Retro68/binutils/gold/incremental.cc

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2012-03-26 19:18:29 +00:00
// inremental.cc -- incremental linking support for gold
// Copyright 2009 Free Software Foundation, Inc.
// Written by Mikolaj Zalewski <mikolajz@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 <cstdarg>
#include "elfcpp.h"
#include "output.h"
#include "incremental.h"
#include "archive.h"
#include "output.h"
#include "target-select.h"
using elfcpp::Convert;
namespace gold {
// Version information. Will change frequently during the development, later
// we could think about backward (and forward?) compatibility.
const unsigned int INCREMENTAL_LINK_VERSION = 1;
namespace internal {
// Header of the .gnu_incremental_input section.
struct Incremental_inputs_header_data
{
// Incremental linker version.
elfcpp::Elf_Word version;
// Numer of input files in the link.
elfcpp::Elf_Word input_file_count;
// Offset of command line options in .gnu_incremental_strtab.
elfcpp::Elf_Word command_line_offset;
// Padding.
elfcpp::Elf_Word reserved;
};
// Data stored in .gnu_incremental_input after the header for each of the
// Incremental_input_header_data::input_file_count input entries.
struct Incremental_inputs_entry_data
{
// Offset of file name in .gnu_incremental_strtab section.
elfcpp::Elf_Word filename_offset;
// Offset of data in .gnu_incremental_input.
elfcpp::Elf_Word data_offset;
// Timestamp (in seconds).
elfcpp::Elf_Xword timestamp_sec;
// Nano-second part of timestamp (if supported).
elfcpp::Elf_Word timestamp_nsec;
// Type of the input entry.
elfcpp::Elf_Half input_type;
// Padding.
elfcpp::Elf_Half reserved;
};
}
// Accessors.
// Reader class for .gnu_incremental_inputs header. See
// internal::Incremental_input_header for fields descriptions.
template<int size, bool big_endian>
class Incremental_inputs_header
{
public:
Incremental_inputs_header(const unsigned char *p)
: p_(reinterpret_cast<const internal::Incremental_inputs_header_data*>(p))
{ }
static const int data_size = sizeof(internal::Incremental_inputs_header_data);
elfcpp::Elf_Word
get_version() const
{ return Convert<32, big_endian>::convert_host(this->p_->version); }
elfcpp::Elf_Word
get_input_file_count() const
{ return Convert<32, big_endian>::convert_host(this->p_->input_file_count); }
elfcpp::Elf_Word
get_command_line_offset() const
{ return Convert<32, big_endian>::convert_host(this->p_->command_line_offset); }
elfcpp::Elf_Word
get_reserved() const
{ return Convert<32, big_endian>::convert_host(this->p_->reserved); }
private:
const internal::Incremental_inputs_header_data* p_;
};
// Writer class for .gnu_incremental_inputs header. See
// internal::Incremental_input_header for fields descriptions.
template<int size, bool big_endian>
class Incremental_inputs_header_write
{
public:
Incremental_inputs_header_write(unsigned char *p)
: p_(reinterpret_cast<internal::Incremental_inputs_header_data*>(p))
{ }
static const int data_size = sizeof(internal::Incremental_inputs_header_data);
void
put_version(elfcpp::Elf_Word v)
{ this->p_->version = Convert<32, big_endian>::convert_host(v); }
void
put_input_file_count(elfcpp::Elf_Word v)
{ this->p_->input_file_count = Convert<32, big_endian>::convert_host(v); }
void
put_command_line_offset(elfcpp::Elf_Word v)
{ this->p_->command_line_offset = Convert<32, big_endian>::convert_host(v); }
void
put_reserved(elfcpp::Elf_Word v)
{ this->p_->reserved = Convert<32, big_endian>::convert_host(v); }
private:
internal::Incremental_inputs_header_data* p_;
};
// Reader class for an .gnu_incremental_inputs entry. See
// internal::Incremental_input_entry for fields descriptions.
