binutils-gdb/gold/layout.cc
Ian Lance Taylor f0641a0b38 Rework stringpool and hash tables so that we always generate the same
output regardless of randomize_va_space.
2006-11-07 04:40:46 +00:00

983 lines
28 KiB
C++

// layout.cc -- lay out output file sections for gold
#include "gold.h"
#include <cassert>
#include <cstring>
#include <algorithm>
#include <iostream>
#include <utility>
#include "output.h"
#include "symtab.h"
#include "layout.h"
namespace gold
{
// Layout_task_runner methods.
// Lay out the sections. This is called after all the input objects
// have been read.
void
Layout_task_runner::run(Workqueue* workqueue)
{
off_t file_size = this->layout_->finalize(this->input_objects_,
this->symtab_);
// Now we know the final size of the output file and we know where
// each piece of information goes.
Output_file* of = new Output_file(this->options_);
of->open(file_size);
// Queue up the final set of tasks.
gold::queue_final_tasks(this->options_, this->input_objects_,
this->symtab_, this->layout_, workqueue, of);
}
// Layout methods.
Layout::Layout(const General_options& options)
: options_(options), namepool_(), sympool_(), signatures_(),
section_name_map_(), segment_list_(), section_list_(),
special_output_list_(), tls_segment_(NULL)
{
// Make space for more than enough segments for a typical file.
// This is just for efficiency--it's OK if we wind up needing more.
segment_list_.reserve(12);
}
// Hash a key we use to look up an output section mapping.
size_t
Layout::Hash_key::operator()(const Layout::Key& k) const
{
return k.first + k.second.first + k.second.second;
}
// Whether to include this section in the link.
template<int size, bool big_endian>
bool
Layout::include_section(Object*, const char*,
const elfcpp::Shdr<size, big_endian>& shdr)
{
// Some section types are never linked. Some are only linked when
// doing a relocateable link.
switch (shdr.get_sh_type())
{
case elfcpp::SHT_NULL:
case elfcpp::SHT_SYMTAB:
case elfcpp::SHT_DYNSYM:
case elfcpp::SHT_STRTAB:
case elfcpp::SHT_HASH:
case elfcpp::SHT_DYNAMIC:
case elfcpp::SHT_SYMTAB_SHNDX:
return false;
case elfcpp::SHT_RELA:
case elfcpp::SHT_REL:
case elfcpp::SHT_GROUP:
return this->options_.is_relocatable();
default:
// FIXME: Handle stripping debug sections here.
return true;
}
}
// Return an output section named NAME, or NULL if there is none.
Output_section*
Layout::find_output_section(const char* name) const
{
for (Section_name_map::const_iterator p = this->section_name_map_.begin();
p != this->section_name_map_.end();
++p)
if (strcmp(p->second->name(), name) == 0)
return p->second;
return NULL;
}
// Return an output segment of type TYPE, with segment flags SET set
// and segment flags CLEAR clear. Return NULL if there is none.
Output_segment*
Layout::find_output_segment(elfcpp::PT type, elfcpp::Elf_Word set,
elfcpp::Elf_Word clear) const
{
for (Segment_list::const_iterator p = this->segment_list_.begin();
p != this->segment_list_.end();
++p)
if (static_cast<elfcpp::PT>((*p)->type()) == type
&& ((*p)->flags() & set) == set
&& ((*p)->flags() & clear) == 0)
return *p;
return NULL;
}
// Return the output section to use for section NAME with type TYPE
// and section flags FLAGS.
Output_section*
Layout::get_output_section(const char* name, Stringpool::Key name_key,
elfcpp::Elf_Word type, elfcpp::Elf_Xword flags)
{
// We should ignore some flags.
flags &= ~ (elfcpp::SHF_INFO_LINK
| elfcpp::SHF_LINK_ORDER
| elfcpp::SHF_GROUP);
const Key key(name_key, std::make_pair(type, flags));
const std::pair<Key, Output_section*> v(key, NULL);
std::pair<Section_name_map::iterator, bool> ins(
this->section_name_map_.insert(v));
if (!ins.second)
return ins.first->second;
else
{
// This is the first time we've seen this name/type/flags
// combination.
