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binutils-gdb/gold/symtab.h

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// symtab.h -- the gold symbol table -*- C++ -*-
// Copyright (C) 2006-2021 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.
// Symbol_table
// The symbol table.
#ifndef GOLD_SYMTAB_H
#define GOLD_SYMTAB_H
#include <string>
#include <utility>
#include <vector>
#include "elfcpp.h"
#include "parameters.h"
#include "stringpool.h"
#include "object.h"
namespace gold
{
class Mapfile;
class Object;
class Relobj;
template<int size, bool big_endian>
class Sized_relobj_file;
template<int size, bool big_endian>
class Sized_pluginobj;
class Dynobj;
template<int size, bool big_endian>
class Sized_dynobj;
template<int size, bool big_endian>
class Sized_incrobj;
class Versions;
class Version_script_info;
class Input_objects;
class Output_data;
class Output_section;
class Output_segment;
class Output_file;
class Output_symtab_xindex;
class Garbage_collection;
class Icf;
// The base class of an entry in the symbol table. The symbol table
// can have a lot of entries, so we don't want this class too big.
// Size dependent fields can be found in the template class
// Sized_symbol. Targets may support their own derived classes.
class Symbol
{
public:
// Because we want the class to be small, we don't use any virtual
// functions. But because symbols can be defined in different
// places, we need to classify them. This enum is the different
// sources of symbols we support.
enum Source
{
// Symbol defined in a relocatable or dynamic input file--this is
// the most common case.
FROM_OBJECT,
// Symbol defined in an Output_data, a special section created by
// the target.
IN_OUTPUT_DATA,
// Symbol defined in an Output_segment, with no associated
// section.
IN_OUTPUT_SEGMENT,
// Symbol value is constant.
IS_CONSTANT,
// Symbol is undefined.
IS_UNDEFINED
};
// When the source is IN_OUTPUT_SEGMENT, we need to describe what
// the offset means.
enum Segment_offset_base
{
// From the start of the segment.
SEGMENT_START,
// From the end of the segment.
SEGMENT_END,
// From the filesz of the segment--i.e., after the loaded bytes
// but before the bytes which are allocated but zeroed.
SEGMENT_BSS
};
// Return the symbol name.
const char*
name() const
{ return this->name_; }
// Return the (ANSI) demangled version of the name, if
// parameters.demangle() is true. Otherwise, return the name. This
// is intended to be used only for logging errors, so it's not
// super-efficient.
std::string
demangled_name() const;
// Return the symbol version. This will return NULL for an
// unversioned symbol.
const char*
version() const
{ return this->version_; }
void
clear_version()
{ this->version_ = NULL; }
// Return whether this version is the default for this symbol name
// (eg, "foo@@V2" is a default version; "foo@V1" is not). Only
// meaningful for versioned symbols.
bool
is_default() const
{
gold_assert(this->version_ != NULL);
return this->is_def_;
}
// Set that this version is the default for this symbol name.
void
set_is_default()
{ this->is_def_ = true; }
// Set that this version is not the default for this symbol name.
void
set_is_not_default()
{ this->is_def_ = false; }
// Return the symbol's name as name@version (or name@@version).
std::string
versioned_name() const;
// Return the symbol source.
Source
source() const
{ return this->source_; }
// Return the object with which this symbol is associated.
Object*
object() const
{
gold_assert(this->source_ == FROM_OBJECT);
return this->u1_.object;
}
// Return the index of the section in the input relocatable or
// dynamic object file.
unsigned int
shndx(bool* is_ordinary) const
{
gold_assert(this->source_ == FROM_OBJECT);
*is_ordinary = this->is_ordinary_shndx_;
return this->u2_.shndx;
}
// Return the output data section with which this symbol is
// associated, if the symbol was specially defined with respect to
// an output data section.
Output_data*
output_data() const
{
gold_assert(this->source_ == IN_OUTPUT_DATA);
return this->u1_.output_data;
}
// If this symbol was defined with respect to an output data
// section, return whether the value is an offset from end.
bool
offset_is_from_end() const
{
gold_assert(this->source_ == IN_OUTPUT_DATA);
return this->u2_.offset_is_from_end;
}
// Return the output segment with which this symbol is associated,
// if the symbol was specially defined with respect to an output
// segment.
Output_segment*
output_segment() const
{
gold_assert(this->source_ == IN_OUTPUT_SEGMENT);
return this->u1_.output_segment;
}
// If this symbol was defined with respect to an output segment,
// return the offset base.
Segment_offset_base
offset_base() const
{
gold_assert(this->source_ == IN_OUTPUT_SEGMENT);
return this->u2_.offset_base;
}
// Return the symbol binding.
elfcpp::STB
binding() const
{ return this->binding_; }
// Return the symbol type.
elfcpp::STT
type() const
{ return this->type_; }
// Set the symbol type.
void
set_type(elfcpp::STT type)
{ this->type_ = type; }
// Return true for function symbol.
bool
is_func() const
{
return (this->type_ == elfcpp::STT_FUNC
|| this->type_ == elfcpp::STT_GNU_IFUNC);
}
// Return the symbol visibility.
elfcpp::STV
visibility() const
{ return this->visibility_; }
// Set the visibility.
void
set_visibility(elfcpp::STV visibility)
{ this->visibility_ = visibility; }
// Override symbol visibility.
void
override_visibility(elfcpp::STV);
// Set whether the symbol was originally a weak undef or a regular undef
// when resolved by a dynamic def or by a special symbol.
inline void
set_undef_binding(elfcpp::STB bind)
{
if (!this->undef_binding_set_ || this->undef_binding_weak_)
{
this->undef_binding_weak_ = bind == elfcpp::STB_WEAK;
this->undef_binding_set_ = true;
}
}
// Return TRUE if a weak undef was resolved by a dynamic def or
// by a special symbol.
inline bool
is_undef_binding_weak() const
{ return this->undef_binding_weak_; }
// Return the non-visibility part of the st_other field.
unsigned char
nonvis() const
{ return this->nonvis_; }
// Set the non-visibility part of the st_other field.
void
set_nonvis(unsigned int nonvis)
{ this->nonvis_ = nonvis; }
// Return whether this symbol is a forwarder. This will never be
// true of a symbol found in the hash table, but may be true of
// symbol pointers attached to object files.
bool
is_forwarder() const
{ return this->is_forwarder_; }
// Mark this symbol as a forwarder.
void
set_forwarder()
{ this->is_forwarder_ = true; }
// Return whether this symbol has an alias in the weak aliases table
// in Symbol_table.
bool
has_alias() const
{ return this->has_alias_; }
// Mark this symbol as having an alias.
void
set_has_alias()
{ this->has_alias_ = true; }
// Return whether this symbol needs an entry in the dynamic symbol
// table.
bool
needs_dynsym_entry() const
{
return (this->needs_dynsym_entry_
|| (this->in_reg()
&& this->in_dyn()
&& this->is_externally_visible()));
}
// Mark this symbol as needing an entry in the dynamic symbol table.
void
set_needs_dynsym_entry()
{ this->needs_dynsym_entry_ = true; }
// Return whether this symbol should be added to the dynamic symbol
// table.
bool
should_add_dynsym_entry(Symbol_table*) const;
// Return whether this symbol has been seen in a regular object.
bool
in_reg() const
{ return this->in_reg_; }
// Mark this symbol as having been seen in a regular object.
void
set_in_reg()
{ this->in_reg_ = true; }
// Forget this symbol was seen in a regular object.
void
clear_in_reg()
{ this->in_reg_ = false; }
// Return whether this symbol has been seen in a dynamic object.
bool
in_dyn() const
{ return this->in_dyn_; }
// Mark this symbol as having been seen in a dynamic object.
void
set_in_dyn()
{ this->in_dyn_ = true; }
// Return whether this symbol is defined in a dynamic object.
bool
from_dyn() const
{ return this->source_ == FROM_OBJECT && this->object()->is_dynamic(); }
// Return whether this symbol has been seen in a real ELF object.
