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, 32 insertions, 5 deletions

diff --git a/gold/archive.cc b/gold/archive.cc
index f5ad574..7fd1a17 100644
--- a/gold/archive.cc
+++ b/gold/archive.cc
@@ -37,6 +37,7 @@
 #include "symtab.h"
 #include "object.h"
 #include "archive.h"
+#include "plugin.h"
 
 namespace gold
 {
@@ -126,6 +127,9 @@ Archive::setup(Input_objects* input_objects)
                        && parameters->options().preread_archive_symbols());
 #ifndef ENABLE_THREADS
   preread_syms = false;
+#else
+  if (parameters->options().has_plugins())
+    preread_syms = false;
 #endif
   if (preread_syms)
     this->read_all_symbols(input_objects);
@@ -439,11 +443,11 @@ Archive::end()
 bool
 Archive::get_file_and_offset(off_t off, Input_objects* input_objects,
                              Input_file** input_file, off_t* memoff,
-                             std::string* member_name)
+                             off_t* memsize, std::string* member_name)
 {
   off_t nested_off;
 
-  this->read_header(off, false, member_name, &nested_off);
+  *memsize = this->read_header(off, false, member_name, &nested_off);
 
   *input_file = this->input_file_;
   *memoff = off + static_cast<off_t>(sizeof(Archive_header));
@@ -488,8 +492,8 @@ Archive::get_file_and_offset(off_t off, Input_objects* input_objects,
             this->nested_archives_.insert(std::make_pair(*member_name, arch));
           gold_assert(ins.second);
         }
-      return arch->get_file_and_offset(nested_off, input_objects,
-                                       input_file, memoff, member_name);
+      return arch->get_file_and_offset(nested_off, input_objects, input_file,
+                                       memoff, memsize, member_name);
     }
 
   // This is an external member of a thin archive.  Open the
@@ -503,6 +507,7 @@ Archive::get_file_and_offset(off_t off, Input_objects* input_objects,
     return false;
 
   *memoff = 0;
+  *memsize = (*input_file)->file().filesize();
   return true;
 }
 
@@ -515,11 +520,26 @@ Archive::get_elf_object_for_member(off_t off, Input_objects* input_objects)
   std::string member_name;
   Input_file* input_file;
   off_t memoff;
+  off_t memsize;
 
   if (!this->get_file_and_offset(off, input_objects, &input_file, &memoff,
-                                 &member_name))
+                                 &memsize, &member_name))
     return NULL;
 
+  if (parameters->options().has_plugins())
+    {
+      Object* obj = parameters->options().plugins()->claim_file(input_file,
+                                                                memoff,
+                                                                memsize);
+      if (obj != NULL)
+        {
+          // The input file was claimed by a plugin, and its symbols
+          // have been provided by the plugin.
+	  input_file->file().claim_for_plugin();
+          return obj;
+        }
+    }
+
   off_t filesize = input_file->file().filesize();
   int read_size = elfcpp::Elf_sizes<64>::ehdr_size;
   if (filesize - memoff < read_size)
@@ -753,6 +773,13 @@ Archive::include_member(Symbol_table* symtab, Layout* layout,
   if (mapfile != NULL)
     mapfile->report_include_archive_member(obj->name(), sym, why);
 
+  Pluginobj* pluginobj = obj->pluginobj();
+  if (pluginobj != NULL)
+    {
+      pluginobj->add_symbols(symtab, layout);
+      return;
+    }
+
   if (input_objects->add_object(obj))
     {
       Read_symbols_data sd;