Output_section* os = this->make_output_section(name, type, flags);
ins.first->second = os;
return os;
}
}
// Return the output section to use for input section SHNDX, with name
// NAME, with header HEADER, from object OBJECT. Set *OFF to the
// offset of this input section without the output section.
template<int size, bool big_endian>
Output_section*
Layout::layout(Relobj* object, unsigned int shndx, const char* name,
const elfcpp::Shdr<size, big_endian>& shdr, off_t* off)
{
if (!this->include_section(object, name, shdr))
return NULL;
// If we are not doing a relocateable link, choose the name to use
// for the output section.
size_t len = strlen(name);
if (!this->options_.is_relocatable())
name = Layout::output_section_name(name, &len);
// FIXME: Handle SHF_OS_NONCONFORMING here.
// Canonicalize the section name.
Stringpool::Key name_key;
name = this->namepool_.add(name, len, &name_key);
// Find the output section. The output section is selected based on
// the section name, type, and flags.
Output_section* os = this->get_output_section(name, name_key,
shdr.get_sh_type(),
shdr.get_sh_flags());
// FIXME: Handle SHF_LINK_ORDER somewhere.
*off = os->add_input_section(object, shndx, name, shdr);
return os;
}
// Add POSD to an output section using NAME, TYPE, and FLAGS.
void
Layout::add_output_section_data(const char* name, elfcpp::Elf_Word type,
elfcpp::Elf_Xword flags,
Output_section_data* posd)
{
// Canonicalize the name.
Stringpool::Key name_key;
name = this->namepool_.add(name, &name_key);
Output_section* os = this->get_output_section(name, name_key, type, flags);
os->add_output_section_data(posd);
}
// Map section flags to segment flags.
elfcpp::Elf_Word
Layout::section_flags_to_segment(elfcpp::Elf_Xword flags)
{
elfcpp::Elf_Word ret = elfcpp::PF_R;
if ((flags & elfcpp::SHF_WRITE) != 0)
ret |= elfcpp::PF_W;
if ((flags & elfcpp::SHF_EXECINSTR) != 0)
ret |= elfcpp::PF_X;
return ret;
}
// Make a new Output_section, and attach it to segments as
// appropriate.
Output_section*
Layout::make_output_section(const char* name, elfcpp::Elf_Word type,
elfcpp::Elf_Xword flags)
{
Output_section* os = new Output_section(name, type, flags, true);
if ((flags & elfcpp::SHF_ALLOC) == 0)
this->section_list_.push_back(os);
else
{
// This output section goes into a PT_LOAD segment.
elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(flags);
// The only thing we really care about for PT_LOAD segments is
// whether or not they are writable, so that is how we search
// for them. People who need segments sorted on some other
// basis will have to wait until we implement a mechanism for
// them to describe the segments they want.
Segment_list::const_iterator p;
for (p = this->segment_list_.begin();
p != this->segment_list_.end();
++p)
{
if ((*p)->type() == elfcpp::PT_LOAD
&& ((*p)->flags() & elfcpp::PF_W) == (seg_flags & elfcpp::PF_W))
{
(*p)->add_output_section(os, seg_flags);
break;
}
}
if (p == this->segment_list_.end())
{
Output_segment* oseg = new Output_segment(elfcpp::PT_LOAD,
seg_flags);
this->segment_list_.push_back(oseg);
oseg->add_output_section(os, seg_flags);
}
// If we see a loadable SHT_NOTE section, we create a PT_NOTE
// segment.
if (type == elfcpp::SHT_NOTE)
{
// See if we already have an equivalent PT_NOTE segment.
for (p = this->segment_list_.begin();
p != segment_list_.end();
++p)
{
if ((*p)->type() == elfcpp::PT_NOTE
&& (((*p)->flags() & elfcpp::PF_W)
== (seg_flags & elfcpp::PF_W)))
{
(*p)->add_output_section(os, seg_flags);
break;
}
}
if (p == this->segment_list_.end())
{
Output_segment* oseg = new Output_segment(elfcpp::PT_NOTE,
seg_flags);
this->segment_list_.push_back(oseg);
oseg->add_output_section(os, seg_flags);
}
}
// If we see a loadable SHF_TLS section, we create a PT_TLS
// segment. There can only be one such segment.
