2009-01-20 Sriraman Tallam <tmsriram@google.com>

	* Makefile.am (CCFILES): Add gc.cc.
	(HFILES): Add gc.h.
	* Makefile.in: Regenerate.
	* gold.cc (Gc_runner): New class.
	(queue_initial_tasks): Call garbage collection related tasks
	when corresponding options are invoked.
	(queue_middle_gc_tasks): New function.
	(queue_middle_tasks): Reorder tasks to allow relocs to be read and
	processed early before laying out sections during garbage collection.
	* gold.h (queue_middle_gc_tasks): New function.
	(is_prefix_of): Move from "layout.cc".
	* i386.cc (Target_i386::gc_process_relocs): New function.
	* layout.cc (is_prefix_of): Remove. Move to "gold.h"
	* main.cc (main): Create object of class "Garbage_collection".
	* object.cc (Relobj::copy_symbols_data): New function.
	(Relobj::is_section_name_included): New function.
	(Sized_relobj::do_layout): Allow this function to be called twice
	during garbage collection and defer layout of section during the
	first call.
	* object.h (Relobj::get_symbols_data): New function.
	(Relobj::is_section_name_included): New function.
	(Relobj::copy_symbols_data): New function.
	(Relobj::set_symbols_data): New function.
	(Relobj::get_relocs_data): New function.
	(Relobj::set_relocs_data): New function.
	(Relobj::is_output_section_offset_invalid): New pure virtual function.
	(Relobj::gc_process_relocs): New function.
	(Relobj::do_gc_process_relocs): New pure virtual function.
	(Relobj::sd_): New data member.
	(Sized_relobj::is_output_section_offset_invalid): New function.
	(Sized_relobj::do_gc_process_relocs): New function.
	* options.h (General_options::gc_sections): Modify to not be a no-op.
	(General_options::print_gc_sections): New option.
	* plugin.cc (Plugin_finish::run): Remove function call to
	Plugin_manager::layout_deferred_objects.  Move it to "gold.cc".
	* powerpc.cc (Target_powerpc::gc_process_relocs): New function.
	* reloc.cc (Read_relocs::run): Add task to process relocs and
	determine unreferenced sections when doing garbage collection.
	(Gc_process_relocs): New class.
	(Sized_relobj::do_gc_process_relocs): New function.
	(Sized_relobj::do_scan_relocs): Don't try to scan the relocs for
	sections that are garbage collected.
	* reloc.h (Gc_process_relocs): New class.
	* sparc.cc (Target_sparc::gc_process_relocs): New function.
	* symtab.cc (Symbol::should_add_dynsym_entry): Do not add entries for
	symbols whose corresponding sections are garbage collected.
	(Symbol_table::Symbol_table): Add new parameter for the garbage
	collection object.
	(Symbol_table::gc_mark_undef_symbols): New function.
	(Symbol_table::gc_mark_symbol_for_shlib): New function.
	(Symbol_table::gc_mark_dyn_syms): New function.
	(Symbol_table::resolve): Do not treat symbols seen in dynamic objects
	as garbage.
	(Symbol_table::add_from_object): Likewise.
	(Symbol_table::add_from_relobj): When building shared objects, do not
	treat externally visible symbols as garbage.
	(Symbol_table::sized_finalize_symbol): Do not check dynamic symbol
	table information for static and relocatable links.
	* symtab.h (Symbol_table::set_gc): New function.
	(Symbol_table::gc): New function.
	(Symbol_table::gc_mark_undef_symbols): New function.
	(Symbol_table::gc_mark_symbol_for_shlib): New function.
	(Symbol_table::gc_mark_dyn_syms): New function.
	(Symbol_table::gc_): New data member.
	* target.h (Sized_target::gc_process_relocs): New pure virtual
	function.
	* x86_64.cc (Target_x86_64::gc_process_relocs): New function.
	* testsuite/testfile.cc (Target_test::gc_process_relocs): New function.

1 files changed, 19 insertions, 1 deletions

diff --git a/gold/target.h b/gold/target.h
index 460ac96..79111ce 100644
--- a/gold/target.h
+++ b/gold/target.h
@@ -1,6 +1,6 @@
 // target.h -- target support for gold   -*- C++ -*-
 
-// Copyright 2006, 2007, 2008 Free Software Foundation, Inc.
+// Copyright 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
 // Written by Ian Lance Taylor <iant@google.com>.
 
 // This file is part of gold.
@@ -259,6 +259,24 @@ class Sized_target : public Target
 	  const char*)
   { gold_unreachable(); }
 
+  // Process the relocs for a section, and record information of the
+  // mapping from source to destination sections. This mapping is later
+  // used to determine unreferenced garbage sections. This procedure is
+  // only called during garbage collection.
+  virtual void
+  gc_process_relocs(const General_options& options,
+	      Symbol_table* symtab,
+	      Layout* layout,
+	      Sized_relobj<size, big_endian>* object,
+	      unsigned int data_shndx,
+	      unsigned int sh_type,
+	      const unsigned char* prelocs,
+	      size_t reloc_count,
+	      Output_section* output_section,
+	      bool needs_special_offset_handling,
+	      size_t local_symbol_count,
+	      const unsigned char* plocal_symbols) = 0;
+
   // Scan the relocs for a section, and record any information
   // required for the symbol.  OPTIONS is the command line options.
   // SYMTAB is the symbol table.  OBJECT is the object in which the