template<int size, bool big_endian>
class Incremental_inputs_entry
{
public:
Incremental_inputs_entry(const unsigned char *p)
: p_(reinterpret_cast<const internal::Incremental_inputs_entry_data*>(p))
{ }
static const int data_size = sizeof(internal::Incremental_inputs_entry_data);
elfcpp::Elf_Word
get_filename_offset(elfcpp::Elf_Word v)
{ return Convert<32, big_endian>::convert_host(this->p_->filename_offset); }
elfcpp::Elf_Word
get_data_offset(elfcpp::Elf_Word v)
{ return Convert<32, big_endian>::convert_host(this->p_->data_offset); }
elfcpp::Elf_Xword
get_timestamp_sec(elfcpp::Elf_Xword v)
{ return Convert<64, big_endian>::convert_host(this->p_->timestamp_sec); }
elfcpp::Elf_Word
get_timestamp_nsec(elfcpp::Elf_Word v)
{ return Convert<32, big_endian>::convert_host(this->p_->timestamp_nsec); }
elfcpp::Elf_Word
get_input_type(elfcpp::Elf_Word v)
{ return Convert<32, big_endian>::convert_host(this->p_->input_type); }
elfcpp::Elf_Word
get_reserved(elfcpp::Elf_Word v)
{ return Convert<32, big_endian>::convert_host(this->p_->reserved); }
private:
const internal::Incremental_inputs_entry_data* p_;
};
// Writer class for an .gnu_incremental_inputs entry. See
// internal::Incremental_input_entry for fields descriptions.
template<int size, bool big_endian>
class Incremental_inputs_entry_write
{
public:
Incremental_inputs_entry_write(unsigned char *p)
: p_(reinterpret_cast<internal::Incremental_inputs_entry_data*>(p))
{ }
static const int data_size = sizeof(internal::Incremental_inputs_entry_data);
void
put_filename_offset(elfcpp::Elf_Word v)
{ this->p_->filename_offset = Convert<32, big_endian>::convert_host(v); }
void
put_data_offset(elfcpp::Elf_Word v)
{ this->p_->data_offset = Convert<32, big_endian>::convert_host(v); }
void
put_timestamp_sec(elfcpp::Elf_Xword v)
{ this->p_->timestamp_sec = Convert<64, big_endian>::convert_host(v); }
void
put_timestamp_nsec(elfcpp::Elf_Word v)
{ this->p_->timestamp_nsec = Convert<32, big_endian>::convert_host(v); }
void
put_input_type(elfcpp::Elf_Word v)
{ this->p_->input_type = Convert<32, big_endian>::convert_host(v); }
void
put_reserved(elfcpp::Elf_Word v)
{ this->p_->reserved = Convert<32, big_endian>::convert_host(v); }
private:
internal::Incremental_inputs_entry_data* p_;
};
// Inform the user why we don't do an incremental link. Not called in
// the obvious case of missing output file. TODO: Is this helpful?
void
vexplain_no_incremental(const char* format, va_list args)
{
char* buf = NULL;
if (vasprintf(&buf, format, args) < 0)
gold_nomem();
gold_info(_("the link might take longer: "
"cannot perform incremental link: %s"), buf);
free(buf);
}
void
explain_no_incremental(const char* format, ...)
{
va_list args;
va_start(args, format);
vexplain_no_incremental(format, args);
va_end(args);
}
// Report an error.
void
Incremental_binary::error(const char* format, ...) const
{
va_list args;
va_start(args, format);
// Current code only checks if the file can be used for incremental linking,
// so errors shouldn't fail the build, but only result in a fallback to a
// full build.
// TODO: when we implement incremental editing of the file, we may need a
// flag that will cause errors to be treated seriously.
vexplain_no_incremental(format, args);
va_end(args);
}
template<int size, bool big_endian>
bool
Sized_incremental_binary<size, big_endian>::do_find_incremental_inputs_section(
Location* location,
unsigned int* strtab_shndx)
{
unsigned int shndx = this->elf_file_.find_section_by_type(
elfcpp::SHT_GNU_INCREMENTAL_INPUTS);
if (shndx == elfcpp::SHN_UNDEF) // Not found.
