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 class MCSymbol; 25 26 /// This represents a section on linux, lots of unix variants and some bare 27 /// metal systems. 28 class MCSectionELF final : public MCSection { 29 /// This is the sh_type field of a section, drawn from the enums below. 30 unsigned Type; 31 32 /// This is the sh_flags field of a section, drawn from the enums below. 33 unsigned Flags; 34 35 unsigned UniqueID; 36 37 /// The size of each entry in this section. This size only makes sense for 38 /// sections that contain fixed-sized entries. If a section does not contain 39 /// fixed-sized entries 'EntrySize' will be 0. 40 unsigned EntrySize; 41 42 /// The section group signature symbol (if not null) and a bool indicating 43 /// whether this is a GRP_COMDAT group. 44 const PointerIntPair<const MCSymbolELF *, 1, bool> Group; 45 46 /// Used by SHF_LINK_ORDER. If non-null, the sh_link field will be set to the 47 /// section header index of the section where LinkedToSym is defined. 48 const MCSymbol *LinkedToSym; 49 50 private: 51 friend class MCContext; 52 53 // The storage of Name is owned by MCContext's ELFUniquingMap. MCSectionELF(StringRef Name,unsigned type,unsigned flags,SectionKind K,unsigned entrySize,const MCSymbolELF * group,bool IsComdat,unsigned UniqueID,MCSymbol * Begin,const MCSymbolELF * LinkedToSym)54 MCSectionELF(StringRef Name, unsigned type, unsigned flags, SectionKind K, 55 unsigned entrySize, const MCSymbolELF *group, bool IsComdat, 56 unsigned UniqueID, MCSymbol *Begin, 57 const MCSymbolELF *LinkedToSym) 58 : MCSection(SV_ELF, Name, K, Begin), Type(type), Flags(flags), 59 UniqueID(UniqueID), EntrySize(entrySize), Group(group, IsComdat), 60 LinkedToSym(LinkedToSym) { 61 if (Group.getPointer()) 62 Group.getPointer()->setIsSignature(); 63 } 64 65 // TODO Delete after we stop supporting generation of GNU-style .zdebug_* 66 // sections. setSectionName(StringRef Name)67 void setSectionName(StringRef Name) { this->Name = Name; } 68 69 public: 70 /// Decides whether a '.section' directive should be printed before the 71 /// section name 72 bool ShouldOmitSectionDirective(StringRef Name, const MCAsmInfo &MAI) const; 73 getType()74 unsigned getType() const { return Type; } getFlags()75 unsigned getFlags() const { return Flags; } getEntrySize()76 unsigned getEntrySize() const { return EntrySize; } setFlags(unsigned F)77 void setFlags(unsigned F) { Flags = F; } getGroup()78 const MCSymbolELF *getGroup() const { return Group.getPointer(); } isComdat()79 bool isComdat() const { return Group.getInt(); } 80 81 void PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T, 82 raw_ostream &OS, 83 const MCExpr *Subsection) const override; 84 bool UseCodeAlign() const override; 85 bool isVirtualSection() const override; 86 StringRef getVirtualSectionKind() const override; 87 isUnique()88 bool isUnique() const { return UniqueID != NonUniqueID; } getUniqueID()89 unsigned getUniqueID() const { return UniqueID; } 90 getLinkedToSection()91 const MCSection *getLinkedToSection() const { 92 return &LinkedToSym->getSection(); 93 } getLinkedToSymbol()94 const MCSymbol *getLinkedToSymbol() const { return LinkedToSym; } 95 classof(const MCSection * S)96 static bool classof(const MCSection *S) { 97 return S->getVariant() == SV_ELF; 98 } 99 }; 100 101 } // end namespace llvm 102 103 #endif // LLVM_MC_MCSECTIONELF_H 104