* 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.
+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.
+
2009-01-20 Chris Faylor <me.sourceware@sourceware.org>
* options.h (General_options::gc_sections): Define as a no-op for now.
errors.cc \
expression.cc \
fileread.cc \
+ gc.cc \
gold.cc \
gold-threads.cc \
layout.cc \
ehframe.h \
errors.h \
fileread.h \
+ gc.h \
gold.h \
gold-threads.h \
layout.h \
cref.$(OBJEXT) defstd.$(OBJEXT) descriptors.$(OBJEXT) \
dirsearch.$(OBJEXT) dynobj.$(OBJEXT) dwarf_reader.$(OBJEXT) \
ehframe.$(OBJEXT) errors.$(OBJEXT) expression.$(OBJEXT) \
- fileread.$(OBJEXT) gold.$(OBJEXT) gold-threads.$(OBJEXT) \
+ fileread.$(OBJEXT) gc.$(OBJEXT) \
+ gold.$(OBJEXT) gold-threads.$(OBJEXT) \
layout.$(OBJEXT) mapfile.$(OBJEXT) merge.$(OBJEXT) \
object.$(OBJEXT) options.$(OBJEXT) output.$(OBJEXT) \
parameters.$(OBJEXT) plugin.$(OBJEXT) readsyms.$(OBJEXT) \
errors.cc \
expression.cc \
fileread.cc \
+ gc.cc \
gold.cc \
gold-threads.cc \
layout.cc \
ehframe.h \
errors.h \
fileread.h \
+ gc.h \
gold.h \
gold-threads.h \
layout.h \
--- /dev/null
+// gc.cc -- garbage collection of unused sections
+
+// Copyright 2009 Free Software Foundation, Inc.
+// Written by Sriraman Tallam <tmsriram@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.
+
+
+#include "gold.h"
+#include "object.h"
+#include "gc.h"
+#include "symtab.h"
+
+namespace gold
+{
+
+// Garbage collection uses a worklist style algorithm to determine the
+// transitive closure of all referenced sections.
+void
+Garbage_collection::do_transitive_closure()
+{
+ while (!this->worklist().empty())
+ {
+ // Add elements from the work list to the referenced list
+ // one by one.
+ Section_id entry = this->worklist().front();
+ this->worklist().pop();
+ if (this->referenced_list().find(entry)
+ == this->referenced_list().end())
+ {
+ this->referenced_list().insert(entry);
+ }
+ else
+ {
+ continue;
+ }
+ Garbage_collection::Section_ref::iterator find_it =
+ this->section_reloc_map().find(entry);
+ if (find_it == this->section_reloc_map().end())
+ continue;
+ Garbage_collection::Sections_reachable v = find_it->second;
+ // Scan the vector of references for each work_list entry.
+ for (Garbage_collection::Sections_reachable::iterator it_v = v.begin();
+ it_v != v.end();
+ ++it_v)
+ {
+ // Do not add already processed sections to the work_list.
+ if (this->referenced_list().find(*it_v)
+ == this->referenced_list().end())
+ {
+ this->worklist().push(*it_v);
+ }
+ }
+ }
+ this->worklist_ready();
+}
+
+} // End namespace gold.
+
--- /dev/null
+// gc.h -- garbage collection of unused sections
+
+// Copyright 2009 Free Software Foundation, Inc.
+// Written by Sriraman Tallam <tmsriram@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_GC_H
+#define GOLD_GC_H
+
+#include <queue>
+
+#include "elfcpp.h"
+#include "symtab.h"
+
+namespace gold
+{
+
+class Object;
+
+template<int size, bool big_endian>
+class Sized_relobj;
+
+template<int sh_type, int size, bool big_endian>
+class Reloc_types;
+
+class Output_section;
+class General_options;
+class Layout;
+
+typedef std::pair<Object *, unsigned int> Section_id;
+
+class Garbage_collection
+{
+ struct Section_id_hash
+ {
+ size_t operator()(const Section_id& loc) const
+ { return reinterpret_cast<uintptr_t>(loc.first) ^ loc.second; }
+ };
+
+ typedef Unordered_set<Section_id, Section_id_hash> Sections_reachable;
+ typedef std::map<Section_id, Sections_reachable> Section_ref;
+ typedef std::queue<Section_id> Worklist_type;
+
+ public :
+ Garbage_collection()
+ :is_worklist_ready_(false)
+ { }
+
+ // Accessor methods for the private members.
+
+ Sections_reachable&
+ referenced_list()
+ { return referenced_list_; }
+
+ Section_ref&
+ section_reloc_map()
+ { return section_reloc_map_; }
+
+ Worklist_type&
+ worklist()
+ { return work_list_; }
+
+ bool
+ is_worklist_ready()
+ { return is_worklist_ready_; }
+
+ void
+ worklist_ready()
+ { is_worklist_ready_ = true; }
+
+ void
+ do_transitive_closure();
+
+ private :
+ Worklist_type work_list_;
+ bool is_worklist_ready_;
+ Section_ref section_reloc_map_;
+ Sections_reachable referenced_list_;
+};
+
+// Data to pass between successive invocations of do_layout
+// in object.cc while garbage collecting. This data structure
+// is filled by using the data from Read_symbols_data.
+
+struct Symbols_data
+{
+ // Section headers.
+ unsigned char* section_headers_data;
+ // Section names.
+ unsigned char* section_names_data;
+ // Size of section name data in bytes.
+ section_size_type section_names_size;
+ // Symbol data.
+ unsigned char* symbols_data;
+ // Size of symbol data in bytes.
+ section_size_type symbols_size;
+ // Offset of external symbols within symbol data. This structure
+ // sometimes contains only external symbols, in which case this will
+ // be zero. Sometimes it contains all symbols.
+ section_offset_type external_symbols_offset;
+ // Symbol names.
+ unsigned char* symbol_names_data;
+ // Size of symbol name data in bytes.
+ section_size_type symbol_names_size;
+};
+
+// This function implements the the generic part of reloc
+// processing to map a section to all the sections it
+// references through relocs. It is used only during garbage
+// collection.
+
+template<int size, bool big_endian, typename Target_type, int sh_type,
+ typename Scan>
+inline void
+gc_process_relocs(
+ const General_options& ,
+ Symbol_table* symtab,
+ Layout*,
+ Target_type* ,
+ Sized_relobj<size, big_endian>* object,
+ unsigned int data_shndx,
+ const unsigned char* prelocs,
+ size_t reloc_count,
+ Output_section*,
+ bool ,
+ size_t local_count,
+ const unsigned char* plocal_syms)
+{
+ Object *src_obj, *dst_obj;
+ unsigned int src_indx, dst_indx;
+
+ src_obj = object;
+ src_indx = data_shndx;
+
+ typedef typename Reloc_types<sh_type, size, big_endian>::Reloc Reltype;
+ const int reloc_size = Reloc_types<sh_type, size, big_endian>::reloc_size;
+ const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
+
+ for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size)
+ {
+ Reltype reloc(prelocs);
+ typename elfcpp::Elf_types<size>::Elf_WXword r_info = reloc.get_r_info();
+ unsigned int r_sym = elfcpp::elf_r_sym<size>(r_info);
+
+ if (r_sym < local_count)
+ {
+ gold_assert(plocal_syms != NULL);
+ typename elfcpp::Sym<size, big_endian> lsym(plocal_syms
+ + r_sym * sym_size);
+ unsigned int shndx = lsym.get_st_shndx();
+ bool is_ordinary;
+ shndx = object->adjust_sym_shndx(r_sym, shndx, &is_ordinary);
+ if (!is_ordinary)
+ continue;
+ dst_obj = src_obj;
+ if (shndx == src_indx)
+ continue;
+ dst_indx = shndx;
+ }
+ else
+ {
+ Symbol* gsym = object->global_symbol(r_sym);
+ gold_assert(gsym != NULL);
+ if (gsym->is_forwarder())
+ gsym = symtab->resolve_forwards(gsym);
+ if (gsym->source() != Symbol::FROM_OBJECT)
+ continue;
+ bool is_ordinary;
+ dst_obj = gsym->object();
+ dst_indx = gsym->shndx(&is_ordinary);
+ if (!is_ordinary)
+ continue;
+ }
+ Section_id p1(src_obj, src_indx);
+ Section_id p2(dst_obj, dst_indx);
+ Garbage_collection::Section_ref::iterator map_it;
+ map_it = symtab->gc()->section_reloc_map().find(p1);
+ if (map_it == symtab->gc()->section_reloc_map().end())
+ {
+ symtab->gc()->section_reloc_map()[p1].insert(p2);
+ }
+ else
+ {
+ Garbage_collection::Sections_reachable& v(map_it->second);
+ v.insert(p2);
+ }
+ }
+ return;
+}
+
+} // End of namespace gold.