// (IN_REG will return TRUE if the symbol has been seen in either
// a real ELF object or an object claimed by a plugin.)
bool
in_real_elf() const
{ return this->in_real_elf_; }
// Mark this symbol as having been seen in a real ELF object.
void
set_in_real_elf()
{ this->in_real_elf_ = true; }
// Return whether this symbol was defined in a section that was
// discarded from the link. This is used to control some error
// reporting.
bool
is_defined_in_discarded_section() const
{ return this->is_defined_in_discarded_section_; }
// Mark this symbol as having been defined in a discarded section.
void
set_is_defined_in_discarded_section()
{ this->is_defined_in_discarded_section_ = true; }
// Return the index of this symbol in the output file symbol table.
// A value of -1U means that this symbol is not going into the
// output file. This starts out as zero, and is set to a non-zero
// value by Symbol_table::finalize. It is an error to ask for the
// symbol table index before it has been set.
unsigned int
symtab_index() const
{
gold_assert(this->symtab_index_ != 0);
return this->symtab_index_;
}
// Set the index of the symbol in the output file symbol table.
void
set_symtab_index(unsigned int index)
{
gold_assert(index != 0);
this->symtab_index_ = index;
}
// Return whether this symbol already has an index in the output
// file symbol table.
bool
has_symtab_index() const
{ return this->symtab_index_ != 0; }
// Return the index of this symbol in the dynamic symbol table. A
// value of -1U means that this symbol is not going into the dynamic
// symbol table. This starts out as zero, and is set to a non-zero
// during Layout::finalize. It is an error to ask for the dynamic
// symbol table index before it has been set.
unsigned int
dynsym_index() const
{
gold_assert(this->dynsym_index_ != 0);
return this->dynsym_index_;
}
// Set the index of the symbol in the dynamic symbol table.
void
set_dynsym_index(unsigned int index)
{
gold_assert(index != 0);
this->dynsym_index_ = index;
}
// Return whether this symbol already has an index in the dynamic
// symbol table.
bool
has_dynsym_index() const
{ return this->dynsym_index_ != 0; }
// Return whether this symbol has an entry in the GOT section.
// For a TLS symbol, this GOT entry will hold its tp-relative offset.
bool
has_got_offset(unsigned int got_type) const
{ return this->got_offsets_.get_offset(got_type) != -1U; }
// Return the offset into the GOT section of this symbol.
unsigned int
got_offset(unsigned int got_type) const
{
unsigned int got_offset = this->got_offsets_.get_offset(got_type);
gold_assert(got_offset != -1U);
return got_offset;
}
// Set the GOT offset of this symbol.
void
set_got_offset(unsigned int got_type, unsigned int got_offset)
{ this->got_offsets_.set_offset(got_type, got_offset); }
// Return the GOT offset list.
const Got_offset_list*
got_offset_list() const
{ return this->got_offsets_.get_list(); }
// Return whether this symbol has an entry in the PLT section.
bool
has_plt_offset() const
{ return this->plt_offset_ != -1U; }
// Return the offset into the PLT section of this symbol.
unsigned int
plt_offset() const
{
gold_assert(this->has_plt_offset());
return this->plt_offset_;
}
// Set the PLT offset of this symbol.
void
set_plt_offset(unsigned int plt_offset)
{
gold_assert(plt_offset != -1U);
this->plt_offset_ = plt_offset;
}
// Return whether this dynamic symbol needs a special value in the
// dynamic symbol table.
bool
needs_dynsym_value() const
{ return this->needs_dynsym_value_; }
// Set that this dynamic symbol needs a special value in the dynamic
// symbol table.
void
set_needs_dynsym_value()
{
gold_assert(this->object()->is_dynamic());
this->needs_dynsym_value_ = true;
}
// Return true if the final value of this symbol is known at link
// time.
bool
final_value_is_known() const;
// Return true if SHNDX represents a common symbol. This depends on
// the target.
static bool
is_common_shndx(unsigned int shndx);
// Return whether this is a defined symbol (not undefined or
// common).
bool
is_defined() const
{
bool is_ordinary;
if (this->source_ != FROM_OBJECT)
return this->source_ != IS_UNDEFINED;
unsigned int shndx = this->shndx(&is_ordinary);
return (is_ordinary
? shndx != elfcpp::SHN_UNDEF
: !Symbol::is_common_shndx(shndx));
}
// Return true if this symbol is from a dynamic object.
bool
is_from_dynobj() const
{
return this->source_ == FROM_OBJECT && this->object()->is_dynamic();
}
// Return whether this is a placeholder symbol from a plugin object.
bool
is_placeholder() const
{
return this->source_ == FROM_OBJECT && this->object()->pluginobj() != NULL;
}
// Return whether this is an undefined symbol.
bool
is_undefined() const
{
bool is_ordinary;
return ((this->source_ == FROM_OBJECT
&& this->shndx(&is_ordinary) == elfcpp::SHN_UNDEF
&& is_ordinary)
|| this->source_ == IS_UNDEFINED);
}
// Return whether this is a weak undefined symbol.
bool
is_weak_undefined() const
{
return (this->is_undefined()
&& (this->binding() == elfcpp::STB_WEAK
|| this->is_undef_binding_weak()
|| parameters->options().weak_unresolved_symbols()));
}
// Return whether this is a strong undefined symbol.
bool
is_strong_undefined() const
{
return (this->is_undefined()
&& this->binding() != elfcpp::STB_WEAK
&& !this->is_undef_binding_weak()
&& !parameters->options().weak_unresolved_symbols());
}
// Return whether this is an absolute symbol.
bool
is_absolute() const
{
bool is_ordinary;
return ((this->source_ == FROM_OBJECT
&& this->shndx(&is_ordinary) == elfcpp::SHN_ABS
&& !is_ordinary)
|| this->source_ == IS_CONSTANT);
}
// Return whether this is a common symbol.
bool
is_common() const
{
if (this->source_ != FROM_OBJECT)
return false;
bool is_ordinary;
unsigned int shndx = this->shndx(&is_ordinary);
return !is_ordinary && Symbol::is_common_shndx(shndx);
}
// Return whether this symbol can be seen outside this object.
bool
is_externally_visible() const
{
return ((this->visibility_ == elfcpp::STV_DEFAULT
|| this->visibility_ == elfcpp::STV_PROTECTED)
&& !this->is_forced_local_);
}
// Return true if this symbol can be preempted by a definition in
// another link unit.
bool
is_preemptible() const
{
// It doesn't make sense to ask whether a symbol defined in
// another object is preemptible.
gold_assert(!this->is_from_dynobj());
// It doesn't make sense to ask whether an undefined symbol
// is preemptible.
gold_assert(!this->is_undefined());
// If a symbol does not have default visibility, it can not be
// seen outside this link unit and therefore is not preemptible.
if (this->visibility_ != elfcpp::STV_DEFAULT)
return false;
// If this symbol has been forced to be a local symbol by a
// version script, then it is not visible outside this link unit
// and is not preemptible.
if (this->is_forced_local_)
return false;
// If we are not producing a shared library, then nothing is
// preemptible.