if ((flags & elfcpp::SHF_TLS) != 0)
{
if (this->tls_segment_ == NULL)
{
this->tls_segment_ = new Output_segment(elfcpp::PT_TLS,
seg_flags);
this->segment_list_.push_back(this->tls_segment_);
}
this->tls_segment_->add_output_section(os, seg_flags);
}
}
return os;
}
// Find the first read-only PT_LOAD segment, creating one if
// necessary.
Output_segment*
Layout::find_first_load_seg()
{
for (Segment_list::const_iterator p = this->segment_list_.begin();
p != this->segment_list_.end();
++p)
{
if ((*p)->type() == elfcpp::PT_LOAD
&& ((*p)->flags() & elfcpp::PF_R) != 0
&& ((*p)->flags() & elfcpp::PF_W) == 0)
return *p;
}
Output_segment* load_seg = new Output_segment(elfcpp::PT_LOAD, elfcpp::PF_R);
this->segment_list_.push_back(load_seg);
return load_seg;
}
// Finalize the layout. When this is called, we have created all the
// output sections and all the output segments which are based on
// input sections. We have several things to do, and we have to do
// them in the right order, so that we get the right results correctly
// and efficiently.
// 1) Finalize the list of output segments and create the segment
// table header.
// 2) Finalize the dynamic symbol table and associated sections.
// 3) Determine the final file offset of all the output segments.
// 4) Determine the final file offset of all the SHF_ALLOC output
// sections.
// 5) Create the symbol table sections and the section name table
// section.
// 6) Finalize the symbol table: set symbol values to their final
// value and make a final determination of which symbols are going
// into the output symbol table.
// 7) Create the section table header.
// 8) Determine the final file offset of all the output sections which
// are not SHF_ALLOC, including the section table header.
// 9) Finalize the ELF file header.
// This function returns the size of the output file.
off_t
Layout::finalize(const Input_objects* input_objects, Symbol_table* symtab)
{
if (input_objects->any_dynamic())
{
// If there are any dynamic objects in the link, then we need
// some additional segments: PT_PHDRS, PT_INTERP, and
// PT_DYNAMIC. We also need to finalize the dynamic symbol
// table and create the dynamic hash table.
abort();
}
// FIXME: Handle PT_GNU_STACK.
Output_segment* load_seg = this->find_first_load_seg();
// Lay out the segment headers.
int size = input_objects->target()->get_size();
bool big_endian = input_objects->target()->is_big_endian();
Output_segment_headers* segment_headers;
segment_headers = new Output_segment_headers(size, big_endian,
this->segment_list_);
load_seg->add_initial_output_data(segment_headers);
this->special_output_list_.push_back(segment_headers);
// FIXME: Attach them to PT_PHDRS if necessary.
// Lay out the file header.
Output_file_header* file_header;
file_header = new Output_file_header(size,
big_endian,
this->options_,
input_objects->target(),
symtab,
segment_headers);
load_seg->add_initial_output_data(file_header);
this->special_output_list_.push_back(file_header);
// We set the output section indexes in set_segment_offsets and
// set_section_offsets.
unsigned int shndx = 1;
// Set the file offsets of all the segments, and all the sections
// they contain.
off_t off = this->set_segment_offsets(input_objects->target(), load_seg,
&shndx);
// Create the symbol table sections.
// FIXME: We don't need to do this if we are stripping symbols.
Output_section* osymtab;
Output_section* ostrtab;
this->create_symtab_sections(size, input_objects, symtab, &off,
&osymtab, &ostrtab);
// Create the .shstrtab section.
Output_section* shstrtab_section = this->create_shstrtab();
// Set the file offsets of all the sections not associated with
// segments.
off = this->set_section_offsets(off, &shndx);
// Now the section index of OSTRTAB is set.
osymtab->set_link(ostrtab->out_shndx());
// Create the section table header.
