[lld][Darwin] Add support for the -sectcreate option.

llvm-svn: 251183
diff --git a/lld/lib/ReaderWriter/MachO/SectCreateFile.h b/lld/lib/ReaderWriter/MachO/SectCreateFile.h
new file mode 100644
index 0000000..ea16e69
--- /dev/null
+++ b/lld/lib/ReaderWriter/MachO/SectCreateFile.h
@@ -0,0 +1,94 @@
+//===---- lib/ReaderWriter/MachO/SectCreateFile.h ---------------*- c++ -*-===//
+//
+//                             The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLD_READER_WRITER_MACHO_SECTCREATE_FILE_H
+#define LLD_READER_WRITER_MACHO_SECTCREATE_FILE_H
+
+#include "lld/Core/DefinedAtom.h"
+#include "lld/Core/Simple.h"
+#include "lld/ReaderWriter/MachOLinkingContext.h"
+
+namespace lld {
+namespace mach_o {
+
+//
+// A FlateNamespaceFile instance may be added as a resolution source of last
+// resort, depending on how -flat_namespace and -undefined are set.
+//
+class SectCreateFile : public File {
+public:
+
+  class SectCreateAtom : public SimpleDefinedAtom {
+  public:
+    SectCreateAtom(const File &file, StringRef segName, StringRef sectName,
+                   std::unique_ptr<MemoryBuffer> content)
+      : SimpleDefinedAtom(file),
+        _combinedName((segName + "/" + sectName).str()),
+        _content(std::move(content)) {}
+
+    uint64_t size() const override { return _content->getBufferSize(); }
+
+    Scope scope() const override { return scopeGlobal; }
+
+    ContentType contentType() const override { return typeSectCreate; }
+
+    SectionChoice sectionChoice() const override { return sectionCustomRequired; }
+
+    StringRef customSectionName() const override { return _combinedName; }
+
+    DeadStripKind deadStrip() const override { return deadStripNever; }
+
+    ArrayRef<uint8_t> rawContent() const override {
+      const uint8_t *data =
+        reinterpret_cast<const uint8_t*>(_content->getBufferStart());
+      return ArrayRef<uint8_t>(data, _content->getBufferSize());
+    }
+
+    StringRef segmentName() const { return _segName; }
+    StringRef sectionName() const { return _sectName; }
+
+  private:
+    std::string _combinedName;
+    StringRef _segName;
+    StringRef _sectName;
+    std::unique_ptr<MemoryBuffer> _content;
+  };
+
+  SectCreateFile() : File("sectcreate", kindObject) {}
+
+  void addSection(StringRef seg, StringRef sect,
+                  std::unique_ptr<MemoryBuffer> content) {
+    _definedAtoms.push_back(
+      new (allocator()) SectCreateAtom(*this, seg, sect, std::move(content)));
+  }
+
+  const AtomVector<DefinedAtom> &defined() const {
+    return _definedAtoms;
+  }
+
+  const AtomVector<UndefinedAtom> &undefined() const {
+    return _noUndefinedAtoms;
+  }
+
+  const AtomVector<SharedLibraryAtom> &sharedLibrary() const {
+    return _noSharedLibraryAtoms;
+  }
+
+  const AtomVector<AbsoluteAtom> &absolute() const {
+    return _noAbsoluteAtoms;
+  }
+
+private:
+  AtomVector<DefinedAtom> _definedAtoms;
+};
+
+} // namespace mach_o
+} // namespace lld
+
+#endif // LLD_READER_WRITER_MACHO_SECTCREATE_FILE_H