info section.
(Layout::add_comdat): Add new parameters. Change type
of signature parameter. Add object and shndx to signatures table.
(Layout::find_kept_object): New function.
* layout.h: Include <cstring>.
(Layout::is_debug_info_section): New function.
(Layout::add_comdat): Add new parameters.
(Layout::find_kept_object): New function.
(Layout::Kept_section): New struct.
(Layout::Signatures): Change type of map range.
* object.cc (Relobj::output_section_address): New function.
(Sized_relobj::include_section_group): Add new parameters. Change
calls to Layout::add_comdat. Change to build table of kept comdat
groups and table mapping discarded sections to kept sections.
(Sized_relobj::include_linkonce_section): Likewise. Add new parameter.
(Sized_relobj::do_layout): Change calls to include_section_group and
include_linkonce_section.
(Sized_relobj::do_finalize_local_symbols): Do not set local symbol
value to zero when section is discarded.
(Sized_relobj::map_to_kept_section): New function.
* object.h (Relobj::output_section_address): New function.
(Relobj::Comdat_group): New type.
(Relobj::find_comdat_group): New function.
(Relobj::Comdat_group_table): New type.
(Relobj::Kept_comdat_section): New type.
(Relobj::Kept_comdat_section_table): New type.
(Relobj::add_comdat_group): New function.
(Relobj::set_kept_comdat_section): New function.
(Relobj::get_kept_comdat_section): New function.
(Relobj::comdat_groups_): New field.
(Relobj::kept_comdat_sections_): New field.
(Symbol_value::input_value): Update comment.
(Sized_relobj::map_to_kept_section) New function.
(Sized_relobj::include_linkonce_section): Add new parameter.
* target-reloc.h (Comdat_behavior): New type.
(get_comdat_behavior): New function.
(relocate_section): Add code to map a discarded section to the
corresponding kept section when applying a relocation.
+2008-04-30 Cary Coutant <ccoutant@google.com>
+
+ * layout.cc (Layout::include_section): Refactored check for debug
+ info section.
+ (Layout::add_comdat): Add new parameters. Change type
+ of signature parameter. Add object and shndx to signatures table.
+ (Layout::find_kept_object): New function.
+ * layout.h: Include <cstring>.
+ (Layout::is_debug_info_section): New function.
+ (Layout::add_comdat): Add new parameters.
+ (Layout::find_kept_object): New function.
+ (Layout::Kept_section): New struct.
+ (Layout::Signatures): Change type of map range.
+ * object.cc (Relobj::output_section_address): New function.
+ (Sized_relobj::include_section_group): Add new parameters. Change
+ calls to Layout::add_comdat. Change to build table of kept comdat
+ groups and table mapping discarded sections to kept sections.
+ (Sized_relobj::include_linkonce_section): Likewise. Add new parameter.
+ (Sized_relobj::do_layout): Change calls to include_section_group and
+ include_linkonce_section.
+ (Sized_relobj::do_finalize_local_symbols): Do not set local symbol
+ value to zero when section is discarded.
+ (Sized_relobj::map_to_kept_section): New function.
+ * object.h (Relobj::output_section_address): New function.
+ (Relobj::Comdat_group): New type.
+ (Relobj::find_comdat_group): New function.
+ (Relobj::Comdat_group_table): New type.
+ (Relobj::Kept_comdat_section): New type.
+ (Relobj::Kept_comdat_section_table): New type.
+ (Relobj::add_comdat_group): New function.
+ (Relobj::set_kept_comdat_section): New function.
+ (Relobj::get_kept_comdat_section): New function.
+ (Relobj::comdat_groups_): New field.
+ (Relobj::kept_comdat_sections_): New field.
+ (Symbol_value::input_value): Update comment.
+ (Sized_relobj::map_to_kept_section) New function.
+ (Sized_relobj::include_linkonce_section): Add new parameter.
+ * target-reloc.h (Comdat_behavior): New type.
+ (get_comdat_behavior): New function.
+ (relocate_section): Add code to map a discarded section to the
+ corresponding kept section when applying a relocation.
+
2008-04-30 Craig Silverstein <csilvers@google.com>
* dwarf_reader.cc (next_generation_count): New static var.
if (parameters->options().strip_debug()
&& (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
{
- // Debugging sections can only be recognized by name.
