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// common.cc -- handle common symbols for gold
// Copyright 2006, 2007 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->options_, 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);
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.
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(const General_options& options, Layout* layout)
{
if (parameters->target().get_size() == 32)
{
#if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
this->do_allocate_commons<32>(options, 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>(options, layout);
#else
gold_unreachable();
#endif
}
else
gold_unreachable();
}
// Allocated the common symbols, sized version.
template<int size>
void
Symbol_table::do_allocate_commons(const General_options&,
Layout* layout)
{
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 = this->commons_.begin();
p != this->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(this->commons_.begin(), this->commons_.end(),
Sort_commons<size>(this));
// Place them in a newly allocated .bss section.
Output_data_space *poc = new Output_data_space(addralign);
layout->add_output_section_data(".bss", elfcpp::SHT_NOBITS,
elfcpp::SHF_WRITE | elfcpp::SHF_ALLOC,
poc);
// Allocate them all.
off_t off = 0;
for (Commons_type::iterator p = this->commons_.begin();
p != this->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);
this->commons_.clear();
}
} // End namespace gold.
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