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More symbol resolution code.

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This commit is contained in:
Ian Lance Taylor 2006-09-07 21:21:41 +00:00
parent 466bbf939d
commit 1564db8db6
5 changed files with 331 additions and 62 deletions
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57
elfcpp/elfcpp.h
View file

@ -437,6 +437,13 @@ elf_st_nonvis(unsigned char other)
return static_cast<STV>(other >> 2);
}
inline unsigned char
elf_st_other(STV vis, unsigned char nonvis)
{
return ((nonvis << 2)
+ (static_cast<unsigned char>(vis) & 3));
}
} // End namespace elfcpp.
// Include internal details after defining the types.
@ -641,6 +648,56 @@ class Sym
const internal::Sym_data<size>* p_;
};
// Writer class for an ELF symbol table entry.
template<int size, bool big_endian>
class Sym_write
{
public:
Sym_write(unsigned char* p)
: p_(reinterpret_cast<internal::Sym_data<size>*>(p))
{ }
void
put_st_name(Elf_Word v)
{ this->p_->st_name = internal::convert_word<big_endian>(v); }
void
put_st_value(typename Elf_types<size>::Elf_Addr v)
{ this->p_->st_value = internal::convert_addr<size, big_endian>(v); }
void
put_st_size(typename Elf_types<size>::Elf_WXword v)
{ this->p_->st_size = internal::convert_wxword<size, big_endian>(v); }
void
put_st_info(unsigned char v)
{ this->p_->st_info = v; }
void
put_st_info(STB bind, STT type)
{ this->p_->st_info = elf_st_info(bind, type); }
void
put_st_other(unsigned char v)
{ this->p_->st_other = v; }
void
put_st_other(STV vis, unsigned char nonvis)
{ this->p_->st_other = elf_st_other(vis, nonvis); }
void
put_st_shndx(Elf_Half v)
{ this->p_->st_shndx = internal::convert_half<big_endian>(v); }
Sym<size, big_endian>
sym()
{ return Sym<size, big_endian>(reinterpret_cast<unsigned char*>(this->p_)); }
private:
internal::Sym_data<size>* p_;
};
} // End namespace elfcpp.
#endif // !defined(ELFPCP_H)

10
gold/po/gold.pot
View file

@ -8,7 +8,7 @@ msgid ""
msgstr ""
"Project-Id-Version: PACKAGE VERSION\n"
"Report-Msgid-Bugs-To: \n"
"POT-Creation-Date: 2006-08-18 15:26-0700\n"
"POT-Creation-Date: 2006-09-07 14:17-0700\n"
"PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
"Language-Team: LANGUAGE <LL@li.org>\n"
@ -220,22 +220,22 @@ msgstr ""
msgid "%s: -%c: %s\n"
msgstr ""
#: resolve.cc:103
#: resolve.cc:135
#, c-format
msgid "%s: %s: invalid STB_LOCAL symbol %s in external symbols\n"
msgstr ""
#: resolve.cc:109
#: resolve.cc:141
#, c-format
msgid "%s: %s: unsupported symbol binding %d for symbol %s\n"
msgstr ""
#: symtab.cc:262
#: symtab.cc:271
#, c-format
msgid "%s: %s: mixing 32-bit and 64-bit ELF objects\n"
msgstr ""
#: symtab.cc:275
#: symtab.cc:284
#, c-format
msgid "%s: %s: bad symbol name offset %u at %lu\n"
msgstr ""

152
gold/resolve.cc
View file

@ -10,13 +10,43 @@
namespace gold
{
// Symbol methods used in this file.
