[binutils.git] / gold / merge.cc

// merge.cc -- handle section merging for gold

// Copyright 2006, 2007 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <[email protected]>.

// 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 <cstdlib>

#include "merge.h"

namespace gold
{

// Sort the entries in a merge mapping.  The key is an input object, a
// section index in that object, and an offset in that section.

bool
Output_merge_base::Merge_key_less::operator()(const Merge_key& mk1,
					      const Merge_key& mk2) const
{
  // The order of different objects and different sections doesn't
  // matter.  We want to get consistent results across links so we
  // don't use pointer comparison.
  if (mk1.object != mk2.object)
    {
      // Two different object files can have the same name: if foo.a
      // includes both bar/qux.o and baz/qux.o, then both end up with
      // the name foo.a(qux.o).  But it's impossible for two different
      // object files to have both the same name and the same offset.
      if (mk1.object->offset() != mk2.object->offset())
        return mk1.object->offset() < mk2.object->offset();
      return mk1.object->name() < mk2.object->name();
    }
  if (mk1.shndx != mk2.shndx)
    return mk1.shndx < mk2.shndx;
  return mk1.offset < mk2.offset;
}

// Add a mapping from an OFFSET in input section SHNDX in object
// OBJECT to an OUTPUT_OFFSET in a merged output section.  This
// manages the mapping used to resolve relocations against merged
// sections.

void
Output_merge_base::add_mapping(Relobj* object, unsigned int shndx,
			       off_t offset, off_t output_offset)
{
  Merge_key mk;
  mk.object = object;
  mk.shndx = shndx;
  mk.offset = offset;
  std::pair<Merge_map::iterator, bool> ins =
    this->merge_map_.insert(std::make_pair(mk, output_offset));
  gold_assert(ins.second);
}

// Return the output address for an input address.  The input address
// is at offset OFFSET in section SHNDX in OBJECT.
// OUTPUT_SECTION_ADDRESS is the address of the output section.  If we
// know the address, set *POUTPUT and return true.  Otherwise return
// false.

bool
Output_merge_base::do_output_address(const Relobj* object, unsigned int shndx,
				     off_t offset,
				     uint64_t output_section_address,
				     uint64_t* poutput) const
{
  gold_assert(output_section_address == this->address());

  Merge_key mk;
  mk.object = object;
  mk.shndx = shndx;
  mk.offset = offset;
  Merge_map::const_iterator p = this->merge_map_.lower_bound(mk);

  // If MK is not in the map, lower_bound returns the next iterator
  // larger than it.
  if (p == this->merge_map_.end()
      || p->first.object != object
      || p->first.shndx != shndx
      || p->first.offset != offset)
    {
      if (p == this->merge_map_.begin())
	return false;
      --p;
    }

  if (p->first.object != object || p->first.shndx != shndx)
    return false;

  // Any input section is fully mapped: we don't need to know the size
  // of the range starting at P->FIRST.OFFSET.
  *poutput = output_section_address + p->second + (offset - p->first.offset);
  return true;
}

// Compute the hash code for a fixed-size constant.

size_t
Output_merge_data::Merge_data_hash::operator()(Merge_data_key k) const
{
  const unsigned char* p = this->pomd_->constant(k);
  uint64_t entsize = this->pomd_->entsize();

  // Fowler/Noll/Vo (FNV) hash (type FNV-1a).
  if (sizeof(size_t) == 8)
    {
      size_t result = static_cast<size_t>(14695981039346656037ULL);
      for (uint64_t i = 0; i < entsize; ++i)
	{
	  result &= (size_t) *p++;
	  result *= 1099511628211ULL;
	}
      return result;
    }
  else
    {
      size_t result = 2166136261UL;
      for (uint64_t i = 0; i < entsize; ++i)
	{
	  result ^= (size_t) *p++;
	  result *= 16777619UL;
	}
      return result;
    }
}

// Return whether one hash table key equals another.

bool
Output_merge_data::Merge_data_eq::operator()(Merge_data_key k1,
					     Merge_data_key k2) const
{
  const unsigned char* p1 = this->pomd_->constant(k1);
  const unsigned char* p2 = this->pomd_->constant(k2);
  return memcmp(p1, p2, this->pomd_->entsize()) == 0;
}