- if (is_prefix_of(".debug", name)
- || is_prefix_of(".gnu.linkonce.wi.", name)
- || is_prefix_of(".line", name)
- || is_prefix_of(".stab", name))
+ if (is_debug_info_section(name))
return false;
}
if (parameters->options().strip_debug_gdb()
// want a linkonce signature to block another linkonce signature.
bool
-Layout::add_comdat(const char* signature, bool group)
+Layout::add_comdat(Relobj* object, unsigned int shndx,
+ const std::string& signature, bool group)
{
- std::string sig(signature);
+ Kept_section kept(object, shndx, group);
std::pair<Signatures::iterator, bool> ins(
- this->signatures_.insert(std::make_pair(sig, group)));
+ this->signatures_.insert(std::make_pair(signature, kept)));
if (ins.second)
{
return true;
}
- if (ins.first->second)
+ if (ins.first->second.group_)
{
// We've already seen a real section group with this signature.
return false;
// This is a real section group, and we've already seen a
// linkonce section with this signature. Record that we've seen
// a section group, and don't include this section group.
- ins.first->second = true;
+ ins.first->second.group_ = true;
return false;
}
else
}
}
+// Find the given comdat signature, and return the object and section
+// index of the kept group.
+Relobj*
+Layout::find_kept_object(const std::string& signature,
+ unsigned int* pshndx) const
+{
+ Signatures::const_iterator p = this->signatures_.find(signature);
+ if (p == this->signatures_.end())
+ return NULL;
+ if (pshndx != NULL)
+ *pshndx = p->second.shndx_;
+ return p->second.object_;
+}
+
// Store the allocated sections into the section list.
void
#ifndef GOLD_LAYOUT_H
#define GOLD_LAYOUT_H
+#include <cstring>
#include <list>
#include <string>
#include <utility>
is_linkonce(const char* name)
{ return strncmp(name, ".gnu.linkonce", sizeof(".gnu.linkonce") - 1) == 0; }
+ // Return true if a section is a debugging section.
+ static inline bool
+ is_debug_info_section(const char* name)
+ {
+ // Debugging sections can only be recognized by name.
+ return (strncmp(name, ".debug", sizeof(".debug") - 1) == 0
+ || strncmp(name, ".gnu.linkonce.wi.",
+ sizeof(".gnu.linkonce.wi.") - 1) == 0
+ || strncmp(name, ".line", sizeof(".line") - 1) == 0
+ || strncmp(name, ".stab", sizeof(".stab") - 1) == 0);
+ }
+
// Record the signature of a comdat section, and return whether to
// include it in the link. The GROUP parameter is true for a
// section group signature, false for a signature derived from a
// .gnu.linkonce section.
bool
- add_comdat(const char*, bool group);
+ add_comdat(Relobj*, unsigned int, const std::string&, bool group);
+
+ // Find the given comdat signature, and return the object and section
+ // index of the kept group.
+ Relobj*
+ find_kept_object(const std::string&, unsigned int*) const;
// Finalize the layout after all the input sections have been added.
off_t
segment_precedes(const Output_segment* seg1, const Output_segment* seg2);
// A mapping used for group signatures.
- typedef Unordered_map<std::string, bool> Signatures;
+ struct Kept_section
+ {
+ Kept_section()
+ : object_(NULL), shndx_(0), group_(false)
+ { }
+ Kept_section(Relobj* object, unsigned int shndx, bool group)
+ : object_(object), shndx_(shndx), group_(group)
+ { }
+ Relobj* object_;
+ unsigned int shndx_;
+ bool group_;
+ };
+ typedef Unordered_map<std::string, Kept_section> Signatures;
// Mapping from input section name/type/flags to output section. We
// use canonicalized strings here.
return false;
}
+// Class Relobj.
+
+// Return the output address of the input section SHNDX.
+uint64_t
+Relobj::output_section_address(unsigned int shndx) const
+{
+ section_offset_type offset;
+ Output_section* os = this->output_section(shndx, &offset);
+ gold_assert(os != NULL && offset != -1);
+ return os->address() + offset;
+}
+
// Class Sized_relobj.
template<int size, bool big_endian>
Layout* layout,
unsigned int index,
const char* name,
- const elfcpp::Shdr<size, big_endian>& shdr,
+ const unsigned char* shdrs,
+ const char* section_names,
+ section_size_type section_names_size,
std::vector<bool>* omit)
{
// Read the section contents.