if (!parameters->options().shared())
return false;
// If the symbol was named in a --dynamic-list script, it is preemptible.
if (parameters->options().in_dynamic_list(this->name()))
return true;
// If the user used -Bsymbolic, then nothing (else) is preemptible.
if (parameters->options().Bsymbolic())
return false;
// If the user used -Bsymbolic-functions, then functions are not
// preemptible. We explicitly check for not being STT_OBJECT,
// rather than for being STT_FUNC, because that is what the GNU
// linker does.
if (this->type() != elfcpp::STT_OBJECT
&& parameters->options().Bsymbolic_functions())
return false;
// Otherwise the symbol is preemptible.
return true;
}
// Return true if this symbol is a function that needs a PLT entry.
bool
needs_plt_entry() const
{
// An undefined symbol from an executable does not need a PLT entry.
if (this->is_undefined() && !parameters->options().shared())
return false;
// An STT_GNU_IFUNC symbol always needs a PLT entry, even when
// doing a static link.
if (this->type() == elfcpp::STT_GNU_IFUNC)
return true;
// We only need a PLT entry for a function.
if (!this->is_func())
return false;
// If we're doing a static link or a -pie link, we don't create
// PLT entries.
if (parameters->doing_static_link()
|| parameters->options().pie())
return false;
// We need a PLT entry if the function is defined in a dynamic
// object, or is undefined when building a shared object, or if it
// is subject to pre-emption.
return (this->is_from_dynobj()
|| this->is_undefined()
|| this->is_preemptible());
}
// When determining whether a reference to a symbol needs a dynamic
// relocation, we need to know several things about the reference.
// These flags may be or'ed together. 0 means that the symbol
// isn't referenced at all.
enum Reference_flags
{
// A reference to the symbol's absolute address. This includes
// references that cause an absolute address to be stored in the GOT.
ABSOLUTE_REF = 1,
// A reference that calculates the offset of the symbol from some
// anchor point, such as the PC or GOT.
RELATIVE_REF = 2,
// A TLS-related reference.
TLS_REF = 4,
// A reference that can always be treated as a function call.
FUNCTION_CALL = 8,
// When set, says that dynamic relocations are needed even if a
// symbol has a plt entry.
FUNC_DESC_ABI = 16,
};
// Given a direct absolute or pc-relative static relocation against
// the global symbol, this function returns whether a dynamic relocation
// is needed.
bool
needs_dynamic_reloc(int flags) const
{
// No dynamic relocations in a static link!
if (parameters->doing_static_link())
return false;
// A reference to an undefined symbol from an executable should be
// statically resolved to 0, and does not need a dynamic relocation.
// This matches gnu ld behavior.
if (this->is_undefined() && !parameters->options().shared())
return false;
// A reference to an absolute symbol does not need a dynamic relocation.
if (this->is_absolute())
return false;
// An absolute reference within a position-independent output file
// will need a dynamic relocation.
if ((flags & ABSOLUTE_REF)
&& parameters->options().output_is_position_independent())
return true;
// A function call that can branch to a local PLT entry does not need
// a dynamic relocation.
if ((flags & FUNCTION_CALL) && this->has_plt_offset())
return false;
// A reference to any PLT entry in a non-position-independent executable
// does not need a dynamic relocation.
if (!(flags & FUNC_DESC_ABI)
&& !parameters->options().output_is_position_independent()
&& this->has_plt_offset())
return false;
// A reference to a symbol defined in a dynamic object or to a
// symbol that is preemptible will need a dynamic relocation.
if (this->is_from_dynobj()
|| this->is_undefined()
|| this->is_preemptible())
return true;
// For all other cases, return FALSE.
return false;
}
// Whether we should use the PLT offset associated with a symbol for
// a relocation. FLAGS is a set of Reference_flags.
bool
use_plt_offset(int flags) const
{
// If the symbol doesn't have a PLT offset, then naturally we
// don't want to use it.
if (!this->has_plt_offset())
return false;
// For a STT_GNU_IFUNC symbol we always have to use the PLT entry.
if (this->type() == elfcpp::STT_GNU_IFUNC)
return true;
// If we are going to generate a dynamic relocation, then we will
// wind up using that, so no need to use the PLT entry.
if (this->needs_dynamic_reloc(flags))
return false;
// If the symbol is from a dynamic object, we need to use the PLT
// entry.
if (this->is_from_dynobj())
return true;
// If we are generating a shared object, and this symbol is
// undefined or preemptible, we need to use the PLT entry.
if (parameters->options().shared()
&& (this->is_undefined() || this->is_preemptible()))
return true;
// If this is a call to a weak undefined symbol, we need to use
// the PLT entry; the symbol may be defined by a library loaded
// at runtime.
if ((flags & FUNCTION_CALL) && this->is_weak_undefined())
return true;
// Otherwise we can use the regular definition.
return false;
}
// Given a direct absolute static relocation against
// the global symbol, where a dynamic relocation is needed, this
// function returns whether a relative dynamic relocation can be used.
// The caller must determine separately whether the static relocation
// is compatible with a relative relocation.
bool
can_use_relative_reloc(bool is_function_call) const
{
// A function call that can branch to a local PLT entry can
// use a RELATIVE relocation.
if (is_function_call && this->has_plt_offset())
return true;
// A reference to a symbol defined in a dynamic object or to a
// symbol that is preemptible can not use a RELATIVE relocation.
if (this->is_from_dynobj()
|| this->is_undefined()
|| this->is_preemptible())
return false;
// For all other cases, return TRUE.
return true;
}
// Return the output section where this symbol is defined. Return
// NULL if the symbol has an absolute value.
Output_section*
output_section() const;
// Set the symbol's output section. This is used for symbols
// defined in scripts. This should only be called after the symbol
// table has been finalized.
void
set_output_section(Output_section*);
// Set the symbol's output segment. This is used for pre-defined
// symbols whose segments aren't known until after layout is done
// (e.g., __ehdr_start).
void
set_output_segment(Output_segment*, Segment_offset_base);
// Set the symbol to undefined. This is used for pre-defined
// symbols whose segments aren't known until after layout is done
// (e.g., __ehdr_start).
void
set_undefined();
// Return whether there should be a warning for references to this
// symbol.
bool
has_warning() const
{ return this->has_warning_; }
// Mark this symbol as having a warning.
void
set_has_warning()
{ this->has_warning_ = true; }
// Return whether this symbol is defined by a COPY reloc from a
// dynamic object.
bool
is_copied_from_dynobj() const
{ return this->is_copied_from_dynobj_; }
// Mark this symbol as defined by a COPY reloc.
void
set_is_copied_from_dynobj()
{ this->is_copied_from_dynobj_ = true; }
// Return whether this symbol is forced to visibility STB_LOCAL
// by a "local:" entry in a version script.
bool
is_forced_local() const
{ return this->is_forced_local_; }
// Mark this symbol as forced to STB_LOCAL visibility.
void
set_is_forced_local()
{ this->is_forced_local_ = true; }
// Return true if this may need a COPY relocation.
// References from an executable object to non-function symbols
// defined in a dynamic object may need a COPY relocation.
bool
may_need_copy_reloc() const
{
return (parameters->options().copyreloc()
&& this->is_from_dynobj()
&& !this->is_func());
}
// Return true if this symbol was predefined by the linker.
bool
is_predefined() const
{ return this->is_predefined_; }
// Return true if this is a C++ vtable symbol.
bool
is_cxx_vtable() const
{ return is_prefix_of("_ZTV", this->name_); }
// Return true if this symbol is protected in a shared object.