return false;
*strtab_shndx = this->elf_file_.section_link(shndx);
*location = this->elf_file_.section_contents(shndx);
return true;
}
template<int size, bool big_endian>
bool
Sized_incremental_binary<size, big_endian>::do_check_inputs(
Incremental_inputs* incremental_inputs)
{
const int entry_size =
Incremental_inputs_entry_write<size, big_endian>::data_size;
const int header_size =
Incremental_inputs_header_write<size, big_endian>::data_size;
unsigned int strtab_shndx;
Location location;
if (!do_find_incremental_inputs_section(&location, &strtab_shndx))
{
explain_no_incremental(_("no incremental data from previous build"));
return false;
}
if (location.data_size < header_size
|| strtab_shndx >= this->elf_file_.shnum()
|| this->elf_file_.section_type(strtab_shndx) != elfcpp::SHT_STRTAB)
{
explain_no_incremental(_("invalid incremental build data"));
return false;
}
Location strtab_location(this->elf_file_.section_contents(strtab_shndx));
View data_view(view(location));
View strtab_view(view(strtab_location));
elfcpp::Elf_strtab strtab(strtab_view.data(), strtab_location.data_size);
Incremental_inputs_header<size, big_endian> header(data_view.data());
if (header.get_version() != INCREMENTAL_LINK_VERSION)
{
explain_no_incremental(_("different version of incremental build data"));
return false;
}
const char* command_line;
// We divide instead of multiplying to make sure there is no integer
// overflow.
size_t max_input_entries = (location.data_size - header_size) / entry_size;
if (header.get_input_file_count() > max_input_entries
|| !strtab.get_c_string(header.get_command_line_offset(), &command_line))
{
explain_no_incremental(_("invalid incremental build data"));
return false;
}
if (incremental_inputs->command_line() != command_line)
{
explain_no_incremental(_("command line changed"));
return false;
}
// TODO: compare incremental_inputs->inputs() with entries in data_view.
return true;
}
namespace
{
// Create a Sized_incremental_binary object of the specified size and
// endianness. Fails if the target architecture is not supported.
template<int size, bool big_endian>
Incremental_binary*
make_sized_incremental_binary(Output_file* file,
const elfcpp::Ehdr<size, big_endian>& ehdr)
{
Target* target = select_target(ehdr.get_e_machine(), size, big_endian,
ehdr.get_e_ident()[elfcpp::EI_OSABI],
ehdr.get_e_ident()[elfcpp::EI_ABIVERSION]);
if (target == NULL)
{
explain_no_incremental(_("unsupported ELF machine number %d"),
ehdr.get_e_machine());
return NULL;
}
return new Sized_incremental_binary<size, big_endian>(file, ehdr, target);
}
} // End of anonymous namespace.
// Create an Incremental_binary object for FILE. Returns NULL is this is not
// possible, e.g. FILE is not an ELF file or has an unsupported target. FILE
// should be opened.
Incremental_binary*
open_incremental_binary(Output_file* file)
{
off_t filesize = file->filesize();
int want = elfcpp::Elf_recognizer::max_header_size;
if (filesize < want)
want = filesize;
const unsigned char* p = file->get_input_view(0, want);
if (!elfcpp::Elf_recognizer::is_elf_file(p, want))
{
explain_no_incremental(_("output is not an ELF file."));
return NULL;
}
int size;
bool big_endian;
std::string error;
if (!elfcpp::Elf_recognizer::is_valid_header(p, want, &size, &big_endian,
&error))
{
explain_no_incremental(error.c_str());
return NULL;
}
Incremental_binary* result = NULL;
if (size == 32)
{
if (big_endian)
{
#ifdef HAVE_TARGET_32_BIG
result = make_sized_incremental_binary<32, true>(
file, elfcpp::Ehdr<32, true>(p));
#else
explain_no_incremental(_("unsupported file: 32-bit, big-endian"));
#endif
}
else
{
#ifdef HAVE_TARGET_32_LITTLE
result = make_sized_incremental_binary<32, false>(
file, elfcpp::Ehdr<32, false>(p));
#else
explain_no_incremental(_("unsupported file: 32-bit, little-endian"));
#endif
}
}
else if (size == 64)
{
if (big_endian)
{
#ifdef HAVE_TARGET_64_BIG
result = make_sized_incremental_binary<64, true>(
file, elfcpp::Ehdr<64, true>(p));
#else
explain_no_incremental(_("unsupported file: 64-bit, big-endian"));
#endif
}
else
{
#ifdef HAVE_TARGET_64_LITTLE
result = make_sized_incremental_binary<64, false>(
file, elfcpp::Ehdr<64, false>(p));
#else
explain_no_incremental(_("unsupported file: 64-bit, little-endian"));
#endif
}
}
else
gold_unreachable();
return result;
}
// Analyzes the output file to check if incremental linking is possible and
// (to be done) what files need to be relinked.
