diff options
Diffstat (limited to 'binutils-2.25/gold/common.cc')
| -rw-r--r-- | binutils-2.25/gold/common.cc | 365 |
1 files changed, 365 insertions, 0 deletions
diff --git a/binutils-2.25/gold/common.cc b/binutils-2.25/gold/common.cc new file mode 100644 index 00000000..b0c7d6e2 --- /dev/null +++ b/binutils-2.25/gold/common.cc @@ -0,0 +1,365 @@ +// common.cc -- handle common symbols for gold + +// Copyright 2006, 2007, 2008, 2009, 2010, 2011, 2012 +// 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 "mapfile.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 arrange to run it +// before anything else which needs to access the symbol table. + +Task_token* +Allocate_commons_task::is_runnable() +{ + return NULL; +} + +// Release a blocker. + +void +Allocate_commons_task::locks(Task_locker* tl) +{ + tl->add(this, this->blocker_); +} + +// Allocate the common symbols. + +void +Allocate_commons_task::run(Workqueue*) +{ + this->symtab_->allocate_commons(this->layout_, this->mapfile_); +} + +// This class is used to sort the common symbol. We normally put the +// larger common symbols first. This can be changed by using +// --sort-commons, which tells the linker to sort by alignment. + +template<int size> +class Sort_commons +{ + public: + Sort_commons(const Symbol_table* symtab, + Symbol_table::Sort_commons_order sort_order) + : symtab_(symtab), sort_order_(sort_order) + { } + + bool operator()(const Symbol* a, const Symbol* b) const; + + private: + // The symbol table. + const Symbol_table* symtab_; + // How to sort. + Symbol_table::Sort_commons_order sort_order_; +}; + +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); + + // The size. + typename Sized_symbol<size>::Size_type sa = psa->symsize(); + typename Sized_symbol<size>::Size_type sb = psb->symsize(); + + // The alignment. + typename Sized_symbol<size>::Value_type aa = psa->value(); + typename Sized_symbol<size>::Value_type ab = psb->value(); + + if (this->sort_order_ == Symbol_table::SORT_COMMONS_BY_ALIGNMENT_DESCENDING) + { + if (aa < ab) + return false; + else if (ab < aa) + return true; + } + else if (this->sort_order_ + == Symbol_table::SORT_COMMONS_BY_ALIGNMENT_ASCENDING) + { + if (aa < ab) + return true; + else if (ab < aa) + return false; + } + else + gold_assert(this->sort_order_ + == Symbol_table::SORT_COMMONS_BY_SIZE_DESCENDING); + + // Sort by descending size. + if (sa < sb) + return false; + else if (sb < sa) + return true; + + if (this->sort_order_ == Symbol_table::SORT_COMMONS_BY_SIZE_DESCENDING) + { + // When the symbols are the same size, we sort them by + // alignment, largest alignment first. + if (aa < ab) + return false; + else if (ab < aa) + 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, Mapfile* mapfile) +{ + Sort_commons_order sort_order; + if (!parameters->options().user_set_sort_common()) + sort_order = SORT_COMMONS_BY_SIZE_DESCENDING; + else + { + const char* order = parameters->options().sort_common(); + if (*order == '\0' || strcmp(order, "descending") == 0) + sort_order = SORT_COMMONS_BY_ALIGNMENT_DESCENDING; + else if (strcmp(order, "ascending") == 0) + sort_order = SORT_COMMONS_BY_ALIGNMENT_ASCENDING; + else + { + gold_error("invalid --sort-common argument: %s", order); + sort_order = SORT_COMMONS_BY_SIZE_DESCENDING; + } + } + + if (parameters->target().get_size() == 32) + { +#if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG) + this->do_allocate_commons<32>(layout, mapfile, sort_order); +#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, mapfile, sort_order); +#else + gold_unreachable(); +#endif + } + else + gold_unreachable(); +} + +// Allocated the common symbols, sized version. + +template<int size> +void +Symbol_table::do_allocate_commons(Layout* layout, Mapfile* mapfile, + Sort_commons_order sort_order) +{ + if (!this->commons_.empty()) + this->do_allocate_commons_list<size>(layout, COMMONS_NORMAL, + &this->commons_, mapfile, + sort_order); + if (!this->tls_commons_.empty()) + this->do_allocate_commons_list<size>(layout, COMMONS_TLS, + &this->tls_commons_, mapfile, + sort_order); + if (!this->small_commons_.empty()) + this->do_allocate_commons_list<size>(layout, COMMONS_SMALL, + &this->small_commons_, mapfile, + sort_order); + if (!this->large_commons_.empty()) + this->do_allocate_commons_list<size>(layout, COMMONS_LARGE, + &this->large_commons_, mapfile, + sort_order); +} + +// 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, + Commons_section_type commons_section_type, + Commons_type* commons, + Mapfile* mapfile, + Sort_commons_order sort_order) +{ + // 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. + std::sort(commons->begin(), commons->end(), + Sort_commons<size>(this, sort_order)); + + // Place them in a newly allocated BSS section. + elfcpp::Elf_Xword flags = elfcpp::SHF_WRITE | elfcpp::SHF_ALLOC; + const char* name; + const char* ds_name; + switch (commons_section_type) + { + case COMMONS_NORMAL: + name = ".bss"; + ds_name = "** common"; + break; + case COMMONS_TLS: + flags |= elfcpp::SHF_TLS; + name = ".tbss"; + ds_name = "** tls common"; + break; + case COMMONS_SMALL: + flags |= parameters->target().small_common_section_flags(); + name = ".sbss"; + ds_name = "** small common"; + break; + case COMMONS_LARGE: + flags |= parameters->target().large_common_section_flags(); + name = ".lbss"; + ds_name = "** large common"; + break; + default: + gold_unreachable(); + } + + Output_data_space* poc; + Output_section* os; + + if (!parameters->incremental_update()) + { + poc = new Output_data_space(addralign, ds_name); + os = layout->add_output_section_data(name, elfcpp::SHT_NOBITS, flags, + poc, ORDER_INVALID, false); + } + else + { + // When doing an incremental update, we need to allocate each common + // directly from the output section's free list. + poc = NULL; + os = layout->find_output_section(name); + } + + if (os != NULL) + { + if (commons_section_type == COMMONS_SMALL) + os->set_is_small_section(); + else if (commons_section_type == COMMONS_LARGE) + os->set_is_large_section(); + } + + // 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; + + // Because we followed forwarding symbols above, but we didn't + // do it reliably before adding symbols to the list, it is + // possible for us to have the same symbol on the list twice. + // This can happen in the horrible case where a program defines + // a common symbol with the same name as a versioned libc + // symbol. That will show up here as a symbol which has already + // been allocated and is therefore no longer a common symbol. + if (!sym->is_common()) + continue; + + Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym); + + // Record the symbol in the map file now, before we change its + // value. Pass the size in separately so that we don't have to + // templatize the map code, which is not performance sensitive. + if (mapfile != NULL) + mapfile->report_allocate_common(sym, ssym->symsize()); + + if (poc != NULL) + { + off = align_address(off, ssym->value()); + ssym->allocate_common(poc, off); + off += ssym->symsize(); + } + else + { + // For an incremental update, allocate from the free list. + off = os->allocate(ssym->symsize(), ssym->value()); + if (off == -1) + gold_fallback(_("out of patch space in section %s; " + "relink with --incremental-full"), + os->name()); + ssym->allocate_common(os, off); + } + } + + if (poc != NULL) + poc->set_current_data_size(off); + + commons->clear(); +} + +} // End namespace gold. |