// This is not the same as checking if visibility() == elfcpp::STV_PROTECTED,
// because the visibility_ field reflects the symbol's visibility from
// outside the shared object.
bool
is_protected() const
{ return this->is_protected_; }
// Mark this symbol as protected in a shared object.
void
set_is_protected()
{ this->is_protected_ = true; }
// Return state of PowerPC64 ELFv2 specific flag.
bool
non_zero_localentry() const
{ return this->non_zero_localentry_; }
// Set PowerPC64 ELFv2 specific flag.
void
set_non_zero_localentry()
{ this->non_zero_localentry_ = true; }
// Completely override existing symbol. Everything bar name_,
// version_, and is_forced_local_ flag are copied. version_ is
// cleared if from->version_ is clear. Returns true if this symbol
// should be forced local.
bool
clone(const Symbol* from);
protected:
// Instances of this class should always be created at a specific
// size.
Symbol()
{ memset(static_cast<void*>(this), 0, sizeof *this); }
// Initialize the general fields.
void
init_fields(const char* name, const char* version,
elfcpp::STT type, elfcpp::STB binding,
elfcpp::STV visibility, unsigned char nonvis);
// Initialize fields from an ELF symbol in OBJECT. ST_SHNDX is the
// section index, IS_ORDINARY is whether it is a normal section
// index rather than a special code.
template<int size, bool big_endian>
void
init_base_object(const char* name, const char* version, Object* object,
const elfcpp::Sym<size, big_endian>&, unsigned int st_shndx,
bool is_ordinary);
// Initialize fields for an Output_data.
void
init_base_output_data(const char* name, const char* version, Output_data*,
elfcpp::STT, elfcpp::STB, elfcpp::STV,
unsigned char nonvis, bool offset_is_from_end,
bool is_predefined);
// Initialize fields for an Output_segment.
void
init_base_output_segment(const char* name, const char* version,
Output_segment* os, elfcpp::STT type,
elfcpp::STB binding, elfcpp::STV visibility,
unsigned char nonvis,
Segment_offset_base offset_base,
bool is_predefined);
// Initialize fields for a constant.
void
init_base_constant(const char* name, const char* version, elfcpp::STT type,
elfcpp::STB binding, elfcpp::STV visibility,
unsigned char nonvis, bool is_predefined);
// Initialize fields for an undefined symbol.
void
init_base_undefined(const char* name, const char* version, elfcpp::STT type,
elfcpp::STB binding, elfcpp::STV visibility,
unsigned char nonvis);
// Override existing symbol.
template<int size, bool big_endian>
void
override_base(const elfcpp::Sym<size, big_endian>&, unsigned int st_shndx,
bool is_ordinary, Object* object, const char* version);
// Override existing symbol with a special symbol.
void
override_base_with_special(const Symbol* from);
// Override symbol version.
void
override_version(const char* version);
// Allocate a common symbol by giving it a location in the output
// file.
void
allocate_base_common(Output_data*);
private:
Symbol(const Symbol&);
Symbol& operator=(const Symbol&);
// Symbol name (expected to point into a Stringpool).
const char* name_;
// Symbol version (expected to point into a Stringpool). This may
// be NULL.
const char* version_;
union
{
// This is used if SOURCE_ == FROM_OBJECT.
// Object in which symbol is defined, or in which it was first
// seen.
Object* object;
// This is used if SOURCE_ == IN_OUTPUT_DATA.
// Output_data in which symbol is defined. Before
// Layout::finalize the symbol's value is an offset within the
// Output_data.
Output_data* output_data;
// This is used if SOURCE_ == IN_OUTPUT_SEGMENT.
// Output_segment in which the symbol is defined. Before
// Layout::finalize the symbol's value is an offset.
Output_segment* output_segment;
} u1_;
union
{
// This is used if SOURCE_ == FROM_OBJECT.
// Section number in object in which symbol is defined.
unsigned int shndx;
// This is used if SOURCE_ == IN_OUTPUT_DATA.
// True if the offset is from the end, false if the offset is
// from the beginning.
bool offset_is_from_end;
// This is used if SOURCE_ == IN_OUTPUT_SEGMENT.
// The base to use for the offset before Layout::finalize.
Segment_offset_base offset_base;
} u2_;
// The index of this symbol in the output file. If the symbol is
// not going into the output file, this value is -1U. This field
// starts as always holding zero. It is set to a non-zero value by
// Symbol_table::finalize.
unsigned int symtab_index_;
// The index of this symbol in the dynamic symbol table. If the
// symbol is not going into the dynamic symbol table, this value is
// -1U. This field starts as always holding zero. It is set to a
// non-zero value during Layout::finalize.
unsigned int dynsym_index_;
// If this symbol has an entry in the PLT section, then this is the
// offset from the start of the PLT section. This is -1U if there
// is no PLT entry.
unsigned int plt_offset_;
// The GOT section entries for this symbol. A symbol may have more
// than one GOT offset (e.g., when mixing modules compiled with two
// different TLS models), but will usually have at most one.
Got_offset_list got_offsets_;
// Symbol type (bits 0 to 3).
elfcpp::STT type_ : 4;
// Symbol binding (bits 4 to 7).
elfcpp::STB binding_ : 4;
// Symbol visibility (bits 8 to 9).
elfcpp::STV visibility_ : 2;
// Rest of symbol st_other field (bits 10 to 15).
unsigned int nonvis_ : 6;
// The type of symbol (bits 16 to 18).
Source source_ : 3;
// True if this is the default version of the symbol (bit 19).
bool is_def_ : 1;
// True if this symbol really forwards to another symbol. This is
// used when we discover after the fact that two different entries
// in the hash table really refer to the same symbol. This will
// never be set for a symbol found in the hash table, but may be set
// for a symbol found in the list of symbols attached to an Object.
// It forwards to the symbol found in the forwarders_ map of
// Symbol_table (bit 20).
bool is_forwarder_ : 1;
// True if the symbol has an alias in the weak_aliases table in
// Symbol_table (bit 21).
bool has_alias_ : 1;
// True if this symbol needs to be in the dynamic symbol table (bit
// 22).
bool needs_dynsym_entry_ : 1;
// True if we've seen this symbol in a regular object (bit 23).
bool in_reg_ : 1;
// True if we've seen this symbol in a dynamic object (bit 24).
bool in_dyn_ : 1;
// True if this is a dynamic symbol which needs a special value in
// the dynamic symbol table (bit 25).
bool needs_dynsym_value_ : 1;
// True if there is a warning for this symbol (bit 26).
bool has_warning_ : 1;
// True if we are using a COPY reloc for this symbol, so that the
// real definition lives in a dynamic object (bit 27).
bool is_copied_from_dynobj_ : 1;
// True if this symbol was forced to local visibility by a version
// script (bit 28).
bool is_forced_local_ : 1;
// True if the field u2_.shndx is an ordinary section
// index, not one of the special codes from SHN_LORESERVE to
// SHN_HIRESERVE (bit 29).
bool is_ordinary_shndx_ : 1;
// True if we've seen this symbol in a "real" ELF object (bit 30).
// If the symbol has been seen in a relocatable, non-IR, object file,
// it's known to be referenced from outside the IR. A reference from
// a dynamic object doesn't count as a "real" ELF, and we'll simply
// mark the symbol as "visible" from outside the IR. The compiler
// can use this distinction to guide its handling of COMDAT symbols.
bool in_real_elf_ : 1;
// True if this symbol is defined in a section which was discarded
// (bit 31).
bool is_defined_in_discarded_section_ : 1;
// True if UNDEF_BINDING_WEAK_ has been set (bit 32).
bool undef_binding_set_ : 1;
// True if this symbol was a weak undef resolved by a dynamic def
// or by a special symbol (bit 33).
bool undef_binding_weak_ : 1;
// True if this symbol is a predefined linker symbol (bit 34).
bool is_predefined_ : 1;
// True if this symbol has protected visibility in a shared object (bit 35).
