// common.cc -- handle common symbols for gold // Copyright 2006, 2007, 2008 Free Software Foundation, Inc. // Written by Ian Lance Taylor <iant@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 <algorithm> #include "workqueue.h" #include "layout.h" #include "output.h" #include "symtab.h" #include "common.h" namespace gold { // Allocate_commons_task methods. // This task allocates the common symbols. We need a lock on the // symbol table. Task_token* Allocate_commons_task::is_runnable() { if (!this->symtab_lock_->is_writable()) return this->symtab_lock_; return NULL; } // Return the locks we hold: one on the symbol table, and one blocker. void Allocate_commons_task::locks(Task_locker* tl) { tl->add(this, this->blocker_); tl->add(this, this->symtab_lock_); } // Allocate the common symbols. void Allocate_commons_task::run(Workqueue*) { this->symtab_->allocate_commons(this->layout_); } // This class is used to sort the common symbol by size. We put the // larger common symbols first. template<int size> class Sort_commons { public: Sort_commons(const Symbol_table* symtab) : symtab_(symtab) { } bool operator()(const Symbol* a, const Symbol* b) const; private: const Symbol_table* symtab_; }; template<int size> bool Sort_commons<size>::operator()(const Symbol* pa, const Symbol* pb) const { if (pa == NULL) return false; if (pb == NULL) return true; const Symbol_table* symtab = this->symtab_; const Sized_symbol<size>* psa = symtab->get_sized_symbol<size>(pa); const Sized_symbol<size>* psb = symtab->get_sized_symbol<size>(pb); // Sort by largest size first. typename Sized_symbol<size>::Size_type sa = psa->symsize(); typename Sized_symbol<size>::Size_type sb = psb->symsize(); if (sa < sb) return false; else if (sb < sa) return true; // When the symbols are the same size, we sort them by alignment, // largest alignment first. typename Sized_symbol<size>::Value_type va = psa->value(); typename Sized_symbol<size>::Value_type vb = psb->value(); if (va < vb) return false; else if (vb < va) return true; // Otherwise we stabilize the sort by sorting by name. return strcmp(psa->name(), psb->name()) < 0; } // Allocate the common symbols. void Symbol_table::allocate_commons(Layout* layout) { if (parameters->target().get_size() == 32) { #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG) this->do_allocate_commons<32>(layout); #else gold_unreachable(); #endif } else if (parameters->target().get_size() == 64) { #if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG) this->do_allocate_commons<64>(layout); #else gold_unreachable(); #endif } else gold_unreachable(); } // Allocated the common symbols, sized version. template<int size> void Symbol_table::do_allocate_commons(Layout* layout) { this->do_allocate_commons_list<size>(layout, false, &this->commons_); this->do_allocate_commons_list<size>(layout, true, &this->tls_commons_); } // Allocate the common symbols in a list. IS_TLS indicates whether // these are TLS common symbols. template<int size> void Symbol_table::do_allocate_commons_list(Layout* layout, bool is_tls, Commons_type* commons) { typedef typename Sized_symbol<size>::Value_type Value_type; typedef typename Sized_symbol<size>::Size_type Size_type; // We've kept a list of all the common symbols. But the symbol may // have been resolved to a defined symbol by now. And it may be a // forwarder. First remove all non-common symbols. bool any = false; uint64_t addralign = 0; for (Commons_type::iterator p = commons->begin(); p != commons->end(); ++p) { Symbol* sym = *p; if (sym->is_forwarder()) { sym = this->resolve_forwards(sym); *p = sym; } if (!sym->is_common()) *p = NULL; else { any = true; Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym); if (ssym->value() > addralign) addralign = ssym->value(); } } if (!any) return; // Sort the common symbols by size, so that they pack better into // memory. std::sort(commons->begin(), commons->end(), Sort_commons<size>(this)); // Place them in a newly allocated BSS section. Output_data_space *poc = new Output_data_space(addralign); const char* name = ".bss"; elfcpp::Elf_Xword flags = elfcpp::SHF_WRITE | elfcpp::SHF_ALLOC; if (is_tls) { name = ".tbss"; flags |= elfcpp::SHF_TLS; } layout->add_output_section_data(name, elfcpp::SHT_NOBITS, flags, poc); // Allocate them all. off_t off = 0; for (Commons_type::iterator p = commons->begin(); p != commons->end(); ++p) { Symbol* sym = *p; if (sym == NULL) break; Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym); off = align_address(off, ssym->value()); ssym->allocate_common(poc, off); off += ssym->symsize(); } poc->set_current_data_size(off); commons->clear(); } } // End namespace gold.