// Add a constant to the end of the section contents.

void
Output_merge_data::add_constant(const unsigned char* p)
{
  uint64_t entsize = this->entsize();
  if (this->len_ + entsize > this->alc_)
    {
      if (this->alc_ == 0)
	this->alc_ = 128 * entsize;
      else
	this->alc_ *= 2;
      this->p_ = static_cast<unsigned char*>(realloc(this->p_, this->alc_));
      if (this->p_ == NULL)
	gold_fatal("out of memory", true);
    }

  memcpy(this->p_ + this->len_, p, entsize);
  this->len_ += entsize;
}

// Add the input section SHNDX in OBJECT to a merged output section
// which holds fixed length constants.  Return whether we were able to
// handle the section; if not, it will be linked as usual without
// constant merging.

bool
Output_merge_data::do_add_input_section(Relobj* object, unsigned int shndx)
{
  off_t len;
  const unsigned char* p = object->section_contents(shndx, &len, false);

  uint64_t entsize = this->entsize();

  if (len % entsize != 0)
    return false;

  for (off_t i = 0; i < len; i += entsize, p += entsize)
    {
      // Add the constant to the section contents.  If we find that it
      // is already in the hash table, we will remove it again.
      Merge_data_key k = this->len_;
      this->add_constant(p);

      std::pair<Merge_data_hashtable::iterator, bool> ins =
	this->hashtable_.insert(k);

      if (!ins.second)
	{
	  // Key was already present.  Remove the copy we just added.
	  this->len_ -= entsize;
	  k = *ins.first;
	}

      // Record the offset of this constant in the output section.
      this->add_mapping(object, shndx, i, k);
    }

  return true;
}

// Set the final data size in a merged output section with fixed size
// constants.

void
Output_merge_data::do_set_address(uint64_t, off_t)
{
  // Release the memory we don't need.
  this->p_ = static_cast<unsigned char*>(realloc(this->p_, this->len_));
  gold_assert(this->p_ != NULL);
  this->set_data_size(this->len_);
}

// Write the data of a merged output section with fixed size constants
// to the file.

void
Output_merge_data::do_write(Output_file* of)
{
  of->write(this->offset(), this->p_, this->len_);
}

// Add an input section to a merged string section.

template<typename Char_type>
bool
Output_merge_string<Char_type>::do_add_input_section(Relobj* object,
						     unsigned int shndx)
{
  off_t len;
  const unsigned char* pdata = object->section_contents(shndx, &len, false);

  const Char_type* p = reinterpret_cast<const Char_type*>(pdata);

  if (len % sizeof(Char_type) != 0)
    {
      fprintf(stderr,
	      _("%s: %s: mergeable string section length not multiple of "
		"character size\n"),
	      program_name, object->name().c_str());
      gold_exit(false);
    }
  len /= sizeof(Char_type);

  off_t i = 0;
  while (i < len)
    {
      off_t plen = 0;
      for (const Char_type* pl = p; *pl != 0; ++pl)
	{
	  ++plen;
	  if (i + plen >= len)
	    {
	      fprintf(stderr,
		      _("%s: %s: entry in mergeable string section "
			"not null terminated\n"),
		      program_name, object->name().c_str());
	      gold_exit(false);
	    }
	}

      const Char_type* str = this->stringpool_.add(p, NULL);

      this->merged_strings_.push_back(Merged_string(object, shndx, i, str));

      p += plen + 1;
      i += plen + 1;
    }

  return true;
}

// Set the final data size of a merged string section.  This is where
// we finalize the mappings from the input sections to the output
// section.

template<typename Char_type>
void
Output_merge_string<Char_type>::do_set_address(uint64_t, off_t)
{
  this->stringpool_.set_string_offsets();

  for (typename Merged_strings::const_iterator p =
	 this->merged_strings_.begin();
       p != this->merged_strings_.end();
       ++p)
    this->add_mapping(p->object, p->shndx, p->offset,
		      this->stringpool_.get_offset(p->string));

  this->set_data_size(this->stringpool_.get_strtab_size());

