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, 19 insertions, 0 deletions

diff --git a/gold/resolve.cc b/gold/resolve.cc
index 0ad990cd05..17544f82a5 100644
--- a/gold/resolve.cc
+++ b/gold/resolve.cc
@@ -26,6 +26,7 @@
 #include "target.h"
 #include "object.h"
 #include "symtab.h"
+#include "plugin.h"
 
 namespace gold
 {
@@ -240,6 +241,24 @@ Symbol_table::resolve(Sized_symbol<size>* to,
       to->set_in_dyn();
     }
 
+  // Record if we've seen this symbol in a real ELF object (i.e., the
+  // symbol is referenced from outside the world known to the plugin).
+  if (object->pluginobj() == NULL)
+    to->set_in_real_elf();
+
+  // If we're processing replacement files, allow new symbols to override
+  // the placeholders from the plugin objects.
+  if (to->source() == Symbol::FROM_OBJECT)
+    {
+      Pluginobj* obj = to->object()->pluginobj();
+      if (obj != NULL
+          && parameters->options().plugins()->in_replacement_phase())
+        {
+          this->override(to, sym, st_shndx, is_ordinary, object, version);
+          return;
+        }
+    }
+
   unsigned int frombits = symbol_to_bits(sym.get_st_bind(),
                                          object->is_dynamic(),
 					 st_shndx, is_ordinary,