Add plugin functionality for link-time optimization (LTO).

include/:
	* plugin-api.h: New file.

gold/:
	* configure.ac (plugins): Add --enable-plugins option.
	* configure: Regenerate.
	* config.in: Regenerate.
	* Makefile.am (LIBDL): New variable.
	(CCFILES): Add plugin.cc.
	(HFILES): Add plugin.h.
	(ldadd_var): Add LIBDL.
	* Makefile.in: Regenerate.

	* archive.cc: Include "plugin.h".
	(Archive::setup): Don't preread archive symbols when using a plugin.
	(Archive::get_file_and_offset): Add memsize parameter.  Change callers.
	(Archive::get_elf_object_for_member): Call plugin hooks for claiming
	files.
	(Archive::include_member): Add symbols from plugin objects.
	* archive.h (Archive::get_file_and_offset): Add memsize parameter.
	* descriptors.cc (Descriptors::open): Check for file descriptors
	abandoned by plugins.
	(Descriptors::claim_for_plugin): New function.
	* descriptors.h (Descriptors::claim_for_plugin): New function.
	(Open_descriptor::is_claimed): New field.
	(claim_descriptor_for_plugin): New function.
	* fileread.cc (File_read::claim_for_plugin): New function.
	* fileread.h (File_read::claim_for_plugin): New function.
	(File_read::descriptor): New function.
	* gold.cc: Include "plugin.h".
	(queue_initial_tasks): Add task to call plugin hooks for generating
	new object files.
	* main.cc: Include "plugin.h".
	(main): Load plugin libraries.
	* object.h (Pluginobj): Declare.
	(Object::pluginobj): New function.
	(Object::do_pluginobj): New function.
	(Object::set_target): New function.
	* options.cc: Include "plugin.h".
	(General_options::parse_plugin): New function.
	(General_options::General_options): Initialize plugins_ field.
	(General_options::add_plugin): New function.
	* options.h (Plugin_manager): Declare.
	(General_options): Add --plugin option.
	(General_options::has_plugins): New function.
	(General_options::plugins): New function.
	(General_options::add_plugin): New function.
	(General_options::plugins_): New field.
	* plugin.cc: New file.
	* plugin.h: New file.
	* readsyms.cc: Include "plugin.h".
	(Read_symbols::do_read_symbols): Check for archive before checking
	for ELF file.  Call plugin hooks to claim files.
	* resolve.cc (Symbol_table::resolve): Record when symbol is referenced
	from a real object file; force override when processing replacement
	files.
	* symtab.cc (Symbol::init_fields): Initialize in_real_elf_ field.
	(Symbol::init_base_object): Likewise.
	(Symbol::init_base_output_data): Likewise.
	(Symbol::init_base_output_segment): Likewise.
	(Symbol::init_base_constant): Likewise.
	(Symbol::init_base_undefined): Likewise.
	(Symbol::output_section): Assert that object is not a plugin.
	(Symbol_table::add_from_pluginobj): New function.
	(Symbol_table::sized_finalize_symbol): Treat symbols from plugins as
	undefined.
	(Symbol_table::sized_write_globals): Likewise.
	(Symbol_table::add_from_pluginobj): Instantiate template.
	* symtab.h (Sized_pluginobj): Declare.
	(Symbol::in_real_elf): New function.
	(Symbol::set_in_real_elf): New function.
	(Symbol::in_real_elf_): New field.
	(Symbol_table::add_from_pluginobj): New function.

	* testsuite/Makefile.am (AM_CFLAGS): New variable.
	(LIBDL): New variable.
	(LDADD): Add LIBDL.
	(check_PROGRAMS): Add plugin_test_1 and plugin_test_2.
	(check_SCRIPTS): Add plugin_test_1.sh and plugin_test_2.sh.
	(check_DATA): Add plugin_test_1.err and plugin_test_2.err.
	(MOSTLYCLEANFILES): Likewise.
	* testsuite/Makefile.in: Regenerate.
	* testsuite/plugin_test.c: New file.
	* testsuite/plugin_test_1.sh: New file.
	* testsuite/plugin_test_2.sh: New file.

1 files changed, 457 insertions, 0 deletions

diff --git a/gold/plugin.h b/gold/plugin.h
new file mode 100644
index 0000000..3f573ce
--- /dev/null
+++ b/gold/plugin.h
@@ -0,0 +1,457 @@
+// plugin.h -- plugin manager for gold      -*- C++ -*-
+
+// Copyright 2008 Free Software Foundation, Inc.