  // Save some memory.
  this->merged_strings_.clear();
}

// Write out a merged string section.

template<typename Char_type>
void
Output_merge_string<Char_type>::do_write(Output_file* of)
{
  this->stringpool_.write(of, this->offset());
}

// Instantiate the templates we need.

template
class Output_merge_string<char>;

template
class Output_merge_string<uint16_t>;

template
class Output_merge_string<uint32_t>;

} // End namespace gold.
Commit	Line	Data
b8e6aad9 ILT	1	// merge.cc -- handle section merging for gold
b8e6aad9 ILT	2
6cb15b7f ILT	3	// Copyright 2006, 2007 Free Software Foundation, Inc.
	4	// Written by Ian Lance Taylor <[email protected]>.
	5
	6	// This file is part of gold.
	7
	8	// This program is free software; you can redistribute it and/or modify
	9	// it under the terms of the GNU General Public License as published by
	10	// the Free Software Foundation; either version 3 of the License, or
	11	// (at your option) any later version.
	12
	13	// This program is distributed in the hope that it will be useful,
	14	// but WITHOUT ANY WARRANTY; without even the implied warranty of
	15	// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	16	// GNU General Public License for more details.
	17
	18	// You should have received a copy of the GNU General Public License
	19	// along with this program; if not, write to the Free Software
	20	// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
	21	// MA 02110-1301, USA.
	22
b8e6aad9 ILT	23	#include "gold.h"
	24
	25	#include <cstdlib>
	26
	27	#include "merge.h"
	28
	29	namespace gold
	30	{
	31
	32	// Sort the entries in a merge mapping. The key is an input object, a
	33	// section index in that object, and an offset in that section.
	34
	35	bool
	36	Output_merge_base::Merge_key_less::operator()(const Merge_key& mk1,
	37	const Merge_key& mk2) const
	38	{
	39	// The order of different objects and different sections doesn't
	40	// matter. We want to get consistent results across links so we
	41	// don't use pointer comparison.
	42	if (mk1.object != mk2.object)
cec9d2f3 ILT	43	{
	44	// Two different object files can have the same name: if foo.a
	45	// includes both bar/qux.o and baz/qux.o, then both end up with
	46	// the name foo.a(qux.o). But it's impossible for two different
	47	// object files to have both the same name and the same offset.
	48	if (mk1.object->offset() != mk2.object->offset())
	49	return mk1.object->offset() < mk2.object->offset();
	50	return mk1.object->name() < mk2.object->name();
	51	}
b8e6aad9 ILT	52	if (mk1.shndx != mk2.shndx)
	53	return mk1.shndx < mk2.shndx;
	54	return mk1.offset < mk2.offset;
	55	}
	56
	57	// Add a mapping from an OFFSET in input section SHNDX in object
	58	// OBJECT to an OUTPUT_OFFSET in a merged output section. This
	59	// manages the mapping used to resolve relocations against merged
	60	// sections.
	61
	62	void
	63	Output_merge_base::add_mapping(Relobj* object, unsigned int shndx,
	64	off_t offset, off_t output_offset)
	65	{
	66	Merge_key mk;
	67	mk.object = object;
	68	mk.shndx = shndx;
	69	mk.offset = offset;
	70	std::pair<Merge_map::iterator, bool> ins =
	71	this->merge_map_.insert(std::make_pair(mk, output_offset));
	72	gold_assert(ins.second);
	73	}
	74
	75	// Return the output address for an input address. The input address
	76	// is at offset OFFSET in section SHNDX in OBJECT.
	77	// OUTPUT_SECTION_ADDRESS is the address of the output section. If we
	78	// know the address, set *POUTPUT and return true. Otherwise return
	79	// false.
	80
	81	bool
	82	Output_merge_base::do_output_address(const Relobj* object, unsigned int shndx,
