1 files changed, 182 insertions, 0 deletions
diff --git a/lib/ReaderWriter/ELF/ExecutableWriter.h b/lib/ReaderWriter/ELF/ExecutableWriter.h
new file mode 100644
index 000000000000..477e3920abae
--- /dev/null
+++ b/lib/ReaderWriter/ELF/ExecutableWriter.h
@@ -0,0 +1,182 @@
+//===- lib/ReaderWriter/ELF/ExecutableWriter.h ----------------------------===//
+//
+//                             The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+#ifndef LLD_READER_WRITER_ELF_EXECUTABLE_WRITER_H
+#define LLD_READER_WRITER_ELF_EXECUTABLE_WRITER_H
+
+#include "OutputELFWriter.h"
+
+namespace lld {
+namespace elf {
+using namespace llvm;
+using namespace llvm::object;
+
+template<class ELFT>
+class ExecutableWriter;
+
+//===----------------------------------------------------------------------===//
+//  ExecutableWriter Class
+//===----------------------------------------------------------------------===//
+template<class ELFT>
+class ExecutableWriter : public OutputELFWriter<ELFT> {
+public:
+  ExecutableWriter(ELFLinkingContext &context, TargetLayout<ELFT> &layout)
+      : OutputELFWriter<ELFT>(context, layout),
+        _runtimeFile(new RuntimeFile<ELFT>(context, "C runtime")) {}
+
+protected:
+  virtual void buildDynamicSymbolTable(const File &file);
+  virtual void addDefaultAtoms();
+  virtual bool createImplicitFiles(std::vector<std::unique_ptr<File> > &);
+  virtual void finalizeDefaultAtomValues();
+  virtual void createDefaultSections();
+
+  virtual bool isNeededTagRequired(const SharedLibraryAtom *sla) const {
+    return this->_layout.isCopied(sla);
+  }
+
+  unique_bump_ptr<InterpSection<ELFT>> _interpSection;
+  std::unique_ptr<RuntimeFile<ELFT> > _runtimeFile;
+};
+
+//===----------------------------------------------------------------------===//
+//  ExecutableWriter
+//===----------------------------------------------------------------------===//
+template<class ELFT>
+void ExecutableWriter<ELFT>::buildDynamicSymbolTable(const File &file) {
+  for (auto sec : this->_layout.sections())
+    if (auto section = dyn_cast<AtomSection<ELFT>>(sec))
+      for (const auto &atom : section->atoms()) {
+        const DefinedAtom *da = dyn_cast<const DefinedAtom>(atom->_atom);
+        if (!da)
+          continue;
+        if (da->dynamicExport() != DefinedAtom::dynamicExportAlways &&
+            !this->_context.isDynamicallyExportedSymbol(da->name()) &&
+            !(this->_context.shouldExportDynamic() &&
+              da->scope() == Atom::Scope::scopeGlobal))
+          continue;
+        this->_dynamicSymbolTable->addSymbol(atom->_atom, section->ordinal(),
+                                             atom->_virtualAddr, atom);
+      }
+
+  // Put weak symbols in the dynamic symbol table.
+  if (this->_context.isDynamic()) {
+    for (const UndefinedAtom *a : file.undefined()) {
+      if (this->_layout.isReferencedByDefinedAtom(a) &&
+          a->canBeNull() != UndefinedAtom::canBeNullNever)
+        this->_dynamicSymbolTable->addSymbol(a, ELF::SHN_UNDEF);
+    }
+  }
+
+  OutputELFWriter<ELFT>::buildDynamicSymbolTable(file);
+}
+
+/// \brief Add absolute symbols by default. These are linker added
+/// absolute symbols
+template<class ELFT>
+void ExecutableWriter<ELFT>::addDefaultAtoms() {
+  OutputELFWriter<ELFT>::addDefaultAtoms();
+  _runtimeFile->addUndefinedAtom(this->_context.entrySymbolName());
+  _runtimeFile->addAbsoluteAtom("__bss_start");
+  _runtimeFile->addAbsoluteAtom("__bss_end");
+  _runtimeFile->addAbsoluteAtom("_end");
+  _runtimeFile->addAbsoluteAtom("end");
+  _runtimeFile->addAbsoluteAtom("__preinit_array_start");
+  _runtimeFile->addAbsoluteAtom("__preinit_array_end");
+  _runtimeFile->addAbsoluteAtom("__init_array_start");
