From 86f2e683461018af5274634f0b119b39576b17e0 Mon Sep 17 00:00:00 2001 From: Ian Lance Taylor Date: Wed, 19 Sep 2007 06:02:29 +0000 Subject: Let special symbols override existing symbols rather than reinitializing them. --- gold/resolve.cc | 377 ++++++++++++++++++++++++++++++++++++-------------------- 1 file changed, 241 insertions(+), 136 deletions(-) (limited to 'gold/resolve.cc') diff --git a/gold/resolve.cc b/gold/resolve.cc index e5ca6e3..599aad4 100644 --- a/gold/resolve.cc +++ b/gold/resolve.cc @@ -51,6 +51,25 @@ Sized_symbol::override(const elfcpp::Sym& sym, this->symsize_ = sym.get_st_size(); } +// 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. + +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; + // 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. VERSION of the version of SYM. @@ -71,121 +90,138 @@ Symbol_table::resolve(Sized_symbol* to, return; } - // 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 - }; + if (!object->is_dynamic()) + { + // Record that we've seen this symbol in a regular object. + to->set_in_reg(); + } + else + { + // Record that we've seen this symbol in a dynamic object. + to->set_in_dyn(); + } - int tobits; - switch (to->binding()) + unsigned int frombits; + switch (sym.get_st_bind()) { case elfcpp::STB_GLOBAL: - tobits = 0; + frombits = global_flag; break; case elfcpp::STB_WEAK: - tobits = 1; + frombits = weak_flag; break; case elfcpp::STB_LOCAL: - // We should only see externally visible symbols in the symbol - // table. - gold_unreachable(); + fprintf(stderr, + _("%s: %s: invalid STB_LOCAL symbol %s in external symbols\n"), + program_name, object->name().c_str(), to->name()); + gold_exit(false); default: - // Any target which wants to handle STB_LOOS, etc., needs to - // define a resolve method. - gold_unreachable(); + 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); } - if (to->source() == Symbol::FROM_OBJECT - && to->object()->is_dynamic()) - tobits |= (1 << 1); + if (!object->is_dynamic()) + frombits |= regular_flag; + else + frombits |= dynamic_flag; - switch (to->shndx()) + switch (sym.get_st_shndx()) { case elfcpp::SHN_UNDEF: - tobits |= (1 << 2); + frombits |= undef_flag; break; case elfcpp::SHN_COMMON: - tobits |= (2 << 2); + frombits |= common_flag; break; default: - if (to->type() == elfcpp::STT_COMMON) - tobits |= (2 << 2); + if (sym.get_st_type() == elfcpp::STT_COMMON) + frombits |= common_flag; + else + frombits |= def_flag; break; } - int frombits; - switch (sym.get_st_bind()) + bool adjust_common_sizes; + if (Symbol_table::should_override(to, frombits, &adjust_common_sizes)) + { + typename Sized_symbol::Size_type tosize = to->symsize(); + + to->override(sym, object, version); + + if (adjust_common_sizes && tosize > to->symsize()) + to->set_symsize(tosize); + } + else + { + if (adjust_common_sizes && sym.get_st_size() > to->symsize()) + to->set_symsize(sym.get_st_size()); + } +} + +// 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, + bool* adjust_common_sizes) +{ + *adjust_common_sizes = false; + + unsigned int tobits; + switch (to->binding()) { case elfcpp::STB_GLOBAL: - frombits = 0; + tobits = global_flag; break; case elfcpp::STB_WEAK: - frombits = 1; + tobits = weak_flag; break; 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); + // We should only see externally visible symbols in the symbol + // table. + gold_unreachable(); 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); + // Any target which wants to handle STB_LOOS, etc., needs to + // define a resolve method. + gold_unreachable(); } - if (!object->is_dynamic()) - { - // Record that we've seen this symbol in a regular object. - to->set_in_reg(); - } + if (to->source() == Symbol::FROM_OBJECT + && to->object()->is_dynamic()) + tobits |= dynamic_flag; else - { - frombits |= (1 << 1); + tobits |= regular_flag; - // Record that we've seen this symbol in a dynamic object. - to->set_in_dyn(); - } - - switch (sym.get_st_shndx()) + switch (to->shndx()) { case elfcpp::SHN_UNDEF: - frombits |= (1 << 2); + tobits |= undef_flag; break; case elfcpp::SHN_COMMON: - frombits |= (2 << 2); + tobits |= common_flag; break; default: - if (sym.get_st_type() == elfcpp::STT_COMMON) - frombits |= (2 << 2); + if (to->type() == elfcpp::STT_COMMON) + tobits |= common_flag; + else + tobits |= def_flag; break; } @@ -199,14 +235,31 @@ 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()); + fprintf(stderr, "%s: multiple definition of %s\n", + program_name, to->name()); // FIXME: Report locations. Record that we have seen an error. - return; + return false; case WEAK_DEF * 16 + DEF: // We've seen a weak definition, and now we see a strong @@ -217,8 +270,7 @@ 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, version); - return; + return true; case DYN_DEF * 16 + DEF: case DYN_WEAK_DEF * 16 + DEF: @@ -226,8 +278,7 @@ 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, version); - return; + return