+
+#endif
// gold.cc -- main linker functions
-// 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.
this->layout_, workqueue, this->mapfile_);
}
+// This class arranges the tasks to process the relocs for garbage collection.
+
+class Gc_runner : public Task_function_runner
+{
+ public:
+ Gc_runner(const General_options& options,
+ const Input_objects* input_objects,
+ Symbol_table* symtab,
+ Layout* layout, Mapfile* mapfile)
+ : options_(options), input_objects_(input_objects), symtab_(symtab),
+ layout_(layout), mapfile_(mapfile)
+ { }
+
+ void
+ run(Workqueue*, const Task*);
+
+ private:
+ const General_options& options_;
+ const Input_objects* input_objects_;
+ Symbol_table* symtab_;
+ Layout* layout_;
+ Mapfile* mapfile_;
+};
+
+void
+Gc_runner::run(Workqueue* workqueue, const Task* task)
+{
+ queue_middle_gc_tasks(this->options_, task, this->input_objects_,
+ this->symtab_, this->layout_, workqueue,
+ this->mapfile_);
+}
+
// Queue up the initial set of tasks for this link job.
void
this_blocker = next_blocker;
}
+ if (parameters->options().relocatable()
+ && parameters->options().gc_sections())
+ gold_error(_("cannot mix -r with garbage collection"));
+
+ if (parameters->options().gc_sections())
+ {
+ workqueue->queue(new Task_function(new Gc_runner(options,
+ input_objects,
+ symtab,
+ layout,
+ mapfile),
+ this_blocker,
+ "Task_function Gc_runner"));
+ }
+ else
+ {
+ workqueue->queue(new Task_function(new Middle_runner(options,
+ input_objects,
+ symtab,
+ layout,
+ mapfile),
+ this_blocker,
+ "Task_function Middle_runner"));
+ }
+}
+
+// Queue up a set of tasks to be done before queueing the middle set
+// of tasks. This is only necessary when garbage collection
+// (--gc-sections) of unused sections is desired. The relocs are read
+// and processed here early to determine the garbage sections before the
+// relocs can be scanned in later tasks.
+
+void
+queue_middle_gc_tasks(const General_options& options,
+ const Task* ,
+ const Input_objects* input_objects,
+ Symbol_table* symtab,
+ Layout* layout,
+ Workqueue* workqueue,
+ Mapfile* mapfile)
+{
+ // Read_relocs for all the objects must be done and processed to find
+ // unused sections before any scanning of the relocs can take place.
+ Task_token* blocker = new Task_token(true);
+ Task_token* symtab_lock = new Task_token(false);
+ for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
+ p != input_objects->relobj_end();
+ ++p)
+ {
+ // We can read and process the relocations in any order.
+ blocker->add_blocker();
+ workqueue->queue(new Read_relocs(options, symtab, layout, *p,
+ symtab_lock, blocker));
+ }
+
+ Task_token* this_blocker = new Task_token(true);
workqueue->queue(new Task_function(new Middle_runner(options,
- input_objects,
- symtab,
- layout,
- mapfile),
- this_blocker,
- "Task_function Middle_runner"));
+ input_objects,
+ symtab,
+ layout,
+ mapfile),
+ this_blocker,
+ "Task_function Middle_runner"));
}
// Queue up the middle set of tasks. These are the tasks which run
Workqueue* workqueue,
Mapfile* mapfile)
{
+ // Add any symbols named with -u options to the symbol table.
+ symtab->add_undefined_symbols_from_command_line();
+
+ // If garbage collection was chosen, relocs have been read and processed
+ // at this point by pre_middle_tasks. Layout can then be done for all
+ // objects.
+ if (parameters->options().gc_sections())
+ {
+ // Find the start symbol if any.
+ Symbol* start_sym;
+ if (parameters->options().entry())
+ start_sym = symtab->lookup(parameters->options().entry());
+ else
+ start_sym = symtab->lookup("_start");
+ if (start_sym !=NULL)
+ {
+ bool is_ordinary;
+ unsigned int shndx = start_sym->shndx(&is_ordinary);
+ if (is_ordinary)
+ {
+ symtab->gc()->worklist().push(
+ Section_id(start_sym->object(), shndx));
+ }
+ }
+ // Symbols named with -u should not be considered garbage.
+ symtab->gc_mark_undef_symbols();
+ gold_assert(symtab->gc() != NULL);
+ // Do a transitive closure on all references to determine the worklist.
+ symtab->gc()->do_transitive_closure();
+ // Call do_layout again to determine the output_sections for all
+ // referenced input sections.
+ for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
+ p != input_objects->relobj_end();
+ ++p)
+ {
+ (*p)->layout(symtab, layout, NULL);
+ }
+ }
+ // Layout deferred objects due to plugins.
+ if (parameters->options().has_plugins())
+ {
+ Plugin_manager* plugins = parameters->options().plugins();
+ gold_assert(plugins != NULL);
+ plugins->layout_deferred_objects();
+ }
+ if (parameters->options().gc_sections())
+ {
+ for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
+ p != input_objects->relobj_end();
+ ++p)
+ {
+ // Update the value of output_section stored in rd.
+ Read_relocs_data *rd = (*p)->get_relocs_data();
+ for (Read_relocs_data::Relocs_list::iterator q = rd->relocs.begin();
+ q != rd->relocs.end();
+ ++q)
+ {
+ q->output_section = (*p)->output_section(q->data_shndx);
+ q->needs_special_offset_handling =
+ (*p)->is_output_section_offset_invalid(q->data_shndx);
+ }
+ }
+ }
+
// We have to support the case of not seeing any input objects, and
// generate an empty file. Existing builds depend on being able to
// pass an empty archive to the linker and get an empty object file
// Define symbols from any linker scripts.
layout->define_script_symbols(symtab);
- // Add any symbols named with -u options to the symbol table.
- symtab->add_undefined_symbols_from_command_line();
-
// Attach sections to segments.
layout->attach_sections_to_segments();
// Make sure we have symbols for any required group signatures.
layout->define_group_signatures(symtab);
- // Read the relocations of the input files. We do this to find
- // which symbols are used by relocations which require a GOT and/or
- // a PLT entry, or a COPY reloc. When we implement garbage
- // collection we will do it here by reading the relocations in a
- // breadth first search by references.