// The visibility_ field will be STV_DEFAULT in this case because we
// must treat it as such from outside the shared object.
bool is_protected_ : 1;
// Used by PowerPC64 ELFv2 to track st_other localentry (bit 36).
bool non_zero_localentry_ : 1;
};
// The parts of a symbol which are size specific. Using a template
// derived class like this helps us use less space on a 32-bit system.
template<int size>
class Sized_symbol : public Symbol
{
public:
typedef typename elfcpp::Elf_types<size>::Elf_Addr Value_type;
typedef typename elfcpp::Elf_types<size>::Elf_WXword Size_type;
Sized_symbol()
{ }
// Initialize fields from an ELF symbol in OBJECT. ST_SHNDX is the
// section index, IS_ORDINARY is whether it is a normal section
// index rather than a special code.
template<bool big_endian>
void
init_object(const char* name, const char* version, Object* object,
const elfcpp::Sym<size, big_endian>&, unsigned int st_shndx,
bool is_ordinary);
// Initialize fields for an Output_data.
void
init_output_data(const char* name, const char* version, Output_data*,
Value_type value, Size_type symsize, elfcpp::STT,
elfcpp::STB, elfcpp::STV, unsigned char nonvis,
bool offset_is_from_end, bool is_predefined);
// Initialize fields for an Output_segment.
void
init_output_segment(const char* name, const char* version, Output_segment*,
Value_type value, Size_type symsize, elfcpp::STT,
elfcpp::STB, elfcpp::STV, unsigned char nonvis,
Segment_offset_base offset_base, bool is_predefined);
// Initialize fields for a constant.
void
init_constant(const char* name, const char* version, Value_type value,
Size_type symsize, elfcpp::STT, elfcpp::STB, elfcpp::STV,
unsigned char nonvis, bool is_predefined);
// Initialize fields for an undefined symbol.
void
init_undefined(const char* name, const char* version, Value_type value,
elfcpp::STT, elfcpp::STB, elfcpp::STV, unsigned char nonvis);
// Override existing symbol.
template<bool big_endian>
void
override(const elfcpp::Sym<size, big_endian>&, unsigned int st_shndx,
bool is_ordinary, Object* object, const char* version);
// Override existing symbol with a special symbol.
void
override_with_special(const Sized_symbol<size>*);
// Return the symbol's value.
Value_type
value() const
{ return this->value_; }
// Return the symbol's size (we can't call this 'size' because that
// is a template parameter).
Size_type
symsize() const
{ return this->symsize_; }
// Set the symbol size. This is used when resolving common symbols.
void
set_symsize(Size_type symsize)
{ this->symsize_ = symsize; }
// Set the symbol value. This is called when we store the final
// values of the symbols into the symbol table.
void
set_value(Value_type value)
{ this->value_ = value; }
// Allocate a common symbol by giving it a location in the output
// file.
void
allocate_common(Output_data*, Value_type value);
// Completely override existing symbol. Everything bar name_,
// version_, and is_forced_local_ flag are copied. version_ is
// cleared if from->version_ is clear. Returns true if this symbol
// should be forced local.
bool
clone(const Sized_symbol<size>* from);
private:
Sized_symbol(const Sized_symbol&);
Sized_symbol& operator=(const Sized_symbol&);
// Symbol value. Before Layout::finalize this is the offset in the
// input section. This is set to the final value during
// Layout::finalize.
Value_type value_;
// Symbol size.
Size_type symsize_;
};
// A struct describing a symbol defined by the linker, where the value
// of the symbol is defined based on an output section. This is used
// for symbols defined by the linker, like "_init_array_start".
struct Define_symbol_in_section
{
// The symbol name.
const char* name;
// The name of the output section with which this symbol should be
// associated. If there is no output section with that name, the
// symbol will be defined as zero.
const char* output_section;
// The offset of the symbol within the output section. This is an
// offset from the start of the output section, unless start_at_end
// is true, in which case this is an offset from the end of the
// output section.
uint64_t value;
// The size of the symbol.
uint64_t size;
// The symbol type.
elfcpp::STT type;
// The symbol binding.
elfcpp::STB binding;
// The symbol visibility.
elfcpp::STV visibility;
// The rest of the st_other field.
unsigned char nonvis;
// If true, the value field is an offset from the end of the output
// section.
bool offset_is_from_end;
// If true, this symbol is defined only if we see a reference to it.
bool only_if_ref;
};
// A struct describing a symbol defined by the linker, where the value
// of the symbol is defined based on a segment. This is used for
// symbols defined by the linker, like "_end". We describe the
// segment with which the symbol should be associated by its
// characteristics. If no segment meets these characteristics, the
// symbol will be defined as zero. If there is more than one segment
// which meets these characteristics, we will use the first one.
struct Define_symbol_in_segment
{
// The symbol name.
const char* name;
// The segment type where the symbol should be defined, typically
// PT_LOAD.
elfcpp::PT segment_type;
// Bitmask of segment flags which must be set.
elfcpp::PF segment_flags_set;
// Bitmask of segment flags which must be clear.
elfcpp::PF segment_flags_clear;
// The offset of the symbol within the segment. The offset is
// calculated from the position set by offset_base.
uint64_t value;
// The size of the symbol.
uint64_t size;
// The symbol type.
elfcpp::STT type;
// The symbol binding.
elfcpp::STB binding;
// The symbol visibility.
elfcpp::STV visibility;
// The rest of the st_other field.
unsigned char nonvis;
// The base from which we compute the offset.
Symbol::Segment_offset_base offset_base;
// If true, this symbol is defined only if we see a reference to it.
bool only_if_ref;
};
// Specify an object/section/offset location. Used by ODR code.
struct Symbol_location
{
// Object where the symbol is defined.
Object* object;
// Section-in-object where the symbol is defined.
unsigned int shndx;
// For relocatable objects, offset-in-section where the symbol is defined.
// For dynamic objects, address where the symbol is defined.
off_t offset;
bool operator==(const Symbol_location& that) const
{
return (this->object == that.object
&& this->shndx == that.shndx
&& this->offset == that.offset);
}
};
// A map from symbol name (as a pointer into the namepool) to all
// the locations the symbols is (weakly) defined (and certain other
// conditions are met). This map will be used later to detect
// possible One Definition Rule (ODR) violations.
struct Symbol_location_hash
{
size_t operator()(const Symbol_location& loc) const
{ return reinterpret_cast<uintptr_t>(loc.object) ^ loc.offset ^ loc.shndx; }
};
// This class manages warnings. Warnings are a GNU extension. When
// we see a section named .gnu.warning.SYM in an object file, and if
// we wind using the definition of SYM from that object file, then we
// will issue a warning for any relocation against SYM from a
// different object file. The text of the warning is the contents of
// the section. This is not precisely the definition used by the old
// GNU linker; the old GNU linker treated an occurrence of
// .gnu.warning.SYM as defining a warning symbol. A warning symbol
// would trigger a warning on any reference. However, it was
// inconsistent in that a warning in a dynamic object only triggered
// if there was no definition in a regular object. This linker is
// different in that we only issue a warning if we use the symbol
// definition from the same object file as the warning section.
class Warnings
{
public:
Warnings()
: warnings_()
{ }
// Add a warning for symbol NAME in object OBJ. WARNING is the text
// of the warning.
void
add_warning(Symbol_table* symtab, const char* name, Object* obj,
const std::string& warning);
// For each symbol for which we should give a warning, make a note
// on the symbol.
void
note_warnings(Symbol_table* symtab);
// Issue a warning for a reference to SYM at RELINFO's location.
template<int size, bool big_endian>
void
issue_warning(const Symbol* sym, const Relocate_info<size, big_endian>*,
size_t relnum, off_t reloffset) const;
private:
Warnings(const Warnings&);
Warnings& operator=(const Warnings&);
// What we need to know to get the warning text.
struct Warning_location
{
// The object the warning is in.
