161 lines
4.5 KiB
C++
161 lines
4.5 KiB
C++
//===- OutputSections.h -----------------------------------------*- C++ -*-===//
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//
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// The LLVM Linker
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLD_ELF_OUTPUT_SECTIONS_H
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#define LLD_ELF_OUTPUT_SECTIONS_H
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#include "Config.h"
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#include "Relocations.h"
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#include "lld/Core/LLVM.h"
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#include "llvm/MC/StringTableBuilder.h"
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#include "llvm/Object/ELF.h"
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namespace lld {
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namespace elf {
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struct PhdrEntry;
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class SymbolBody;
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struct EhSectionPiece;
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class EhInputSection;
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class InputSection;
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class InputSectionBase;
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class MergeInputSection;
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class OutputSection;
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template <class ELFT> class ObjectFile;
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template <class ELFT> class SharedFile;
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class SharedSymbol;
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class DefinedRegular;
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// This represents a section in an output file.
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// It is composed of multiple InputSections.
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// The writer creates multiple OutputSections and assign them unique,
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// non-overlapping file offsets and VAs.
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class OutputSection final {
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public:
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OutputSection(StringRef Name, uint32_t Type, uint64_t Flags);
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uint64_t getLMA() const { return Addr + LMAOffset; }
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template <typename ELFT> void writeHeaderTo(typename ELFT::Shdr *SHdr);
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unsigned SectionIndex;
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uint32_t getPhdrFlags() const;
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void updateAlignment(uint32_t Val) {
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if (Val > Alignment)
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Alignment = Val;
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}
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// If true, this section will be page aligned on disk.
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// Typically the first section of each PT_LOAD segment has this flag.
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bool PageAlign = false;
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// Pointer to the first section in PT_LOAD segment, which this section
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// also resides in. This field is used to correctly compute file offset
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// of a section. When two sections share the same load segment, difference
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// between their file offsets should be equal to difference between their
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// virtual addresses. To compute some section offset we use the following
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// formula: Off = Off_first + VA - VA_first.
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OutputSection *FirstInPtLoad = nullptr;
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StringRef Name;
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// The following fields correspond to Elf_Shdr members.
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uint64_t Size = 0;
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uint64_t Entsize = 0;
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uint64_t Offset = 0;
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uint64_t Flags = 0;
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uint64_t LMAOffset = 0;
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uint64_t Addr = 0;
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uint32_t Alignment = 0;
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uint32_t ShName = 0;
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uint32_t Type = 0;
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uint32_t Info = 0;
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uint32_t Link = 0;
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void addSection(InputSectionBase *C);
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void sort(std::function<int(InputSectionBase *S)> Order);
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void sortInitFini();
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void sortCtorsDtors();
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template <class ELFT> void writeTo(uint8_t *Buf);
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template <class ELFT> void finalize();
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template <class ELFT> void assignOffsets();
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std::vector<InputSection *> Sections;
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// Location in the output buffer.
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uint8_t *Loc = nullptr;
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};
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// All output sections that are handled by the linker specially are
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// globally accessible. Writer initializes them, so don't use them
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// until Writer is initialized.
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struct Out {
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static uint8_t First;
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static OutputSection *Bss;
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static OutputSection *BssRelRo;
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static OutputSection *Opd;
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static uint8_t *OpdBuf;
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static PhdrEntry *TlsPhdr;
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static OutputSection *DebugInfo;
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static OutputSection *ElfHeader;
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static OutputSection *ProgramHeaders;
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static OutputSection *PreinitArray;
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static OutputSection *InitArray;
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static OutputSection *FiniArray;
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};
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struct SectionKey {
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StringRef Name;
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uint64_t Flags;
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uint64_t Alignment;
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};
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}
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}
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namespace llvm {
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template <> struct DenseMapInfo<lld::elf::SectionKey> {
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static lld::elf::SectionKey getEmptyKey();
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static lld::elf::SectionKey getTombstoneKey();
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static unsigned getHashValue(const lld::elf::SectionKey &Val);
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static bool isEqual(const lld::elf::SectionKey &LHS,
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const lld::elf::SectionKey &RHS);
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};
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}
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namespace lld {
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namespace elf {
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// This class knows how to create an output section for a given
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// input section. Output section type is determined by various
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// factors, including input section's sh_flags, sh_type and
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// linker scripts.
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class OutputSectionFactory {
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public:
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OutputSectionFactory(std::vector<OutputSection *> &OutputSections);
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~OutputSectionFactory();
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template <class ELFT>
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void addInputSec(InputSectionBase *IS, StringRef OutsecName);
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private:
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llvm::SmallDenseMap<SectionKey, OutputSection *> Map;
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std::vector<OutputSection *> &OutputSections;
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};
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template <class ELFT> uint64_t getHeaderSize() {
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if (Config->OFormatBinary)
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return 0;
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return Out::ElfHeader->Size + Out::ProgramHeaders->Size;
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}
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} // namespace elf
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} // namespace lld
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#endif
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