12 | |
13 | #ifndef LLVM_MC_MCSECTIONCOFF_H |
14 | #define LLVM_MC_MCSECTIONCOFF_H |
15 | |
16 | #include "llvm/ADT/StringRef.h" |
17 | #include "llvm/MC/MCSection.h" |
18 | #include "llvm/MC/SectionKind.h" |
19 | #include <cassert> |
20 | |
21 | namespace llvm { |
22 | |
23 | class MCSymbol; |
24 | |
25 | /// This represents a section on Windows |
26 | class MCSectionCOFF final : public MCSection { |
27 | // FIXME: The following fields should not be mutable, but are for now so the |
28 | // asm parser can honor the .linkonce directive. |
29 | |
30 | /// This is the Characteristics field of a section, drawn from the enums |
31 | /// below. |
32 | mutable unsigned Characteristics; |
33 | |
34 | /// The unique IDs used with the .pdata and .xdata sections created internally |
35 | /// by the assembler. This ID is used to ensure that for every .text section, |
36 | /// there is exactly one .pdata and one .xdata section, which is required by |
37 | /// the Microsoft incremental linker. This data is mutable because this ID is |
38 | /// not notionally part of the section. |
39 | mutable unsigned WinCFISectionID = ~0U; |
40 | |
41 | /// The COMDAT symbol of this section. Only valid if this is a COMDAT section. |
42 | /// Two COMDAT sections are merged if they have the same COMDAT symbol. |
43 | MCSymbol *COMDATSymbol; |
44 | |
45 | /// This is the Selection field for the section symbol, if it is a COMDAT |
46 | /// section (Characteristics & IMAGE_SCN_LNK_COMDAT) != 0 |
47 | mutable int Selection; |
48 | |
49 | private: |
50 | friend class MCContext; |
51 | // The storage of Name is owned by MCContext's COFFUniquingMap. |
52 | MCSectionCOFF(StringRef Name, unsigned Characteristics, |
53 | MCSymbol *COMDATSymbol, int Selection, SectionKind K, |
54 | MCSymbol *Begin) |
55 | : MCSection(SV_COFF, Name, K, Begin), Characteristics(Characteristics), |
56 | COMDATSymbol(COMDATSymbol), Selection(Selection) { |
57 | assert((Characteristics & 0x00F00000) == 0 && |
58 | "alignment must not be set upon section creation" ); |
59 | } |
60 | |
61 | public: |
62 | /// Decides whether a '.section' directive should be printed before the |
63 | /// section name |
64 | bool shouldOmitSectionDirective(StringRef Name, const MCAsmInfo &MAI) const; |
65 | |
66 | unsigned getCharacteristics() const { return Characteristics; } |
67 | MCSymbol *getCOMDATSymbol() const { return COMDATSymbol; } |
68 | int getSelection() const { return Selection; } |
69 | |
70 | void setSelection(int Selection) const; |
71 | |
72 | void printSwitchToSection(const MCAsmInfo &MAI, const Triple &T, |
73 | raw_ostream &OS, |
74 | const MCExpr *Subsection) const override; |
75 | bool useCodeAlign() const override; |
76 | bool isVirtualSection() const override; |
77 | StringRef getVirtualSectionKind() const override; |
78 | |
79 | unsigned getOrAssignWinCFISectionID(unsigned *NextID) const { |
80 | if (WinCFISectionID == ~0U) |
81 | WinCFISectionID = (*NextID)++; |
82 | return WinCFISectionID; |
83 | } |
84 | |
85 | static bool isImplicitlyDiscardable(StringRef Name) { |
86 | return Name.starts_with(Prefix: ".debug" ); |
87 | } |
88 | |
89 | static bool classof(const MCSection *S) { return S->getVariant() == SV_COFF; } |
90 | }; |
91 | |
92 | } // end namespace llvm |
93 | |
94 | #endif // LLVM_MC_MCSECTIONCOFF_H |
95 | |