Object* object;
// The warning text.
std::string text;
Warning_location()
: object(NULL), text()
{ }
void
set(Object* o, const std::string& t)
{
this->object = o;
this->text = t;
}
};
// A mapping from warning symbol names (canonicalized in
// Symbol_table's namepool_ field) to warning information.
typedef Unordered_map<const char*, Warning_location> Warning_table;
Warning_table warnings_;
};
// The main linker symbol table.
class Symbol_table
{
public:
// The different places where a symbol definition can come from.
enum Defined
{
// Defined in an object file--the normal case.
OBJECT,
// Defined for a COPY reloc.
COPY,
// Defined on the command line using --defsym.
DEFSYM,
// Defined (so to speak) on the command line using -u.
UNDEFINED,
// Defined in a linker script.
SCRIPT,
// Predefined by the linker.
PREDEFINED,
// Defined by the linker during an incremental base link, but not
// a predefined symbol (e.g., common, defined in script).
INCREMENTAL_BASE,
};
// The order in which we sort common symbols.
enum Sort_commons_order
{
SORT_COMMONS_BY_SIZE_DESCENDING,
SORT_COMMONS_BY_ALIGNMENT_DESCENDING,
SORT_COMMONS_BY_ALIGNMENT_ASCENDING
};
// COUNT is an estimate of how many symbols will be inserted in the
// symbol table. It's ok to put 0 if you don't know; a correct
// guess will just save some CPU by reducing hashtable resizes.
Symbol_table(unsigned int count, const Version_script_info& version_script);
~Symbol_table();
void
set_icf(Icf* icf)
{ this->icf_ = icf;}
Icf*
icf() const
{ return this->icf_; }
// Returns true if ICF determined that this is a duplicate section.
bool
is_section_folded(Relobj* obj, unsigned int shndx) const;
void
set_gc(Garbage_collection* gc)
{ this->gc_ = gc; }
Garbage_collection*
gc() const
{ return this->gc_; }
// During garbage collection, this keeps undefined symbols.
void
gc_mark_undef_symbols(Layout*);
// This tells garbage collection that this symbol is referenced.
void
gc_mark_symbol(Symbol* sym);
// During garbage collection, this keeps sections that correspond to
// symbols seen in dynamic objects.
inline void
gc_mark_dyn_syms(Symbol* sym);
// Add COUNT external symbols from the relocatable object RELOBJ to
// the symbol table. SYMS is the symbols, SYMNDX_OFFSET is the
// offset in the symbol table of the first symbol, SYM_NAMES is
// their names, SYM_NAME_SIZE is the size of SYM_NAMES. This sets
// SYMPOINTERS to point to the symbols in the symbol table. It sets
// *DEFINED to the number of defined symbols.
template<int size, bool big_endian>
void
add_from_relobj(Sized_relobj_file<size, big_endian>* relobj,
const unsigned char* syms, size_t count,
size_t symndx_offset, const char* sym_names,
size_t sym_name_size,
typename Sized_relobj_file<size, big_endian>::Symbols*,
size_t* defined);
// Add one external symbol from the plugin object OBJ to the symbol table.
// Returns a pointer to the resolved symbol in the symbol table.
template<int size, bool big_endian>
Symbol*
add_from_pluginobj(Sized_pluginobj<size, big_endian>* obj,
const char* name, const char* ver,
elfcpp::Sym<size, big_endian>* sym);
// Add COUNT dynamic symbols from the dynamic object DYNOBJ to the
// symbol table. SYMS is the symbols. SYM_NAMES is their names.
// SYM_NAME_SIZE is the size of SYM_NAMES. The other parameters are
// symbol version data.
template<int size, bool big_endian>
void
add_from_dynobj(Sized_dynobj<size, big_endian>* dynobj,
const unsigned char* syms, size_t count,
const char* sym_names, size_t sym_name_size,
const unsigned char* versym, size_t versym_size,
const std::vector<const char*>*,
typename Sized_relobj_file<size, big_endian>::Symbols*,
size_t* defined);
// Add one external symbol from the incremental object OBJ to the symbol
// table. Returns a pointer to the resolved symbol in the symbol table.
template<int size, bool big_endian>
Sized_symbol<size>*
add_from_incrobj(Object* obj, const char* name,
const char* ver, elfcpp::Sym<size, big_endian>* sym);
// Define a special symbol based on an Output_data. It is a
// multiple definition error if this symbol is already defined.
Symbol*
define_in_output_data(const char* name, const char* version, Defined,
Output_data*, uint64_t value, uint64_t symsize,
elfcpp::STT type, elfcpp::STB binding,
elfcpp::STV visibility, unsigned char nonvis,
bool offset_is_from_end, bool only_if_ref);
// Define a special symbol based on an Output_segment. It is a
// multiple definition error if this symbol is already defined.
Symbol*
define_in_output_segment(const char* name, const char* version, Defined,
Output_segment*, uint64_t value, uint64_t symsize,
elfcpp::STT type, elfcpp::STB binding,
elfcpp::STV visibility, unsigned char nonvis,
Symbol::Segment_offset_base, bool only_if_ref);
// Define a special symbol with a constant value. It is a multiple
// definition error if this symbol is already defined.
Symbol*
define_as_constant(const char* name, const char* version, Defined,
uint64_t value, uint64_t symsize, elfcpp::STT type,
elfcpp::STB binding, elfcpp::STV visibility,
unsigned char nonvis, bool only_if_ref,
bool force_override);
// Define a set of symbols in output sections. If ONLY_IF_REF is
// true, only define them if they are referenced.
void
define_symbols(const Layout*, int count, const Define_symbol_in_section*,
bool only_if_ref);
// Define a set of symbols in output segments. If ONLY_IF_REF is
// true, only defined them if they are referenced.
void
define_symbols(const Layout*, int count, const Define_symbol_in_segment*,
bool only_if_ref);
// Add a target-specific global symbol.
// (Used by SPARC backend to add STT_SPARC_REGISTER symbols.)
void
add_target_global_symbol(Symbol* sym)
{ this->target_symbols_.push_back(sym); }
// Define SYM using a COPY reloc. POSD is the Output_data where the
// symbol should be defined--typically a .dyn.bss section. VALUE is
// the offset within POSD.
template<int size>
void
define_with_copy_reloc(Sized_symbol<size>* sym, Output_data* posd,
typename elfcpp::Elf_types<size>::Elf_Addr);
// Look up a symbol.
Symbol*
lookup(const char*, const char* version = NULL) const;
// Return the real symbol associated with the forwarder symbol FROM.
