// resolve.cc -- symbol resolution for gold
-// Copyright 2006, 2007 Free Software Foundation, Inc.
+// Copyright 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.
// This file is part of gold.
#include "target.h"
#include "object.h"
#include "symtab.h"
+#include "plugin.h"
namespace gold
{
// Symbol methods used in this file.
+// This symbol is being overridden by another symbol whose version is
+// VERSION. Update the VERSION_ field accordingly.
+
+inline void
+Symbol::override_version(const char* version)
+{
+ if (version == NULL)
+ {
+ // This is the case where this symbol is NAME/VERSION, and the
+ // version was not marked as hidden. That makes it the default
+ // version, so we create NAME/NULL. Later we see another symbol
+ // NAME/NULL, and that symbol is overriding this one. In this
+ // case, since NAME/VERSION is the default, we make NAME/NULL
+ // override NAME/VERSION as well. They are already the same
+ // Symbol structure. Setting the VERSION_ field to NULL ensures
+ // that it will be output with the correct, empty, version.
+ this->version_ = version;
+ }
+ else
+ {
+ // This is the case where this symbol is NAME/VERSION_ONE, and
+ // now we see NAME/VERSION_TWO, and NAME/VERSION_TWO is
+ // overriding NAME. If VERSION_ONE and VERSION_TWO are
+ // different, then this can only happen when VERSION_ONE is NULL
+ // and VERSION_TWO is not hidden.
+ gold_assert(this->version_ == version || this->version_ == NULL);
+ this->version_ = version;
+ }
+}
+
+// This symbol is being overidden by another symbol whose visibility
+// is VISIBILITY. Updated the VISIBILITY_ field accordingly.
+
+inline void
+Symbol::override_visibility(elfcpp::STV visibility)
+{
+ // The rule for combining visibility is that we always choose the
+ // most constrained visibility. In order of increasing constraint,
+ // visibility goes PROTECTED, HIDDEN, INTERNAL. This is the reverse
+ // of the numeric values, so the effect is that we always want the
+ // smallest non-zero value.
+ if (visibility != elfcpp::STV_DEFAULT)
+ {
+ if (this->visibility_ == elfcpp::STV_DEFAULT)
+ this->visibility_ = visibility;
+ else if (this->visibility_ > visibility)
+ this->visibility_ = visibility;
+ }
+}
+
// Override the fields in Symbol.
template<int size, bool big_endian>
void
Symbol::override_base(const elfcpp::Sym<size, big_endian>& sym,
+ unsigned int st_shndx, bool is_ordinary,
Object* object, const char* version)
{
gold_assert(this->source_ == FROM_OBJECT);
this->u_.from_object.object = object;
- if (version != NULL && this->version() != version)
- {
- gold_assert(this->version() == NULL);
- this->version_ = version;
- }
- // FIXME: Handle SHN_XINDEX.
- this->u_.from_object.shndx = sym.get_st_shndx();
+ this->override_version(version);
+ this->u_.from_object.shndx = st_shndx;
+ this->is_ordinary_shndx_ = is_ordinary;
this->type_ = sym.get_st_type();
this->binding_ = sym.get_st_bind();
- this->visibility_ = sym.get_st_visibility();
+ this->override_visibility(sym.get_st_visibility());
this->nonvis_ = sym.get_st_nonvis();
if (object->is_dynamic())
this->in_dyn_ = true;
template<bool big_endian>
void
Sized_symbol<size>::override(const elfcpp::Sym<size, big_endian>& sym,
+ unsigned st_shndx, bool is_ordinary,
Object* object, const char* version)
{
- this->override_base(sym, object, version);
+ this->override_base(sym, st_shndx, is_ordinary, object, version);
this->value_ = sym.get_st_value();
this->symsize_ = sym.get_st_size();
}
void
Symbol_table::override(Sized_symbol<size>* tosym,
const elfcpp::Sym<size, big_endian>& fromsym,
+ unsigned int st_shndx, bool is_ordinary,