// Override the fields in Symbol.
template<int size, bool big_endian>
void
Symbol::override_base(const elfcpp::Sym<size, big_endian>& sym,
Object* object)
{
this->object_ = object;
this->shnum_ = sym.get_st_shndx(); // FIXME: Handle SHN_XINDEX.
this->type_ = sym.get_st_type();
this->binding_ = sym.get_st_bind();
this->visibility_ = sym.get_st_visibility();
this->other_ = sym.get_st_nonvis();
}
// Override the fields in Sized_symbol.
template<int size>
template<bool big_endian>
void
Sized_symbol<size>::override(const elfcpp::Sym<size, big_endian>& sym,
Object* object)
{
this->override_base(sym, object);
this->value_ = sym.get_st_value();
this->size_ = sym.get_st_size();
}
// Resolve a symbol. This is called the second and subsequent times
// we see a symbol. TO is the pre-existing symbol. SYM is the new
// symbol, seen in OBJECT.
template<int size, bool big_endian>
void
Symbol_table::resolve(Symbol* to,
Symbol_table::resolve(Sized_symbol<size>* to,
const elfcpp::Sym<size, big_endian>& sym,
Object* object)
{
@ -84,6 +114,8 @@ Symbol_table::resolve(Symbol* to,
break;
default:
if (to->type() == elfcpp::STT_COMMON)
tobits |= (2 << 2);
break;
}
@ -113,7 +145,12 @@ Symbol_table::resolve(Symbol* to,
}
if (object->is_dynamic())
frombits |= (1 << 1);
{
frombits |= (1 << 1);
// Record that we've seen this symbol in a dynamic object.
to->set_in_dyn();
}
switch (sym.get_st_shndx())
{
@ -126,9 +163,13 @@ Symbol_table::resolve(Symbol* to,
break;
default:
if (sym.get_st_type() == elfcpp::STT_COMMON)
frombits |= (2 << 2);
break;
}
// FIXME: Warn if either but not both of TO and SYM are STT_TLS.
// We use a giant switch table for symbol resolution. This code is
// unwieldy, but: 1) it is efficient; 2) we definitely handle all
// cases; 3) it is easy to change the handling of a particular case.
@ -147,64 +188,124 @@ Symbol_table::resolve(Symbol* to,
return;
case WEAK_DEF * 16 + DEF:
// In the original SVR4 linker, a weak definition followed by a
// regular definition was treated as a multiple definition
// error. In the Solaris linker and the GNU linker, a weak
// definition followed by a regular definition causes the
// regular definition to be ignored. We are currently
// compatible with the GNU linker. In the future we should add
// a target specific option to change this. FIXME.
// We've seen a weak definition, and now we see a strong
// definition. In the original SVR4 linker, this was treated as
// a multiple definition error. In the Solaris linker and the
// GNU linker, a weak definition followed by a regular
// definition causes the weak definition to be overridden. We
// are currently compatible with the GNU linker. In the future
// we should add a target specific option to change this.
// FIXME.
to->override(sym, object);
return;
case DYN_DEF * 16 + DEF:
case DYN_WEAK_DEF * 16 + DEF:
// We've seen a definition in a dynamic object, and now we see a
// definition in a regular object. The definition in the
// regular object overrides the definition in the dynamic
// object.
to->override(sym, object);
return;
case UNDEF * 16 + DEF:
case WEAK_UNDEF * 16 + DEF:
case DYN_UNDEF * 16 + DEF:
case DYN_WEAK_UNDEF * 16 + DEF:
// We've seen an undefined reference, and now we see a
// definition. We use the definition.
to->override(sym, object);
return;
case COMMON * 16 + DEF:
case WEAK_COMMON * 16 + DEF:
case DYN_COMMON * 16 + DEF:
case DYN_WEAK_COMMON * 16 + DEF:
// We've seen a common symbol and now we see a definition. The
// definition overrides. FIXME: We should optionally issue a
// warning.
to->override(sym, object);
return;
case DEF * 16 + WEAK_DEF:
case WEAK_DEF * 16 + WEAK_DEF:
// We've seen a definition and now we see a weak definition. We
// ignore the new weak definition.