Symbol*
resolve_forwards(const Symbol* from) const;
// Return the sized version of a symbol in this table.
template<int size>
Sized_symbol<size>*
get_sized_symbol(Symbol*) const;
template<int size>
const Sized_symbol<size>*
get_sized_symbol(const Symbol*) const;
// Return the count of undefined symbols seen.
size_t
saw_undefined() const
{ return this->saw_undefined_; }
void
set_has_gnu_output()
{ this->has_gnu_output_ = true; }
// Allocate the common symbols
void
allocate_commons(Layout*, Mapfile*);
// Add a warning for symbol NAME in object OBJ. WARNING is the text
// of the warning.
void
add_warning(const char* name, Object* obj, const std::string& warning)
{ this->warnings_.add_warning(this, name, obj, warning); }
// Canonicalize a symbol name for use in the hash table.
const char*
canonicalize_name(const char* name)
{ return this->namepool_.add(name, true, NULL); }
// Possibly issue a warning for a reference to SYM at LOCATION which
// is in OBJ.
template<int size, bool big_endian>
void
issue_warning(const Symbol* sym,
const Relocate_info<size, big_endian>* relinfo,
size_t relnum, off_t reloffset) const
{ this->warnings_.issue_warning(sym, relinfo, relnum, reloffset); }
// Check candidate_odr_violations_ to find symbols with the same name
// but apparently different definitions (different source-file/line-no).
void
detect_odr_violations(const Task*, const char* output_file_name) const;
// Add any undefined symbols named on the command line to the symbol
// table.
void
add_undefined_symbols_from_command_line(Layout*);
// SYM is defined using a COPY reloc. Return the dynamic object
// where the original definition was found.
Dynobj*
get_copy_source(const Symbol* sym) const;
// Set the dynamic symbol indexes. INDEX is the index of the first
// global dynamic symbol. Return the count of forced-local symbols in
// *PFORCED_LOCAL_COUNT. Pointers to the symbols are stored into
// the vector. The names are stored into the Stringpool. This
// returns an updated dynamic symbol index.
unsigned int
set_dynsym_indexes(unsigned int index, unsigned int* pforced_local_count,
std::vector<Symbol*>*, Stringpool*, Versions*);
// Finalize the symbol table after we have set the final addresses
// of all the input sections. This sets the final symbol indexes,
// values and adds the names to *POOL. *PLOCAL_SYMCOUNT is the
// index of the first global symbol. OFF is the file offset of the
// global symbol table, DYNOFF is the offset of the globals in the
// dynamic symbol table, DYN_GLOBAL_INDEX is the index of the first
// global dynamic symbol, and DYNCOUNT is the number of global
// dynamic symbols. This records the parameters, and returns the
// new file offset. It updates *PLOCAL_SYMCOUNT if it created any
// local symbols.
off_t
finalize(off_t off, off_t dynoff, size_t dyn_global_index, size_t dyncount,
Stringpool* pool, unsigned int* plocal_symcount);
// Set the final file offset of the symbol table.
void
set_file_offset(off_t off)
{ this->offset_ = off; }
// Status code of Symbol_table::compute_final_value.
enum Compute_final_value_status
{
// No error.
CFVS_OK,
// Unsupported symbol section.
CFVS_UNSUPPORTED_SYMBOL_SECTION,
// No output section.
CFVS_NO_OUTPUT_SECTION
};
// Compute the final value of SYM and store status in location PSTATUS.
// During relaxation, this may be called multiple times for a symbol to
// compute its would-be final value in each relaxation pass.
template<int size>
typename Sized_symbol<size>::Value_type
compute_final_value(const Sized_symbol<size>* sym,
Compute_final_value_status* pstatus) const;
// Return the index of the first global symbol.
unsigned int
first_global_index() const
{ return this->first_global_index_; }
// Return the total number of symbols in the symbol table.
unsigned int
output_count() const
{ return this->output_count_; }
// Write out the global symbols.
void
write_globals(const Stringpool*, const Stringpool*,
Output_symtab_xindex*, Output_symtab_xindex*,
Output_file*) const;
// Write out a section symbol. Return the updated offset.
void
write_section_symbol(const Output_section*, Output_symtab_xindex*,
Output_file*, off_t) const;
// Loop over all symbols, applying the function F to each.
template<int size, typename F>
void
for_all_symbols(F f) const
{
for (Symbol_table_type::const_iterator p = this->table_.begin();
p != this->table_.end();
++p)
{
Sized_symbol<size>* sym = static_cast<Sized_symbol<size>*>(p->second);
f(sym);
}
}
// Dump statistical information to stderr.
void
print_stats() const;
// Return the version script information.
const Version_script_info&
version_script() const
{ return version_script_; }
// Completely override existing symbol.
template<int size>
void
clone(Sized_symbol<size>* to, const Sized_symbol<size>* from)
{
if (to->clone(from))
this->force_local(to);
}
private:
Symbol_table(const Symbol_table&);
Symbol_table& operator=(const Symbol_table&);
// The type of the list of common symbols.
typedef std::vector<Symbol*> Commons_type;
// The type of the symbol hash table.
typedef std::pair<Stringpool::Key, Stringpool::Key> Symbol_table_key;
// The hash function. The key values are Stringpool keys.
struct Symbol_table_hash
{
inline size_t
operator()(const Symbol_table_key& key) const
{
return key.first ^ key.second;
}
};
struct Symbol_table_eq
{
bool
operator()(const Symbol_table_key&, const Symbol_table_key&) const;
};
typedef Unordered_map<Symbol_table_key, Symbol*, Symbol_table_hash,
Symbol_table_eq> Symbol_table_type;
typedef Unordered_map<const char*,
Unordered_set<Symbol_location, Symbol_location_hash> >
Odr_map;
// Make FROM a forwarder symbol to TO.
void
make_forwarder(Symbol* from, Symbol* to);
// Add a symbol.
template<int size, bool big_endian>
Sized_symbol<size>*
add_from_object(Object*, const char* name, Stringpool::Key name_key,
const char* version, Stringpool::Key version_key,
bool def, const elfcpp::Sym<size, big_endian>& sym,
unsigned int st_shndx, bool is_ordinary,
unsigned int orig_st_shndx);
// Define a default symbol.
template<int size, bool big_endian>
void
define_default_version(Sized_symbol<size>*, bool,
Symbol_table_type::iterator);
// Resolve symbols.
template<int size, bool big_endian>
void
resolve(Sized_symbol<size>* to,
const elfcpp::Sym<size, big_endian>& sym,
unsigned int st_shndx, bool is_ordinary,
unsigned int orig_st_shndx,
Object*, const char* version,
bool is_default_version);
template<int size, bool big_endian>
void
resolve(Sized_symbol<size>* to, const Sized_symbol<size>* from);
// Record that a symbol is forced to be local by a version script or
// by visibility.
void
force_local(Symbol*);
// Adjust NAME and *NAME_KEY for wrapping.
const char*
wrap_symbol(const char* name, Stringpool::Key* name_key);
// Whether we should override a symbol, based on flags in
// resolve.cc.
static bool
should_override(const Symbol*, unsigned int, elfcpp::STT, Defined,
Object*, bool*, bool*, bool);
// Report a problem in symbol resolution.
static void
report_resolve_problem(bool is_error, const char* msg, const Symbol* to,
Defined, Object* object);
// Override a symbol.
template<int size, bool big_endian>
void
override(Sized_symbol<size>* tosym,
const elfcpp::Sym<size, big_endian>& fromsym,
unsigned int st_shndx, bool is_ordinary,
Object* object, const char* version);
// Whether we should override a symbol with a special symbol which
// is automatically defined by the linker.
static bool
should_override_with_special(const Symbol*, elfcpp::STT, Defined);
// Override a symbol with a special symbol.
template<int size>
void
override_with_special(Sized_symbol<size>* tosym,
const Sized_symbol<size>* fromsym);
// Record all weak alias sets for a dynamic object.
