forked from OSchip/llvm-project
105 lines
3.7 KiB
C++
105 lines
3.7 KiB
C++
//===- OutputSection.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_MACHO_OUTPUT_SECTION_H
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#define LLD_MACHO_OUTPUT_SECTION_H
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#include "Symbols.h"
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#include "lld/Common/LLVM.h"
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/TinyPtrVector.h"
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#include <limits>
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namespace lld {
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namespace macho {
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class Defined;
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class InputSection;
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class OutputSegment;
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// The default order value for OutputSections that are not constructed from
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// InputSections (i.e. SyntheticSections). We make it less than INT_MAX in order
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// not to conflict with the ordering of zerofill sections, which must always be
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// placed at the end of their segment.
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constexpr int UnspecifiedInputOrder = std::numeric_limits<int>::max() - 1024;
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// Output sections represent the finalized sections present within the final
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// linked executable. They can represent special sections (like the symbol
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// table), or represent coalesced sections from the various inputs given to the
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// linker with the same segment / section name.
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class OutputSection {
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public:
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enum Kind {
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ConcatKind,
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SyntheticKind,
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};
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OutputSection(Kind kind, StringRef name) : name(name), sectionKind(kind) {}
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virtual ~OutputSection() = default;
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Kind kind() const { return sectionKind; }
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// These accessors will only be valid after finalizing the section.
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uint64_t getSegmentOffset() const;
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// How much space the section occupies in the address space.
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virtual uint64_t getSize() const = 0;
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// How much space the section occupies in the file. Most sections are copied
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// as-is so their file size is the same as their address space size.
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virtual uint64_t getFileSize() const { return getSize(); }
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// Hidden sections omit header content, but body content may still be present.
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virtual bool isHidden() const { return false; }
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// Unneeded sections are omitted entirely (header and body).
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virtual bool isNeeded() const { return true; }
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// The implementations of this method can assume that it is only called right
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// before addresses get assigned to this particular OutputSection. In
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// particular, this means that it gets called only after addresses have been
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// assigned to output sections that occur earlier in the output binary.
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// Naturally, this means different sections' finalize() methods cannot execute
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// concurrently with each other. As such, avoid using this method for
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// operations that do not require this strict sequential guarantee.
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//
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// Operations that need to occur late in the linking process, but which do not
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// need the sequential guarantee, should be named `finalizeContents()`. See
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// e.g. LinkEditSection::finalizeContents() and
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// CStringSection::finalizeContents().
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virtual void finalize() {}
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virtual void writeTo(uint8_t *buf) const = 0;
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// Handle section$start$ and section$end$ symbols.
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void assignAddressesToStartEndSymbols();
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StringRef name;
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llvm::TinyPtrVector<Defined *> sectionStartSymbols;
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llvm::TinyPtrVector<Defined *> sectionEndSymbols;
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OutputSegment *parent = nullptr;
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// For output sections that don't have explicit ordering requirements, their
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// output order should be based on the order of the input sections they
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// contain.
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int inputOrder = UnspecifiedInputOrder;
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uint32_t index = 0;
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uint64_t addr = 0;
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uint64_t fileOff = 0;
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uint32_t align = 1;
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uint32_t flags = 0;
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uint32_t reserved1 = 0;
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uint32_t reserved2 = 0;
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private:
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Kind sectionKind;
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};
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} // namespace macho
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} // namespace lld
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#endif
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