New drop, with first cut of section layout code.

gold/layout.h

@@ -0,0 +1,181 @@
+// layout.h -- lay out output file sections for gold  -*- C++ -*-
+
+#ifndef GOLD_LAYOUT_H
+#define GOLD_LAYOUT_H
+
+#include <list>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "options.h"
+#include "workqueue.h"
+#include "object.h"
+#include "stringpool.h"
+
+namespace gold
+{
+
+class Output_section;
+class Output_segment;
+
+// This Task handles mapping the input sections to output sections and
+// laying them out in memory.
+
+class Layout_task : public Task
+{
+ public:
+  // OPTIONS is the command line options, INPUT_OBJECTS is the list of
+  // input objects, THIS_BLOCKER is a token which blocks this task
+  // from executing until all the input symbols have been read.
+  Layout_task(const General_options& options, const Object_list* input_objects,
+	      Task_token* this_blocker)
+    : options_(options), input_objects_(input_objects),
+      this_blocker_(this_blocker)
+  { }
+
+  ~Layout_task();
+
+  // The standard Task methods.
+
+  Is_runnable_type
+  is_runnable(Workqueue*);
+
+  Task_locker*
+  locks(Workqueue*);
+
+  void
+  run(Workqueue*);
+
+ private:
+  Layout_task(const Layout_task&);
+  Layout_task& operator=(const Layout_task&);
+
+  const General_options& options_;
+  const Object_list* input_objects_;
+  Task_token* this_blocker_;
+};
+
+// This class handles the details of laying out input sections.
+
+class Layout
+{
+ public:
+  Layout(const General_options& options)
+    : options_(options), namepool_(), signatures_(),
+      section_name_map_(), segment_list_()
+  { }
+
+  // Given an input section named NAME with data in SHDR from the
+  // object file OBJECT, return the output section where this input
+  // section should go.  Set *OFFSET to the offset within the output
+  // section.
+  template<int size, bool big_endian>
+  Output_section*
+  layout(Object *object, const char* name,
+	 const elfcpp::Shdr<size, big_endian>& shdr, off_t* offset);
+
+  // Return whether a section is a .gnu.linkonce section, given the
+  // section name.
+  static inline bool
+  is_linkonce(const char* name)
+  { return strncmp(name, ".gnu.linkonce", sizeof(".gnu.linkonce") - 1) == 0; }
+
+  // Record the signature of a comdat section, and return whether to
+  // include it in the link.  The GROUP parameter is true for a
+  // section group signature, false for a signature derived from a
+  // .gnu.linkonce section.
+  bool
+  add_comdat(const char*, bool group);
+
+ private:
+  Layout(const Layout&);
+  Layout& operator=(const Layout&);
+
+  // Mapping from .gnu.linkonce section names to output section names.
+  struct Linkonce_mapping
+  {
+    const char* from;
+    int fromlen;
+    const char* to;
+  };
+  static const Linkonce_mapping linkonce_mapping[];
+  static const int linkonce_mapping_count;
+
+  // Return whether to include this section in the link.
+  template<int size, bool big_endian>
+  bool
+  include_section(Object* object, const char* name,
+		  const elfcpp::Shdr<size, big_endian>&);
+
+  // Return the output section name to use for a linkonce section
+  // name.
+  static const char*
+  linkonce_output_name(const char* name);
+
+  // Create a new Output_section.
+  Output_section*
+  make_output_section(const char* name, elfcpp::Elf_Word type,
+		      elfcpp::Elf_Xword flags);
+
+  // Return whether SEG1 comes before SEG2 in the output file.
+  static bool
+  Layout::segment_precedes(const Output_segment* seg1,
+			   const Output_segment* seg2);
+
+  // Map from section flags to segment flags.
+  static elfcpp::Elf_Word
+  section_flags_to_segment(elfcpp::Elf_Xword flags);
+
+  // A mapping used for group signatures.
+  typedef Unordered_map<std::string, bool> Signatures;
+
+  // Mapping from input section name/type/flags to output section.  We
+  // use canonicalized strings here.
+
+  typedef std::pair<const char*,
+		    std::pair<elfcpp::Elf_Word, elfcpp::Elf_Xword> > Key;
+
+  struct Hash_key
+  {
+    size_t
+    operator()(const Key& k) const;
+  };
+
+  typedef Unordered_map<Key, Output_section*, Hash_key> Section_name_map;
+
+  // A comparison class for segments.
+
+  struct Compare_segments
+  {
+    bool
+    operator()(const Output_segment* seg1, const Output_segment* seg2)
+    { return Layout::segment_precedes(seg1, seg2); }
+  };
+
+  // The list of segments.
+
+  typedef std::list<Output_segment*> Segment_list;
+
+  // The list of sections not attached to a segment.
+
+  typedef std::list<Output_section*> Section_list;
+
+  // A reference to the options on the command line.
+  const General_options& options_;
+  // The output section names.
+  Stringpool namepool_;
+  // The list of group sections and linkonce sections which we have seen.
+  Signatures signatures_;
+  // The mapping from input section name/type/flags to output sections.
+  Section_name_map section_name_map_;
+  // The list of output segments.
+  Segment_list segment_list_;
+  // The list of output sections which are not attached to any output
+  // segment.
+  Section_list section_list_;
+};
+
+} // End namespace gold.
+
+#endif // !defined(GOLD_LAYOUT_H)