+// Written by Cary Coutant <ccoutant@google.com>.
+
+// This file is part of gold.
+
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+// MA 02110-1301, USA.
+
+#ifndef GOLD_PLUGIN_H
+#define GOLD_PLUGIN_H
+
+#include <list>
+#include <string>
+
+#include "object.h"
+#include "plugin-api.h"
+#include "workqueue.h"
+
+namespace gold
+{
+
+class General_options;
+class Input_file;
+class Input_objects;
+class Symbol_table;
+class Layout;
+class Dirsearch;
+class Mapfile;
+class Task_token;
+class Pluginobj;
+
+// This class represents a single plugin library.
+
+class Plugin
+{
+ public:
+  Plugin(const char* args)
+    : handle_(NULL),
+      args_(args),
+      claim_file_handler_(NULL),
+      all_symbols_read_handler_(NULL),
+      cleanup_handler_(NULL)      
+  { }
+
+  ~Plugin()
+  { }
+
+  // Load the library and call its entry point.
+  void
+  load();
+
+  // Call the claim-file handler.
+  bool
+  claim_file(struct ld_plugin_input_file *plugin_input_file);
+
+  // Call the all-symbols-read handler.
+  void
+  all_symbols_read();
+
+  // Call the cleanup handler.
+  void
+  cleanup();
+
+  // Register a claim-file handler.
+  void
+  set_claim_file_handler(ld_plugin_claim_file_handler handler)
+  { this->claim_file_handler_ = handler; }
+
+  // Register an all-symbols-read handler.
+  void
+  set_all_symbols_read_handler(ld_plugin_all_symbols_read_handler handler)
+  { this->all_symbols_read_handler_ = handler; }
+
+  // Register a claim-file handler.
+  void
+  set_cleanup_handler(ld_plugin_cleanup_handler handler)
+  { this->cleanup_handler_ = handler; }
+
+ private:
+  Plugin(const Plugin&);
+  Plugin& operator=(const Plugin&);
+
+  // The shared library handle returned by dlopen.
+  void* handle_;
+  // The argument string given to --plugin.
+  const char* args_;
+  // The plugin's event handlers.
+  ld_plugin_claim_file_handler claim_file_handler_;
+  ld_plugin_all_symbols_read_handler all_symbols_read_handler_;
+  ld_plugin_cleanup_handler cleanup_handler_;
+};
+
+// A manager class for plugins.
+
+class Plugin_manager
+{
+ public:
+  Plugin_manager(const General_options& options)
+    : plugins_(), in_replacement_phase_(false), options_(options),
+      workqueue_(NULL), input_objects_(NULL), symtab_(NULL), layout_(NULL),
+      dirpath_(NULL), mapfile_(NULL), this_blocker_(NULL)
+  { this->current_ = plugins_.end(); }
+
+  ~Plugin_manager();
+
+  // Add a plugin library.
+  void
+  add_plugin(const char* args)
+  { this->plugins_.push_back(new Plugin(args)); }
+
+  // Load all plugin libraries.
+  void
+  load_plugins();
+
+  // Call the plugin claim-file handlers in turn to see if any claim the file.
+  Pluginobj*
+  claim_file(Input_file *input_file, off_t offset, off_t filesize);
+
+  // Call the all-symbols-read handlers.
+  void
+  all_symbols_read(Workqueue* workqueue, Input_objects* input_objects,
+                   Symbol_table* symtab, Layout* layout, Dirsearch* dirpath,
+                   Mapfile* mapfile, Task_token** last_blocker);
+
+  // Call the cleanup handlers.
+  void
+  cleanup();
+
+  // Register a claim-file handler.
+  void
+  set_claim_file_handler(ld_plugin_claim_file_handler handler)
+  {
+    gold_assert(this->current_ != plugins_.end());
+    (*this->current_)->set_claim_file_handler(handler);
+  }
+
+  // Register an all-symbols-read handler.
+  void
+  set_all_symbols_read_handler(ld_plugin_all_symbols_read_handler handler)
+  {
+    gold_assert(this->current_ != plugins_.end());
+    (*this->current_)->set_all_symbols_read_handler(handler);
+  }
+
+  // Register a claim-file handler.