- //
- // We could also read the relocations during the first pass, and
- // mark symbols at that time. That is how the old GNU linker works.
- // Doing that is more complex, since we may later decide to discard
- // some of the sections, and thus change our minds about the types
- // of references made to the symbols.
Task_token* blocker = new Task_token(true);
Task_token* symtab_lock = new Task_token(false);
- for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
- p != input_objects->relobj_end();
- ++p)
+
+ // If doing garbage collection, the relocations have already been read.
+ // Otherwise, read and scan the relocations.
+ if (parameters->options().gc_sections())
{
- // We can read and process the relocations in any order. But we
- // only want one task to write to the symbol table at a time.
- // So we queue up a task for each object to read the
- // relocations. That task will in turn queue a task to wait
- // until it can write to the symbol table.
- blocker->add_blocker();
- workqueue->queue(new Read_relocs(options, symtab, layout, *p,
- symtab_lock, blocker));
+ for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
+ p != input_objects->relobj_end();
+ ++p)
+ {
+ blocker->add_blocker();
+ workqueue->queue(new Scan_relocs(options, symtab, layout, *p,
+ (*p)->get_relocs_data(),symtab_lock, blocker));
+ }
+ }
+ else
+ {
+ // Read the relocations of the input files. We do this to find
+ // which symbols are used by relocations which require a GOT and/or
+ // a PLT entry, or a COPY reloc. When we implement garbage
+ // collection we will do it here by reading the relocations in a
+ // breadth first search by references.
+ //
+ // We could also read the relocations during the first pass, and
+ // mark symbols at that time. That is how the old GNU linker works.
+ // Doing that is more complex, since we may later decide to discard
+ // some of the sections, and thus change our minds about the types
+ // of references made to the symbols.
+ for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
+ p != input_objects->relobj_end();
+ ++p)
+ {
+ // We can read and process the relocations in any order. But we
+ // only want one task to write to the symbol table at a time.
+ // So we queue up a task for each object to read the
+ // relocations. That task will in turn queue a task to wait
+ // until it can write to the symbol table.
+ blocker->add_blocker();
+ workqueue->queue(new Read_relocs(options, symtab, layout, *p,
+ symtab_lock, blocker));
+ }
}
// Allocate common symbols. This requires write access to the
// gold.h -- general definitions 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.
Layout*,
Mapfile*);
+// Queue up the set of tasks to be done before
+// the middle set of tasks. Only used when garbage
+// collection is to be done.
+extern void
+queue_middle_gc_tasks(const General_options&,
+ const Task*,
+ const Input_objects*,
+ Symbol_table*,
+ Layout*,
+ Workqueue*,
+ Mapfile*);
+
// Queue up the middle set of tasks.
extern void
queue_middle_tasks(const General_options&,
Workqueue*,
Output_file* of);
+inline bool
+is_prefix_of(const char* prefix, const char* str)
+{
+ return strncmp(prefix, str, strlen(prefix)) == 0;
+}
+
} // End namespace gold.
#endif // !defined(GOLD_GOLD_H)
// i386.cc -- i386 target support for gold.
-// 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.
got_mod_index_offset_(-1U), tls_base_symbol_defined_(false)
{ }
+ // Process the relocations to determine unreferenced sections for
+ // garbage collection.
+ void
+ gc_process_relocs(const General_options& options,
+ Symbol_table* symtab,
+ Layout* layout,
+ Sized_relobj<32, false>* 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);
+
// Scan the relocations to look for symbol adjustments.
void
scan_relocs(const General_options& options,
}
}
+// Process relocations for gc.
+
+void
+Target_i386::gc_process_relocs(const General_options& options,
+ Symbol_table* symtab,
+ Layout* layout,
+ Sized_relobj<32, false>* object,
+ unsigned int data_shndx,
+ unsigned int,
+ 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)
+{
+ gold::gc_process_relocs<32, false, Target_i386, elfcpp::SHT_REL,
+ Target_i386::Scan>(
+ options,
+ symtab,
+ layout,
+ this,
+ object,
+ data_shndx,
+ prelocs,
+ reloc_count,
+ output_section,
+ needs_special_offset_handling,
+ local_symbol_count,
+ plocal_symbols);
+}
+
// Scan relocations for a section.
void
// layout.cc -- lay out output file sections for gold
-// 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.
return k.first + k.second.first + k.second.second;
}
-// Return whether PREFIX is a prefix of STR.
-
-static inline bool
-is_prefix_of(const char* prefix, const char* str)
-{
- return strncmp(prefix, str, strlen(prefix)) == 0;
-}
-
// Returns whether the given section is in the list of
// debug-sections-used-by-some-version-of-gdb. Currently,
// we've checked versions of gdb up to and including 6.7.1.
// main.cc -- gold main function.
-// 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.
#include "symtab.h"
#include "layout.h"
#include "plugin.h"
+#include "gc.h"
using namespace gold;
// The list of input objects.
Input_objects input_objects;
+ // The Garbage Collection Object.
+ Garbage_collection gc;
+
// The symbol table. We're going to guess here how many symbols
// we're going to see based on the number of input files. Even when
// this is off, it means at worst we don't quite optimize hashtable
Symbol_table symtab(command_line.number_of_input_files() * 1024,
command_line.version_script());
+ if (parameters->options().gc_sections())
+ symtab.set_gc(&gc);
+
// The layout object.
Layout layout(command_line.options(), &command_line.script_options());
// object.cc -- support for an object file for linking in gold
-// 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.
#include "demangle.h"
#include "libiberty.h"
+#include "gc.h"
#include "target-select.h"
#include "dwarf_reader.h"
#include "layout.h"
return false;
}
+// Class Relobj
+
+// To copy the symbols data read from the file to a local data structure.
+// This function is called from do_layout only while doing garbage
+// collection.
+
+void
+Relobj::copy_symbols_data(Symbols_data* gc_sd, Read_symbols_data* sd,
+ unsigned int section_header_size)
+{
+ gc_sd->section_headers_data =
+ new unsigned char[(section_header_size)];
+ memcpy(gc_sd->section_headers_data, sd->section_headers->data(),
+ section_header_size);
+ gc_sd->section_names_data =
+ new unsigned char[sd->section_names_size];
+ memcpy(gc_sd->section_names_data, sd->section_names->data(),
+ sd->section_names_size);
+ gc_sd->section_names_size = sd->section_names_size;
+ if (sd->symbols != NULL)
+ {
+ gc_sd->symbols_data =
+ new unsigned char[sd->symbols_size];
+ memcpy(gc_sd->symbols_data, sd->symbols->data(),
+ sd->symbols_size);
+ }
+ else
+ {
+ gc_sd->symbols_data = NULL;
+ }
+ gc_sd->symbols_size = sd->symbols_size;
+ gc_sd->external_symbols_offset = sd->external_symbols_offset;
+ if (sd->symbol_names != NULL)
+ {
+ gc_sd->symbol_names_data =
+ new unsigned char[sd->symbol_names_size];
+ memcpy(gc_sd->symbol_names_data, sd->symbol_names->data(),
+ sd->symbol_names_size);
+ }
+ else
+ {
+ gc_sd->symbol_names_data = NULL;
+ }
+ gc_sd->symbol_names_size = sd->symbol_names_size;
+}
+
+// This function determines if a particular section name must be included
+// in the link. This is used during garbage collection to determine the
+// roots of the worklist.
