1 //===- MCSectionELF.h - ELF 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 MCSectionELF class. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #ifndef LLVM_MC_MCSECTIONELF_H 14 #define LLVM_MC_MCSECTIONELF_H 15 16 #include "llvm/ADT/StringRef.h" 17 #include "llvm/MC/MCSection.h" 18 #include "llvm/MC/MCSymbolELF.h" 19 #include "llvm/MC/SectionKind.h" 20 21 namespace llvm { 22 23 class MCSymbol; 24 25 /// This represents a section on linux, lots of unix variants and some bare 26 /// metal systems. 27 class MCSectionELF final : public MCSection { 28 /// This is the sh_type field of a section, drawn from the enums below. 29 unsigned Type; 30 31 /// This is the sh_flags field of a section, drawn from the enums below. 32 unsigned Flags; 33 34 unsigned UniqueID; 35 36 /// The size of each entry in this section. This size only makes sense for 37 /// sections that contain fixed-sized entries. If a section does not contain 38 /// fixed-sized entries 'EntrySize' will be 0. 39 unsigned EntrySize; 40 41 const MCSymbolELF *Group; 42 43 /// Used by SHF_LINK_ORDER. If non-null, the sh_link field will be set to the 44 /// section header index of the section where LinkedToSym is defined. 45 const MCSymbol *LinkedToSym; 46 47 private: 48 friend class MCContext; 49 50 // The storage of Name is owned by MCContext's ELFUniquingMap. 51 MCSectionELF(StringRef Name, unsigned type, unsigned flags, SectionKind K, 52 unsigned entrySize, const MCSymbolELF *group, unsigned UniqueID, 53 MCSymbol *Begin, const MCSymbolELF *LinkedToSym) 54 : MCSection(SV_ELF, Name, K, Begin), Type(type), Flags(flags), 55 UniqueID(UniqueID), EntrySize(entrySize), Group(group), 56 LinkedToSym(LinkedToSym) { 57 if (Group) 58 Group->setIsSignature(); 59 } 60 61 // TODO Delete after we stop supporting generation of GNU-style .zdebug_* 62 // sections. 63 void setSectionName(StringRef Name) { this->Name = Name; } 64 65 public: 66 /// Decides whether a '.section' directive should be printed before the 67 /// section name 68 bool ShouldOmitSectionDirective(StringRef Name, const MCAsmInfo &MAI) const; 69 70 unsigned getType() const { return Type; } 71 unsigned getFlags() const { return Flags; } 72 unsigned getEntrySize() const { return EntrySize; } 73 void setFlags(unsigned F) { Flags = F; } 74 const MCSymbolELF *getGroup() const { return Group; } 75 76 void PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T, 77 raw_ostream &OS, 78 const MCExpr *Subsection) const override; 79 bool UseCodeAlign() const override; 80 bool isVirtualSection() const override; 81 StringRef getVirtualSectionKind() const override; 82 83 bool isUnique() const { return UniqueID != NonUniqueID; } 84 unsigned getUniqueID() const { return UniqueID; } 85 86 const MCSection *getLinkedToSection() const { 87 return &LinkedToSym->getSection(); 88 } 89 const MCSymbol *getLinkedToSymbol() const { return LinkedToSym; } 90 91 static bool classof(const MCSection *S) { 92 return S->getVariant() == SV_ELF; 93 } 94 }; 95 96 } // end namespace llvm 97 98 #endif // LLVM_MC_MCSECTIONELF_H 99