bool
Incremental_checker::can_incrementally_link_output_file()
{
Output_file output(this->output_name_);
if (!output.open_for_modification())
return false;
Incremental_binary* binary = open_incremental_binary(&output);
if (binary == NULL)
return false;
return binary->check_inputs(this->incremental_inputs_);
}
// Add the command line to the string table, setting
// command_line_key_. In incremental builds, the command line is
// stored in .gnu_incremental_inputs so that the next linker run can
// check if the command line options didn't change.
void
Incremental_inputs::report_command_line(int argc, const char* const* argv)
{
// Always store 'gold' as argv[0] to avoid a full relink if the user used a
// different path to the linker.
std::string args("gold");
// Copied from collect_argv in main.cc.
for (int i = 1; i < argc; ++i)
{
// Adding/removing these options should result in a full relink.
if (strcmp(argv[i], "--incremental-changed") == 0
|| strcmp(argv[i], "--incremental-unchanged") == 0
|| strcmp(argv[i], "--incremental-unknown") == 0)
continue;
args.append(" '");
// Now append argv[i], but with all single-quotes escaped
const char* argpos = argv[i];
while (1)
{
const int len = strcspn(argpos, "'");
args.append(argpos, len);
if (argpos[len] == '\0')
break;
args.append("'\"'\"'");
argpos += len + 1;
}
args.append("'");
}
this->command_line_ = args;
this->strtab_->add(this->command_line_.c_str(), false,
&this->command_line_key_);
}
// Record that the input argument INPUT is an achive ARCHIVE. This is
// called by Read_symbols after finding out the type of the file.
void
Incremental_inputs::report_archive(const Input_argument* input,
Archive* archive)
{
Hold_lock hl(*this->lock_);
Input_info info;
info.type = INCREMENTAL_INPUT_ARCHIVE;
info.archive = archive;
info.mtime = archive->file().get_mtime();
this->inputs_map_.insert(std::make_pair(input, info));
}
// Record that the input argument INPUT is an object OBJ. This is
// called by Read_symbols after finding out the type of the file.
void
Incremental_inputs::report_object(const Input_argument* input,
Object* obj)
{
Hold_lock hl(*this->lock_);
Input_info info;
info.type = (obj->is_dynamic()
? INCREMENTAL_INPUT_SHARED_LIBRARY
: INCREMENTAL_INPUT_OBJECT);
info.object = obj;
info.mtime = obj->input_file()->file().get_mtime();
this->inputs_map_.insert(std::make_pair(input, info));
}
// Record that the input argument INPUT is an script SCRIPT. This is
// called by read_script after parsing the script and reading the list
// of inputs added by this script.
void
Incremental_inputs::report_script(const Input_argument* input,
Timespec mtime,
Script_info* script)
{
Hold_lock hl(*this->lock_);
Input_info info;
info.type = INCREMENTAL_INPUT_SCRIPT;
info.script = script;
info.mtime = mtime;
this->inputs_map_.insert(std::make_pair(input, info));
}
// Compute indexes in the order in which the inputs should appear in
// .gnu_incremental_inputs. This needs to be done after all the
// scripts are parsed. The function is first called for the command
// line inputs arguments and may call itself recursively for e.g. a
// list of elements of a group or a list of inputs added by a script.
// The [BEGIN; END) interval to analyze and *INDEX is the current
// value of the index (that will be updated).
void
Incremental_inputs::finalize_inputs(
Input_argument_list::const_iterator begin,
Input_argument_list::const_iterator end,
unsigned int* index)
{
for (Input_argument_list::const_iterator p = begin; p != end; ++p)
{
if (p->is_group())
{
finalize_inputs(p->group()->begin(), p->group()->end(), index);
continue;
}
Inputs_info_map::iterator it = this->inputs_map_.find(&(*p));
// TODO: turn it into an assert when the code will be more stable.