+
+bool
+Relobj::is_section_name_included(const char* name)
+{
+ if (is_prefix_of(".ctors", name)
+ || is_prefix_of(".dtors", name)
+ || is_prefix_of(".note", name)
+ || is_prefix_of(".init", name)
+ || is_prefix_of(".fini", name)
+ || is_prefix_of(".gcc_except_table", name)
+ || is_prefix_of(".jcr", name)
+ || is_prefix_of(".preinit_array", name)
+ || (is_prefix_of(".text", name)
+ && strstr(name, "personality"))
+ || (is_prefix_of(".data", name)
+ && strstr(name, "personality"))
+ || (is_prefix_of(".gnu.linkonce.d", name) &&
+ strstr(name, "personality")))
+ {
+ return true;
+ }
+ return false;
+}
+
// Class Sized_relobj.
template<int size, bool big_endian>
// Lay out the input sections. We walk through the sections and check
// whether they should be included in the link. If they should, we
// pass them to the Layout object, which will return an output section
-// and an offset.
+// and an offset.
+// During garbage collection (gc-sections), this function is called
+// twice. When it is called the first time, it is for setting up some
+// sections as roots to a work-list and to do comdat processing. Actual
+// layout happens the second time around after all the relevant sections
+// have been determined. The first time, is_worklist_ready is false.
+// It is then set to true after the worklist is processed and the relevant
+// sections are determined. Then, this function is called again to
+// layout the sections.
template<int size, bool big_endian>
void
Read_symbols_data* sd)
{
const unsigned int shnum = this->shnum();
+ bool is_gc_pass_one = (parameters->options().gc_sections()
+ && !symtab->gc()->is_worklist_ready());
+ bool is_gc_pass_two = (parameters->options().gc_sections()
+ && symtab->gc()->is_worklist_ready());
if (shnum == 0)
return;
+ Symbols_data* gc_sd;
+ if (is_gc_pass_one)
+ {
+ // During garbage collection save the symbols data to use it when
+ // re-entering this function.
+ gc_sd = new Symbols_data;
+ this->copy_symbols_data(gc_sd, sd, This::shdr_size * shnum);
+ this->set_symbols_data(gc_sd);
+ }
+ else if (is_gc_pass_two)
+ {
+ gc_sd = this->get_symbols_data();
+ }
+
+ const unsigned char* section_headers_data = NULL;
+ section_size_type section_names_size;
+ const unsigned char* symbols_data = NULL;
+ section_size_type symbols_size;
+ section_offset_type external_symbols_offset;
+ const unsigned char* symbol_names_data = NULL;
+ section_size_type symbol_names_size;
+
+ if (parameters->options().gc_sections())
+ {
+ section_headers_data = gc_sd->section_headers_data;
+ section_names_size = gc_sd->section_names_size;
+ symbols_data = gc_sd->symbols_data;
+ symbols_size = gc_sd->symbols_size;
+ external_symbols_offset = gc_sd->external_symbols_offset;
+ symbol_names_data = gc_sd->symbol_names_data;
+ symbol_names_size = gc_sd->symbol_names_size;
+ }
+ else
+ {
+ section_headers_data = sd->section_headers->data();
+ section_names_size = sd->section_names_size;
+ if (sd->symbols != NULL)
+ symbols_data = sd->symbols->data();
+ symbols_size = sd->symbols_size;
+ external_symbols_offset = sd->external_symbols_offset;
+ if (sd->symbol_names != NULL)
+ symbol_names_data = sd->symbol_names->data();
+ symbol_names_size = sd->symbol_names_size;
+ }
// Get the section headers.
- const unsigned char* shdrs = sd->section_headers->data();
+ const unsigned char* shdrs = section_headers_data;
const unsigned char* pshdrs;
// Get the section names.
- const unsigned char* pnamesu = sd->section_names->data();
+ const unsigned char* pnamesu = parameters->options().gc_sections() ?
+ gc_sd->section_names_data :
+ sd->section_names->data();
const char* pnames = reinterpret_cast<const char*>(pnamesu);
// If any input files have been claimed by plugins, we need to defer
Output_sections& out_sections(this->output_sections());
std::vector<Address>& out_section_offsets(this->section_offsets_);
- out_sections.resize(shnum);
- out_section_offsets.resize(shnum);
+ if (!is_gc_pass_two)
+ {
+ out_sections.resize(shnum);
+ out_section_offsets.resize(shnum);
+ }
// If we are only linking for symbols, then there is nothing else to
// do here.
if (this->input_file()->just_symbols())
{
- delete sd->section_headers;
- sd->section_headers = NULL;
- delete sd->section_names;
- sd->section_names = NULL;
+ if (!is_gc_pass_two)
+ {
+ delete sd->section_headers;
+ sd->section_headers = NULL;
+ delete sd->section_names;
+ sd->section_names = NULL;
+ }
return;
}
{
typename This::Shdr shdr(pshdrs);
- if (shdr.get_sh_name() >= sd->section_names_size)
+ if (shdr.get_sh_name() >= section_names_size)
{
this->error(_("bad section name offset for section %u: %lu"),
i, static_cast<unsigned long>(shdr.get_sh_name()));
const char* name = pnames + shdr.get_sh_name();
- if (this->handle_gnu_warning_section(name, i, symtab))
- {
- if (!relocatable)
- omit[i] = true;
- }
+ if (!is_gc_pass_two)
+ {
+ if (this->handle_gnu_warning_section(name, i, symtab))
+ {
+ if (!relocatable)
+ omit[i] = true;
+ }
- // The .note.GNU-stack section is special. It gives the
- // protection flags that this object file requires for the stack
- // in memory.
- if (strcmp(name, ".note.GNU-stack") == 0)
- {
- seen_gnu_stack = true;
- gnu_stack_flags |= shdr.get_sh_flags();
- omit[i] = true;
- }
+ // The .note.GNU-stack section is special. It gives the
+ // protection flags that this object file requires for the stack
+ // in memory.
+ if (strcmp(name, ".note.GNU-stack") == 0)
+ {
+ seen_gnu_stack = true;
+ gnu_stack_flags |= shdr.get_sh_flags();
+ omit[i] = true;
+ }
- bool discard = omit[i];
- if (!discard)
- {
- if (shdr.get_sh_type() == elfcpp::SHT_GROUP)
- {
- if (!this->include_section_group(symtab, layout, i, name, shdrs,
- pnames, sd->section_names_size,
- &omit))
- discard = true;
- }
- else if ((shdr.get_sh_flags() & elfcpp::SHF_GROUP) == 0
- && Layout::is_linkonce(name))
- {
- if (!this->include_linkonce_section(layout, i, name, shdr))
- discard = true;
+ bool discard = omit[i];
+ if (!discard)
+ {
+ if (shdr.get_sh_type() == elfcpp::SHT_GROUP)
+ {
+ if (!this->include_section_group(symtab, layout, i, name,
+ shdrs, pnames,
+ section_names_size,
+ &omit))
+ discard = true;
+ }
+ else if ((shdr.get_sh_flags() & elfcpp::SHF_GROUP) == 0
+ && Layout::is_linkonce(name))
+ {
+ if (!this->include_linkonce_section(layout, i, name, shdr))
+ discard = true;
+ }
}
- }
- if (discard)
- {
- // Do not include this section in the link.
