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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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152
gold/resolve.cc
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@ -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);