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::coff {
  20 static const int pageSize = 4096;
  21 class COFFLinkerContext;
  22
  23 void writeResult(COFFLinkerContext &ctx);
  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() const { return header.VirtualAddress; }
  49   uint64_t getFileOff() const { return header.PointerToRawData; }
  50   void writeHeaderTo(uint8_t *buf, bool isDebug);
  51   void addContributingPartialSection(PartialSection *sec);
  52
  53   // Returns the size of this section in an executable memory image.
  54   // This may be smaller than the raw size (the raw size is multiple
  55   // of disk sector size, so there may be padding at end), or may be
  56   // larger (if that's the case, the loader reserves spaces after end
  57   // of raw data).
  58   uint64_t getVirtualSize() { return header.VirtualSize; }
  59
  60   // Returns the size of the section in the output file.
  61   uint64_t getRawSize() { return header.SizeOfRawData; }
  62
  63   // Set offset into the string table storing this section name.
  64   // Used only when the name is longer than 8 bytes.
  65   void setStringTableOff(uint32_t v) { stringTableOff = v; }
  66
  67   bool isCodeSection() const {
  68     return (header.Characteristics & llvm::COFF::IMAGE_SCN_CNT_CODE) &&
  69            (header.Characteristics & llvm::COFF::IMAGE_SCN_MEM_READ) &&
  70            (header.Characteristics & llvm::COFF::IMAGE_SCN_MEM_EXECUTE);
  71   }
  72
  73   // N.B. The section index is one based.
  74   uint32_t sectionIndex = 0;
  75
  76   llvm::StringRef name;
  77   llvm::object::coff_section header = {};
  78
  79   std::vector<Chunk *> chunks;
  80   std::vector<Chunk *> origChunks;
  81
  82   std::vector<PartialSection *> contribSections;
  83
  84 private:
  85   uint32_t stringTableOff = 0;
  86 };
  87
  88 } // namespace lld::coff
  89
  90 #endif