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/PointerIntPair.h" 17 #include "llvm/ADT/StringRef.h" 18 #include "llvm/MC/MCSection.h" 19 #include "llvm/MC/MCSymbolELF.h" 20 #include "llvm/MC/SectionKind.h" 21 22 namespace llvm { 23 24 /// This represents a section on linux, lots of unix variants and some bare 25 /// metal systems. 26 class MCSectionELF final : public MCSection { 27 /// This is the sh_type field of a section, drawn from the enums below. 28 unsigned Type; 29 30 /// This is the sh_flags field of a section, drawn from the enums below. 31 unsigned Flags; 32 33 unsigned UniqueID; 34 35 /// The size of each entry in this section. This size only makes sense for 36 /// sections that contain fixed-sized entries. If a section does not contain 37 /// fixed-sized entries 'EntrySize' will be 0. 38 unsigned EntrySize; 39 40 /// The section group signature symbol (if not null) and a bool indicating 41 /// whether this is a GRP_COMDAT group. 42 const PointerIntPair<const MCSymbolELF *, 1, bool> Group; 43 44 /// Used by SHF_LINK_ORDER. If non-null, the sh_link field will be set to the 45 /// section header index of the section where LinkedToSym is defined. 46 const MCSymbol *LinkedToSym; 47 48 private: 49 friend class MCContext; 50 51 // The storage of Name is owned by MCContext's ELFUniquingMap. 52 MCSectionELF(StringRef Name, unsigned type, unsigned flags, SectionKind K, 53 unsigned entrySize, const MCSymbolELF *group, bool IsComdat, 54 unsigned UniqueID, MCSymbol *Begin, 55 const MCSymbolELF *LinkedToSym) 56 : MCSection(SV_ELF, Name, K, Begin), Type(type), Flags(flags), 57 UniqueID(UniqueID), EntrySize(entrySize), Group(group, IsComdat), 58 LinkedToSym(LinkedToSym) { 59 if (Group.getPointer()) 60 Group.getPointer()->setIsSignature(); 61 } 62 63 // TODO Delete after we stop supporting generation of GNU-style .zdebug_* 64 // sections. 65 void setSectionName(StringRef Name) { this->Name = Name; } 66 67 public: 68 /// Decides whether a '.section' directive should be printed before the 69 /// section name 70 bool shouldOmitSectionDirective(StringRef Name, const MCAsmInfo &MAI) const; 71 72 unsigned getType() const { return Type; } 73 unsigned getFlags() const { return Flags; } 74 unsigned getEntrySize() const { return EntrySize; } 75 void setFlags(unsigned F) { Flags = F; } 76 const MCSymbolELF *getGroup() const { return Group.getPointer(); } 77 bool isComdat() const { return Group.getInt(); } 78 79 void printSwitchToSection(const MCAsmInfo &MAI, const Triple &T, 80 raw_ostream &OS, 81 const MCExpr *Subsection) const override; 82 bool useCodeAlign() const override; 83 bool isVirtualSection() const override; 84 StringRef getVirtualSectionKind() const override; 85 86 bool isUnique() const { return UniqueID != NonUniqueID; } 87 unsigned getUniqueID() const { return UniqueID; } 88 89 const MCSection *getLinkedToSection() const { 90 return &LinkedToSym->getSection(); 91 } 92 const MCSymbol *getLinkedToSymbol() const { return LinkedToSym; } 93 94 static bool classof(const MCSection *S) { 95 return S->getVariant() == SV_ELF; 96 } 97 }; 98 99 } // end namespace llvm 100 101 #endif // LLVM_MC_MCSECTIONELF_H 102