template<int size>
void
record_weak_aliases(std::vector<Sized_symbol<size>*>*);
// Define a special symbol.
template<int size, bool big_endian>
Sized_symbol<size>*
define_special_symbol(const char** pname, const char** pversion,
bool only_if_ref, elfcpp::STV visibility,
Sized_symbol<size>** poldsym,
bool* resolve_oldsym, bool is_forced_local);
// Define a symbol in an Output_data, sized version.
template<int size>
Sized_symbol<size>*
do_define_in_output_data(const char* name, const char* version, Defined,
Output_data*,
typename elfcpp::Elf_types<size>::Elf_Addr value,
typename elfcpp::Elf_types<size>::Elf_WXword ssize,
elfcpp::STT type, elfcpp::STB binding,
elfcpp::STV visibility, unsigned char nonvis,
bool offset_is_from_end, bool only_if_ref);
// Define a symbol in an Output_segment, sized version.
template<int size>
Sized_symbol<size>*
do_define_in_output_segment(
const char* name, const char* version, Defined, Output_segment* os,
typename elfcpp::Elf_types<size>::Elf_Addr value,
typename elfcpp::Elf_types<size>::Elf_WXword ssize,
elfcpp::STT type, elfcpp::STB binding,
elfcpp::STV visibility, unsigned char nonvis,
Symbol::Segment_offset_base offset_base, bool only_if_ref);
// Define a symbol as a constant, sized version.
template<int size>
Sized_symbol<size>*
do_define_as_constant(
const char* name, const char* version, Defined,
typename elfcpp::Elf_types<size>::Elf_Addr value,
typename elfcpp::Elf_types<size>::Elf_WXword ssize,
elfcpp::STT type, elfcpp::STB binding,
elfcpp::STV visibility, unsigned char nonvis,
bool only_if_ref, bool force_override);
// Add any undefined symbols named on the command line to the symbol
// table, sized version.
template<int size>
void
do_add_undefined_symbols_from_command_line(Layout*);
// Add one undefined symbol.
template<int size>
void
add_undefined_symbol_from_command_line(const char* name);
// Types of common symbols.
enum Commons_section_type
{
COMMONS_NORMAL,
COMMONS_TLS,
COMMONS_SMALL,
COMMONS_LARGE
};
// Allocate the common symbols, sized version.
template<int size>
void
do_allocate_commons(Layout*, Mapfile*, Sort_commons_order);
// Allocate the common symbols from one list.
template<int size>
void
do_allocate_commons_list(Layout*, Commons_section_type, Commons_type*,
Mapfile*, Sort_commons_order);
// Returns all of the lines attached to LOC, not just the one the
// instruction actually came from. This helps the ODR checker avoid
// false positives.
static std::vector<std::string>
linenos_from_loc(const Task* task, const Symbol_location& loc);
// Implement detect_odr_violations.
template<int size, bool big_endian>
void
sized_detect_odr_violations() const;
// Finalize symbols specialized for size.
template<int size>
off_t
sized_finalize(off_t, Stringpool*, unsigned int*);
// Finalize a symbol. Return whether it should be added to the
// symbol table.
template<int size>
bool
sized_finalize_symbol(Symbol*);
// Add a symbol the final symtab by setting its index.
template<int size>
void
add_to_final_symtab(Symbol*, Stringpool*, unsigned int* pindex, off_t* poff);
// Write globals specialized for size and endianness.
template<int size, bool big_endian>
void
sized_write_globals(const Stringpool*, const Stringpool*,
Output_symtab_xindex*, Output_symtab_xindex*,
Output_file*) const;
// Write out a symbol to P.
template<int size, bool big_endian>
void
sized_write_symbol(Sized_symbol<size>*,
typename elfcpp::Elf_types<size>::Elf_Addr value,
unsigned int shndx, elfcpp::STB,
const Stringpool*, unsigned char* p) const;
// Possibly warn about an undefined symbol from a dynamic object.
void
warn_about_undefined_dynobj_symbol(Symbol*) const;
// Write out a section symbol, specialized for size and endianness.
template<int size, bool big_endian>
void
sized_write_section_symbol(const Output_section*, Output_symtab_xindex*,
Output_file*, off_t) const;
// The type of the list of symbols which have been forced local.
typedef std::vector<Symbol*> Forced_locals;
// A map from symbols with COPY relocs to the dynamic objects where
// they are defined.
typedef Unordered_map<const Symbol*, Dynobj*> Copied_symbol_dynobjs;
// We increment this every time we see a new undefined symbol, for
// use in archive groups.
size_t saw_undefined_;
// The index of the first global symbol in the output file.
unsigned int first_global_index_;
// The file offset within the output symtab section where we should
// write the table.
off_t offset_;
// The number of global symbols we want to write out.
unsigned int output_count_;
// The file offset of the global dynamic symbols, or 0 if none.
off_t dynamic_offset_;
// The index of the first global dynamic symbol (including
// forced-local symbols).
unsigned int first_dynamic_global_index_;
// The number of global dynamic symbols (including forced-local symbols),
// or 0 if none.
unsigned int dynamic_count_;
// Set if a STT_GNU_IFUNC or STB_GNU_UNIQUE symbol will be output.
bool has_gnu_output_;
// The symbol hash table.
Symbol_table_type table_;
// A pool of symbol names. This is used for all global symbols.
// Entries in the hash table point into this pool.
Stringpool namepool_;
// Forwarding symbols.
Unordered_map<const Symbol*, Symbol*> forwarders_;
// Weak aliases. A symbol in this list points to the next alias.
// The aliases point to each other in a circular list.
Unordered_map<Symbol*, Symbol*> weak_aliases_;
// We don't expect there to be very many common symbols, so we keep
// a list of them. When we find a common symbol we add it to this
// list. It is possible that by the time we process the list the
// symbol is no longer a common symbol. It may also have become a
// forwarder.
Commons_type commons_;
// This is like the commons_ field, except that it holds TLS common
// symbols.
Commons_type tls_commons_;
// This is for small common symbols.
Commons_type small_commons_;
// This is for large common symbols.
Commons_type large_commons_;
// A list of symbols which have been forced to be local. We don't
// expect there to be very many of them, so we keep a list of them
// rather than walking the whole table to find them.
Forced_locals forced_locals_;
// Manage symbol warnings.
Warnings warnings_;
// Manage potential One Definition Rule (ODR) violations.
Odr_map candidate_odr_violations_;
// When we emit a COPY reloc for a symbol, we define it in an
// Output_data. When it's time to emit version information for it,
// we need to know the dynamic object in which we found the original
// definition. This maps symbols with COPY relocs to the dynamic
// object where they were defined.
Copied_symbol_dynobjs copied_symbol_dynobjs_;
// Information parsed from the version script, if any.
const Version_script_info& version_script_;
Garbage_collection* gc_;
Icf* icf_;
// Target-specific symbols, if any.
std::vector<Symbol*> target_symbols_;
};
// We inline get_sized_symbol for efficiency.
template<int size>
Sized_symbol<size>*
Symbol_table::get_sized_symbol(Symbol* sym) const
{
gold_assert(size == parameters->target().get_size());
return static_cast<Sized_symbol<size>*>(sym);
}
template<int size>
const Sized_symbol<size>*
Symbol_table::get_sized_symbol(const Symbol* sym) const
{
gold_assert(size == parameters->target().get_size());
return static_cast<const Sized_symbol<size>*>(sym);
}
} // End namespace gold.
#endif // !defined(GOLD_SYMTAB_H)
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