Output_section_headers* oshdrs = this->create_shdrs(size, big_endian, &off);
file_header->set_section_info(oshdrs, shstrtab_section);
// Now we know exactly where everything goes in the output file.
return off;
}
// Return whether SEG1 should be before SEG2 in the output file. This
// is based entirely on the segment type and flags. When this is
// called the segment addresses has normally not yet been set.
bool
Layout::segment_precedes(const Output_segment* seg1,
const Output_segment* seg2)
{
elfcpp::Elf_Word type1 = seg1->type();
elfcpp::Elf_Word type2 = seg2->type();
// The single PT_PHDR segment is required to precede any loadable
// segment. We simply make it always first.
if (type1 == elfcpp::PT_PHDR)
{
assert(type2 != elfcpp::PT_PHDR);
return true;
}
if (type2 == elfcpp::PT_PHDR)
return false;
// The single PT_INTERP segment is required to precede any loadable
// segment. We simply make it always second.
if (type1 == elfcpp::PT_INTERP)
{
assert(type2 != elfcpp::PT_INTERP);
return true;
}
if (type2 == elfcpp::PT_INTERP)
return false;
// We then put PT_LOAD segments before any other segments.
if (type1 == elfcpp::PT_LOAD && type2 != elfcpp::PT_LOAD)
return true;
if (type2 == elfcpp::PT_LOAD && type1 != elfcpp::PT_LOAD)
return false;
// We put the PT_TLS segment last, because that is where the dynamic
// linker expects to find it (this is just for efficiency; other
// positions would also work correctly).
if (type1 == elfcpp::PT_TLS && type2 != elfcpp::PT_TLS)
return false;
if (type2 == elfcpp::PT_TLS && type1 != elfcpp::PT_TLS)
return true;
const elfcpp::Elf_Word flags1 = seg1->flags();
const elfcpp::Elf_Word flags2 = seg2->flags();
// The order of non-PT_LOAD segments is unimportant. We simply sort
// by the numeric segment type and flags values. There should not
// be more than one segment with the same type and flags.
if (type1 != elfcpp::PT_LOAD)
{
if (type1 != type2)
return type1 < type2;
assert(flags1 != flags2);
return flags1 < flags2;
}
// We sort PT_LOAD segments based on the flags. Readonly segments
// come before writable segments. Then executable segments come
// before non-executable segments. Then the unlikely case of a
// non-readable segment comes before the normal case of a readable
// segment. If there are multiple segments with the same type and
// flags, we require that the address be set, and we sort by
// virtual address and then physical address.
if ((flags1 & elfcpp::PF_W) != (flags2 & elfcpp::PF_W))
return (flags1 & elfcpp::PF_W) == 0;
if ((flags1 & elfcpp::PF_X) != (flags2 & elfcpp::PF_X))
return (flags1 & elfcpp::PF_X) != 0;
if ((flags1 & elfcpp::PF_R) != (flags2 & elfcpp::PF_R))
return (flags1 & elfcpp::PF_R) == 0;
uint64_t vaddr1 = seg1->vaddr();
uint64_t vaddr2 = seg2->vaddr();
if (vaddr1 != vaddr2)
return vaddr1 < vaddr2;
uint64_t paddr1 = seg1->paddr();
uint64_t paddr2 = seg2->paddr();
assert(paddr1 != paddr2);
return paddr1 < paddr2;
}
// Set the file offsets of all the segments, and all the sections they
// contain. They have all been created. LOAD_SEG must be be laid out
// first. Return the offset of the data to follow.
off_t
Layout::set_segment_offsets(const Target* target, Output_segment* load_seg,
unsigned int *pshndx)
{
// Sort them into the final order.
std::sort(this->segment_list_.begin(), this->segment_list_.end(),
Layout::Compare_segments());
// Find the PT_LOAD segments, and set their addresses and offsets
// and their section's addresses and offsets.