Object* object, const char* version)
{
- tosym->override(fromsym, object, version);
+ tosym->override(fromsym, st_shndx, is_ordinary, object, version);
if (tosym->has_alias())
{
Symbol* sym = this->weak_aliases_[tosym];
gold_assert(sym != NULL);
- Sized_symbol<size>* ssym;
- ssym = this->get_sized_symbol SELECT_SIZE_NAME(size) (sym
- SELECT_SIZE(size));
+ Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym);
do
{
- ssym->override(fromsym, object, version);
+ ssym->override(fromsym, st_shndx, is_ordinary, object, version);
sym = this->weak_aliases_[ssym];
gold_assert(sym != NULL);
- ssym = this->get_sized_symbol SELECT_SIZE_NAME(size) (
- sym SELECT_SIZE(size));
+ ssym = this->get_sized_symbol<size>(sym);
}
while (ssym != tosym);
}
static unsigned int
symbol_to_bits(elfcpp::STB binding, bool is_dynamic,
- unsigned int shndx, elfcpp::STT type)
+ unsigned int shndx, bool is_ordinary, elfcpp::STT type)
{
unsigned int bits;
switch (binding)
{
case elfcpp::STB_GLOBAL:
+ case elfcpp::STB_GNU_UNIQUE:
bits = global_flag;
break;
break;
case elfcpp::SHN_COMMON:
- bits |= common_flag;
+ if (!is_ordinary)
+ bits |= common_flag;
break;
default:
if (type == elfcpp::STT_COMMON)
bits |= common_flag;
+ else if (!is_ordinary && Symbol::is_common_shndx(shndx))
+ bits |= common_flag;
else
bits |= def_flag;
break;
}
// Resolve a symbol. This is called the second and subsequent times
-// we see a symbol. TO is the pre-existing symbol. ORIG_SYM is the
-// new symbol, seen in OBJECT. SYM is almost always identical to
-// ORIG_SYM, but may be munged (for instance, if we determine the
-// symbol is in a to-be-discarded section, we'll set sym's shndx to
-// UNDEFINED). VERSION of the version of SYM.
+// we see a symbol. TO is the pre-existing symbol. ST_SHNDX is the
+// section index for SYM, possibly adjusted for many sections.
+// IS_ORDINARY is whether ST_SHNDX is a normal section index rather
+// than a special code. ORIG_ST_SHNDX is the original section index,
+// before any munging because of discarded sections, except that all
+// non-ordinary section indexes are mapped to SHN_UNDEF. VERSION is
+// the version of SYM.
template<int size, bool big_endian>
void
Symbol_table::resolve(Sized_symbol<size>* to,
const elfcpp::Sym<size, big_endian>& sym,
- const elfcpp::Sym<size, big_endian>& orig_sym,
+ unsigned int st_shndx, bool is_ordinary,
+ unsigned int orig_st_shndx,
Object* object, const char* version)
{
- if (object->target()->has_resolve())
+ if (parameters->target().has_resolve())
{
Sized_target<size, big_endian>* sized_target;
- sized_target = object->sized_target
- SELECT_SIZE_ENDIAN_NAME(size, big_endian) (
- SELECT_SIZE_ENDIAN_ONLY(size, big_endian));
+ sized_target = parameters->sized_target<size, big_endian>();
sized_target->resolve(to, sym, object, version);
return;
}
// Record that we've seen this symbol in a regular object.
to->set_in_reg();
}
+ else if (st_shndx == elfcpp::SHN_UNDEF
+ && (to->visibility() == elfcpp::STV_HIDDEN
+ || to->visibility() == elfcpp::STV_INTERNAL))
+ {
+ // A dynamic object cannot reference a hidden or internal symbol
+ // defined in another object.
+ gold_warning(_("%s symbol '%s' in %s is referenced by DSO %s"),
+ (to->visibility() == elfcpp::STV_HIDDEN
+ ? "hidden"
+ : "internal"),
+ to->demangled_name().c_str(),
+ to->object()->name().c_str(),
+ object->name().c_str());
+ return;
+ }
else
{
// Record that we've seen this symbol in a dynamic object.
to->set_in_dyn();
}
+ // Record if we've seen this symbol in a real ELF object (i.e., the
+ // symbol is referenced from outside the world known to the plugin).