	83	off_t offset,
	84	uint64_t output_section_address,
	85	uint64_t* poutput) const
	86	{
	87	gold_assert(output_section_address == this->address());
	88
	89	Merge_key mk;
	90	mk.object = object;
	91	mk.shndx = shndx;
	92	mk.offset = offset;
	93	Merge_map::const_iterator p = this->merge_map_.lower_bound(mk);
	94
	95	// If MK is not in the map, lower_bound returns the next iterator
	96	// larger than it.
c077629b ILT	97	if (p == this->merge_map_.end()
c077629b ILT	98	\|\| p->first.object != object
b8e6aad9 ILT	99	\|\| p->first.shndx != shndx
	100	\|\| p->first.offset != offset)
	101	{
	102	if (p == this->merge_map_.begin())
	103	return false;
	104	--p;
	105	}
	106
	107	if (p->first.object != object \|\| p->first.shndx != shndx)
	108	return false;
	109
	110	// Any input section is fully mapped: we don't need to know the size
	111	// of the range starting at P->FIRST.OFFSET.
	112	*poutput = output_section_address + p->second + (offset - p->first.offset);
	113	return true;
	114	}
	115
	116	// Compute the hash code for a fixed-size constant.
	117
	118	size_t
	119	Output_merge_data::Merge_data_hash::operator()(Merge_data_key k) const
	120	{
	121	const unsigned char* p = this->pomd_->constant(k);
	122	uint64_t entsize = this->pomd_->entsize();
	123
	124	// Fowler/Noll/Vo (FNV) hash (type FNV-1a).
	125	if (sizeof(size_t) == 8)
	126	{
	127	size_t result = static_cast<size_t>(14695981039346656037ULL);
	128	for (uint64_t i = 0; i < entsize; ++i)
	129	{
	130	result &= (size_t) *p++;
	131	result *= 1099511628211ULL;
	132	}
	133	return result;
	134	}
	135	else
	136	{
	137	size_t result = 2166136261UL;
	138	for (uint64_t i = 0; i < entsize; ++i)
	139	{
	140	result ^= (size_t) *p++;
	141	result *= 16777619UL;
	142	}
	143	return result;
	144	}
	145	}
	146
	147	// Return whether one hash table key equals another.
	148
	149	bool
	150	Output_merge_data::Merge_data_eq::operator()(Merge_data_key k1,
	151	Merge_data_key k2) const
	152	{
	153	const unsigned char* p1 = this->pomd_->constant(k1);
	154	const unsigned char* p2 = this->pomd_->constant(k2);
	155	return memcmp(p1, p2, this->pomd_->entsize()) == 0;
	156	}
	157
	158	// Add a constant to the end of the section contents.
	159
	160	void
	161	Output_merge_data::add_constant(const unsigned char* p)
	162	{
163	uint64_t entsize = this->entsize();
164	if (this->len_ + entsize > this->alc_)
165	{
166	if (this->alc_ == 0)
167	this->alc_ = 128 * entsize;
168	else
169	this->alc_ *= 2;
170	this->p_ = static_cast<unsigned char*>(realloc(this->p_, this->alc_));
171	if (this->p_ == NULL)
172	gold_fatal("out of memory", true);
173	}
174
175	memcpy(this->p_ + this->len_, p, entsize);
176	this->len_ += entsize;
177	}
178
179	// Add the input section SHNDX in OBJECT to a merged output section
180	// which holds fixed length constants. Return whether we were able to
181	// handle the section; if not, it will be linked as usual without
182	// constant merging.
183
184	bool
185	Output_merge_data::do_add_input_section(Relobj* object, unsigned int shndx)
186	{
187	off_t len;
9eb9fa57	188	const unsigned char* p = object->section_contents(shndx, &len, false);
b8e6aad9 ILT	189
	190	uint64_t entsize = this->entsize();
	191
	192	if (len % entsize != 0)
	193	return false;
	194
	195	for (off_t i = 0; i < len; i += entsize, p += entsize)
	196	{
	197	// Add the constant to the section contents. If we find that it
	198	// is already in the hash table, we will remove it again.
	199	Merge_data_key k = this->len_;
	200	this->add_constant(p);
	201