+ typename This::Shdr shdr(shdrs + index * This::shdr_size);
const unsigned char* pcon = this->get_view(shdr.get_sh_offset(),
shdr.get_sh_size(), true, false);
const elfcpp::Elf_Word* pword =
return false;
}
- const char* signature = psymnames + sym.get_st_name();
+ std::string signature(psymnames + sym.get_st_name());
// It seems that some versions of gas will create a section group
// associated with a section symbol, and then fail to give a name to
// the section symbol. In such a case, use the name of the section.
- std::string secname;
if (signature[0] == '\0' && sym.get_st_type() == elfcpp::STT_SECTION)
{
bool is_ordinary;
symndx, sym_shndx);
return false;
}
- secname = this->section_name(sym_shndx);
- signature = secname.c_str();
+ typename This::Shdr member_shdr(shdrs + sym_shndx * This::shdr_size);
+ if (member_shdr.get_sh_name() < section_names_size)
+ signature = section_names + member_shdr.get_sh_name();
}
- // Record this section group, and see whether we've already seen one
- // with the same signature.
+ // Record this section group in the layout, and see whether we've already
+ // seen one with the same signature.
+ bool include_group = ((flags & elfcpp::GRP_COMDAT) == 0
+ || layout->add_comdat(this, index, signature, true));
+
+ if (include_group && parameters->options().relocatable())
+ layout->layout_group(symtab, this, index, name, signature.c_str(),
+ shdr, pword);
+
+ Relobj* kept_object = NULL;
+ Comdat_group* kept_group = NULL;
- if ((flags & elfcpp::GRP_COMDAT) == 0
- || layout->add_comdat(signature, true))
+ if (!include_group)
{
- if (parameters->options().relocatable())
- layout->layout_group(symtab, this, index, name, signature, shdr,
- pword);
- return true;
+ // This group is being discarded. Find the object and group
+ // that was kept in its place.
+ unsigned int kept_group_index = 0;
+ kept_object = layout->find_kept_object(signature, &kept_group_index);
+ if (kept_object != NULL)
+ kept_group = kept_object->find_comdat_group(kept_group_index);
+ }
+ else if (flags & elfcpp::GRP_COMDAT)
+ {
+ // This group is being kept. Create the table to map section names
+ // to section indexes and add it to the table of groups.
+ kept_group = new Comdat_group();
+ this->add_comdat_group(index, kept_group);
}
- // This is a duplicate. We want to discard the sections in this
- // group.
size_t count = shdr.get_sh_size() / sizeof(elfcpp::Elf_Word);
for (size_t i = 1; i < count; ++i)
{
this->error(_("invalid section group %u refers to earlier section %u"),
index, secnum);
- (*omit)[secnum] = true;
+ // Get the name of the member section.
+ typename This::Shdr member_shdr(shdrs + secnum * This::shdr_size);
+ if (member_shdr.get_sh_name() >= section_names_size)
+ {
+ // This is an error, but it will be diagnosed eventually
+ // in do_layout, so we don't need to do anything here but
+ // ignore it.
+ continue;
+ }
+ std::string mname(section_names + member_shdr.get_sh_name());
+
+ if (!include_group)
+ {
+ (*omit)[secnum] = true;
+ if (kept_group != NULL)
+ {
+ // Find the corresponding kept section, and store that info
+ // in the discarded section table.
+ Comdat_group::const_iterator p = kept_group->find(mname);
+ if (p != kept_group->end())
+ {
+ Kept_comdat_section* kept =
+ new Kept_comdat_section(kept_object, p->second);
+ this->set_kept_comdat_section(secnum, kept);
+ }
+ }
+ }
+ else if (flags & elfcpp::GRP_COMDAT)
+ {
+ // Add the section to the kept group table.
