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.

2 files changed, 247 insertions, 0 deletions

diff --git a/include/ChangeLog b/include/ChangeLog
index ece1aae..adcc2b7 100644
--- a/include/ChangeLog
+++ b/include/ChangeLog
@@ -1,3 +1,8 @@
+2008-09-18  Cary Coutant  <ccoutant@google.com>
+
+	Add plugin functionality for link-time optimization (LTO).
+	* plugin-api.h: New file.
+
 2008-09-09  Jason Merrill  <jason@redhat.com>
 
 	* demangle.h (enum demangle_component_type): Add
diff --git a/include/plugin-api.h b/include/plugin-api.h
new file mode 100644
index 0000000..9863086
--- /dev/null
+++ b/include/plugin-api.h
@@ -0,0 +1,242 @@
+/* plugin-api.h -- External linker plugin API.  */
+
+/* Copyright 2008 Free Software Foundation, Inc.
+   Written by Cary Coutant <ccoutant@google.com>.
+
+   This file is part of binutils.
+
+   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.  */
+
+/* This file defines the interface for writing a linker plugin, which is
+   described at < http://gcc.gnu.org/wiki/whopr/driver >.  */
+
+#ifndef PLUGIN_API_H
+#define PLUGIN_API_H
+
+#include <stdint.h>
+#include <sys/types.h>
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+/* Status code returned by most API routines.  */
+
+enum ld_plugin_status
+{
+  LDPS_OK = 0,
+  LDPS_NO_SYMS,         // Attempt to get symbols that haven't been added.
+  LDPS_ERR,
+  /* Additional Error codes TBD.  */
+};
+
+/* The version of the API specification.  */
+
+enum ld_plugin_api_version
+{
+  LD_PLUGIN_API_VERSION = 1,
+};
+
+/* The type of output file being generated by the linker.  */
+
+enum ld_plugin_output_file_type
+{
+  LDPO_REL,
+  LDPO_EXEC,
+  LDPO_DYN,
+};
+
+/* An input file managed by the plugin library.  */
+
+struct ld_plugin_input_file
+{
+  const char *name;
+  int fd;
+  off_t offset;
+  off_t filesize;
+  void *handle;
+};
+
+/* A symbol belonging to an input file managed by the plugin library.  */
+
+struct ld_plugin_symbol
+{
+  char *name;
+  char *version;
+  int def;
+  int visibility;
+  uint64_t size;
+  char *comdat_key;
+  int resolution;
+};
+
+/* Whether the symbol is a definition, reference, or common, weak or not.  */
+
+enum ld_plugin_symbol_kind
+{
+  LDPK_DEF,
+  LDPK_WEAKDEF,
+  LDPK_UNDEF,
+  LDPK_WEAKUNDEF,
+  LDPK_COMMON,
+};
+
+/* The visibility of the symbol.  */
+
+enum ld_plugin_symbol_visibility
+{
+  LDPV_DEFAULT,
+  LDPV_PROTECTED,
+  LDPV_INTERNAL,
+  LDPV_HIDDEN,
+};
+
+/* How a symbol is resolved.  */
+
+enum ld_plugin_symbol_resolution
+{
+  LDPR_UNKNOWN = 0,
+  LDPR_UNDEF,
+  LDPR_PREVAILING_DEF,
+  LDPR_PREVAILING_DEF_IRONLY,
+  LDPR_PREEMPTED_REG,
+  LDPR_PREEMPTED_IR,
+  LDPR_RESOLVED_IR,
+  LDPR_RESOLVED_EXEC,
+  LDPR_RESOLVED_DYN,
+};
+
+/* The plugin library's "claim file" handler.  */
+
+typedef
+enum ld_plugin_status
+(*ld_plugin_claim_file_handler) (
+  const struct ld_plugin_input_file *file, int *claimed);
+
+/* The plugin library's "all symbols read" handler.  */
+
+typedef
+enum ld_plugin_status
+(*ld_plugin_all_symbols_read_handler) (void);
+
+/* The plugin library's cleanup handler.  */
+
+typedef
+enum ld_plugin_status
+(*ld_plugin_cleanup_handler) (void);
+
+/* The linker's interface for registering the "claim file" handler.  */
+
+typedef
+enum ld_plugin_status
+(*ld_plugin_register_claim_file) (ld_plugin_claim_file_handler handler);
+
+/* The linker's interface for registering the "all symbols read" handler.  */
+
+typedef
+enum ld_plugin_status
+(*ld_plugin_register_all_symbols_read) (
+  ld_plugin_all_symbols_read_handler handler);
+
+/* The linker's interface for registering the cleanup handler.  */
+
+typedef
+enum ld_plugin_status
+(*ld_plugin_register_cleanup) (ld_plugin_cleanup_handler handler);
+
+/* The linker's interface for adding symbols from a claimed input file.  */
+
+typedef
+enum ld_plugin_status
+(*ld_plugin_add_symbols) (void *handle, int nsyms,
+                          const struct ld_plugin_symbol *syms);
+
+/* The linker's interface for retrieving symbol resolution information.  */
+
+typedef
+enum ld_plugin_status
+(*ld_plugin_get_symbols) (const void *handle, int nsyms,
+                          struct ld_plugin_symbol *syms);
+
+/* The linker's interface for adding a compiled input file.  */
+
+typedef
+enum ld_plugin_status
+(*ld_plugin_add_input_file) (char *pathname);
+
+/* The linker's interface for issuing a warning or error message.  */
+
+typedef
+enum ld_plugin_status
+(*ld_plugin_message) (int level, char *format, ...);
+
+enum ld_plugin_level
+{
+  LDPL_INFO,
+  LDPL_WARNING,
+  LDPL_ERROR,
+  LDPL_FATAL,
+};
+
+/* Values for the tv_tag field of the transfer vector.  */
+
+enum ld_plugin_tag
+{
+  LDPT_NULL = 0,
+  LDPT_API_VERSION,
+  LDPT_GOLD_VERSION,
+  LDPT_LINKER_OUTPUT,
+  LDPT_OPTION,
+  LDPT_REGISTER_CLAIM_FILE_HOOK,
+  LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK,
+  LDPT_REGISTER_CLEANUP_HOOK,
+  LDPT_ADD_SYMBOLS,
+  LDPT_GET_SYMBOLS,
+  LDPT_ADD_INPUT_FILE,
+  LDPT_MESSAGE,
+};
+
+/* The plugin transfer vector.  */
+
+struct ld_plugin_tv
+{
+  enum ld_plugin_tag tv_tag;
+  union
+  {
+    int tv_val;
+    const char *tv_string;
+    ld_plugin_register_claim_file tv_register_claim_file;
+    ld_plugin_register_all_symbols_read tv_register_all_symbols_read;
+    ld_plugin_register_cleanup tv_register_cleanup;
+    ld_plugin_add_symbols tv_add_symbols;
+    ld_plugin_get_symbols tv_get_symbols;
+    ld_plugin_add_input_file tv_add_input_file;
+    ld_plugin_message tv_message;
+  } tv_u;
+};
+
+/* The plugin library's "onload" entry point.  */
+
+typedef
+enum ld_plugin_status
+(*ld_plugin_onload) (struct ld_plugin_tv *tv);
+
+#ifdef __cplusplus
+};
+#endif
+
+#endif /* !defined(PLUGIN_API_H) */