X-Git-Url: http://git.efficios.com/?a=blobdiff_plain;f=gold%2Fresolve.cc;h=a10895641fd023bec185ccf688c9f5cb833a6619;hb=660df28acfa1b58c978d65d9cb26d37023f791ce;hp=86645a4a188eb95b227e8c624a3692e9b159b9ff;hpb=593f47df457d5e059f49b1ce62d1b51d4a7cc3e4;p=deliverable%2Fbinutils-gdb.git diff --git a/gold/resolve.cc b/gold/resolve.cc index 86645a4a18..a10895641f 100644 --- a/gold/resolve.cc +++ b/gold/resolve.cc @@ -1,32 +1,111 @@ // resolve.cc -- symbol resolution for gold +// Copyright (C) 2006-2019 Free Software Foundation, Inc. +// Written by Ian Lance Taylor . + +// 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. + #include "gold.h" #include "elfcpp.h" #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 void Symbol::override_base(const elfcpp::Sym& sym, - Object* object) + unsigned int st_shndx, bool is_ordinary, + Object* object, const char* version) { - assert(this->source_ == FROM_OBJECT); - this->u_.from_object.object = object; - // FIXME: Handle SHN_XINDEX. - this->u_.from_object.shnum = sym.get_st_shndx(); - this->type_ = sym.get_st_type(); + gold_assert(this->source_ == FROM_OBJECT); + this->u1_.object = object; + this->override_version(version); + this->u2_.shndx = st_shndx; + this->is_ordinary_shndx_ = is_ordinary; + // Don't override st_type from plugin placeholder symbols. + if (object->pluginobj() == NULL) + 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; + else + this->in_reg_ = true; } // Override the fields in Sized_symbol. @@ -35,146 +114,384 @@ template template void Sized_symbol::override(const elfcpp::Sym& sym, - Object* object) + unsigned st_shndx, bool is_ordinary, + Object* object, const char* version) { - this->override_base(sym, object); + this->override_base(sym, st_shndx, is_ordinary, object, version); this->value_ = sym.get_st_value(); this->symsize_ = 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. +// Override TOSYM with symbol FROMSYM, defined in OBJECT, with version +// VERSION. This handles all aliases of TOSYM. template void -Symbol_table::resolve(Sized_symbol* to, - const elfcpp::Sym& sym, - Object* object) +Symbol_table::override(Sized_symbol* tosym, + const elfcpp::Sym& fromsym, + unsigned int st_shndx, bool is_ordinary, + Object* object, const char* version) { - if (object->target()->has_resolve()) + tosym->override(fromsym, st_shndx, is_ordinary, object, version); + if (tosym->has_alias()) { - Sized_target* sized_target; - sized_target = object->sized_target - SELECT_SIZE_ENDIAN_NAME(size, big_endian) ( - SELECT_SIZE_ENDIAN_ONLY(size, big_endian)); - sized_target->resolve(to, sym, object); - return; + Symbol* sym = this->weak_aliases_[tosym]; + gold_assert(sym != NULL); + Sized_symbol* ssym = this->get_sized_symbol(sym); + do + { + ssym->override(fromsym, st_shndx, is_ordinary, object, version); + sym = this->weak_aliases_[ssym]; + gold_assert(sym != NULL); + ssym = this->get_sized_symbol(sym); + } + while (ssym != tosym); } +} - // Build a little code for each symbol. - // Bit 0: 0 for global, 1 for weak. - // Bit 1: 0 for regular object, 1 for shared object - // Bits 2-3: 0 for normal, 1 for undefined, 2 for common - // This gives us values from 0 to 11: +// The resolve functions build a little code for each symbol. +// Bit 0: 0 for global, 1 for weak. +// Bit 1: 0 for regular object, 1 for shared object +// Bits 2-3: 0 for normal, 1 for undefined, 2 for common +// This gives us values from 0 to 11. - enum - { - DEF = 0, - WEAK_DEF = 1, - DYN_DEF = 2, - DYN_WEAK_DEF = 3, - UNDEF = 4, - WEAK_UNDEF = 5, - DYN_UNDEF = 6, - DYN_WEAK_UNDEF = 7, - COMMON = 8, - WEAK_COMMON = 9, - DYN_COMMON = 10, - DYN_WEAK_COMMON = 11 - }; +static const int global_or_weak_shift = 0; +static const unsigned int global_flag = 0 << global_or_weak_shift; +static const unsigned int weak_flag = 1 << global_or_weak_shift; + +static const int regular_or_dynamic_shift = 1; +static const unsigned int regular_flag = 0 << regular_or_dynamic_shift; +static const unsigned int dynamic_flag = 1 << regular_or_dynamic_shift; + +static const int def_undef_or_common_shift = 2; +static const unsigned int def_flag = 0 << def_undef_or_common_shift; +static const unsigned int undef_flag = 1 << def_undef_or_common_shift; +static const unsigned int common_flag = 2 << def_undef_or_common_shift; - int tobits; - switch (to->binding()) +// This convenience function combines all the flags based on facts +// about the symbol. + +static unsigned int +symbol_to_bits(elfcpp::STB binding, bool is_dynamic, + unsigned int shndx, bool is_ordinary) +{ + unsigned int bits; + + switch (binding) { case elfcpp::STB_GLOBAL: - tobits = 0; + case elfcpp::STB_GNU_UNIQUE: + bits = global_flag; break; case elfcpp::STB_WEAK: - tobits = 1; + bits = weak_flag; break; case elfcpp::STB_LOCAL: // We should only see externally visible symbols in the symbol // table. - abort(); + gold_error(_("invalid STB_LOCAL symbol in external symbols")); + bits = global_flag; + break; default: // Any target which wants to handle STB_LOOS, etc., needs to // define a resolve method. - abort(); + gold_error(_("unsupported symbol binding %d"), static_cast(binding)); + bits = global_flag; } - if (to->object() != NULL && to->object()->is_dynamic()) - tobits |= (1 << 1); + if (is_dynamic) + bits |= dynamic_flag; + else + bits |= regular_flag; - switch (to->shnum()) + switch (shndx) { case elfcpp::SHN_UNDEF: - tobits |= (1 << 2); + bits |= undef_flag; break; case elfcpp::SHN_COMMON: - tobits |= (2 << 2); + if (!is_ordinary) + bits |= common_flag; break; default: - if (to->type() == elfcpp::STT_COMMON) - tobits |= (2 << 2); + if (!is_ordinary && Symbol::is_common_shndx(shndx)) + bits |= common_flag; + else + bits |= def_flag; break; } - int frombits; - switch (sym.get_st_bind()) - { - case elfcpp::STB_GLOBAL: - frombits = 0; - break; - - case elfcpp::STB_WEAK: - frombits = 1; - break; + return bits; +} - case elfcpp::STB_LOCAL: - fprintf(stderr, - _("%s: %s: invalid STB_LOCAL symbol %s in external symbols\n"), - program_name, object->name().c_str(), to->name()); - gold_exit(false); +// Resolve a symbol. This is called the second and subsequent times +// 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. - default: - fprintf(stderr, - _("%s: %s: unsupported symbol binding %d for symbol %s\n"), - program_name, object->name().c_str(), - static_cast(sym.get_st_bind()), to->name()); - gold_exit(false); +template +void +Symbol_table::resolve(Sized_symbol* to, + const elfcpp::Sym& sym, + unsigned int st_shndx, bool is_ordinary, + unsigned int orig_st_shndx, + Object* object, const char* version, + bool is_default_version) +{ + bool to_is_ordinary; + const unsigned int to_shndx = to->shndx(&to_is_ordinary); + + // It's possible for a symbol to be defined in an object file + // using .symver to give it a version, and for there to also be + // a linker script giving that symbol the same version. We + // don't want to give a multiple-definition error for this + // harmless redefinition. + if (to->source() == Symbol::FROM_OBJECT + && to->object() == object + && to->is_defined() + && is_ordinary + && to_is_ordinary + && to_shndx == st_shndx + && to->value() == sym.get_st_value()) + return; + + // Likewise for an absolute symbol defined twice with the same value. + if (!is_ordinary + && st_shndx == elfcpp::SHN_ABS + && !to_is_ordinary + && to_shndx == elfcpp::SHN_ABS + && to->value() == sym.get_st_value()) + return; + + if (parameters->target().has_resolve()) + { + Sized_target* sized_target; + sized_target = parameters->sized_target(); + if (sized_target->resolve(to, sym, object, version)) + return; } - if (object->is_dynamic()) + if (!object->is_dynamic()) + { + if (sym.get_st_type() == elfcpp::STT_COMMON + && (is_ordinary || !Symbol::is_common_shndx(st_shndx))) + { + gold_warning(_("STT_COMMON symbol '%s' in %s " + "is not in a common section"), + to->demangled_name().c_str(), + to->object()->name().c_str()); + 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)) + { + // The symbol is hidden, so a reference from a shared object + // cannot bind to it. We tried issuing a warning in this case, + // but that produces false positives when the symbol is + // actually resolved in a different shared object (PR 15574). + return; + } + else { - frombits |= (1 << 1); - // Record that we've seen this symbol in a dynamic object. to->set_in_dyn(); } - switch (sym.get_st_shndx()) + // 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 && !object->is_dynamic()) + to->set_in_real_elf(); + + // If we're processing replacement files, allow new symbols to override + // the placeholders from the plugin objects. + // Treat common symbols specially since it is possible that an ELF + // file increased the size of the alignment. + if (to->source() == Symbol::FROM_OBJECT) { - case elfcpp::SHN_UNDEF: - frombits |= (1 << 2); - break; + Pluginobj* obj = to->object()->pluginobj(); + if (obj != NULL + && parameters->options().plugins()->in_replacement_phase()) + { + bool adjust_common = false; + typename Sized_symbol::Size_type tosize = 0; + typename Sized_symbol::Value_type tovalue = 0; + if (to->is_common() + && !is_ordinary && Symbol::is_common_shndx(st_shndx)) + { + adjust_common = true; + tosize = to->symsize(); + tovalue = to->value(); + } + this->override(to, sym, st_shndx, is_ordinary, object, version); + if (adjust_common) + { + if (tosize > to->symsize()) + to->set_symsize(tosize); + if (tovalue > to->value()) + to->set_value(tovalue); + } + return; + } + } - case elfcpp::SHN_COMMON: - frombits |= (2 << 2); - break; + // A new weak undefined reference, merging with an old weak + // reference, could be a One Definition Rule (ODR) violation -- + // especially if the types or sizes of the references differ. We'll + // store such pairs and look them up later to make sure they + // actually refer to the same lines of code. We also check + // combinations of weak and strong, which might occur if one case is + // inline and the other is not. (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.) + if (parameters->options().detect_odr_violations() + && (sym.get_st_bind() == elfcpp::STB_WEAK + || to->binding() == elfcpp::STB_WEAK) + && orig_st_shndx != elfcpp::SHN_UNDEF + && to_is_ordinary + && to_shndx != elfcpp::SHN_UNDEF + && sym.get_st_size() != 0 // Ignore weird 0-sized symbols. + && to->symsize() != 0 + && (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 fromloc + = { object, orig_st_shndx, static_cast(sym.get_st_value()) }; + Symbol_location toloc = { to->object(), to_shndx, + static_cast(to->value()) }; + this->candidate_odr_violations_[to->name()].insert(fromloc); + this->candidate_odr_violations_[to->name()].insert(toloc); + } - default: - if (sym.get_st_type() == elfcpp::STT_COMMON) - frombits |= (2 << 2); - break; + // Plugins don't provide a symbol type, so adopt the existing type + // if the FROM symbol is from a plugin. + elfcpp::STT fromtype = (object->pluginobj() != NULL + ? to->type() + : sym.get_st_type()); + unsigned int frombits = symbol_to_bits(sym.get_st_bind(), + object->is_dynamic(), + st_shndx, is_ordinary); + + bool adjust_common_sizes; + bool adjust_dyndef; + typename Sized_symbol::Size_type tosize = to->symsize(); + if (Symbol_table::should_override(to, frombits, fromtype, OBJECT, + object, &adjust_common_sizes, + &adjust_dyndef, is_default_version)) + { + elfcpp::STB orig_tobinding = to->binding(); + typename Sized_symbol::Value_type tovalue = to->value(); + this->override(to, sym, st_shndx, is_ordinary, object, version); + if (adjust_common_sizes) + { + if (tosize > to->symsize()) + to->set_symsize(tosize); + if (tovalue > to->value()) + to->set_value(tovalue); + } + if (adjust_dyndef) + { + // We are overriding an UNDEF or WEAK UNDEF with a DYN DEF. + // Remember which kind of UNDEF it was for future reference. + to->set_undef_binding(orig_tobinding); + } + } + else + { + if (adjust_common_sizes) + { + if (sym.get_st_size() > tosize) + to->set_symsize(sym.get_st_size()); + if (sym.get_st_value() > to->value()) + to->set_value(sym.get_st_value()); + } + if (adjust_dyndef) + { + // We are keeping a DYN DEF after seeing an UNDEF or WEAK UNDEF. + // Remember which kind of UNDEF it was. + to->set_undef_binding(sym.get_st_bind()); + } + // The ELF ABI says that even for a reference to a symbol we + // merge the visibility. + to->override_visibility(sym.get_st_visibility()); + } + + // If we have a non-WEAK reference from a regular object to a + // dynamic object, mark the dynamic object as needed. + if (to->is_from_dynobj() && to->in_reg() && !to->is_undef_binding_weak()) + to->object()->set_is_needed(); + + 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, object); + else if (tosize < sym.get_st_size()) + Symbol_table::report_resolve_problem(false, + _("common of '%s' overidden by " + "larger common"), + to, OBJECT, object); + else + Symbol_table::report_resolve_problem(false, + _("multiple common of '%s'"), + to, OBJECT, object); + } +} + +// Handle the core of symbol resolution. This is called with the +// existing symbol, TO, and a bitflag describing the new symbol. This +// returns true if we should override the existing symbol with the new +// one, and returns false otherwise. It sets *ADJUST_COMMON_SIZES to +// true if we should set the symbol size to the maximum of the TO and +// FROM sizes. It handles error conditions. + +bool +Symbol_table::should_override(const Symbol* to, unsigned int frombits, + elfcpp::STT fromtype, Defined defined, + Object* object, bool* adjust_common_sizes, + bool* adjust_dyndef, bool is_default_version) +{ + *adjust_common_sizes = false; + *adjust_dyndef = false; + + unsigned int tobits; + if (to->source() == Symbol::IS_UNDEFINED) + tobits = symbol_to_bits(to->binding(), false, elfcpp::SHN_UNDEF, true); + else if (to->source() != Symbol::FROM_OBJECT) + tobits = symbol_to_bits(to->binding(), false, elfcpp::SHN_ABS, false); + else + { + bool is_ordinary; + unsigned int shndx = to->shndx(&is_ordinary); + tobits = symbol_to_bits(to->binding(), + to->object()->is_dynamic(), + shndx, + is_ordinary); } - // FIXME: Warn if either but not both of TO and SYM are STT_TLS. + if ((to->type() == elfcpp::STT_TLS) ^ (fromtype == elfcpp::STT_TLS) + && !to->is_placeholder()) + Symbol_table::report_resolve_problem(true, + _("symbol '%s' used as both __thread " + "and non-__thread"), + to, defined, object); // We use a giant switch table for symbol resolution. This code is // unwieldy, but: 1) it is efficient; 2) we definitely handle all @@ -184,14 +501,40 @@ Symbol_table::resolve(Sized_symbol* to, // but that is no easier to understand than this large switch // statement. + // These are the values generated by the bit codes. + enum + { + DEF = global_flag | regular_flag | def_flag, + WEAK_DEF = weak_flag | regular_flag | def_flag, + DYN_DEF = global_flag | dynamic_flag | def_flag, + DYN_WEAK_DEF = weak_flag | dynamic_flag | def_flag, + UNDEF = global_flag | regular_flag | undef_flag, + WEAK_UNDEF = weak_flag | regular_flag | undef_flag, + DYN_UNDEF = global_flag | dynamic_flag | undef_flag, + DYN_WEAK_UNDEF = weak_flag | dynamic_flag | undef_flag, + COMMON = global_flag | regular_flag | common_flag, + WEAK_COMMON = weak_flag | regular_flag | common_flag, + DYN_COMMON = global_flag | dynamic_flag | common_flag, + DYN_WEAK_COMMON = weak_flag | dynamic_flag | common_flag + }; + switch (tobits * 16 + frombits) { case DEF * 16 + DEF: // Two definitions of the same symbol. - fprintf(stderr, "%s: %s: multiple definition of %s\n", - program_name, object->name().c_str(), to->name()); - // FIXME: Report locations. Record that we have seen an error. - return; + + // 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 != NULL && object->just_symbols())) + return false; + + if (!parameters->options().muldefs()) + Symbol_table::report_resolve_problem(true, + _("multiple definition of '%s'"), + to, defined, object); + return false; case WEAK_DEF * 16 + DEF: // We've seen a weak definition, and now we see a strong @@ -202,8 +545,7 @@ Symbol_table::resolve(Sized_symbol* to, // 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; + return true; case DYN_DEF * 16 + DEF: case DYN_WEAK_DEF * 16 + DEF: @@ -211,8 +553,7 @@ Symbol_table::resolve(Sized_symbol* to, // definition in a regular object. The definition in the // regular object overrides the definition in the dynamic // object. - to->override(sym, object); - return; + return true; case UNDEF * 16 + DEF: case WEAK_UNDEF * 16 + DEF: @@ -220,135 +561,192 @@ Symbol_table::resolve(Sized_symbol* to, 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; + return true; 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; + // definition overrides. + if (parameters->options().warn_common()) + Symbol_table::report_resolve_problem(false, + _("definition