diff options
Diffstat (limited to 'gold/gold.cc')
| -rw-r--r-- | gold/gold.cc | 230 |
1 files changed, 198 insertions, 32 deletions
diff --git a/gold/gold.cc b/gold/gold.cc index 8d86a1b..818a346 100644 --- a/gold/gold.cc +++ b/gold/gold.cc @@ -1,6 +1,6 @@ // 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. @@ -122,6 +122,38 @@ Middle_runner::run(Workqueue* workqueue, const Task* task) 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 @@ -166,13 +198,69 @@ queue_initial_tasks(const General_options& options, 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 @@ -188,6 +276,70 @@ queue_middle_tasks(const General_options& options, 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 @@ -240,9 +392,6 @@ queue_middle_tasks(const General_options& options, // 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(); @@ -259,31 +408,48 @@ queue_middle_tasks(const General_options& options, // 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 |