+ if (object->pluginobj() == NULL)
+ to->set_in_real_elf();
+
+ // If we're processing replacement files, allow new symbols to override
+ // the placeholders from the plugin objects.
+ if (to->source() == Symbol::FROM_OBJECT)
+ {
+ Pluginobj* obj = to->object()->pluginobj();
+ if (obj != NULL
+ && parameters->options().plugins()->in_replacement_phase())
+ {
+ this->override(to, sym, st_shndx, is_ordinary, object, version);
+ return;
+ }
+ }
+
unsigned int frombits = symbol_to_bits(sym.get_st_bind(),
object->is_dynamic(),
- sym.get_st_shndx(),
+ st_shndx, is_ordinary,
sym.get_st_type());
bool adjust_common_sizes;
+ typename Sized_symbol<size>::Size_type tosize = to->symsize();
if (Symbol_table::should_override(to, frombits, object,
&adjust_common_sizes))
{
- typename Sized_symbol<size>::Size_type tosize = to->symsize();
-
- this->override(to, sym, object, version);
-
+ this->override(to, sym, st_shndx, is_ordinary, object, version);
if (adjust_common_sizes && tosize > to->symsize())
to->set_symsize(tosize);
}
else
{
- if (adjust_common_sizes && sym.get_st_size() > to->symsize())
+ if (adjust_common_sizes && sym.get_st_size() > tosize)
to->set_symsize(sym.get_st_size());
+ // The ELF ABI says that even for a reference to a symbol we
+ // merge the visibility.
+ to->override_visibility(sym.get_st_visibility());
+ }
+
+ if (adjust_common_sizes && parameters->options().warn_common())
+ {
+ if (tosize > sym.get_st_size())
+ Symbol_table::report_resolve_problem(false,
+ _("common of '%s' overriding "
+ "smaller common"),
+ to, object);
+ else if (tosize < sym.get_st_size())
+ Symbol_table::report_resolve_problem(false,
+ _("common of '%s' overidden by "
+ "larger common"),
+ to, object);
+ else
+ Symbol_table::report_resolve_problem(false,
+ _("multiple common of '%s'"),
+ to, object);
}
// A new weak undefined reference, merging with an old weak
// actually refer to the same lines of code. (Note: not all ODR
// violations can be found this way, and not everything this finds
// is an ODR violation. But it's helpful to warn about.)
- // We use orig_sym here because we want the symbol exactly as it
- // appears in the object file, not munged via our future processing.
- if (orig_sym.get_st_bind() == elfcpp::STB_WEAK
+ bool to_is_ordinary;
+ if (parameters->options().detect_odr_violations()
+ && sym.get_st_bind() == elfcpp::STB_WEAK
&& to->binding() == elfcpp::STB_WEAK
- && orig_sym.get_st_shndx() != elfcpp::SHN_UNDEF
- && to->shndx() != elfcpp::SHN_UNDEF
- && orig_sym.get_st_size() != 0 // Ignore weird 0-sized symbols.
+ && orig_st_shndx != elfcpp::SHN_UNDEF
+ && to->shndx(&to_is_ordinary) != elfcpp::SHN_UNDEF
+ && to_is_ordinary
+ && sym.get_st_size() != 0 // Ignore weird 0-sized symbols.
&& to->symsize() != 0
- && (orig_sym.get_st_type() != to->type()
- || orig_sym.get_st_size() != to->symsize())
+ && (sym.get_st_type() != to->type()
+ || sym.get_st_size() != to->symsize())
// C does not have a concept of ODR, so we only need to do this
// on C++ symbols. These have (mangled) names starting with _Z.