of '%s' overriding " + "common"), + to, defined, object); + return true; 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; + return false; 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; + return true; 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; + return true; case COMMON * 16 + WEAK_DEF: case WEAK_COMMON * 16 + WEAK_DEF: // A weak definition does not override a common definition. - return; + return false; 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; + // object. + if (parameters->options().warn_common()) + Symbol_table::report_resolve_problem(false, + _("definition of '%s' overriding " + "dynamic common definition"), + to, defined, object); + return true; case DEF * 16 + DYN_DEF: case WEAK_DEF * 16 + DYN_DEF: + // Ignore a dynamic definition if we already have a definition. + return false; + case DYN_DEF * 16 + DYN_DEF: case DYN_WEAK_DEF * 16 + DYN_DEF: - // Ignore a dynamic definition if we already have a definition. - return; + // Ignore a dynamic definition if we already have a definition, + // unless the existing definition is an unversioned definition + // in the same dynamic object, and the new definition is a + // default version. + if (to->object() == object + && to->version() == NULL + && is_default_version) + return true; + // Or, if the existing definition is in an unused --as-needed library, + // and the reference is weak, let the new definition override. + if (to->in_reg() + && to->is_undef_binding_weak() + && to->object()->as_needed() + && !to->object()->is_needed()) + return true; + return false; 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; + return true; + + case WEAK_UNDEF * 16 + DYN_DEF: + // When overriding a weak undef by a dynamic definition, + // we need to remember that the original undef was weak. + *adjust_dyndef = true; + return true; 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; + return false; 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; + return false; case UNDEF * 16 + DYN_WEAK_DEF: - case WEAK_UNDEF * 16 + DYN_WEAK_DEF: + // When overriding an undef by a dynamic weak definition, + // we need to remember that the original undef was not weak. + *adjust_dyndef = true; + return true; + 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; + return true; + + case WEAK_UNDEF * 16 + DYN_WEAK_DEF: + // When overriding a weak undef by a dynamic definition, + // we need to remember that the original undef was weak. + *adjust_dyndef = true; + return true; 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; + return false; + + case DYN_COMMON * 16 + DYN_DEF: + case DYN_WEAK_COMMON * 16 + DYN_DEF: + case DYN_DEF * 16 + DYN_WEAK_DEF: + case DYN_WEAK_DEF * 16 + DYN_WEAK_DEF: + case DYN_COMMON * 16 + DYN_WEAK_DEF: + case DYN_WEAK_COMMON * 16 + DYN_WEAK_DEF: + // If the existing definition is in an unused --as-needed library, + // and the reference is weak, let a new dynamic definition override. + if (to->in_reg() + && to->is_undef_binding_weak() + && to->object()->as_needed() + && !to->object()->is_needed()) + return true; + return false; case DEF * 16 + UNDEF: case WEAK_DEF * 16 + UNDEF: - case DYN_DEF * 16 + UNDEF: - case DYN_WEAK_DEF * 16 + UNDEF: case UNDEF * 16 + UNDEF: // A new undefined reference tells us nothing. - return; + return false; + + case DYN_DEF * 16 + UNDEF: + case DYN_WEAK_DEF * 16 + UNDEF: + // For a dynamic def, we need to remember which kind of undef we see. + *adjust_dyndef = true; + return false; case WEAK_UNDEF * 16 + UNDEF: case DYN_UNDEF * 16 + UNDEF: case DYN_WEAK_UNDEF * 16 + UNDEF: // A strong undef overrides a dynamic or weak undef. - to->override(sym, object); - return; + return true; case COMMON * 16 + UNDEF: case WEAK_COMMON * 16 + UNDEF: case DYN_COMMON * 16 + UNDEF: case DYN_WEAK_COMMON * 16 + UNDEF: // A new undefined reference tells us nothing. - return; + return false; case DEF * 16 + WEAK_UNDEF: case WEAK_DEF * 16 + WEAK_UNDEF: - case DYN_DEF * 16 + WEAK_UNDEF: - case DYN_WEAK_DEF * 16 + WEAK_UNDEF: case UNDEF * 16 + WEAK_UNDEF: case WEAK_UNDEF * 16 + WEAK_UNDEF: case DYN_UNDEF * 16 + WEAK_UNDEF: - case DYN_WEAK_UNDEF * 16 + WEAK_UNDEF: case