if (it == this->inputs_map_.end())
{
gold_error("internal error: %s: incremental build info not provided",
(p->is_file() ? p->file().name() : "[group]"));
continue;
}
Input_info* info = &it->second;
info->index = *index;
(*index)++;
this->strtab_->add(p->file().name(), false, &info->filename_key);
if (info->type == INCREMENTAL_INPUT_SCRIPT)
{
finalize_inputs(info->script->inputs()->begin(),
info->script->inputs()->end(),
index);
}
}
}
// Finalize the incremental link information. Called from
// Layout::finalize.
void
Incremental_inputs::finalize()
{
unsigned int index = 0;
finalize_inputs(this->inputs_->begin(), this->inputs_->end(), &index);
// Sanity check.
for (Inputs_info_map::const_iterator p = this->inputs_map_.begin();
p != this->inputs_map_.end();
++p)
{
gold_assert(p->second.filename_key != 0);
}
this->strtab_->set_string_offsets();
}
// Create the content of the .gnu_incremental_inputs section.
Output_section_data*
Incremental_inputs::create_incremental_inputs_section_data()
{
switch (parameters->size_and_endianness())
{
#ifdef HAVE_TARGET_32_LITTLE
case Parameters::TARGET_32_LITTLE:
return this->sized_create_inputs_section_data<32, false>();
#endif
#ifdef HAVE_TARGET_32_BIG
case Parameters::TARGET_32_BIG:
return this->sized_create_inputs_section_data<32, true>();
#endif
#ifdef HAVE_TARGET_64_LITTLE
case Parameters::TARGET_64_LITTLE:
return this->sized_create_inputs_section_data<64, false>();
#endif
#ifdef HAVE_TARGET_64_BIG
case Parameters::TARGET_64_BIG:
return this->sized_create_inputs_section_data<64, true>();
#endif
default:
gold_unreachable();
}
}
// Sized creation of .gnu_incremental_inputs section.
template<int size, bool big_endian>
Output_section_data*
Incremental_inputs::sized_create_inputs_section_data()
{
const int entry_size =
Incremental_inputs_entry_write<size, big_endian>::data_size;
const int header_size =
Incremental_inputs_header_write<size, big_endian>::data_size;
unsigned int sz = header_size + entry_size * this->inputs_map_.size();
unsigned char* buffer = new unsigned char[sz];
unsigned char* inputs_base = buffer + header_size;
Incremental_inputs_header_write<size, big_endian> header_writer(buffer);
gold_assert(this->command_line_key_ > 0);
int cmd_offset = this->strtab_->get_offset_from_key(this->command_line_key_);
header_writer.put_version(INCREMENTAL_LINK_VERSION);
header_writer.put_input_file_count(this->inputs_map_.size());
header_writer.put_command_line_offset(cmd_offset);
header_writer.put_reserved(0);
for (Inputs_info_map::const_iterator it = this->inputs_map_.begin();
it != this->inputs_map_.end();
++it)
{
gold_assert(it->second.index < this->inputs_map_.size());
unsigned char* entry_buffer =
inputs_base + it->second.index * entry_size;
Incremental_inputs_entry_write<size, big_endian> entry(entry_buffer);
int filename_offset =
this->strtab_->get_offset_from_key(it->second.filename_key);
entry.put_filename_offset(filename_offset);
// TODO: add per input data and timestamp. Currently we store
// an out-of-bounds offset for future version of gold to reject
// such an incremental_inputs section.
entry.put_data_offset(0xffffffff);
entry.put_timestamp_sec(it->second.mtime.seconds);
entry.put_timestamp_nsec(it->second.mtime.nanoseconds);
entry.put_input_type(it->second.type);
entry.put_reserved(0);
}
return new Output_data_const_buffer(buffer, sz, 8,
"** incremental link inputs list");
}
// Instantiate the templates we need.
#ifdef HAVE_TARGET_32_LITTLE
template
class Sized_incremental_binary<32, false>;
#endif
#ifdef HAVE_TARGET_32_BIG
template
class Sized_incremental_binary<32, true>;
#endif
#ifdef HAVE_TARGET_64_LITTLE
template
class Sized_incremental_binary<64, false>;
#endif
#ifdef HAVE_TARGET_64_BIG
template
class Sized_incremental_binary<64, true>;
#endif
} // End namespace gold.