+ gold_assert(kept_group != NULL);
+ kept_group->insert(std::make_pair(mname, secnum));
+ }
}
- return false;
+ return include_group;
}
// Whether to include a linkonce section in the link. NAME is the
bool
Sized_relobj<size, big_endian>::include_linkonce_section(
Layout* layout,
+ unsigned int index,
const char* name,
const elfcpp::Shdr<size, big_endian>&)
{
symname = name + strlen(linkonce_t);
else
symname = strrchr(name, '.') + 1;
- bool include1 = layout->add_comdat(symname, false);
- bool include2 = layout->add_comdat(name, true);
+ std::string sig1(symname);
+ std::string sig2(name);
+ bool include1 = layout->add_comdat(this, index, sig1, false);
+ bool include2 = layout->add_comdat(this, index, sig2, true);
+
+ if (!include2)
+ {
+ // The section is being discarded on the basis of its section
+ // name (i.e., the kept section was also a linkonce section).
+ // In this case, the section index stored with the layout object
+ // is the linkonce section that was kept.
+ unsigned int kept_group_index = 0;
+ Relobj* kept_object = layout->find_kept_object(sig2, &kept_group_index);
+ if (kept_object != NULL)
+ {
+ Kept_comdat_section* kept =
+ new Kept_comdat_section(kept_object, kept_group_index);
+ this->set_kept_comdat_section(index, kept);
+ }
+ }
+ else if (!include1)
+ {
+ // The section is being discarded on the basis of its symbol
+ // name. This means that the corresponding kept section was
+ // part of a comdat group, and it will be difficult to identify
+ // the specific section within that group that corresponds to
+ // this linkonce section. We'll handle the simple case where
+ // the group has only one member section. Otherwise, it's not
+ // worth the effort.
+ unsigned int kept_group_index = 0;
+ Relobj* kept_object = layout->find_kept_object(sig1, &kept_group_index);
+ if (kept_object != NULL)
+ {
+ Comdat_group* kept_group =
+ kept_object->find_comdat_group(kept_group_index);
+ if (kept_group != NULL && kept_group->size() == 1)
+ {
+ Comdat_group::const_iterator p = kept_group->begin();
+ gold_assert(p != kept_group->end());
+ Kept_comdat_section* kept =
+ new Kept_comdat_section(kept_object, p->second);
+ this->set_kept_comdat_section(index, kept);
+ }
+ }
+ }
+
return include1 && include2;
}
return;
// Get the section headers.
- const unsigned char* pshdrs = sd->section_headers->data();
+ const unsigned char* shdrs = sd->section_headers->data();
+ const unsigned char* pshdrs;
// Get the section names.
const unsigned char* pnamesu = sd->section_names->data();
std::vector<unsigned int> reloc_shndx(shnum, 0);
std::vector<unsigned int> reloc_type(shnum, elfcpp::SHT_NULL);
// Skip the first, dummy, section.
- pshdrs += This::shdr_size;
+ pshdrs = shdrs + This::shdr_size;
for (unsigned int i = 1; i < shnum; ++i, pshdrs += This::shdr_size)
{
typename This::Shdr shdr(pshdrs);
std::vector<unsigned int> eh_frame_sections;
// Skip the first, dummy, section.
- pshdrs = sd->section_headers->data() + This::shdr_size;
+ pshdrs = shdrs + This::shdr_size;
for (unsigned int i = 1; i < shnum; ++i, pshdrs += This::shdr_size)
{
typename This::Shdr shdr(pshdrs);
{
if (shdr.get_sh_type() == elfcpp::SHT_GROUP)
{
- if (!this->include_section_group(symtab, layout, i, name, shdr,
+ if (!this->include_section_group(symtab, layout, i, name, shdrs,
+ pnames, sd->section_names_size,
&omit))
discard = true;
}
else if ((shdr.get_sh_flags() & elfcpp::SHF_GROUP) == 0
&& Layout::is_linkonce(name))
{
- if (!this->include_linkonce_section(layout, name, shdr))
+ if (!this->include_linkonce_section(layout, i, name, shdr))
discard = true;
}
}
if (os == NULL)
{
- lv.set_output_value(0);
+ // This local symbol belongs to a section we are discarding.