- out_sections[i] = NULL;
- out_section_offsets[i] = invalid_address;
- continue;
- }
+ if (discard)
+ {
+ // Do not include this section in the link.
+ out_sections[i] = NULL;
+ out_section_offsets[i] = invalid_address;
+ continue;
+ }
+ }
+
+ if (is_gc_pass_one)
+ {
+ if (is_section_name_included(name)
+ || shdr.get_sh_type() == elfcpp::SHT_INIT_ARRAY
+ || shdr.get_sh_type() == elfcpp::SHT_FINI_ARRAY)
+ {
+ symtab->gc()->worklist().push(Section_id(this, i));
+ }
+ }
// When doing a relocatable link we are going to copy input
// reloc sections into the output. We only want to copy the
// ones associated with sections which are not being discarded.
// However, we don't know that yet for all sections. So save
- // reloc sections and process them later.
+ // reloc sections and process them later. Garbage collection is
+ // not triggered when relocatable code is desired.
if (emit_relocs
&& (shdr.get_sh_type() == elfcpp::SHT_REL
|| shdr.get_sh_type() == elfcpp::SHT_RELA))
// determine which sections are being discarded, and discard the
// corresponding information.
if (!relocatable
- && strcmp(name, ".eh_frame") == 0
- && this->check_eh_frame_flags(&shdr))
- {
- eh_frame_sections.push_back(i);
- continue;
- }
+ && strcmp(name, ".eh_frame") == 0
+ && this->check_eh_frame_flags(&shdr))
+ {
+ if (is_gc_pass_one)
+ {
+ out_sections[i] = reinterpret_cast<Output_section*>(1);
+ out_section_offsets[i] = invalid_address;
+ }
+ else
+ eh_frame_sections.push_back(i);
+ continue;
+ }
+ if (is_gc_pass_two)
+ {
+ // This is executed during the second pass of garbage
+ // collection. do_layout has been called before and some
+ // sections have been already discarded. Simply ignore
+ // such sections this time around.
+ if (out_sections[i] == NULL)
+ {
+ gold_assert(out_section_offsets[i] == invalid_address);
+ continue;
+ }
+ if ((shdr.get_sh_flags() & elfcpp::SHF_ALLOC) != 0)
+ if (symtab->gc()->referenced_list().find(Section_id(this,i))
+ == symtab->gc()->referenced_list().end())
+ {
+ if (parameters->options().print_gc_sections())
+ gold_info(_("%s: Removing unused section from '%s'"
+ " in file '%s"),
+ program_name, this->section_name(i).c_str(),
+ this->name().c_str());
+ out_sections[i] = NULL;
+ out_section_offsets[i] = invalid_address;
+ continue;
+ }
+ }
+ // Defer layout here if input files are claimed by plugins. When gc
+ // is turned on this function is called twice. For the second call
+ // should_defer_layout should be false.
if (should_defer_layout && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC))
{
- this->deferred_layout_.push_back(Deferred_layout(i, name, pshdrs,
+ gold_assert(!is_gc_pass_two);
+ this->deferred_layout_.push_back(Deferred_layout(i, name,
+ pshdrs,
reloc_shndx[i],
reloc_type[i]));
-
// Put dummy values here; real values will be supplied by
// do_layout_deferred_sections.
+ out_sections[i] = reinterpret_cast<Output_section*>(2);
+ out_section_offsets[i] = invalid_address;
+ continue;
+ }
+ // During gc_pass_two if a section that was previously deferred is
+ // found, do not layout the section as layout_deferred_sections will
+ // do it later from gold.cc.
+ if (is_gc_pass_two
+ && (out_sections[i] == reinterpret_cast<Output_section*>(2)))
+ continue;
+
+ if (is_gc_pass_one)
+ {
+ // This is during garbage collection. The out_sections are
+ // assigned in the second call to this function.
out_sections[i] = reinterpret_cast<Output_section*>(1);
out_section_offsets[i] = invalid_address;
}
else
{
+ // When garbage collection is switched on the actual layout
+ // only happens in the second call.
this->layout_section(layout, i, name, shdr, reloc_shndx[i],
reloc_type[i]);
}
}
- layout->layout_gnu_stack(seen_gnu_stack, gnu_stack_flags);
+ if (!is_gc_pass_one)
+ layout->layout_gnu_stack(seen_gnu_stack, gnu_stack_flags);
// When doing a relocatable link handle the reloc sections at the
- // end.
+ // end. Garbage collection is not turned on for relocatable code.
if (emit_relocs)
this->size_relocatable_relocs();
+ gold_assert(!parameters->options().gc_sections() || reloc_sections.empty());
for (std::vector<unsigned int>::const_iterator p = reloc_sections.begin();
p != reloc_sections.end();
++p)
{
unsigned int i = *p;
const unsigned char* pshdr;
- pshdr = sd->section_headers->data() + i * This::shdr_size;
+ pshdr = section_headers_data + i * This::shdr_size;
typename This::Shdr shdr(pshdr);
unsigned int data_shndx = this->adjust_shndx(shdr.get_sh_info());
}
// Handle the .eh_frame sections at the end.
+ gold_assert(!is_gc_pass_one || eh_frame_sections.empty());
for (std::vector<unsigned int>::const_iterator p = eh_frame_sections.begin();
p != eh_frame_sections.end();
++p)
{
gold_assert(this->has_eh_frame_);
- gold_assert(sd->external_symbols_offset != 0);
+ gold_assert(external_symbols_offset != 0);
unsigned int i = *p;
const unsigned char *pshdr;
- pshdr = sd->section_headers->data() + i * This::shdr_size;
+ pshdr = section_headers_data + i * This::shdr_size;
typename This::Shdr shdr(pshdr);
off_t offset;
Output_section* os = layout->layout_eh_frame(this,
- sd->symbols->data(),
- sd->symbols_size,
- sd->symbol_names->data(),
- sd->symbol_names_size,
+ symbols_data,
+ symbols_size,
+ symbol_names_data,
+ symbol_names_size,
i, shdr,
reloc_shndx[i],
reloc_type[i],
this->set_relocs_must_follow_section_writes();
}
- delete sd->section_headers;
- sd->section_headers = NULL;
- delete sd->section_names;
- sd->section_names = NULL;
+ if (is_gc_pass_two)
+ {
+ delete[] gc_sd->section_headers_data;
+ delete[] gc_sd->section_names_data;
+ delete[] gc_sd->symbols_data;
+ delete[] gc_sd->symbol_names_data;
+ }
+ else
+ {
+ delete sd->section_headers;
+ sd->section_headers = NULL;
+ delete sd->section_names;
+ sd->section_names = NULL;
+ }
}
// Layout sections whose layout was deferred while waiting for
// object.h -- support for an object file for linking in 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.
class Dynobj;
class Object_merge_map;
class Relocatable_relocs;
+class Symbols_data;
template<typename Stringpool_char>
class Stringpool_template;
relocs_must_follow_section_writes_(false)
{ }
+ // During garbage collection, the Read_symbols_data pass for
+ // each object is stored as layout needs to be done after
+ // reloc processing.
+ Symbols_data*
+ get_symbols_data()
+ { return this->sd_; }
+
+ // Decides which section names have to be included in the worklist
+ // as roots.