+  void
+  set_cleanup_handler(ld_plugin_cleanup_handler handler)
+  {
+    gold_assert(this->current_ != plugins_.end());
+    (*this->current_)->set_cleanup_handler(handler);
+  }
+
+  // Make a new Pluginobj object.  This is called when the plugin calls
+  // the add_symbols API.
+  Pluginobj*
+  make_plugin_object(unsigned int handle);
+
+  // Return the Pluginobj associated with the given HANDLE.
+  Pluginobj*
+  object(unsigned int handle) const
+  {
+    if (handle >= this->objects_.size())
+      return NULL;
+    return this->objects_[handle];
+  }
+
+  // Add a new input file.
+  ld_plugin_status
+  add_input_file(char *pathname);
+
+  // Return TRUE if we are in the replacement phase.
+  bool
+  in_replacement_phase() const
+  { return this->in_replacement_phase_; }
+
+ private:
+  Plugin_manager(const Plugin_manager&);
+  Plugin_manager& operator=(const Plugin_manager&);
+
+  typedef std::list<Plugin*> Plugin_list;
+  typedef std::vector<Pluginobj*> Object_list;
+
+  // The list of plugin libraries.
+  Plugin_list plugins_;
+  // A pointer to the current plugin.  Used while loading plugins.
+  Plugin_list::iterator current_;
+
+  // The list of plugin objects.  The index of an item in this list
+  // serves as the "handle" that we pass to the plugins.
+  Object_list objects_;
+
+  // The file currently up for claim by the plugins.
+  Input_file* input_file_;
+  struct ld_plugin_input_file plugin_input_file_;
+
+  // TRUE after the all symbols read event; indicates that we are
+  // processing replacement files whose symbols should replace the
+  // placeholder symbols from the Pluginobj objects.
+  bool in_replacement_phase_;
+
+  const General_options& options_;
+  Workqueue* workqueue_;
+  Input_objects* input_objects_;
+  Symbol_table* symtab_;
+  Layout* layout_;
+  Dirsearch* dirpath_;
+  Mapfile* mapfile_;
+  Task_token* this_blocker_;
+};
+
+
+// An object file claimed by a plugin.  This is an abstract base class.
+// The implementation is the template class Sized_pluginobj.
+
+class Pluginobj : public Object
+{
+ public:
+
+  typedef std::vector<Symbol*> Symbols;
+
+  Pluginobj(const std::string& name, Input_file* input_file, off_t offset);
+
+  // Fill in the symbol resolution status for the given plugin symbols.
+  ld_plugin_status
+  get_symbol_resolution_info(int nsyms, ld_plugin_symbol* syms) const;
+
+  // Add symbol information to the global symbol table.
+  void
+  add_symbols(Symbol_table* symtab, Layout* layout)
+  { this->do_add_symbols(symtab, layout); }
+
+  // Store the incoming symbols from the plugin for later processing.
+  void
+  store_incoming_symbols(int nsyms, const struct ld_plugin_symbol* syms)
+  {
+    this->nsyms_ = nsyms;
+    this->syms_ = syms;
+  }
+
+  // Return TRUE if the comdat group with key COMDAT_KEY from this object
+  // should be kept.
+  bool
+  include_comdat_group(std::string comdat_key, Layout* layout);
+
+ protected:
+  // Return TRUE if this is an object claimed by a plugin.
+  virtual Pluginobj*
+  do_pluginobj()
+  { return this; }
+
+  // Add symbol information to the global symbol table--implemented by
+  // child class.
+  virtual void
+  do_add_symbols(Symbol_table*, Layout*) = 0;
+
+  // The number of symbols provided by the plugin.
+  int nsyms_;
+  
+  // The symbols provided by the plugin.
+  const struct ld_plugin_symbol* syms_;
+
+  // The entries in the symbol table for the external symbols.
+  Symbols symbols_;
+
+ private:
+  // Map a comdat key symbol to a boolean indicating whether the comdat
+  // group in this object with that key should be kept.
+  typedef Unordered_map<std::string, bool> Comdat_map;
+  Comdat_map comdat_map_;
+};
+
+// A plugin object, size-specific version.
+
+template<int size, bool big_endian>
+class Sized_pluginobj : public Pluginobj
+{
+ public:
+  Sized_pluginobj(const std::string& name, Input_file* input_file,
+                  off_t offset);
+
+  // Read the symbols.
+  void
+  do_read_symbols(Read_symbols_data*);
+
+  // Lay out the input sections.
