lld/MachO/OutputSection.h

   1 //===- OutputSection.h ------------------------------------------*- 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 #ifndef LLD_MACHO_OUTPUT_SECTION_H
  10 #define LLD_MACHO_OUTPUT_SECTION_H
  11
  12 #include "lld/Common/LLVM.h"
  13 #include "llvm/ADT/DenseMap.h"
  14
  15 namespace lld {
  16 namespace macho {
  17
  18 class InputSection;
  19 class OutputSegment;
  20
  21 // Output sections represent the finalized sections present within the final
  22 // linked executable. They can represent special sections (like the symbol
  23 // table), or represent coalesced sections from the various inputs given to the
  24 // linker with the same segment / section name.
  25 class OutputSection {
  26 public:
  27   enum Kind {
  28     MergedKind,
  29     SyntheticKind,
  30   };
  31
  32   OutputSection(Kind kind, StringRef name) : name(name), sectionKind(kind) {}
  33   virtual ~OutputSection() = default;
  34   Kind kind() const { return sectionKind; }
  35
  36   // These accessors will only be valid after finalizing the section.
  37   uint64_t getSegmentOffset() const;
  38
  39   // How much space the section occupies in the address space.
  40   virtual uint64_t getSize() const = 0;
  41   // How much space the section occupies in the file. Most sections are copied
  42   // as-is so their file size is the same as their address space size.
  43   virtual uint64_t getFileSize() const { return getSize(); }
  44
  45   // Hidden sections omit header content, but body content may still be present.
  46   virtual bool isHidden() const { return false; }
  47   // Unneeded sections are omitted entirely (header and body).
  48   virtual bool isNeeded() const { return true; }
  49
  50   // Specifically finalizes addresses and section size, not content.
  51   virtual void finalize() {
  52     // TODO investigate refactoring synthetic section finalization logic into
  53     // overrides of this function.
  54   }
  55
  56   virtual void writeTo(uint8_t *buf) const = 0;
  57
  58   StringRef name;
  59   OutputSegment *parent = nullptr;
  60
  61   uint32_t index = 0;
  62   uint64_t addr = 0;
  63   uint64_t fileOff = 0;
  64   uint32_t align = 1;
  65   uint32_t flags = 0;
  66   uint32_t reserved1 = 0;
  67   uint32_t reserved2 = 0;
  68
  69 private:
  70   Kind sectionKind;
  71 };
  72
  73 } // namespace macho
  74 } // namespace lld
  75
  76 #endif