return;
case DYN_DEF * 16 + WEAK_DEF:
case DYN_WEAK_DEF * 16 + WEAK_DEF:
// We've seen a dynamic definition and now we see a regular weak
// definition. The regular weak definition overrides.
to->override(sym, object);
return;
case UNDEF * 16 + WEAK_DEF:
case WEAK_UNDEF * 16 + WEAK_DEF:
case DYN_UNDEF * 16 + WEAK_DEF:
case DYN_WEAK_UNDEF * 16 + WEAK_DEF:
// A weak definition of a currently undefined symbol.
to->override(sym, object);
return;
case COMMON * 16 + WEAK_DEF:
case WEAK_COMMON * 16 + WEAK_DEF:
// A weak definition does not override a common definition.
return;
case DYN_COMMON * 16 + WEAK_DEF:
case DYN_WEAK_COMMON * 16 + WEAK_DEF:
// A weak definition does override a definition in a dynamic
// object. FIXME: We should optionally issue a warning.
to->override(sym, object);
return;
case DEF * 16 + DYN_DEF:
case WEAK_DEF * 16 + DYN_DEF:
case DYN_DEF * 16 + DYN_DEF:
case DYN_WEAK_DEF * 16 + DYN_DEF:
// Ignore a dynamic definition if we already have a definition.
return;
case UNDEF * 16 + DYN_DEF:
case WEAK_UNDEF * 16 + DYN_DEF:
case DYN_UNDEF * 16 + DYN_DEF:
case DYN_WEAK_UNDEF * 16 + DYN_DEF:
// Use a dynamic definition if we have a reference.
to->override(sym, object);
return;
case COMMON * 16 + DYN_DEF:
case WEAK_COMMON * 16 + DYN_DEF:
case DYN_COMMON * 16 + DYN_DEF:
case DYN_WEAK_COMMON * 16 + DYN_DEF:
// Ignore a dynamic definition if we already have a common
// definition.
return;
case DEF * 16 + DYN_WEAK_DEF:
case WEAK_DEF * 16 + DYN_WEAK_DEF:
case DYN_DEF * 16 + DYN_WEAK_DEF:
case DYN_WEAK_DEF * 16 + DYN_WEAK_DEF:
// Ignore a weak dynamic definition if we already have a
// definition.
return;
case UNDEF * 16 + DYN_WEAK_DEF:
case WEAK_UNDEF * 16 + DYN_WEAK_DEF:
case DYN_UNDEF * 16 + DYN_WEAK_DEF:
case DYN_WEAK_UNDEF * 16 + DYN_WEAK_DEF:
// Use a weak dynamic definition if we have a reference.
to->override(sym, object);
return;
case COMMON * 16 + DYN_WEAK_DEF:
case WEAK_COMMON * 16 + DYN_WEAK_DEF:
case DYN_COMMON * 16 + DYN_WEAK_DEF:
case DYN_WEAK_COMMON * 16 + DYN_WEAK_DEF:
// Ignore a weak dynamic definition if we already have a common
// definition.
return;
case DEF * 16 + UNDEF:
case WEAK_DEF * 16 + UNDEF:
@ -218,6 +319,8 @@ Symbol_table::resolve(Symbol* to,
case WEAK_COMMON * 16 + UNDEF:
case DYN_COMMON * 16 + UNDEF:
case DYN_WEAK_COMMON * 16 + UNDEF:
// A new undefined reference tells us nothing.
return;
case DEF * 16 + WEAK_UNDEF:
case WEAK_DEF * 16 + WEAK_UNDEF:
@ -231,6 +334,8 @@ Symbol_table::resolve(Symbol* to,
case WEAK_COMMON * 16 + WEAK_UNDEF:
case DYN_COMMON * 16 + WEAK_UNDEF:
case DYN_WEAK_COMMON * 16 + WEAK_UNDEF:
// A new weak undefined reference tells us nothing.
