1//===- MCSectionXCOFF.h - XCOFF 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 MCSectionXCOFF class.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_MC_MCSECTIONXCOFF_H
14#define LLVM_MC_MCSECTIONXCOFF_H
15
16#include "llvm/BinaryFormat/XCOFF.h"
17#include "llvm/MC/MCSection.h"
18#include "llvm/MC/MCSymbolXCOFF.h"
19
20namespace llvm {
21
22// This class represents an XCOFF `Control Section`, more commonly referred to
23// as a csect. A csect represents the smallest possible unit of data/code which
24// will be relocated as a single block. A csect can either be:
25// 1) Initialized: The Type will be XTY_SD, and the symbols inside the csect
26//    will have a label definition representing their offset within the csect.
27// 2) Uninitialized: The Type will be XTY_CM, it will contain a single symbol,
28//    and may not contain label definitions.
29// 3) An external reference providing a symbol table entry for a symbol
30//    contained in another XCOFF object file. External reference csects are not
31//    implemented yet.
32class MCSectionXCOFF final : public MCSection {
33  friend class MCContext;
34
35  std::optional<XCOFF::CsectProperties> CsectProp;
36  MCSymbolXCOFF *const QualName;
37  StringRef SymbolTableName;
38  std::optional<XCOFF::DwarfSectionSubtypeFlags> DwarfSubtypeFlags;
39  bool MultiSymbolsAllowed;
40  static constexpr unsigned DefaultAlignVal = 4;
41  static constexpr unsigned DefaultTextAlignVal = 32;
42
43  MCSectionXCOFF(StringRef Name, XCOFF::StorageMappingClass SMC,
44                 XCOFF::SymbolType ST, SectionKind K, MCSymbolXCOFF *QualName,
45                 MCSymbol *Begin, StringRef SymbolTableName,
46                 bool MultiSymbolsAllowed)
47      : MCSection(SV_XCOFF, Name, K, Begin),
48        CsectProp(XCOFF::CsectProperties(SMC, ST)), QualName(QualName),
49        SymbolTableName(SymbolTableName), DwarfSubtypeFlags(std::nullopt),
50        MultiSymbolsAllowed(MultiSymbolsAllowed) {
51    assert(
52        (ST == XCOFF::XTY_SD || ST == XCOFF::XTY_CM || ST == XCOFF::XTY_ER) &&
53        "Invalid or unhandled type for csect.");
54    assert(QualName != nullptr && "QualName is needed.");
55    if (SMC == XCOFF::XMC_UL)
56      assert((ST == XCOFF::XTY_CM || ST == XCOFF::XTY_ER) &&
57             "Invalid csect type for storage mapping class XCOFF::XMC_UL");
58
59    QualName->setRepresentedCsect(this);
60    QualName->setStorageClass(XCOFF::C_HIDEXT);
61    if (ST != XCOFF::XTY_ER) {
62      // For a csect for program code, set the alignment to 32 bytes by default.
63      // For other csects, set the alignment to 4 bytes by default.
64      if (SMC == XCOFF::XMC_PR)
65        setAlignment(Align(DefaultTextAlignVal));
66      else
67        setAlignment(Align(DefaultAlignVal));
68    }
69  }
70
71  MCSectionXCOFF(StringRef Name, SectionKind K, MCSymbolXCOFF *QualName,
72                 XCOFF::DwarfSectionSubtypeFlags DwarfSubtypeFlags,
73                 MCSymbol *Begin, StringRef SymbolTableName,
74                 bool MultiSymbolsAllowed)
75      : MCSection(SV_XCOFF, Name, K, Begin), QualName(QualName),
76        SymbolTableName(SymbolTableName), DwarfSubtypeFlags(DwarfSubtypeFlags),
77        MultiSymbolsAllowed(MultiSymbolsAllowed) {
78    assert(QualName != nullptr && "QualName is needed.");
79
80    // FIXME: use a more meaningful name for non csect sections.
81    QualName->setRepresentedCsect(this);
82
83    // Use default text alignment as the alignment for DWARF sections.
84    setAlignment(Align(DefaultTextAlignVal));
85  }
86
87  void printCsectDirective(raw_ostream &OS) const;
88
89public:
90  ~MCSectionXCOFF();
91
92  static bool classof(const MCSection *S) {
93    return S->getVariant() == SV_XCOFF;
94  }
95
96  XCOFF::StorageMappingClass getMappingClass() const {
97    assert(isCsect() && "Only csect section has mapping class property!");
98    return CsectProp->MappingClass;
99  }
100  XCOFF::StorageClass getStorageClass() const {
101    return QualName->getStorageClass();
102  }
103  XCOFF::VisibilityType getVisibilityType() const {
104    return QualName->getVisibilityType();
105  }
106  XCOFF::SymbolType getCSectType() const {
107    assert(isCsect() && "Only csect section has symbol type property!");
108    return CsectProp->Type;
109  }
110  MCSymbolXCOFF *getQualNameSymbol() const { return QualName; }
111
112  void printSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
113                            raw_ostream &OS,
114                            const MCExpr *Subsection) const override;
115  bool useCodeAlign() const override;
116  bool isVirtualSection() const override;
117  StringRef getSymbolTableName() const { return SymbolTableName; }
118  void setSymbolTableName(StringRef STN) { SymbolTableName = STN; }
119  bool isMultiSymbolsAllowed() const { return MultiSymbolsAllowed; }
120  bool isCsect() const { return CsectProp.has_value(); }
121  bool isDwarfSect() const { return DwarfSubtypeFlags.has_value(); }
122  std::optional<XCOFF::DwarfSectionSubtypeFlags> getDwarfSubtypeFlags() const {
123    return DwarfSubtypeFlags;
124  }
125  std::optional<XCOFF::CsectProperties> getCsectProp() const {
126    return CsectProp;
127  }
128};
129
130} // end namespace llvm
131
132#endif
133