[PECOFF][Writer] Separate AtomChunk from SectionChunk.

The optional data directory header contains addresses to some atoms such
as the import address table in data section. Such fields can naturally
be set by relocation if we make the optional data driectory as an atom.

Currently we assume that atoms are always in a section, so we can't create
a file header with atoms. This patch separates section chunk from atom
chunk, to allow atom-based file header.

llvm-svn: 185521

1 files changed, 31 insertions, 15 deletions

diff --git a/lld/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp b/lld/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp
index f30dcd7ca6b..f6c8b60643b 100644
--- a/lld/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp
+++ b/lld/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp
@@ -293,18 +293,9 @@ private:
   std::vector<SectionChunk *> _sections;
 };
 
-/// A SectionChunk represents a section containing atoms. It consists of a
-/// section header that to be written to PECOFF header and atoms which to be
-/// written to the raw data section.
-class SectionChunk : public Chunk {
+/// An AtomChunk represents a section containing atoms.
+class AtomChunk : public Chunk {
 public:
-  /// Returns the size of the section on disk. The returned value is multiple
-  /// of disk sector, so the size may include the null padding at the end of
-  /// section.
-  virtual uint64_t size() const {
-    return llvm::RoundUpToAlignment(_size, _align);
-  }
-
   virtual void write(uint8_t *fileBuffer) {
     for (const auto *layout : _atomLayouts) {
       const DefinedAtom *atom = dyn_cast<const DefinedAtom>(layout->_atom);
@@ -363,17 +354,43 @@ public:
   // Set the file offset of the beginning of this section.
   virtual void setFileOffset(uint64_t fileOffset) {
     Chunk::setFileOffset(fileOffset);
-    _sectionHeader.PointerToRawData = fileOffset;
     for (AtomLayout *layout : _atomLayouts)
       layout->_fileOffset += fileOffset;
   }
 
   virtual void setVirtualAddress(uint32_t rva) {
-    _sectionHeader.VirtualAddress = rva;
     for (AtomLayout *layout : _atomLayouts)
       layout->_virtualAddr += rva;
   }
 
+protected:
+  AtomChunk(Kind kind) : Chunk(kind) {}
+  std::vector<AtomLayout *> _atomLayouts;
+};
+
+/// A SectionChunk represents a section containing atoms. It consists of a
+/// section header that to be written to PECOFF header and atoms which to be
+/// written to the raw data section.
+class SectionChunk : public AtomChunk {
+public:
+  /// Returns the size of the section on disk. The returned value is multiple
+  /// of disk sector, so the size may include the null padding at the end of
+  /// section.
+  virtual uint64_t size() const {
+    return llvm::RoundUpToAlignment(_size, _align);
+  }
+
+  // Set the file offset of the beginning of this section.
+  virtual void setFileOffset(uint64_t fileOffset) {
+    AtomChunk::setFileOffset(fileOffset);
+    _sectionHeader.PointerToRawData = fileOffset;
+  }
+
+  virtual void setVirtualAddress(uint32_t rva) {
+    _sectionHeader.VirtualAddress = rva;
+    AtomChunk::setVirtualAddress(rva);
+  }
+
   virtual uint32_t getVirtualAddress() { return _sectionHeader.VirtualAddress; }
 
   const llvm::object::coff_section &getSectionHeader() {
@@ -385,7 +402,7 @@ public:
 protected:
   SectionChunk(SectionHeaderTableChunk *table, StringRef sectionName,
                uint32_t characteristics)
-      : Chunk(kindSection),
+      : AtomChunk(kindSection),
         _sectionHeader(createSectionHeader(sectionName, characteristics)) {
     // The section should be aligned to disk sector.
     _align = SECTOR_SIZE;
@@ -446,7 +463,6 @@ private:
   }
 
   llvm::object::coff_section _sectionHeader;
-  std::vector<AtomLayout *> _atomLayouts;
   mutable llvm::BumpPtrAllocator _storage;
 };