return;
case DEF * 16 + DYN_UNDEF:
case WEAK_DEF * 16 + DYN_UNDEF:
@ -244,6 +349,8 @@ Symbol_table::resolve(Symbol* to,
case WEAK_COMMON * 16 + DYN_UNDEF:
case DYN_COMMON * 16 + DYN_UNDEF:
case DYN_WEAK_COMMON * 16 + DYN_UNDEF:
// A new dynamic undefined reference tells us nothing.
return;
case DEF * 16 + DYN_WEAK_UNDEF:
case WEAK_DEF * 16 + DYN_WEAK_UNDEF:
@ -257,15 +364,29 @@ Symbol_table::resolve(Symbol* to,
case WEAK_COMMON * 16 + DYN_WEAK_UNDEF:
case DYN_COMMON * 16 + DYN_WEAK_UNDEF:
case DYN_WEAK_COMMON * 16 + DYN_WEAK_UNDEF:
// A new weak dynamic undefined reference tells us nothing.
return;
case DEF * 16 + COMMON:
// A common symbol does not override a definition.
return;
case WEAK_DEF * 16 + COMMON:
case DYN_DEF * 16 + COMMON:
case DYN_WEAK_DEF * 16 + COMMON:
// A common symbol does override a weak definition or a dynamic
// definition.
to->override(sym, object);
return;
case UNDEF * 16 + COMMON:
case WEAK_UNDEF * 16 + COMMON:
case DYN_UNDEF * 16 + COMMON:
case DYN_WEAK_UNDEF * 16 + COMMON:
// A common symbol is a definition for a reference.
to->override(sym, object);
return;
case COMMON * 16 + COMMON:
case WEAK_COMMON * 16 + COMMON:
case DYN_COMMON * 16 + COMMON:
@ -309,8 +430,11 @@ Symbol_table::resolve(Symbol* to,
case WEAK_COMMON * 16 + DYN_WEAK_COMMON:
case DYN_COMMON * 16 + DYN_WEAK_COMMON:
case DYN_WEAK_COMMON * 16 + DYN_WEAK_COMMON:
abort();
break;
default:
abort();
}
}
@ -321,28 +445,28 @@ Symbol_table::resolve(Symbol* to,
template
void
Symbol_table::resolve<32, true>(
Symbol* to,
Sized_symbol<32>* to,
const elfcpp::Sym<32, true>& sym,
Object* object);
template
void
Symbol_table::resolve<32, false>(
Symbol* to,
Sized_symbol<32>* to,
const elfcpp::Sym<32, false>& sym,
Object* object);
template
void
Symbol_table::resolve<64, true>(
Symbol* to,
Sized_symbol<64>* to,
const elfcpp::Sym<64, true>& sym,
Object* object);
template
void
Symbol_table::resolve<64, false>(
Symbol* to,
Sized_symbol<64>* to,
const elfcpp::Sym<64, false>& sym,
Object* object);

51
gold/symtab.cc
View file

@ -15,10 +15,6 @@ namespace gold
// Class Symbol.
Symbol::~Symbol()
{
}
// Initialize the fields in the base class Symbol.
template<int size, bool big_endian>
@ -34,9 +30,10 @@ Symbol::init_base(const char* name, const char* version, Object* object,
this->binding_ = sym.get_st_bind();
this->visibility_ = sym.get_st_visibility();
this->other_ = sym.get_st_nonvis();
this->special_ = false;
this->def_ = false;
this->forwarder_ = false;
this->is_special_ = false;
this->is_def_ = false;
this->is_forwarder_ = false;
this->in_dyn_ = object->is_dynamic();
}
// Initialize the fields in Sized_symbol.
@ -107,11 +104,22 @@ Symbol_table::resolve_forwards(Symbol* from) const
// Resolve a Symbol with another Symbol. This is only used in the
// unusual case where there are references to both an unversioned
// symbol and a symbol with a version, and we then discover that that
// version is the default version.