+ // In some cases when applying relocations later, we will
+ // attempt to match it to the corresponding kept section,
+ // so we leave the input value unchanged here.
continue;
}
else if (mo[shndx].offset == -1)
return false;
}
+// Look for a kept section corresponding to the given discarded section,
+// and return its output address. This is used only for relocations in
+// debugging sections. If we can't find the kept section, return 0.
+
+template<int size, bool big_endian>
+typename Sized_relobj<size, big_endian>::Address
+Sized_relobj<size, big_endian>::map_to_kept_section(
+ unsigned int shndx,
+ bool* found) const
+{
+ Kept_comdat_section *kept = this->get_kept_comdat_section(shndx);
+ if (kept != NULL)
+ {
+ gold_assert(kept->object_ != NULL);
+ *found = true;
+ return (static_cast<Address>
+ (kept->object_->output_section_address(kept->shndx_)));
+ }
+ *found = false;
+ return 0;
+}
+
// Input_objects methods.
// Add a regular relocatable object to the list. Return false if this
Relobj(const std::string& name, Input_file* input_file, off_t offset = 0)
: Object(name, input_file, false, offset),
map_to_output_(),
+ comdat_groups_(),
+ kept_comdat_sections_(),
map_to_relocatable_relocs_(NULL),
object_merge_map_(NULL),
relocs_must_follow_section_writes_(false)
this->map_to_output_[shndx].offset = off;
}
+ // Return the output address of the input section SHNDX.
+ uint64_t
+ output_section_address(unsigned int shndx) const;
+
// Return true if we need to wait for output sections to be written
// before we can apply relocations. This is true if the object has
// any relocations for sections which require special handling, such
return (*this->map_to_relocatable_relocs_)[reloc_shndx];
}
+ // Information needed to keep track of kept comdat groups. This is
+ // simply a map from the section name to its section index. This may
+ // not be a one-to-one mapping, but we ignore that possibility since
+ // this is used only to attempt to handle stray relocations from
+ // non-comdat debug sections that refer to comdat loadable sections.
+ typedef Unordered_map<std::string, unsigned int> Comdat_group;
+
+ // Find a comdat group table given its group section SHNDX.
+ Comdat_group*
+ find_comdat_group(unsigned int shndx) const
+ {
+ Comdat_group_table::const_iterator p =
+ this->comdat_groups_.find(shndx);
+ if (p != this->comdat_groups_.end())
+ return p->second;
+ return NULL;
+ }
+
protected:
// What we need to know to map an input section to an output
// section. We keep an array of these, one for each input section,
section_offset_type offset;
};
+ // A map from group section index to the table of group members.
+ typedef std::map<unsigned int, Comdat_group*> Comdat_group_table;
+
+ // To keep track of discarded comdat sections, we need to map a member
+ // section index to the object and section index of the corresponding
+ // kept section.
+ struct Kept_comdat_section
+ {
+ Kept_comdat_section(Relobj* object, unsigned int shndx)
+ : object_(object), shndx_(shndx)
+ { }
+ Relobj* object_;
+ unsigned int shndx_;
+ };
+ typedef std::map<unsigned int, Kept_comdat_section*>
+ Kept_comdat_section_table;
+
// Read the relocs--implemented by child class.
virtual void
do_read_relocs(Read_relocs_data*) = 0;
map_to_output() const
{ return this->map_to_output_; }
+ // Record a new comdat group whose group section index is SHNDX.
+ void
+ add_comdat_group(unsigned int shndx, Comdat_group* group)
+ { this->comdat_groups_[shndx] = group; }
+
+ // Record a mapping from discarded section SHNDX to the corresponding
+ // kept section.
+ void
+ set_kept_comdat_section(unsigned int shndx, Kept_comdat_section* kept)
+ {
+ this->kept_comdat_sections_[shndx] = kept;
+ }
+
+ // Find the kept section corresponding to the discarded section SHNDX.
+ Kept_comdat_section*
+ get_kept_comdat_section(unsigned int shndx) const
+ {
+ Kept_comdat_section_table::const_iterator p =
+ this->kept_comdat_sections_.find(shndx);
+ if (p == this->kept_comdat_sections_.end())
+ return NULL;
+ return p->second;
+ }
+
// Set the size of the relocatable relocs array.
void
size_relocatable_relocs()
private:
// Mapping from input sections to output section.
std::vector<Map_to_output> map_to_output_;
+ // Table of kept comdat groups.