&& to->name()[0] == '_' && to->name()[1] == 'Z')
{
- Symbol_location from_location
- = { object, orig_sym.get_st_shndx(), orig_sym.get_st_value() };
- Symbol_location to_location = { to->object(), to->shndx(), to->value() };
- this->candidate_odr_violations_[to->name()].insert(from_location);
- this->candidate_odr_violations_[to->name()].insert(to_location);
+ Symbol_location fromloc
+ = { object, orig_st_shndx, sym.get_st_value() };
+ Symbol_location toloc = { to->object(), to->shndx(&to_is_ordinary),
+ to->value() };
+ this->candidate_odr_violations_[to->name()].insert(fromloc);
+ this->candidate_odr_violations_[to->name()].insert(toloc);
}
}
{
*adjust_common_sizes = false;
- unsigned int tobits = symbol_to_bits(to->binding(),
- (to->source() == Symbol::FROM_OBJECT
- && to->object()->is_dynamic()),
- to->shndx(),
- to->type());
+ unsigned int tobits;
+ if (to->source() == Symbol::IS_UNDEFINED)
+ tobits = symbol_to_bits(to->binding(), false, elfcpp::SHN_UNDEF, true,
+ to->type());
+ else if (to->source() != Symbol::FROM_OBJECT)
+ tobits = symbol_to_bits(to->binding(), false, elfcpp::SHN_ABS, false,
+ to->type());
+ else
+ {
+ bool is_ordinary;
+ unsigned int shndx = to->shndx(&is_ordinary);
+ tobits = symbol_to_bits(to->binding(),
+ to->object()->is_dynamic(),
+ shndx,
+ is_ordinary,
+ to->type());
+ }
// FIXME: Warn if either but not both of TO and SYM are STT_TLS.
{
case DEF * 16 + DEF:
// Two definitions of the same symbol.
- // FIXME: Do a better job of reporting locations.
- gold_error(_("%s: multiple definition of %s"),
- object != NULL ? object->name().c_str() : _("command line"),
- to->name());
- gold_error(_("%s: previous definition here"),
- (to->source() == Symbol::FROM_OBJECT
- ? to->object()->name().c_str()
- : _("command line")));
+
+ // If either symbol is defined by an object included using
+ // --just-symbols, then don't warn. This is for compatibility
+ // with the GNU linker. FIXME: This is a hack.
+ if ((to->source() == Symbol::FROM_OBJECT && to->object()->just_symbols())
+ || object->just_symbols())
+ return false;
+
+ Symbol_table::report_resolve_problem(true,
+ _("multiple definition of '%s'"),
+ to, object);
return false;
case WEAK_DEF * 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, version a
- // warning.
+ // definition overrides.
+ if (parameters->options().warn_common())
+ Symbol_table::report_resolve_problem(false,
+ _("definition of '%s' overriding "
+ "common"),
+ to, object);
return true;
case DEF * 16 + WEAK_DEF:
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.
+ // object.
+ if (parameters->options().warn_common())
+ Symbol_table::report_resolve_problem(false,
+ _("definition of '%s' overriding "
+ "dynamic common definition"),
+ to, object);
return true;
case DEF * 16 + DYN_DEF:
case DEF * 16 + COMMON:
// A common symbol does not override a definition.
+ if (parameters->options().warn_common())
+ Symbol_table::report_resolve_problem(false,
+ _("common '%s' overridden by "
+ "previous definition"),
+ to, object);
return false;
case WEAK_DEF * 16 + COMMON:
}
}
+// Issue an error or warning due to symbol resolution. IS_ERROR
+// indicates an error rather than a warning. MSG is the error
+// message; it is expected to have a %s for the symbol name. TO is
+// the existing symbol. OBJECT is where the new symbol was found.
+
+// FIXME: We should have better location information here. When the
+// symbol is defined, we should be able to pull the location from the
+// debug info if there is any.