uint64_t addr = target->text_segment_address();
off_t off = 0;
bool was_readonly = false;
for (Segment_list::iterator p = this->segment_list_.begin();
p != this->segment_list_.end();
++p)
{
if ((*p)->type() == elfcpp::PT_LOAD)
{
if (load_seg != NULL && load_seg != *p)
abort();
load_seg = NULL;
// If the last segment was readonly, and this one is not,
// then skip the address forward one page, maintaining the
// same position within the page. This lets us store both
// segments overlapping on a single page in the file, but
// the loader will put them on different pages in memory.
uint64_t orig_addr = addr;
uint64_t orig_off = off;
uint64_t aligned_addr = addr;
uint64_t abi_pagesize = target->abi_pagesize();
if (was_readonly && ((*p)->flags() & elfcpp::PF_W) != 0)
{
uint64_t align = (*p)->addralign();
addr = align_address(addr, align);
aligned_addr = addr;
if ((addr & (abi_pagesize - 1)) != 0)
addr = addr + abi_pagesize;
}
unsigned int shndx_hold = *pshndx;
off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
uint64_t new_addr = (*p)->set_section_addresses(addr, &off, pshndx);
// Now that we know the size of this segment, we may be able
// to save a page in memory, at the cost of wasting some
// file space, by instead aligning to the start of a new
// page. Here we use the real machine page size rather than
// the ABI mandated page size.
if (aligned_addr != addr)
{
uint64_t common_pagesize = target->common_pagesize();
uint64_t first_off = (common_pagesize
- (aligned_addr
& (common_pagesize - 1)));
uint64_t last_off = new_addr & (common_pagesize - 1);
if (first_off > 0
&& last_off > 0
&& ((aligned_addr & ~ (common_pagesize - 1))
!= (new_addr & ~ (common_pagesize - 1)))
&& first_off + last_off <= common_pagesize)
{
*pshndx = shndx_hold;
addr = align_address(aligned_addr, common_pagesize);
off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
new_addr = (*p)->set_section_addresses(addr, &off, pshndx);
}
}
addr = new_addr;
if (((*p)->flags() & elfcpp::PF_W) == 0)
was_readonly = true;
}
}
// Handle the non-PT_LOAD segments, setting their offsets from their
// section's offsets.
for (Segment_list::iterator p = this->segment_list_.begin();
p != this->segment_list_.end();
++p)
{
if ((*p)->type() != elfcpp::PT_LOAD)
(*p)->set_offset();
}
return off;
}
// Set the file offset of all the sections not associated with a
// segment.
off_t
Layout::set_section_offsets(off_t off, unsigned int* pshndx)
{
for (Layout::Section_list::iterator p = this->section_list_.begin();
p != this->section_list_.end();
++p)
{
(*p)->set_out_shndx(*pshndx);
++*pshndx;
if ((*p)->offset() != -1)
continue;
off = align_address(off, (*p)->addralign());
(*p)->set_address(0, off);
off += (*p)->data_size();
}
return off;
}
// Create the symbol table sections.
void
Layout::create_symtab_sections(int size, const Input_objects* input_objects,
Symbol_table* symtab,
off_t* poff,
Output_section** posymtab,
Output_section** postrtab)
{
int symsize;
unsigned int align;
if (size == 32)
{
symsize = elfcpp::Elf_sizes<32>::sym_size;
align = 4;
}
else if (size == 64)
{
symsize = elfcpp::Elf_sizes<64>::sym_size;
align = 8;
}
else
abort();
off_t off = *poff;
off = align_address(off, align);
off_t startoff = off;
// Save space for the dummy symbol at the start of the section. We
// never bother to write this out--it will just be left as zero.
off += symsize;
for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
p != input_objects->relobj_end();
++p)
{
Task_lock_obj<Object> tlo(**p);
off = (*p)->finalize_local_symbols(off, &this->sympool_);
}
unsigned int local_symcount = (off - startoff) / symsize;
assert(local_symcount * symsize == off - startoff);
off = symtab->finalize(off, &this->sympool_);
this->sympool_.set_string_offsets();
const char* symtab_name = this->namepool_.add(".symtab", NULL);
Output_section* osymtab = new Output_section_symtab(symtab_name,
off - startoff);
this->section_list_.push_back(osymtab);
const char* strtab_name = this->namepool_.add(".strtab", NULL);
Output_section *ostrtab = new Output_section_strtab(strtab_name,
&this->sympool_);
this->section_list_.push_back(ostrtab);
this->special_output_list_.push_back(ostrtab);
osymtab->set_address(0, startoff);
osymtab->set_info(local_symcount);
osymtab->set_entsize(symsize);
osymtab->set_addralign(align);
*poff = off;
*posymtab = osymtab;
*postrtab = ostrtab;
}
// Create the .shstrtab section, which holds the names of the
// sections. At the time this is called, we have created all the
// output sections except .shstrtab itself.