	202	std::pair<Merge_data_hashtable::iterator, bool> ins =
	203	this->hashtable_.insert(k);
	204
	205	if (!ins.second)
	206	{
	207	// Key was already present. Remove the copy we just added.
	208	this->len_ -= entsize;
	209	k = *ins.first;
	210	}
	211
	212	// Record the offset of this constant in the output section.
	213	this->add_mapping(object, shndx, i, k);
	214	}
	215
	216	return true;
	217	}
	218
	219	// Set the final data size in a merged output section with fixed size
	220	// constants.
	221
	222	void
	223	Output_merge_data::do_set_address(uint64_t, off_t)
	224	{
	225	// Release the memory we don't need.
	226	this->p_ = static_cast<unsigned char*>(realloc(this->p_, this->len_));
	227	gold_assert(this->p_ != NULL);
	228	this->set_data_size(this->len_);
	229	}
	230
	231	// Write the data of a merged output section with fixed size constants
	232	// to the file.
	233
	234	void
	235	Output_merge_data::do_write(Output_file* of)
	236	{
	237	of->write(this->offset(), this->p_, this->len_);
	238	}
	239
b8e6aad9 ILT	240	// Add an input section to a merged string section.
	241
	242	template<typename Char_type>
	243	bool
	244	Output_merge_string<Char_type>::do_add_input_section(Relobj* object,
	245	unsigned int shndx)
	246	{
	247	off_t len;
9eb9fa57	248	const unsigned char* pdata = object->section_contents(shndx, &len, false);
b8e6aad9 ILT	249
	250	const Char_type* p = reinterpret_cast<const Char_type*>(pdata);
	251
	252	if (len % sizeof(Char_type) != 0)
	253	{
	254	fprintf(stderr,
	255	_("%s: %s: mergeable string section length not multiple of "
	256	"character size\n"),
	257	program_name, object->name().c_str());
	258	gold_exit(false);
	259	}
	260	len /= sizeof(Char_type);
	261
	262	off_t i = 0;
	263	while (i < len)
	264	{
	265	off_t plen = 0;
	266	for (const Char_type* pl = p; *pl != 0; ++pl)
	267	{
	268	++plen;
	269	if (i + plen >= len)
	270	{
	271	fprintf(stderr,
	272	_("%s: %s: entry in mergeable string section "
	273	"not null terminated\n"),
	274	program_name, object->name().c_str());
	275	gold_exit(false);
	276	}
	277	}
	278
	279	const Char_type* str = this->stringpool_.add(p, NULL);
	280
42e3fe0d	281	this->merged_strings_.push_back(Merged_string(object, shndx, i, str));
b8e6aad9 ILT	282
	283	p += plen + 1;
	284	i += plen + 1;
	285	}
	286
	287	return true;
	288	}
	289
	290	// Set the final data size of a merged string section. This is where
	291	// we finalize the mappings from the input sections to the output
	292	// section.
	293
	294	template<typename Char_type>
	295	void
	296	Output_merge_string<Char_type>::do_set_address(uint64_t, off_t)
	297	{
	298	this->stringpool_.set_string_offsets();
	299
42e3fe0d ILT	300	for (typename Merged_strings::const_iterator p =
	301	this->merged_strings_.begin();
	302	p != this->merged_strings_.end();
b8e6aad9	303	++p)
42e3fe0d ILT	304	this->add_mapping(p->object, p->shndx, p->offset,
42e3fe0d ILT	305	this->stringpool_.get_offset(p->string));
b8e6aad9 ILT	306
	307	this->set_data_size(this->stringpool_.get_strtab_size());
	308
	309	// Save some memory.
42e3fe0d	310	this->merged_strings_.clear();
b8e6aad9 ILT	311	}
	312
	313	// Write out a merged string section.
	314
	315	template<typename Char_type>
	316	void
	317	Output_merge_string<Char_type>::do_write(Output_file* of)
	318	{
	319	this->stringpool_.write(of, this->offset());
	320	}
	321
	322	// Instantiate the templates we need.
	323
	324	template
	325	class Output_merge_string<char>;
	326
	327	template
	328	class Output_merge_string<uint16_t>;
	329
	330	template
	331	class Output_merge_string<uint32_t>;
	332
	333	} // End namespace gold.