lld/COFF/Writer.h

   1 //===- Writer.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_COFF_WRITER_H
  10 #define LLD_COFF_WRITER_H
  11
  12 #include "Chunks.h"
  13 #include "llvm/ADT/StringRef.h"
  14 #include "llvm/Object/COFF.h"
  15 #include <chrono>
  16 #include <cstdint>
  17 #include <vector>
  18
  19 namespace lld {
  20 namespace coff {
  21 static const int pageSize = 4096;
  22
  23 void writeResult();
  24
  25 class PartialSection {
  26 public:
  27   PartialSection(StringRef n, uint32_t chars)
  28       : name(n), characteristics(chars) {}
  29   StringRef name;
  30   unsigned characteristics;
  31   std::vector<Chunk *> chunks;
  32 };
  33
  34 // OutputSection represents a section in an output file. It's a
  35 // container of chunks. OutputSection and Chunk are 1:N relationship.
  36 // Chunks cannot belong to more than one OutputSections. The writer
  37 // creates multiple OutputSections and assign them unique,
  38 // non-overlapping file offsets and RVAs.
  39 class OutputSection {
  40 public:
  41   OutputSection(llvm::StringRef n, uint32_t chars) : name(n) {
  42     header.Characteristics = chars;
  43   }
  44   void addChunk(Chunk *c);
  45   void insertChunkAtStart(Chunk *c);
  46   void merge(OutputSection *other);
  47   void setPermissions(uint32_t c);
  48   uint64_t getRVA() { return header.VirtualAddress; }
  49   uint64_t getFileOff() { return header.PointerToRawData; }
  50   void writeHeaderTo(uint8_t *buf);
  51   void addContributingPartialSection(PartialSection *sec);
  52
  53   // Clear the output sections static container.
  54   static void clear();
  55
  56   // Returns the size of this section in an executable memory image.
  57   // This may be smaller than the raw size (the raw size is multiple
  58   // of disk sector size, so there may be padding at end), or may be
  59   // larger (if that's the case, the loader reserves spaces after end
  60   // of raw data).
  61   uint64_t getVirtualSize() { return header.VirtualSize; }
  62
  63   // Returns the size of the section in the output file.
  64   uint64_t getRawSize() { return header.SizeOfRawData; }
  65
  66   // Set offset into the string table storing this section name.
  67   // Used only when the name is longer than 8 bytes.
  68   void setStringTableOff(uint32_t v) { stringTableOff = v; }
  69
  70   // N.B. The section index is one based.
  71   uint32_t sectionIndex = 0;
  72
  73   llvm::StringRef name;
  74   llvm::object::coff_section header = {};
  75
  76   std::vector<Chunk *> chunks;
  77   std::vector<Chunk *> origChunks;
  78
  79   std::vector<PartialSection *> contribSections;
  80
  81 private:
  82   uint32_t stringTableOff = 0;
  83 };
  84
  85 } // namespace coff
  86 } // namespace lld
  87
  88 #endif