+ Comdat_group_table comdat_groups_;
+ // Table mapping discarded comdat sections to corresponding kept sections.
+ Kept_comdat_section_table kept_comdat_sections_;
// Mapping from input section index to the information recorded for
// the relocations. This is only used for a relocatable link.
std::vector<Relocatable_relocs*>* map_to_relocatable_relocs_;
{ this->u_.value = value; }
// Return the input value. This is only called by
- // finalize_local_symbols.
+ // finalize_local_symbols and (in special cases) relocate_section.
Value
input_value() const
{ return this->u_.value; }
get_symbol_location_info(unsigned int shndx, off_t offset,
Symbol_location_info* info);
+ // Look for a kept section corresponding to the given discarded section,
+ // and return its output address. This is used only for relocations in
+ // debugging sections.
+ Address
+ map_to_kept_section(unsigned int shndx, bool* found) const;
+
protected:
// Read the symbols.
void
// Whether to include a section group in the link.
bool
include_section_group(Symbol_table*, Layout*, unsigned int, const char*,
- const elfcpp::Shdr<size, big_endian>&,
+ const unsigned char*, const char *, section_size_type,
std::vector<bool>*);
// Whether to include a linkonce section in the link.
bool
- include_linkonce_section(Layout*, const char*,
+ include_linkonce_section(Layout*, unsigned int, const char*,
const elfcpp::Shdr<size, big_endian>&);
// Views and sizes when relocating.
}
}
+// Behavior for relocations to discarded comdat sections.
+
+enum Comdat_behavior
+{
+ CB_UNDETERMINED, // Not yet determined -- need to look at section name.
+ CB_PRETEND, // Attempt to map to the corresponding kept section.
+ CB_IGNORE, // Ignore the relocation.
+ CB_WARNING // Print a warning.
+};
+
+// Decide what the linker should do for relocations that refer to discarded
+// comdat sections. This decision is based on the name of the section being
+// relocated.
+
+inline Comdat_behavior
+get_comdat_behavior(const char* name)
+{
+ if (Layout::is_debug_info_section(name))
+ return CB_PRETEND;
+ if (strcmp(name, ".eh_frame") == 0
+ || strcmp(name, ".gcc_except_table") == 0)
+ return CB_IGNORE;
+ return CB_WARNING;
+}
+
// This function implements the generic part of relocation processing.
// The template parameter Relocate must be a class type which provides
// a single function, relocate(), which implements the machine
Sized_relobj<size, big_endian>* object = relinfo->object;
unsigned int local_count = object->local_symbol_count();
+ Comdat_behavior comdat_behavior = CB_UNDETERMINED;
+
for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size)
{
Reltype reloc(prelocs);
{
sym = NULL;
psymval = object->local_symbol(r_sym);
+
+ // If the local symbol belongs to a section we are discarding,
+ // and that section is a debug section, try to find the
+ // corresponding kept section and map this symbol to its
+ // counterpart in the kept section.
+ bool is_ordinary;
+ unsigned int shndx = psymval->input_shndx(&is_ordinary);
+ if (is_ordinary
+ && shndx != elfcpp::SHN_UNDEF
+ && !object->is_section_included(shndx))
+ {
+ if (comdat_behavior == CB_UNDETERMINED)
+ {
+ const char* name =
+ object->section_name(relinfo->data_shndx).c_str();
+ comdat_behavior = get_comdat_behavior(name);
+ }
+ if (comdat_behavior == CB_PRETEND)
+ {
+ bool found;
+ typename elfcpp::Elf_types<size>::Elf_Addr value =
+ object->map_to_kept_section(shndx, &found);
+ if (found)
+ symval.set_output_value(value + psymval->input_value());
+ else
+ symval.set_output_value(0);
+ }
+ else
+ {
+ if (comdat_behavior == CB_WARNING)
+ gold_warning_at_location(relinfo, i, offset,
+ _("Relocation refers to discarded "
+ "comdat section"));
+ symval.set_output_value(0);
+ }
+ symval.set_no_output_symtab_entry();
+ psymval = &symval;
+ }
}
else
{
projects / binutils-gdb.git / commitdiff