+
+void
+Symbol_table::report_resolve_problem(bool is_error, const char* msg,
+ const Symbol* to, Object* object)
+{
+ std::string demangled(to->demangled_name());
+ size_t len = strlen(msg) + demangled.length() + 10;
+ char* buf = new char[len];
+ snprintf(buf, len, msg, demangled.c_str());
+
+ const char* objname;
+ if (object != NULL)
+ objname = object->name().c_str();
+ else
+ objname = _("command line");
+
+ if (is_error)
+ gold_error("%s: %s", objname, buf);
+ else
+ gold_warning("%s: %s", objname, buf);
+
+ delete[] buf;
+
+ if (to->source() == Symbol::FROM_OBJECT)
+ objname = to->object()->name().c_str();
+ else
+ objname = _("command line");
+ gold_info("%s: %s: previous definition here", program_name, objname);
+}
+
// A special case of should_override which is only called for a strong
// defined symbol from a regular object file. This is used when
// defining special symbols.
case IN_OUTPUT_SEGMENT:
this->u_.in_output_segment = from->u_.in_output_segment;
break;
- case CONSTANT:
+ case IS_CONSTANT:
+ case IS_UNDEFINED:
break;
default:
gold_unreachable();
break;
}
- if (from->version_ != NULL && this->version_ != from->version_)
- {
- gold_assert(this->version_ == NULL);
- this->version_ = from->version_;
- }
-
+ this->override_version(from->version_);
this->type_ = from->type_;
this->binding_ = from->binding_;
- this->visibility_ = from->visibility_;
+ this->override_visibility(from->visibility_);
this->nonvis_ = from->nonvis_;
// Special symbols are always considered to be regular symbols.
// somehow.
gold_assert(!from->is_target_special_ || this->is_target_special_);
gold_assert(!from->is_forwarder_);
- gold_assert(!from->has_got_offset_);
gold_assert(!from->has_plt_offset_);
gold_assert(!from->has_warning_);
gold_assert(!from->is_copied_from_dynobj_);
+ gold_assert(!from->is_forced_local_);
}
// Override a symbol with a special symbol.
{
Symbol* sym = this->weak_aliases_[tosym];
gold_assert(sym != NULL);
- Sized_symbol<size>* ssym;
- ssym = this->get_sized_symbol SELECT_SIZE_NAME(size) (sym
- SELECT_SIZE(size));
+ Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym);
do
{
ssym->override_with_special(fromsym);
sym = this->weak_aliases_[ssym];
gold_assert(sym != NULL);
- ssym = this->get_sized_symbol SELECT_SIZE_NAME(size) (
- sym SELECT_SIZE(size));
+ ssym = this->get_sized_symbol<size>(sym);
}
while (ssym != tosym);
}
+ if (tosym->binding() == elfcpp::STB_LOCAL
+ || ((tosym->visibility() == elfcpp::STV_HIDDEN
+ || tosym->visibility() == elfcpp::STV_INTERNAL)
+ && (tosym->binding() == elfcpp::STB_GLOBAL
+ || tosym->binding() == elfcpp::STB_GNU_UNIQUE
+ || tosym->binding() == elfcpp::STB_WEAK)
+ && !parameters->options().relocatable()))
+ this->force_local(tosym);
}
// Instantiate the templates we need. We could use the configure
Symbol_table::resolve<32, false>(
Sized_symbol<32>* to,
const elfcpp::Sym<32, false>& sym,
- const elfcpp::Sym<32, false>& orig_sym,
+ unsigned int st_shndx,
+ bool is_ordinary,
+ unsigned int orig_st_shndx,
Object* object,
const char* version);
#endif
Symbol_table::resolve<32, true>(
Sized_symbol<32>* to,
const elfcpp::Sym<32, true>& sym,
- const elfcpp::Sym<32, true>& orig_sym,
+ unsigned int st_shndx,
+ bool is_ordinary,
+ unsigned int orig_st_shndx,
Object* object,
const char* version);
#endif
Symbol_table::resolve<64, false>(
Sized_symbol<64>* to,
const elfcpp::Sym<64, false>& sym,
- const elfcpp::Sym<64, false>& orig_sym,
+ unsigned int st_shndx,
+ bool is_ordinary,
+ unsigned int orig_st_shndx,
Object* object,
const char* version);
#endif
Symbol_table::resolve<64, true>(
Sized_symbol<64>* to,
const elfcpp::Sym<64, true>& sym,
- const elfcpp::Sym<64, true>& orig_sym,
+ unsigned int st_shndx,
+ bool is_ordinary,
+ unsigned int orig_st_shndx,
Object* object,
const char* version);
#endif
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