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[/] [open8_urisc/] [trunk/] [gnu/] [binutils/] [gold/] [common.cc] - Blame information for rev 27

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1 27 khays
// common.cc -- handle common symbols for gold
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// Copyright 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
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// Written by Ian Lance Taylor <iant@google.com>.
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// This file is part of gold.
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 3 of the License, or
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// (at your option) any later version.
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
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// MA 02110-1301, USA.
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#include "gold.h"
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#include <algorithm>
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#include "workqueue.h"
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#include "mapfile.h"
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#include "layout.h"
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#include "output.h"
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#include "symtab.h"
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#include "common.h"
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namespace gold
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{
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// Allocate_commons_task methods.
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// This task allocates the common symbols.  We arrange to run it
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// before anything else which needs to access the symbol table.
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Task_token*
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Allocate_commons_task::is_runnable()
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{
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  return NULL;
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}
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// Release a blocker.
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void
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Allocate_commons_task::locks(Task_locker* tl)
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{
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  tl->add(this, this->blocker_);
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}
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// Allocate the common symbols.
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void
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Allocate_commons_task::run(Workqueue*)
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{
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  this->symtab_->allocate_commons(this->layout_, this->mapfile_);
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}
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// This class is used to sort the common symbol.  We normally put the
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// larger common symbols first.  This can be changed by using
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// --sort-commons, which tells the linker to sort by alignment.
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template<int size>
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class Sort_commons
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{
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 public:
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  Sort_commons(const Symbol_table* symtab,
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               Symbol_table::Sort_commons_order sort_order)
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    : symtab_(symtab), sort_order_(sort_order)
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  { }
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  bool operator()(const Symbol* a, const Symbol* b) const;
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 private:
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  // The symbol table.
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  const Symbol_table* symtab_;
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  // How to sort.
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  Symbol_table::Sort_commons_order sort_order_;
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};
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template<int size>
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bool
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Sort_commons<size>::operator()(const Symbol* pa, const Symbol* pb) const
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{
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  if (pa == NULL)
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    return false;
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  if (pb == NULL)
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    return true;
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  const Symbol_table* symtab = this->symtab_;
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  const Sized_symbol<size>* psa = symtab->get_sized_symbol<size>(pa);
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  const Sized_symbol<size>* psb = symtab->get_sized_symbol<size>(pb);
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  // The size.
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  typename Sized_symbol<size>::Size_type sa = psa->symsize();
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  typename Sized_symbol<size>::Size_type sb = psb->symsize();
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  // The alignment.
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  typename Sized_symbol<size>::Value_type aa = psa->value();
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  typename Sized_symbol<size>::Value_type ab = psb->value();
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  if (this->sort_order_ == Symbol_table::SORT_COMMONS_BY_ALIGNMENT_DESCENDING)
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    {
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      if (aa < ab)
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        return false;
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      else if (ab < aa)
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        return true;
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    }
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  else if (this->sort_order_
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           == Symbol_table::SORT_COMMONS_BY_ALIGNMENT_ASCENDING)
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    {
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      if (aa < ab)
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        return true;
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      else if (ab < aa)
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        return false;
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    }
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  else
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    gold_assert(this->sort_order_
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                == Symbol_table::SORT_COMMONS_BY_SIZE_DESCENDING);
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  // Sort by descending size.
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  if (sa < sb)
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    return false;
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  else if (sb < sa)
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    return true;
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  if (this->sort_order_ == Symbol_table::SORT_COMMONS_BY_SIZE_DESCENDING)
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    {
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      // When the symbols are the same size, we sort them by
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      // alignment, largest alignment first.
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      if (aa < ab)
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        return false;
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      else if (ab < aa)
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        return true;
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    }
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  // Otherwise we stabilize the sort by sorting by name.
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  return strcmp(psa->name(), psb->name()) < 0;
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}
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// Allocate the common symbols.
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void
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Symbol_table::allocate_commons(Layout* layout, Mapfile* mapfile)
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{
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  Sort_commons_order sort_order;
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  if (!parameters->options().user_set_sort_common())
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    sort_order = SORT_COMMONS_BY_SIZE_DESCENDING;
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  else
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    {
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      const char* order = parameters->options().sort_common();
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      if (*order == '\0' || strcmp(order, "descending") == 0)
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        sort_order = SORT_COMMONS_BY_ALIGNMENT_DESCENDING;
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      else if (strcmp(order, "ascending") == 0)
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        sort_order = SORT_COMMONS_BY_ALIGNMENT_ASCENDING;
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      else
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        {
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          gold_error("invalid --sort-common argument: %s", order);
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          sort_order = SORT_COMMONS_BY_SIZE_DESCENDING;
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        }
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    }
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  if (parameters->target().get_size() == 32)
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    {
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#if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
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      this->do_allocate_commons<32>(layout, mapfile, sort_order);
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#else
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      gold_unreachable();
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#endif
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    }
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  else if (parameters->target().get_size() == 64)
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    {
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#if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG)
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      this->do_allocate_commons<64>(layout, mapfile, sort_order);
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#else
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      gold_unreachable();
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#endif
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    }
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  else
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    gold_unreachable();
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}
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// Allocated the common symbols, sized version.