Output_section*
Layout::create_shstrtab()
{
// FIXME: We don't need to create a .shstrtab section if we are
// stripping everything.
const char* name = this->namepool_.add(".shstrtab", NULL);
this->namepool_.set_string_offsets();
Output_section* os = new Output_section_strtab(name, &this->namepool_);
this->section_list_.push_back(os);
this->special_output_list_.push_back(os);
return os;
}
// Create the section headers. SIZE is 32 or 64. OFF is the file
// offset.
Output_section_headers*
Layout::create_shdrs(int size, bool big_endian, off_t* poff)
{
Output_section_headers* oshdrs;
oshdrs = new Output_section_headers(size, big_endian, this->segment_list_,
this->section_list_,
&this->namepool_);
off_t off = align_address(*poff, oshdrs->addralign());
oshdrs->set_address(0, off);
off += oshdrs->data_size();
*poff = off;
this->special_output_list_.push_back(oshdrs);
return oshdrs;
}
// The mapping of .gnu.linkonce section names to real section names.
#define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
const Layout::Linkonce_mapping Layout::linkonce_mapping[] =
{
MAPPING_INIT("d.rel.ro", ".data.rel.ro"), // Must be before "d".
MAPPING_INIT("t", ".text"),
MAPPING_INIT("r", ".rodata"),
MAPPING_INIT("d", ".data"),
MAPPING_INIT("b", ".bss"),
MAPPING_INIT("s", ".sdata"),
MAPPING_INIT("sb", ".sbss"),
MAPPING_INIT("s2", ".sdata2"),
MAPPING_INIT("sb2", ".sbss2"),
MAPPING_INIT("wi", ".debug_info"),
MAPPING_INIT("td", ".tdata"),
MAPPING_INIT("tb", ".tbss"),
MAPPING_INIT("lr", ".lrodata"),
MAPPING_INIT("l", ".ldata"),
MAPPING_INIT("lb", ".lbss"),
};
#undef MAPPING_INIT
const int Layout::linkonce_mapping_count =
sizeof(Layout::linkonce_mapping) / sizeof(Layout::linkonce_mapping[0]);
// Return the name of the output section to use for a .gnu.linkonce
// section. This is based on the default ELF linker script of the old
// GNU linker. For example, we map a name like ".gnu.linkonce.t.foo"
// to ".text". Set *PLEN to the length of the name. *PLEN is
// initialized to the length of NAME.
const char*
Layout::linkonce_output_name(const char* name, size_t *plen)
{
const char* s = name + sizeof(".gnu.linkonce") - 1;
if (*s != '.')
return name;
++s;
const Linkonce_mapping* plm = linkonce_mapping;
for (int i = 0; i < linkonce_mapping_count; ++i, ++plm)
{
if (strncmp(s, plm->from, plm->fromlen) == 0 && s[plm->fromlen] == '.')
{
*plen = plm->tolen;
return plm->to;
}
}
return name;
}
// Choose the output section name to use given an input section name.
// Set *PLEN to the length of the name. *PLEN is initialized to the
// length of NAME.
const char*
Layout::output_section_name(const char* name, size_t* plen)
{
if (Layout::is_linkonce(name))
{
// .gnu.linkonce sections are laid out as though they were named
// for the sections are placed into.
return Layout::linkonce_output_name(name, plen);
}
// If the section name has no '.', or only an initial '.', we use
// the name unchanged (i.e., ".text" is unchanged).
// Otherwise, if the section name does not include ".rel", we drop
// the last '.' and everything that follows (i.e., ".text.XXX"
// becomes ".text").