COMMON * 16 + WEAK_UNDEF: 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; + // A new weak undefined reference tells us nothing unless the + // exisiting symbol is a dynamic weak reference. + return false; + + case DYN_WEAK_UNDEF * 16 + WEAK_UNDEF: + // A new weak reference overrides an existing dynamic weak reference. + // This is necessary because a dynamic weak reference remembers + // the old binding, which may not be weak. If we keeps the existing + // dynamic weak reference, the weakness may be dropped in the output. + return true; + + case DYN_DEF * 16 + WEAK_UNDEF: + case DYN_WEAK_DEF * 16 + WEAK_UNDEF: + // For a dynamic def, we need to remember which kind of undef we see. + *adjust_dyndef = true; + return false; case DEF * 16 + DYN_UNDEF: case WEAK_DEF * 16 + DYN_UNDEF: @@ -363,7 +761,7 @@ Symbol_table::resolve(Sized_symbol* to, case DYN_COMMON * 16 + DYN_UNDEF: case DYN_WEAK_COMMON * 16 + DYN_UNDEF: // A new dynamic undefined reference tells us nothing. - return; + return false; case DEF * 16 + DYN_WEAK_UNDEF: case WEAK_DEF * 16 + DYN_WEAK_UNDEF: @@ -378,50 +776,46 @@ Symbol_table::resolve(Sized_symbol* to, 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; + return false; case DEF * 16 + COMMON: // A common symbol does not override a definition. - return; + if (parameters->options().warn_common()) + Symbol_table::report_resolve_problem(false, + _("common '%s' overridden by " + "previous definition"), + to, defined, object); + return false; 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; + return true; 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; + return true; case COMMON * 16 + COMMON: // Set the size to the maximum. - if (sym.get_st_size() > to->symsize()) - to->set_symsize(sym.get_st_size()); - return; + *adjust_common_sizes = true; + return false; case WEAK_COMMON * 16 + COMMON: // I'm not sure just what a weak common symbol means, but // presumably it can be overridden by a regular common symbol. - to->override(sym, object); - return; + return true; case DYN_COMMON * 16 + COMMON: case DYN_WEAK_COMMON * 16 + COMMON: - { - // Use the real common symbol, but adjust the size if necessary. - typename Sized_symbol::Size_type symsize = to->symsize(); - to->override(sym, object); - if (to->symsize() < symsize) - to->set_symsize(symsize); - } - return; + // Use the real common symbol, but adjust the size if necessary. + *adjust_common_sizes = true; + return true; case DEF * 16 + WEAK_COMMON: case WEAK_DEF * 16 + WEAK_COMMON: @@ -429,15 +823,14 @@ Symbol_table::resolve(Sized_symbol* to, case DYN_WEAK_DEF * 16 + WEAK_COMMON: // Whatever a weak common symbol is, it won't override a // definition. - return; + return false; case UNDEF * 16 + WEAK_COMMON: case WEAK_UNDEF * 16 + WEAK_COMMON: case DYN_UNDEF * 16 + WEAK_COMMON: case DYN_WEAK_UNDEF * 16 + WEAK_COMMON: // A weak common symbol is better than an undefined symbol. - to->override(sym, object); - return; + return true; case COMMON * 16 + WEAK_COMMON: case WEAK_COMMON * 16 + WEAK_COMMON: @@ -445,7 +838,7 @@ Symbol_table::resolve(Sized_symbol* to, case DYN_WEAK_COMMON * 16 + WEAK_COMMON: // Ignore a weak common symbol in the presence of a real common // symbol. - return; + return false; case DEF * 16 + DYN_COMMON: case WEAK_DEF * 16 + DYN_COMMON: @@ -453,84 +846,367 @@ Symbol_table::resolve(Sized_symbol* to, case DYN_WEAK_DEF * 16 + DYN_COMMON: // Ignore a dynamic common symbol in the presence of a // definition. - return; + return false; case UNDEF * 16 + DYN_COMMON: case WEAK_UNDEF * 16 + DYN_COMMON: case DYN_UNDEF * 16 + DYN_COMMON: case DYN_WEAK_UNDEF * 16 + DYN_COMMON: // A dynamic common symbol is a definition of sorts. - to->override(sym, object); - return; + return true; case COMMON * 16 + DYN_COMMON: case WEAK_COMMON * 16 + DYN_COMMON: case DYN_COMMON * 16 + DYN_COMMON: case DYN_WEAK_COMMON * 16 + DYN_COMMON: // Set the size to the maximum. - if (sym.get_st_size() > to->symsize()) - to->set_symsize(sym.get_st_size()); - return; + *adjust_common_sizes = true; + return false; case DEF * 16 + DYN_WEAK_COMMON: case WEAK_DEF * 16 + DYN_WEAK_COMMON: case DYN_DEF * 16 + DYN_WEAK_COMMON: case DYN_WEAK_DEF * 16 + DYN_WEAK_COMMON: // A common symbol is ignored in the face of a definition. - return; + return false; case UNDEF * 16 + DYN_WEAK_COMMON: case WEAK_UNDEF * 16 + DYN_WEAK_COMMON: case DYN_UNDEF * 16 + DYN_WEAK_COMMON: case DYN_WEAK_UNDEF * 16 + DYN_WEAK_COMMON: // I guess a weak common symbol is better than a definition. - to->override(sym, object); - return; + return true; case COMMON * 16 + DYN_WEAK_COMMON: case WEAK_COMMON * 16 + DYN_WEAK_COMMON: case DYN_COMMON * 16 + DYN_WEAK_COMMON: case DYN_WEAK_COMMON * 16 + DYN_WEAK_COMMON: // Set the size to the maximum. - if (sym.get_st_size() > to->symsize()) - to->set_symsize(sym.get_st_size()); - return; + *adjust_common_sizes = true; + return false; + + default: + gold_unreachable(); + } +} + +// 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. DEFINED/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, Defined defined, + 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; + switch (defined) + { + case OBJECT: + objname = object->name().c_str(); + break; + case COPY: + objname = _("COPY reloc"); + break; + case DEFSYM: + case UNDEFINED: + objname = _("command line"); + break; + case SCRIPT: + objname = _("linker script"); + break; + case PREDEFINED: + case INCREMENTAL_BASE: + objname = _("linker defined"); + break; + default: + gold_unreachable(); + } + + 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); +} + +// 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 +Symbol::clone(const Symbol* from) +{ + // Don't allow cloning after dynamic linking info is attached to symbols. + // We aren't prepared to merge such. + gold_assert(!this->has_symtab_index() && !from->has_symtab_index()); + gold_assert(!this->has_dynsym_index() && !from->has_dynsym_index()); + gold_assert(this->got_offset_list() == NULL + && from->got_offset_list() == NULL); + gold_assert(!this->has_plt_offset() && !from->has_plt_offset()); + + if (!from->version_) + this->version_ = from->version_; + this->u1_ = from->u1_; + this->u2_ = from->u2_; + this->type_ = from->type_; + this->binding_ = from->binding_; + this->visibility_ = from->visibility_; + this->nonvis_ = from->nonvis_; + this->source_ = from->source_; + this->is_def_ = from->is_def_; + this->is_forwarder_ = from->is_forwarder_; + this->has_alias_ = from->has_alias_; + this->needs_dynsym_entry_ = from->needs_dynsym_entry_; + this->in_reg_ = from->in_reg_; + this->in_dyn_ = from->in_dyn_; + this->needs_dynsym_value_ = from->needs_dynsym_value_; + this->has_warning_ = from->has_warning_; + this->is_copied_from_dynobj_ = from->is_copied_from_dynobj_; + this->is_ordinary_shndx_ = from->is_ordinary_shndx_; + this->in_real_elf_ = from->in_real_elf_; + this->is_defined_in_discarded_section_ + = from->is_defined_in_discarded_section_; + this->undef_binding_set_ = from->undef_binding_set_; + this->undef_binding_weak_ = from->undef_binding_weak_; + this->is_predefined_ = from->is_predefined_; + this->is_protected_ = from->is_protected_; + this->non_zero_localentry_ = from->non_zero_localentry_; + + return !this->is_forced_local_ && from->is_forced_local_; +} + +template +bool +Sized_symbol::clone(const Sized_symbol* from) +{ + this->value_ = from->value_; + this->symsize_ = from->symsize_; + return Symbol::clone(from); +} + +// 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. + +bool +Symbol_table::should_override_with_special(const Symbol* to, + elfcpp::STT fromtype, + Defined defined) +{ + bool adjust_common_sizes; + bool adjust_dyn_def; + unsigned int frombits = global_flag | regular_flag | def_flag; + bool ret = Symbol_table::should_override(to, frombits, fromtype, defined, + NULL, &adjust_common_sizes, + &adjust_dyn_def, false); + gold_assert(!adjust_common_sizes && !adjust_dyn_def); + return ret; +} + +// Override symbol base with a special symbol. + +void +Symbol::override_base_with_special(const Symbol* from) +{ + bool same_name = this->name_ == from->name_; + gold_assert(same_name || this->has_alias()); + + // If we are overriding an undef, remember the original binding. + if (this->is_undefined()) + this->set_undef_binding(this->binding_); + + this->source_ = from->source_; + switch (from->source_) + { + case FROM_OBJECT: + case IN_OUTPUT_DATA: + case IN_OUTPUT_SEGMENT: + this->u1_ = from->u1_; + this->u2_ = from->u2_; + break; + case IS_CONSTANT: + case IS_UNDEFINED: + break; default: - abort(); + gold_unreachable(); + break; + } + + if (same_name) + { + // When overriding a versioned symbol with a special symbol, we + // may be changing the version. This will happen if we see a + // special symbol such as "_end" defined in a shared object with + // one version (from a version script), but we want to define it + // here with a different version (from a different version + // script). + this->version_ = from->version_; + } + this->type_ = from->type_; + this->binding_ = from->binding_; + this->override_visibility(from->visibility_); + this->nonvis_ = from->nonvis_; + + // Special symbols are always considered to be regular symbols. + this->in_reg_ = true; + + if (from->needs_dynsym_entry_) + this->needs_dynsym_entry_ = true; + if (from->needs_dynsym_value_) + this->needs_dynsym_value_ = true; + + this->is_predefined_ = from->is_predefined_; + + // We shouldn't see these flags. If we do, we need to handle them + // somehow. + gold_assert(!from->is_forwarder_); + 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. + +template +void +Sized_symbol::override_with_special(const Sized_symbol* from) +{ + this->override_base_with_special(from); + this->value_ = from->value_; + this->symsize_ = from->symsize_; +} + +// Override TOSYM with the special symbol FROMSYM. This handles all +// aliases of TOSYM. + +template +void +Symbol_table::override_with_special(Sized_symbol* tosym, + const Sized_symbol* fromsym) +{ + tosym->override_with_special(fromsym); + if (tosym->has_alias()) + { + Symbol* sym = this->weak_aliases_[tosym]; + gold_assert(sym != NULL); + Sized_symbol* ssym = this->get_sized_symbol(sym); + do + { + ssym->override_with_special(fromsym); + sym = this->weak_aliases_[ssym]; + gold_assert(sym != NULL); + ssym = this->get_sized_symbol(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 // script to restrict this to only the ones needed for implemented // targets. +// We have to instantiate both big and little endian versions because +// these are used by other templates that depends on size only. + +#if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG) template void -Symbol_table::resolve<32, true>( +Symbol_table::resolve<32, false>( Sized_symbol<32>* to, - const elfcpp::Sym<32, true>& sym, - Object* object); + const elfcpp::Sym<32, false>& sym, + unsigned int st_shndx, + bool is_ordinary, + unsigned int orig_st_shndx, + Object* object, + const char* version, + bool is_default_version); template void -Symbol_table::resolve<32, false>( +Symbol_table::resolve<32, true>( Sized_symbol<32>* to, - const elfcpp::Sym<32, false>& sym, - Object* object); + const elfcpp::Sym<32, true>& sym, + unsigned int st_shndx, + bool is_ordinary, + unsigned int orig_st_shndx, + Object* object, + const char* version, + bool is_default_version); +#endif + +#if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG) +template +void +Symbol_table::resolve<64, false>( + Sized_symbol<64>* to, + const elfcpp::Sym<64, false>& sym, + unsigned int st_shndx, + bool is_ordinary, + unsigned int orig_st_shndx, + Object* object, + const char* version, + bool is_default_version); template void Symbol_table::resolve<64, true>( Sized_symbol<64>* to, const elfcpp::Sym<64, true>& sym, - Object* object); + unsigned int st_shndx, + bool is_ordinary, + unsigned int orig_st_shndx, + Object* object, + const char* version, + bool is_default_version); +#endif + +#if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG) +template +void +Symbol_table::override_with_special<32>(Sized_symbol<32>*, + const Sized_symbol<32>*); +#endif +#if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG) template void -Symbol_table::resolve<64, false>( - Sized_symbol<64>* to, - const elfcpp::Sym<64, false>& sym, - Object* object); +Symbol_table::override_with_special<64>(Sized_symbol<64>*, + const Sized_symbol<64>*); +#endif +template +bool +Sized_symbol<32>::clone(const Sized_symbol<32>*); + +template +bool +Sized_symbol<64>::clone(const Sized_symbol<64>*); } // End namespace gold.