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template<int size>
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void
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Symbol_table::do_allocate_commons(Layout* layout, Mapfile* mapfile,
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                                  Sort_commons_order sort_order)
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{
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  if (!this->commons_.empty())
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    this->do_allocate_commons_list<size>(layout, COMMONS_NORMAL,
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                                         &this->commons_, mapfile,
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                                         sort_order);
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  if (!this->tls_commons_.empty())
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    this->do_allocate_commons_list<size>(layout, COMMONS_TLS,
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                                         &this->tls_commons_, mapfile,
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                                         sort_order);
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  if (!this->small_commons_.empty())
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    this->do_allocate_commons_list<size>(layout, COMMONS_SMALL,
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                                         &this->small_commons_, mapfile,
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                                         sort_order);
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  if (!this->large_commons_.empty())
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    this->do_allocate_commons_list<size>(layout, COMMONS_LARGE,
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                                         &this->large_commons_, mapfile,
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                                         sort_order);
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}
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// Allocate the common symbols in a list.  IS_TLS indicates whether
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// these are TLS common symbols.
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template<int size>
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void
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Symbol_table::do_allocate_commons_list(
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    Layout* layout,
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    Commons_section_type commons_section_type,
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    Commons_type* commons,
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    Mapfile* mapfile,
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    Sort_commons_order sort_order)
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{
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  typedef typename Sized_symbol<size>::Value_type Value_type;
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  typedef typename Sized_symbol<size>::Size_type Size_type;
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  // We've kept a list of all the common symbols.  But the symbol may
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  // have been resolved to a defined symbol by now.  And it may be a
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  // forwarder.  First remove all non-common symbols.
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  bool any = false;
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  uint64_t addralign = 0;
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  for (Commons_type::iterator p = commons->begin();
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       p != commons->end();
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       ++p)
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    {
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      Symbol* sym = *p;
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      if (sym->is_forwarder())
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        {
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          sym = this->resolve_forwards(sym);
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          *p = sym;
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        }
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      if (!sym->is_common())
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        *p = NULL;
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      else
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        {
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          any = true;
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          Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym);
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          if (ssym->value() > addralign)
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            addralign = ssym->value();
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        }
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    }
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  if (!any)
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    return;
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  // Sort the common symbols.
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  std::sort(commons->begin(), commons->end(),
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            Sort_commons<size>(this, sort_order));
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  // Place them in a newly allocated BSS section.
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  elfcpp::Elf_Xword flags = elfcpp::SHF_WRITE | elfcpp::SHF_ALLOC;
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  const char* name;
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  const char* ds_name;
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  switch (commons_section_type)
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    {
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    case COMMONS_NORMAL:
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      name = ".bss";
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      ds_name = "** common";
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      break;
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    case COMMONS_TLS:
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      flags |= elfcpp::SHF_TLS;
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      name = ".tbss";
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      ds_name = "** tls common";
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      break;
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    case COMMONS_SMALL:
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      flags |= parameters->target().small_common_section_flags();
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      name = ".sbss";
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      ds_name = "** small common";
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      break;
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    case COMMONS_LARGE:
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      flags |= parameters->target().large_common_section_flags();
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      name = ".lbss";
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      ds_name = "** large common";
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      break;
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    default:
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      gold_unreachable();
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    }
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  Output_data_space* poc = new Output_data_space(addralign, ds_name);
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  Output_section* os = layout->add_output_section_data(name,
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                                                       elfcpp::SHT_NOBITS,
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                                                       flags, poc,
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                                                       ORDER_INVALID,
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                                                       false);
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  if (os != NULL)
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    {
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      if (commons_section_type == COMMONS_SMALL)
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        os->set_is_small_section();
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      else if (commons_section_type == COMMONS_LARGE)
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        os->set_is_large_section();
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    }
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  // Allocate them all.
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  off_t off = 0;
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  for (Commons_type::iterator p = commons->begin();
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       p != commons->end();
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       ++p)
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    {
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      Symbol* sym = *p;
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      if (sym == NULL)
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        break;
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      // Because we followed forwarding symbols above, but we didn't
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      // do it reliably before adding symbols to the list, it is
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      // possible for us to have the same symbol on the list twice.
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      // This can happen in the horrible case where a program defines
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      // a common symbol with the same name as a versioned libc
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      // symbol.  That will show up here as a symbol which has already
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      // been allocated and is therefore no longer a common symbol.
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      if (!sym->is_common())
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        continue;
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      Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym);
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      // Record the symbol in the map file now, before we change its
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      // value.  Pass the size in separately so that we don't have to
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      // templatize the map code, which is not performance sensitive.
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      if (mapfile != NULL)
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        mapfile->report_allocate_common(sym, ssym->symsize());
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      off = align_address(off, ssym->value());
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      ssym->allocate_common(poc, off);
334
      off += ssym->symsize();
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    }
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  poc->set_current_data_size(off);
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  commons->clear();
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}
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} // End namespace gold.

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