// version is the default version. Because this is unusual, we do
// this the slow way, by converting back to an ELF symbol.
template<int size, bool big_endian>
void
Symbol_table::resolve(Symbol*, const Symbol*)
Symbol_table::resolve(Sized_symbol<size>* to, const Sized_symbol<size>* from)
{
unsigned char buf[elfcpp::Elf_sizes<size>::sym_size];
elfcpp::Sym_write<size, big_endian> esym(buf);
// We don't bother to set the st_name field.
esym.put_st_value(from->value());
esym.put_st_size(from->symsize());
esym.put_st_info(from->binding(), from->type());
esym.put_st_other(from->visibility(), from->other());
esym.put_st_shndx(from->shnum());
Symbol_table::resolve(to, esym.sym(), from->object());
}
// Add one symbol from OBJECT to the symbol table. NAME is symbol
@ -162,11 +170,11 @@ Symbol_table::add_from_object(Sized_object<size, big_endian>* object,
// ins.first->second: the value (Symbol*).
// ins.second: true if new entry was inserted, false if not.
Symbol* ret;
Sized_symbol<size>* ret;
if (!ins.second)
{
// We already have an entry for NAME/VERSION.
ret = ins.first->second;
ret = this->get_sized_symbol<size>(ins.first->second);
assert(ret != NULL);
Symbol_table::resolve(ret, sym, object);
@ -182,7 +190,9 @@ Symbol_table::add_from_object(Sized_object<size, big_endian>* object,
{
// This is the unfortunate case where we already have
// entries for both NAME/VERSION and NAME/NULL.
Symbol_table::resolve(ret, insdef.first->second);
const Sized_symbol<size>* sym2 =
this->get_sized_symbol<size>(insdef.first->second);
Symbol_table::resolve<size, big_endian>(ret, sym2);
this->make_forwarder(insdef.first->second, ret);
insdef.first->second = ret;
}
@ -196,18 +206,19 @@ Symbol_table::add_from_object(Sized_object<size, big_endian>* object,
{
// We already have an entry for NAME/NULL. Make
// NAME/VERSION point to it.
ret = insdef.first->second;
ret = this->get_sized_symbol<size>(insdef.first->second);
Symbol_table::resolve(ret, sym, object);
ins.first->second = ret;
}
else
{
Sized_symbol<size>* rs;
Sized_target<size, big_endian>* target = object->sized_target();
if (target->has_make_symbol())
if (!target->has_make_symbol())
ret = new Sized_symbol<size>();
else
{
rs = target->make_symbol();
if (rs == NULL)
ret = target->make_symbol();
if (ret == NULL)
{
// This means that we don't want a symbol table
// entry after all.
@ -222,11 +233,9 @@ Symbol_table::add_from_object(Sized_object<size, big_endian>* object,
return NULL;
}
}
else
rs = new Sized_symbol<size>();
rs->init(name, version, object, sym);
ret = rs;
ret->init(name, version, object, sym);
ins.first->second = ret;
if (def)
{

123
gold/symtab.h
View file

@ -32,8 +32,6 @@ class Sized_target;
class Symbol
{
public:
virtual ~Symbol();
// Return the symbol name.
const char*
name() const
@ -45,18 +43,6 @@ class Symbol
version() const
{ return this->version_; }
// 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->forwarder_; }
// Mark this symbol as a forwarder.
void
set_forwarder()
{ this->forwarder_ = true; }
// Return the object with which this symbol is associated.
Object*
object() const
@ -67,11 +53,48 @@ class Symbol
binding() const
{ return this->binding_; }
// Return the symbol type.
elfcpp::STT
type() const
{ return this->type_; }
// Return the symbol visibility.
elfcpp::STV
visibility() const
{ return this->visibility_; }
// Return the non-visibility part of the st_other field.
unsigned char
other() const
{ return this->other_; }
// Return the section index.
unsigned int
shnum() const
{ return this->shnum_; }
// 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 was seen in a dynamic object.
bool
in_dyn() const
{ return this->in_dyn_; }
// Mark this symbol as seen in a dynamic object.
void
set_in_dyn()
{ this->in_dyn_ = true; }
protected:
// Instances of this class should always be created at a specific
// size.