+  _runtimeFile->addAbsoluteAtom("__init_array_end");
+  if (this->_context.isRelaOutputFormat()) {
+    _runtimeFile->addAbsoluteAtom("__rela_iplt_start");
+    _runtimeFile->addAbsoluteAtom("__rela_iplt_end");
+  } else {
+    _runtimeFile->addAbsoluteAtom("__rel_iplt_start");
+    _runtimeFile->addAbsoluteAtom("__rel_iplt_end");
+  }
+  _runtimeFile->addAbsoluteAtom("__fini_array_start");
+  _runtimeFile->addAbsoluteAtom("__fini_array_end");
+}
+
+/// \brief Hook in lld to add CRuntime file
+template <class ELFT>
+bool ExecutableWriter<ELFT>::createImplicitFiles(
+    std::vector<std::unique_ptr<File> > &result) {
+  // Add the default atoms as defined by executables
+  ExecutableWriter<ELFT>::addDefaultAtoms();
+  OutputELFWriter<ELFT>::createImplicitFiles(result);
+  result.push_back(std::move(_runtimeFile));
+  return true;
+}
+
+template <class ELFT> void ExecutableWriter<ELFT>::createDefaultSections() {
+  OutputELFWriter<ELFT>::createDefaultSections();
+  if (this->_context.isDynamic()) {
+    _interpSection.reset(new (this->_alloc) InterpSection<ELFT>(
+        this->_context, ".interp", DefaultLayout<ELFT>::ORDER_INTERP,
+        this->_context.getInterpreter()));
+    this->_layout.addSection(_interpSection.get());
+  }
+}
+
+/// Finalize the value of all the absolute symbols that we
+/// created
+template <class ELFT> void ExecutableWriter<ELFT>::finalizeDefaultAtomValues() {
+  OutputELFWriter<ELFT>::finalizeDefaultAtomValues();
+  auto bssStartAtomIter = this->_layout.findAbsoluteAtom("__bss_start");
+  auto bssEndAtomIter = this->_layout.findAbsoluteAtom("__bss_end");
+  auto underScoreEndAtomIter = this->_layout.findAbsoluteAtom("_end");
+  auto endAtomIter = this->_layout.findAbsoluteAtom("end");
+
+  auto startEnd = [&](StringRef sym, StringRef sec) -> void {
+    std::string start = ("__" + sym + "_start").str();
+    std::string end = ("__" + sym + "_end").str();
+    auto s = this->_layout.findAbsoluteAtom(start);
+    auto e = this->_layout.findAbsoluteAtom(end);
+    auto section = this->_layout.findOutputSection(sec);
+    if (section) {
+      (*s)->_virtualAddr = section->virtualAddr();
+      (*e)->_virtualAddr = section->virtualAddr() + section->memSize();
+    } else {
+      (*s)->_virtualAddr = 0;
+      (*e)->_virtualAddr = 0;
+    }
+  };
+
+  startEnd("preinit_array", ".preinit_array");
+  startEnd("init_array", ".init_array");
+  if (this->_context.isRelaOutputFormat())
+    startEnd("rela_iplt", ".rela.plt");
+  else
+    startEnd("rel_iplt", ".rel.plt");
+  startEnd("fini_array", ".fini_array");
+
+  assert(!(bssStartAtomIter == this->_layout.absoluteAtoms().end() ||
+           bssEndAtomIter == this->_layout.absoluteAtoms().end() ||
+           underScoreEndAtomIter == this->_layout.absoluteAtoms().end() ||
+           endAtomIter == this->_layout.absoluteAtoms().end()) &&
+         "Unable to find the absolute atoms that have been added by lld");
+
+  auto bssSection = this->_layout.findOutputSection(".bss");
+
+  // If we don't find a bss section, then don't set these values
+  if (bssSection) {
+    (*bssStartAtomIter)->_virtualAddr = bssSection->virtualAddr();
+    (*bssEndAtomIter)->_virtualAddr =
+        bssSection->virtualAddr() + bssSection->memSize();
+    (*underScoreEndAtomIter)->_virtualAddr = (*bssEndAtomIter)->_virtualAddr;
+    (*endAtomIter)->_virtualAddr = (*bssEndAtomIter)->_virtualAddr;
+  } else if (auto dataSection = this->_layout.findOutputSection(".data")) {
+    (*underScoreEndAtomIter)->_virtualAddr =
+        dataSection->virtualAddr() + dataSection->memSize();
+    (*endAtomIter)->_virtualAddr = (*underScoreEndAtomIter)->_virtualAddr;
+  }
+}
+
+} // namespace elf
+} // namespace lld
+
+#endif // LLD_READER_WRITER_ELF_EXECUTABLE_WRITER_H