forked from OSchip/llvm-project
147 lines
4.8 KiB
C++
147 lines
4.8 KiB
C++
//===- OutputSections.h -----------------------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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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 "InputSection.h"
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#include "LinkerScript.h"
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#include "Relocations.h"
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#include "lld/Common/LLVM.h"
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#include "llvm/MC/StringTableBuilder.h"
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#include "llvm/Object/ELF.h"
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#include <array>
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namespace lld {
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namespace elf {
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struct PhdrEntry;
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class InputSection;
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class InputSectionBase;
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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 : public BaseCommand, public SectionBase {
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public:
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OutputSection(StringRef name, uint32_t type, uint64_t flags);
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static bool classof(const SectionBase *s) {
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return s->kind() == SectionBase::Output;
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}
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static bool classof(const BaseCommand *c);
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uint64_t getLMA() const { return ptLoad ? addr + ptLoad->lmaOffset : addr; }
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template <typename ELFT> void writeHeaderTo(typename ELFT::Shdr *sHdr);
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uint32_t sectionIndex = UINT32_MAX;
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unsigned sortRank;
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uint32_t getPhdrFlags() const;
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// Pointer to the PT_LOAD segment, which this section resides in. This field
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// is used to correctly compute file offset of a section. When two sections
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// share the same load segment, difference between their file offsets should
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// be equal to difference between their virtual addresses. To compute some
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// section offset we use the following formula: Off = Off_first + VA -
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// VA_first, where Off_first and VA_first is file offset and VA of first
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// section in PT_LOAD.
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PhdrEntry *ptLoad = nullptr;
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// Pointer to a relocation section for this section. Usually nullptr because
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// we consume relocations, but if --emit-relocs is specified (which is rare),
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// it may have a non-null value.
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OutputSection *relocationSection = nullptr;
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// Initially this field is the number of InputSections that have been added to
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// the OutputSection so far. Later on, after a call to assignAddresses, it
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// corresponds to the Elf_Shdr member.
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uint64_t size = 0;
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// The following fields correspond to Elf_Shdr members.
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uint64_t offset = 0;
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uint64_t addr = 0;
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uint32_t shName = 0;
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void recordSection(InputSectionBase *isec);
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void commitSection(InputSection *isec);
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void finalizeInputSections();
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// The following members are normally only used in linker scripts.
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MemoryRegion *memRegion = nullptr;
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MemoryRegion *lmaRegion = nullptr;
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Expr addrExpr;
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Expr alignExpr;
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Expr lmaExpr;
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Expr subalignExpr;
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std::vector<BaseCommand *> sectionCommands;
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std::vector<StringRef> phdrs;
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llvm::Optional<std::array<uint8_t, 4>> filler;
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ConstraintKind constraint = ConstraintKind::NoConstraint;
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std::string location;
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std::string memoryRegionName;
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std::string lmaRegionName;
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bool nonAlloc = false;
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bool noload = false;
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bool expressionsUseSymbols = false;
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bool usedInExpression = false;
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bool inOverlay = false;
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// Tracks whether the section has ever had an input section added to it, even
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// if the section was later removed (e.g. because it is a synthetic section
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// that wasn't needed). This is needed for orphan placement.
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bool hasInputSections = false;
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void finalize();
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template <class ELFT> void writeTo(uint8_t *buf);
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// Check that the addends for dynamic relocations were written correctly.
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void checkDynRelAddends(const uint8_t *bufStart);
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template <class ELFT> void maybeCompress();
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void sort(llvm::function_ref<int(InputSectionBase *s)> order);
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void sortInitFini();
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void sortCtorsDtors();
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private:
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// Used for implementation of --compress-debug-sections option.
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std::vector<uint8_t> zDebugHeader;
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llvm::SmallVector<char, 0> compressedData;
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std::array<uint8_t, 4> getFiller();
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};
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int getPriority(StringRef s);
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InputSection *getFirstInputSection(const OutputSection *os);
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std::vector<InputSection *> getInputSections(const OutputSection *os);
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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 *bufferStart;
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static uint8_t first;
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static PhdrEntry *tlsPhdr;
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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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uint64_t getHeaderSize();
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extern std::vector<OutputSection *> outputSections;
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} // namespace elf
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} // namespace lld
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#endif
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