+ bool
+ is_section_name_included(const char *name);
+
+ void
+ copy_symbols_data(Symbols_data* gc_sd, Read_symbols_data* sd,
+ unsigned int section_header_size);
+
+ void
+ set_symbols_data(Symbols_data* sd)
+ { this->sd_ = sd; }
+
+ // During garbage collection, the Read_relocs pass for all objects
+ // is done before scanning the relocs. In that case, this->rd_ is
+ // used to store the information from Read_relocs for each object.
+ // This data is also used to compute the list of relevant sections.
+ Read_relocs_data*
+ get_relocs_data()
+ { return this->rd_; }
+
+ void
+ set_relocs_data(Read_relocs_data* rd)
+ { this->rd_ = rd; }
+
+ virtual bool
+ is_output_section_offset_invalid(unsigned int shndx) const = 0;
+
// Read the relocs.
void
read_relocs(Read_relocs_data* rd)
{ return this->do_read_relocs(rd); }
+ // Process the relocs, during garbage collection only.
+ void
+ gc_process_relocs(const General_options& options, Symbol_table* symtab,
+ Layout* layout, Read_relocs_data* rd)
+ { return this->do_gc_process_relocs(options, symtab, layout, rd); }
+
// Scan the relocs and adjust the symbol table.
void
scan_relocs(const General_options& options, Symbol_table* symtab,
virtual void
do_read_relocs(Read_relocs_data*) = 0;
+ // Process the relocs--implemented by child class.
+ virtual void
+ do_gc_process_relocs(const General_options&, Symbol_table*, Layout*,
+ Read_relocs_data*) = 0;
+
// Scan the relocs--implemented by child class.
virtual void
do_scan_relocs(const General_options&, Symbol_table*, Layout*,
// Whether we need to wait for output sections to be written before
// we can apply relocations.
bool relocs_must_follow_section_writes_;
+ // Used to store the relocs data computed by the Read_relocs pass.
+ // Used during garbage collection of unused sections.
+ Read_relocs_data* rd_;
+ // Used to store the symbols data computed by the Read_symbols pass.
+ // Again used during garbage collection when laying out referenced
+ // sections.
+ gold::Symbols_data *sd_;
};
// This class is used to handle relocations against a section symbol
~Sized_relobj();
+ // Checks if the offset of input section SHNDX within its output
+ // section is invalid.
+ bool
+ is_output_section_offset_invalid(unsigned int shndx) const
+ { return this->get_output_section_offset(shndx) == invalid_address; }
+
// Set up the object file based on the ELF header.
void
setup(const typename elfcpp::Ehdr<size, big_endian>&);
void
do_read_relocs(Read_relocs_data*);
+ // Process the relocs to find list of referenced sections. Used only
+ // during garbage collection.
+ void
+ do_gc_process_relocs(const General_options&, Symbol_table*, Layout*,
+ Read_relocs_data*);
+
// Scan the relocs and adjust the symbol table.
void
do_scan_relocs(const General_options&, Symbol_table*, Layout*,
// options.h -- handle command line options 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.
N_("Check segment addresses for overlaps (default)"),
N_("Do not check segment addresses for overlaps"));
- DEFINE_bool(gc_sections, options::TWO_DASHES, '\0', true,
- N_("(noop) Garbage collect sections"),
- N_("(noop) Do not garbage collect sections"));
-
#ifdef HAVE_ZLIB_H
DEFINE_enum(compress_debug_sections, options::TWO_DASHES, '\0', "none",
N_("Compress .debug_* sections in the output file"),
DEFINE_special(static, options::ONE_DASH, '\0',
N_("Do not link against shared libraries"), NULL);
+ DEFINE_bool(gc_sections, options::TWO_DASHES, '\0', false,
+ N_("Remove unused sections"),
+ N_("Don't remove unused sections (default)"));
+
+ DEFINE_bool(print_gc_sections, options::TWO_DASHES, '\0', false,
+ N_("List removed unused sections on stderr"),
+ N_("Do not list removed unused sections"));
+
DEFINE_bool(stats, options::TWO_DASHES, '\0', false,
N_("Print resource usage statistics"), NULL);
-// plugin.c -- plugin manager for gold -*- C++ -*-
+// plugin.cc -- plugin manager for gold -*- C++ -*-
// Copyright 2008, 2009 Free Software Foundation, Inc.
// Written by Cary Coutant <ccoutant@google.com>.
}
// Class Plugin_finish. This task runs after all replacement files have
-// been added. It calls Layout::layout for any deferred sections and
-// calls each plugin's cleanup handler.
+// been added. It calls each plugin's cleanup handler.
class Plugin_finish : public Task
{
{
Plugin_manager* plugins = parameters->options().plugins();
gold_assert(plugins != NULL);
- plugins->layout_deferred_objects();
plugins->cleanup();
}
// powerpc.cc -- powerpc target support for gold.
-// Copyright 2008 Free Software Foundation, Inc.
+// Copyright 2008, 2009 Free Software Foundation, Inc.
// Written by David S. Miller <davem@davemloft.net>
// and David Edelsohn <edelsohn@gnu.org>
{
}
+ // Process the relocations to determine unreferenced sections for
+ // garbage collection.
+ 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);
+
// Scan the relocations to look for symbol adjustments.
void
scan_relocs(const General_options& options,
}
}
+// Process relocations for gc.
+
+template<int size, bool big_endian>
+void
+Target_powerpc<size, big_endian>::gc_process_relocs(
+ const General_options& options,
+ Symbol_table* symtab,
+ Layout* layout,
+ Sized_relobj<size, big_endian>* object,
+ unsigned int data_shndx,
+ unsigned int,
+ 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)
+{
+ typedef Target_powerpc<size, big_endian> Powerpc;
+ typedef typename Target_powerpc<size, big_endian>::Scan Scan;
+
+ gold::gc_process_relocs<size, big_endian, Powerpc, elfcpp::SHT_RELA, Scan>(
+ options,
+ symtab,
+ layout,
+ this,
+ object,
+ data_shndx,
+ prelocs,
+ reloc_count,
+ output_section,
+ needs_special_offset_handling,
+ local_symbol_count,
+ plocal_symbols);
+}
+
// Scan relocations for a section.
template<int size, bool big_endian>
// reloc.cc -- relocate input files for gold.
-// 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.
{
Read_relocs_data *rd = new Read_relocs_data;
this->object_->read_relocs(rd);
+ this->object_->set_relocs_data(rd);
this->object_->release();
- workqueue->queue_next(new Scan_relocs(this->options_, this->symtab_,
- this->layout_, this->object_, rd,
- this->symtab_lock_, this->blocker_));
+ // If garbage collection is desired, we must process the relocs
+ // instead of scanning the relocs as reloc processing is necessary
+ // to determine unused sections.
+ if (parameters->options().gc_sections())
+ {
+ workqueue->queue_next(new Gc_process_relocs(this->options_,
+ this->symtab_,
+ this->layout_,
+ this->object_, rd,
+ this->symtab_lock_,
+ this->blocker_));
+ }
+ else
+ {
+ workqueue->queue_next(new Scan_relocs(this->options_, this->symtab_,
+ this->layout_, this->object_, rd,
+ this->symtab_lock_,
+ this->blocker_));
+ }
}
// Return a debugging name for the task.
return "Read_relocs " + this->object_->name();
}
+// Gc_process_relocs methods.
+
+// These tasks process the relocations read by Read_relocs and
+// determine which sections are referenced and which are garbage.
+// This task is done only when --gc-sections is used.