@ -84,6 +107,11 @@ class Symbol
init_base(const char *name, const char* version, Object* object,
const elfcpp::Sym<size, big_endian>&);
// Override existing symbol.
template<int size, bool big_endian>
void
override_base(const elfcpp::Sym<size, big_endian>&, Object* object);
private:
Symbol(const Symbol&);
Symbol& operator=(const Symbol&);
@ -107,9 +135,9 @@ class Symbol
unsigned int other_ : 6;
// True if this symbol always requires special target-specific
// handling.
bool special_ : 1;
bool is_special_ : 1;
// True if this is the default version of the symbol.
bool def_ : 1;
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
@ -117,7 +145,9 @@ class Symbol
// 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.
bool forwarder_ : 1;
bool is_forwarder_ : 1;
// True if we've seen this symbol in a dynamic object.
bool in_dyn_ : 1;
};
// The parts of a symbol which are size specific. Using a template
@ -127,6 +157,9 @@ 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()
{ }
@ -136,14 +169,30 @@ class Sized_symbol : public Symbol
init(const char *name, const char* version, Object* object,
const elfcpp::Sym<size, big_endian>&);
// Override existing symbol.
template<bool big_endian>
void
override(const elfcpp::Sym<size, big_endian>&, Object* object);
// 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->size_; }
private:
Sized_symbol(const Sized_symbol&);
Sized_symbol& operator=(const Sized_symbol&);
// Symbol value.
typename elfcpp::Elf_types<size>::Elf_Addr value_;
Value_type value_;
// Symbol size.
typename elfcpp::Elf_types<size>::Elf_WXword size_;
Size_type size_;
};
// The main linker symbol table.
@ -153,7 +202,7 @@ class Symbol_table
public:
Symbol_table();
virtual ~Symbol_table();
~Symbol_table();
// Add COUNT external symbols from OBJECT to the symbol table. SYMS
// is the symbols, SYM_NAMES is their names, SYM_NAME_SIZE is the
@ -175,6 +224,15 @@ class Symbol_table
get_size() const
{ return this->size_; }
// Return the sized version of a symbol in this table.
template<int size>
Sized_symbol<size>*
get_sized_symbol(Symbol*);
template<int size>
const Sized_symbol<size>*
get_sized_symbol(const Symbol*);
private:
Symbol_table(const Symbol_table&);
Symbol_table& operator=(const Symbol_table&);
@ -198,10 +256,13 @@ class Symbol_table
// Resolve symbols.
template<int size, bool big_endian>
static void
resolve(Symbol* to, const elfcpp::Sym<size, big_endian>& sym, Object*);
resolve(Sized_symbol<size>* to,
const elfcpp::Sym<size, big_endian>& sym,
Object*);
template<int size, bool big_endian>
static void
resolve(Symbol* to, const Symbol* from);
resolve(Sized_symbol<size>* to, const Sized_symbol<size>* from);
typedef std::pair<const char*, const char*> Symbol_table_key;
@ -233,6 +294,24 @@ class Symbol_table
Unordered_map<Symbol*, Symbol*> forwarders_;
};
// We inline get_sized_symbol for efficiency.
template<int size>
Sized_symbol<size>*
Symbol_table::get_sized_symbol(Symbol* sym)
{
assert(size == this->get_size());
return static_cast<Sized_symbol<size>*>(sym);
}
template<int size>
const Sized_symbol<size>*
Symbol_table::get_sized_symbol(const Symbol* sym)
{
assert(size == this->get_size());
return static_cast<const Sized_symbol<size>*>(sym);
}
} // End namespace gold.
#endif // !defined(GOLD_SYMTAB_H)