true; case UNDEF * 16 + DEF: case WEAK_UNDEF * 16 + DEF: @@ -235,8 +286,7 @@ 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, version); - return; + return true; case COMMON * 16 + DEF: case WEAK_COMMON * 16 + DEF: @@ -245,56 +295,51 @@ Symbol_table::resolve(Sized_symbol* to, // We've seen a common symbol and now we see a definition. The // definition overrides. FIXME: We should optionally issue, version a // warning. - to->override(sym, object, version); - return; + 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, version); - 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, version); - 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, version); - return; + return true; 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; + 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, version); - return; + return true; case COMMON * 16 + DYN_DEF: case WEAK_COMMON * 16 + DYN_DEF: @@ -302,7 +347,7 @@ Symbol_table::resolve(Sized_symbol* to, 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: @@ -310,15 +355,14 @@ Symbol_table::resolve(Sized_symbol* to, 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: 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, version); - return; + return true; case COMMON * 16 + DYN_WEAK_DEF: case WEAK_COMMON * 16 + DYN_WEAK_DEF: @@ -326,7 +370,7 @@ Symbol_table::resolve(Sized_symbol* to, case DYN_WEAK_COMMON * 16 + DYN_WEAK_DEF: // Ignore a weak dynamic definition if we already have a common // definition. - return; + return false; case DEF * 16 + UNDEF: case WEAK_DEF * 16 + UNDEF: @@ -334,21 +378,20 @@ Symbol_table::resolve(Sized_symbol* to, case DYN_WEAK_DEF * 16 + UNDEF: case UNDEF * 16 + UNDEF: // A new undefined reference tells us nothing. - return; + 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, version); - 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: @@ -363,7 +406,7 @@ Symbol_table::resolve(Sized_symbol* to, case DYN_COMMON * 16 + WEAK_UNDEF: case DYN_WEAK_COMMON * 16 + WEAK_UNDEF: // A new weak undefined reference tells us nothing. - return; + return false; case DEF * 16 + DYN_UNDEF: case WEAK_DEF * 16 + DYN_UNDEF: @@ -378,7 +421,7 @@ 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: @@ -393,50 +436,41 @@ 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; + 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, version); - 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, version); - 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, version); - 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, version); - 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: @@ -444,15 +478,14 @@ 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, version); - return; + return true; case COMMON * 16 + WEAK_COMMON: case WEAK_COMMON * 16 + WEAK_COMMON: @@ -460,7 +493,7 @@ 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: @@ -468,54 +501,114 @@ 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, version); - 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, version); - 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(); } } +// 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) +{ + bool adjust_common_sizes; + unsigned int frombits = global_flag | regular_flag | def_flag; + bool ret = Symbol_table::should_override(to, frombits, &adjust_common_sizes); + gold_assert(!adjust_common_sizes); + return ret; +} + +// Override symbol base with a special symbol. + +void +Symbol::override_base_with_special(const Symbol* from) +{ + this->source_ = from->source_; + switch (from->source_) + { + case FROM_OBJECT: + this->u_.from_object = from->u_.from_object; + break; + case IN_OUTPUT_DATA: + this->u_.in_output_data = from->u_.in_output_data; + break; + case IN_OUTPUT_SEGMENT: + this->u_.in_output_segment = from->u_.in_output_segment; + break; + case CONSTANT: + break; + default: + gold_unreachable(); + break; + } + + if (from->version_ != NULL && this->version_ != from->version_) + { + gold_assert(this->version_ == NULL); + this->version_ = from->version_; + } + + this->type_ = from->type_; + this->binding_ = from->binding_; + this->visibility_ = from->visibility_; + this->nonvis_ = from->nonvis_; + + // Special symbols are always considered to be regular symbols. + this->in_reg_ = true; +} + +// 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_; +} + // Instantiate the templates we need. We could use the configure // script to restrict this to only the ones needed for implemented // targets. @@ -560,4 +653,16 @@ Symbol_table::resolve<64, true>( const char* version); #endif +#if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG) +template +void +Sized_symbol<32>::override_with_special(const Sized_symbol<32>*); +#endif + +#if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG) +template +void +Sized_symbol<64>::override_with_special(const Sized_symbol<64>*); +#endif + } // End namespace gold. -- cgit v1.1