+
+Task_token*
+Gc_process_relocs::is_runnable()
+{
+ if (this->object_->is_locked())
+ return this->object_->token();
+ return NULL;
+}
+
+void
+Gc_process_relocs::locks(Task_locker* tl)
+{
+ tl->add(this, this->object_->token());
+ tl->add(this, this->blocker_);
+}
+
+void
+Gc_process_relocs::run(Workqueue*)
+{
+ this->object_->gc_process_relocs(this->options_, this->symtab_, this->layout_,
+ this->rd_);
+ this->object_->release();
+}
+
+// Return a debugging name for the task.
+
+std::string
+Gc_process_relocs::get_name() const
+{
+ return "Gc_process_relocs " + this->object_->name();
+}
+
// Scan_relocs methods.
// These tasks scan the relocations read by Read_relocs and mark up
}
}
+// Process the relocs to generate mappings from source sections to referenced
+// sections. This is used during garbage colletion to determine garbage
+// sections.
+
+template<int size, bool big_endian>
+void
+Sized_relobj<size, big_endian>::do_gc_process_relocs(const General_options& options,
+ Symbol_table* symtab,
+ Layout* layout,
+ Read_relocs_data* rd)
+{
+ Sized_target<size, big_endian>* target = this->sized_target();
+
+ const unsigned char* local_symbols;
+ if (rd->local_symbols == NULL)
+ local_symbols = NULL;
+ else
+ local_symbols = rd->local_symbols->data();
+
+ for (Read_relocs_data::Relocs_list::iterator p = rd->relocs.begin();
+ p != rd->relocs.end();
+ ++p)
+ {
+ if (!parameters->options().relocatable())
+ {
+ // As noted above, when not generating an object file, we
+ // only scan allocated sections. We may see a non-allocated
+ // section here if we are emitting relocs.
+ if (p->is_data_section_allocated)
+ target->gc_process_relocs(options, symtab, layout, this,
+ p->data_shndx, p->sh_type,
+ p->contents->data(), p->reloc_count,
+ p->output_section,
+ p->needs_special_offset_handling,
+ this->local_symbol_count_,
+ local_symbols);
+ }
+ }
+}
+
+
// Scan the relocs and adjust the symbol table. This looks for
// relocations which require GOT/PLT/COPY relocations.
p != rd->relocs.end();
++p)
{
+ // When garbage collection is on, unreferenced sections are not included
+ // in the link that would have been included normally. This is known only
+ // after Read_relocs hence this check has to be done again.
+ if (parameters->options().gc_sections())
+ {
+ if (p->output_section == NULL)
+ continue;
+ }
if (!parameters->options().relocatable())
{
// As noted above, when not generating an object file, we
#ifdef HAVE_TARGET_32_LITTLE
template
void
+Sized_relobj<32, false>::do_gc_process_relocs(const General_options& options,
+ Symbol_table* symtab,
+ Layout* layout,
+ Read_relocs_data* rd);
+#endif
+
+#ifdef HAVE_TARGET_32_BIG
+template
+void
+Sized_relobj<32, true>::do_gc_process_relocs(const General_options& options,
+ Symbol_table* symtab,
+ Layout* layout,
+ Read_relocs_data* rd);
+#endif
+
+#ifdef HAVE_TARGET_64_LITTLE
+template
+void
+Sized_relobj<64, false>::do_gc_process_relocs(const General_options& options,
+ Symbol_table* symtab,
+ Layout* layout,
+ Read_relocs_data* rd);
+#endif
+
+#ifdef HAVE_TARGET_64_BIG
+template
+void
+Sized_relobj<64, true>::do_gc_process_relocs(const General_options& options,
+ Symbol_table* symtab,
+ Layout* layout,
+ Read_relocs_data* rd);
+#endif
+
+#ifdef HAVE_TARGET_32_LITTLE
+template
+void
Sized_relobj<32, false>::do_scan_relocs(const General_options& options,
Symbol_table* symtab,
Layout* layout,
// reloc.h -- relocate input files 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.
Task_token* blocker_;
};
+// Process the relocs to figure out which sections are garbage.
+// Very similar to scan relocs.
+
+class Gc_process_relocs : public Task
+{
+ public:
+ // SYMTAB_LOCK is used to lock the symbol table. BLOCKER should be
+ // unblocked when the task completes.
+ Gc_process_relocs(const General_options& options, Symbol_table* symtab,
+ Layout* layout, Relobj* object, Read_relocs_data* rd,
+ Task_token* symtab_lock, Task_token* blocker)
+ : options_(options), symtab_(symtab), layout_(layout), object_(object),
+ rd_(rd), symtab_lock_(symtab_lock), blocker_(blocker)
+ { }
+
+ // The standard Task methods.
+
+ Task_token*
+ is_runnable();
+
+ void
+ locks(Task_locker*);
+
+ void
+ run(Workqueue*);
+
+ std::string
+ get_name() const;
+
+ private:
+ const General_options& options_;
+ Symbol_table* symtab_;
+ Layout* layout_;
+ Relobj* object_;
+ Read_relocs_data* rd_;
+ Task_token* symtab_lock_;
+ Task_token* blocker_;
+};
+
// Scan the relocations for an object to see if they require any
// GOT/PLT/COPY relocations.
// sparc.cc -- sparc target support for gold.
-// Copyright 2008 Free Software Foundation, Inc.
+// Copyright 2008, 2009 Free Software Foundation, Inc.
// Written by David S. Miller <davem@davemloft.net>.
// This file is part of gold.
{
}
+ // Process the relocations to determine unreferenced sections for
+ // garbage collection.
+ 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);
+
// Scan the relocations to look for symbol adjustments.
void
scan_relocs(const General_options& options,
}
}
+// Process relocations for gc.
+
+template<int size, bool big_endian>
+void
+Target_sparc<size, big_endian>::gc_process_relocs(
+ const General_options& options,
+ Symbol_table* symtab,
+ Layout* layout,
+ Sized_relobj<size, big_endian>* object,
+ unsigned int data_shndx,
+ unsigned int,
+ 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)
+{
+ typedef Target_sparc<size, big_endian> Sparc;
+ typedef typename Target_sparc<size, big_endian>::Scan Scan;
+
+ gold::gc_process_relocs<size, big_endian, Sparc, elfcpp::SHT_RELA, Scan>(
+ options,
+ symtab,
+ layout,
+ this,
+ object,
+ data_shndx,
+ prelocs,
+ reloc_count,
+ output_section,
+ needs_special_offset_handling,
+ local_symbol_count,
+ plocal_symbols);
+}
+
// Scan relocations for a section.
template<int size, bool big_endian>
// symtab.cc -- the gold symbol table
-// 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.
#include <utility>
#include "demangle.h"
+#include "gc.h"
#include "object.h"
#include "dwarf_reader.h"
#include "dynobj.h"
if (this->needs_dynsym_entry())
return true;
+ // If this symbol's section is not added, the symbol need not be added.
+ // The section may have been GCed. Note that export_dynamic is being
+ // overridden here. This should not be done for shared objects.
+ if (parameters->options().gc_sections()
+ && !parameters->options().shared()
+ && this->source() == Symbol::FROM_OBJECT
+ && !this->object()->is_dynamic())
+ {
+ Relobj* relobj = static_cast<Relobj*>(this->object());
+ bool is_ordinary;
+ unsigned int shndx = this->shndx(&is_ordinary);
+ if (is_ordinary && shndx != elfcpp::SHN_UNDEF
+ && !relobj->is_section_included(shndx))
+ return false;
+ }
+
// If the symbol was forced local in a version script, do not add it.
if (this->is_forced_local())
return false;
const Version_script_info& version_script)
: saw_undefined_(0), offset_(0), table_(count), namepool_(),
forwarders_(), commons_(), tls_commons_(), forced_locals_(), warnings_(),
- version_script_(version_script)
+ version_script_(version_script), gc_(NULL)
{
namepool_.reserve(count);
}
return k1.first == k2.first && k1.second == k2.second;
}
+// For symbols that have been listed with -u option, add them to the
+// work list to avoid gc'ing them.