+  void
+  do_layout(Symbol_table*, Layout*, Read_symbols_data*);
+
+  // Add the symbols to the symbol table.
+  void
+  do_add_symbols(Symbol_table*, Read_symbols_data*);
+
+  void
+  do_add_symbols(Symbol_table*, Layout*);
+
+  // Get the size of a section.
+  uint64_t
+  do_section_size(unsigned int shndx);
+
+  // Get the name of a section.
+  std::string
+  do_section_name(unsigned int shndx);
+
+  // Return a view of the contents of a section.
+  Object::Location
+  do_section_contents(unsigned int shndx);
+
+  // Return section flags.
+  uint64_t
+  do_section_flags(unsigned int shndx);
+
+  // Return section address.
+  uint64_t
+  do_section_address(unsigned int shndx);
+
+  // Return section type.
+  unsigned int
+  do_section_type(unsigned int shndx);
+
+  // Return the section link field.
+  unsigned int
+  do_section_link(unsigned int shndx);
+
+  // Return the section link field.
+  unsigned int
+  do_section_info(unsigned int shndx);
+
+  // Return the section alignment.
+  uint64_t
+  do_section_addralign(unsigned int shndx);
+
+  // Return the Xindex structure to use.
+  Xindex*
+  do_initialize_xindex();
+
+  // Get symbol counts.
+  void
+  do_get_global_symbol_counts(const Symbol_table*, size_t*, size_t*) const;
+
+  // Add placeholder symbols from a claimed file.
+  ld_plugin_status
+  add_symbols_from_plugin(int nsyms, const ld_plugin_symbol* syms);
+
+ protected:
+
+ private:
+};
+
+// This Task handles adding the symbols to the symbol table.  These
+// tasks must be run in the same order as the arguments appear on the
+// command line.
+
+class Add_plugin_symbols : public Task
+{
+ public:
+  // THIS_BLOCKER is used to prevent this task from running before the
+  // one for the previous input file.  NEXT_BLOCKER is used to prevent
+  // the next task from running.
+  Add_plugin_symbols(Symbol_table* symtab,
+	             Layout* layout,
+	             Pluginobj* obj,
+	             Task_token* this_blocker,
+	             Task_token* next_blocker)
+    : symtab_(symtab), layout_(layout), obj_(obj),
+      this_blocker_(this_blocker), next_blocker_(next_blocker)
+  { }
+
+  ~Add_plugin_symbols();
+
+  // The standard Task methods.
+
+  Task_token*
+  is_runnable();
+
+  void
+  locks(Task_locker*);
+
+  void
+  run(Workqueue*);
+
+  std::string
+  get_name() const
+  { return "Add_plugin_symbols " + this->obj_->name(); }
+
+private:
+  Symbol_table* symtab_;
+  Layout* layout_;
+  Pluginobj* obj_;
+  Task_token* this_blocker_;
+  Task_token* next_blocker_;
+};
+
+// This Task handles handles the "all symbols read" event hook.
+// The plugin may add additional input files at this time, which must
+// be queued for reading.
+
+class Plugin_hook : public Task
+{
+ public:
+  Plugin_hook(const General_options& options, Input_objects* input_objects,
+	      Symbol_table* symtab, Layout* layout, Dirsearch* dirpath,
+	      Mapfile* mapfile, Task_token* this_blocker,
+	      Task_token* next_blocker)
+    : options_(options), input_objects_(input_objects), symtab_(symtab),
+      layout_(layout), dirpath_(dirpath), mapfile_(mapfile),
+      this_blocker_(this_blocker), next_blocker_(next_blocker)
+  { }
+
+  ~Plugin_hook();
+
+  // The standard Task methods.
+
+  Task_token*
+  is_runnable();
+
+  void
+  locks(Task_locker*);
+
+  void
+  run(Workqueue*);
+
+  std::string
+  get_name() const
+  { return "Plugin_hook"; }
+
+ private:
+  // Call the plugin hook.
+  void
+  do_plugin_hook(Workqueue*);
+
+  const General_options& options_;
+  Input_objects* input_objects_;
+  Symbol_table* symtab_;
+  Layout* layout_;
+  Dirsearch* dirpath_;
+  Mapfile* mapfile_;
+  Task_token* this_blocker_;
+  Task_token* next_blocker_;
+};
+
+} // End namespace gold.
+
+#endif // !defined(GOLD_PLUGIN_H)