// Otherwise, if the section name has zero or one '.' after the
// ".rel", we use the name unchanged (i.e., ".rel.text" is
// unchanged).
// Otherwise, we drop the last '.' and everything that follows
// (i.e., ".rel.text.XXX" becomes ".rel.text").
const char* s = name;
if (*s == '.')
++s;
const char* sdot = strchr(s, '.');
if (sdot == NULL)
return name;
const char* srel = strstr(s, ".rel");
if (srel == NULL)
{
*plen = sdot - name;
return name;
}
sdot = strchr(srel + 1, '.');
if (sdot == NULL)
return name;
sdot = strchr(sdot + 1, '.');
if (sdot == NULL)
return name;
*plen = sdot - name;
return name;
}
// Record the signature of a comdat section, and return whether to
// include it in the link. If GROUP is true, this is a regular
// section group. If GROUP is false, this is a group signature
// derived from the name of a linkonce section. We want linkonce
// signatures and group signatures to block each other, but we don't
// want a linkonce signature to block another linkonce signature.
bool
Layout::add_comdat(const char* signature, bool group)
{
std::string sig(signature);
std::pair<Signatures::iterator, bool> ins(
this->signatures_.insert(std::make_pair(sig, group)));
if (ins.second)
{
// This is the first time we've seen this signature.
return true;
}
if (ins.first->second)
{
// We've already seen a real section group with this signature.
return false;
}
else if (group)
{
// This is a real section group, and we've already seen a
// linkonce section with tihs signature. Record that we've seen
// a section group, and don't include this section group.
ins.first->second = true;
return false;
}
else
{
// We've already seen a linkonce section and this is a linkonce
// section. These don't block each other--this may be the same
// symbol name with different section types.
return true;
}
}
// Write out data not associated with a section or the symbol table.
void
Layout::write_data(Output_file* of) const
{
for (Data_list::const_iterator p = this->special_output_list_.begin();
p != this->special_output_list_.end();
++p)
(*p)->write(of);
}
// Write_data_task methods.
// We can always run this task.
Task::Is_runnable_type
Write_data_task::is_runnable(Workqueue*)
{
return IS_RUNNABLE;
}
// We need to unlock FINAL_BLOCKER when finished.
Task_locker*
Write_data_task::locks(Workqueue* workqueue)
{
return new Task_locker_block(*this->final_blocker_, workqueue);
}
// Run the task--write out the data.
void
Write_data_task::run(Workqueue*)
{
this->layout_->write_data(this->of_);
}
// Write_symbols_task methods.
// We can always run this task.
Task::Is_runnable_type
Write_symbols_task::is_runnable(Workqueue*)
{
return IS_RUNNABLE;
}
// We need to unlock FINAL_BLOCKER when finished.
Task_locker*
Write_symbols_task::locks(Workqueue* workqueue)
{
return new Task_locker_block(*this->final_blocker_, workqueue);
}
// Run the task--write out the symbols.
void
Write_symbols_task::run(Workqueue*)
{
this->symtab_->write_globals(this->target_, this->sympool_, this->of_);
}
// Close_task_runner methods.
// Run the task--close the file.
void
Close_task_runner::run(Workqueue*)
{
this->of_->close();
}
// Instantiate the templates we need. We could use the configure
// script to restrict this to only the ones for implemented targets.
template
Output_section*
Layout::layout<32, false>(Relobj* object, unsigned int shndx, const char* name,
const elfcpp::Shdr<32, false>& shdr, off_t*);
template
Output_section*
Layout::layout<32, true>(Relobj* object, unsigned int shndx, const char* name,
const elfcpp::Shdr<32, true>& shdr, off_t*);
template
Output_section*
Layout::layout<64, false>(Relobj* object, unsigned int shndx, const char* name,
const elfcpp::Shdr<64, false>& shdr, off_t*);
template
Output_section*
Layout::layout<64, true>(Relobj* object, unsigned int shndx, const char* name,
const elfcpp::Shdr<64, true>& shdr, off_t*);
} // End namespace gold.