+
+void
+Symbol_table::gc_mark_undef_symbols()
+{
+ for (options::String_set::const_iterator p =
+ parameters->options().undefined_begin();
+ p != parameters->options().undefined_end();
+ ++p)
+ {
+ const char* name = p->c_str();
+ Symbol* sym = this->lookup(name);
+ gold_assert (sym != NULL);
+ if (sym->source() == Symbol::FROM_OBJECT
+ && !sym->object()->is_dynamic())
+ {
+ Relobj* obj = static_cast<Relobj*>(sym->object());
+ bool is_ordinary;
+ unsigned int shndx = sym->shndx(&is_ordinary);
+ if (is_ordinary)
+ {
+ gold_assert(this->gc_ != NULL);
+ this->gc_->worklist().push(Section_id(obj, shndx));
+ }
+ }
+ }
+}
+
+void
+Symbol_table::gc_mark_symbol_for_shlib(Symbol* sym)
+{
+ if (!sym->is_from_dynobj()
+ && sym->is_externally_visible())
+ {
+ //Add the object and section to the work list.
+ Relobj* obj = static_cast<Relobj*>(sym->object());
+ bool is_ordinary;
+ unsigned int shndx = sym->shndx(&is_ordinary);
+ if (is_ordinary && shndx != elfcpp::SHN_UNDEF)
+ {
+ gold_assert(this->gc_!= NULL);
+ this->gc_->worklist().push(Section_id(obj, shndx));
+ }
+ }
+}
+
+// When doing garbage collection, keep symbols that have been seen in
+// dynamic objects.
+inline void
+Symbol_table::gc_mark_dyn_syms(Symbol* sym)
+{
+ if (sym->in_dyn() && sym->source() == Symbol::FROM_OBJECT
+ && !sym->object()->is_dynamic())
+ {
+ Relobj *obj = static_cast<Relobj*>(sym->object());
+ bool is_ordinary;
+ unsigned int shndx = sym->shndx(&is_ordinary);
+ if (is_ordinary && shndx != elfcpp::SHN_UNDEF)
+ {
+ gold_assert(this->gc_ != NULL);
+ this->gc_->worklist().push(Section_id(obj, shndx));
+ }
+ }
+}
+
// Make TO a symbol which forwards to FROM.
void
to->set_in_reg();
if (from->in_dyn())
to->set_in_dyn();
+ if (parameters->options().gc_sections())
+ this->gc_mark_dyn_syms(to);
}
// Record that a symbol is forced to be local by a version script.
this->resolve(ret, sym, st_shndx, is_ordinary, orig_st_shndx, object,
version);
+ if (parameters->options().gc_sections())
+ this->gc_mark_dyn_syms(ret);
if (def)
{
this->resolve(ret, sym, st_shndx, is_ordinary, orig_st_shndx, object,
version);
+ if (parameters->options().gc_sections())
+ this->gc_mark_dyn_syms(ret);
ins.first->second = ret;
}
else
res = this->add_from_object(relobj, name, name_key, ver, ver_key,
def, *psym, st_shndx, is_ordinary,
orig_st_shndx);
+
+ // If building a shared library using garbage collection, do not
+ // treat externally visible symbols as garbage.
+ if (parameters->options().gc_sections()
+ && parameters->options().shared())
+ this->gc_mark_symbol_for_shlib(res);
if (local)
this->force_local(res);
if (os == NULL)
{
sym->set_symtab_index(-1U);
- gold_assert(sym->dynsym_index() == -1U);
+ bool static_or_reloc = (parameters->doing_static_link() ||
+ parameters->options().relocatable());
+ gold_assert(static_or_reloc || sym->dynsym_index() == -1U);
+
return false;
}
#include <utility>
#include <vector>
+#include "gc.h"
#include "elfcpp.h"
#include "parameters.h"
#include "stringpool.h"
class Output_segment;
class Output_file;
class Output_symtab_xindex;
+class Garbage_collection;
// The base class of an entry in the symbol table. The symbol table
// can have a lot of entries, so we don't want this class to big.
~Symbol_table();
+ void
+ set_gc(Garbage_collection* gc)
+ { this->gc_ = gc; }
+
+ Garbage_collection*
+ gc()
+ { return this->gc_; }
+
+ // During garbage collection, this keeps undefined symbols.
+ void
+ gc_mark_undef_symbols();
+
+ // During garbage collection, this ensures externally visible symbols
+ // are not treated as garbage while building shared objects.
+ void
+ gc_mark_symbol_for_shlib(Symbol* sym);
+
+ // During garbage collection, this keeps sections that correspond to
+ // symbols seen in dynamic objects.
+ inline void
+ gc_mark_dyn_syms(Symbol* sym);
+
// Add COUNT external symbols from the relocatable object RELOBJ to
// the symbol table. SYMS is the symbols, SYMNDX_OFFSET is the
// offset in the symbol table of the first symbol, SYM_NAMES is
Copied_symbol_dynobjs copied_symbol_dynobjs_;
// Information parsed from the version script, if any.
const Version_script_info& version_script_;
+ Garbage_collection* gc_;
};
// We inline get_sized_symbol for efficiency.
// 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.
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
// testfile.cc -- Dummy ELF objects for testing purposes.
-// 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.
{ }
void
+ gc_process_relocs(const General_options&, Symbol_table*, Layout*,
+ Sized_relobj<size, big_endian>*, unsigned int,
+ unsigned int, const unsigned char*, size_t, Output_section*,
+ bool, size_t, const unsigned char*)
+ { ERROR("call to Target_test::gc_process_relocs"); }
+
+ void
scan_relocs(const General_options&, Symbol_table*, Layout*,
Sized_relobj<size, big_endian>*, unsigned int,
unsigned int, const unsigned char*, size_t, Output_section*,
// x86_64.cc -- x86_64 target support for gold.
-// 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.
// Scan the relocations to look for symbol adjustments.
void
+ gc_process_relocs(const General_options& options,
+ Symbol_table* symtab,
+ Layout* layout,
+ Sized_relobj<64, false>* 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);
+
+ // Scan the relocations to look for symbol adjustments.
+ void
scan_relocs(const General_options& options,
Symbol_table* symtab,
Layout* layout,
}
}
+void
+Target_x86_64::gc_process_relocs(const General_options& options,
+ Symbol_table* symtab,
+ Layout* layout,
+ Sized_relobj<64, false>* 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)
+{
+
+ if (sh_type == elfcpp::SHT_REL)
+ {
+ return;
+ }
+
+ gold::gc_process_relocs<64, false, Target_x86_64, elfcpp::SHT_RELA,
+ Target_x86_64::Scan>(
+ options,
+ symtab,
+ layout,
+ this,
+ object,
+ data_shndx,
+ prelocs,
+ reloc_count,
+ output_section,
+ needs_special_offset_handling,
+ local_symbol_count,
+ plocal_symbols);
+
+}
// Scan relocations for a section.
void
projects / external / binutils.git / commitdiff