1 // symtab.h -- the gold symbol table -*- C++ -*-
3 // Copyright 2006, 2007 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
6 // This file is part of gold.
8 // This program is free software; you can redistribute it and/or modify
9 // it under the terms of the GNU General Public License as published by
10 // the Free Software Foundation; either version 3 of the License, or
11 // (at your option) any later version.
13 // This program is distributed in the hope that it will be useful,
14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 // GNU General Public License for more details.
18 // You should have received a copy of the GNU General Public License
19 // along with this program; if not, write to the Free Software
20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
21 // MA 02110-1301, USA.
31 #include "parameters.h"
32 #include "stringpool.h"
43 template<int size, bool big_endian>
46 template<int size, bool big_endian>
49 class Version_script_info;
56 // The base class of an entry in the symbol table. The symbol table
57 // can have a lot of entries, so we don't want this class to big.
58 // Size dependent fields can be found in the template class
59 // Sized_symbol. Targets may support their own derived classes.
64 // Because we want the class to be small, we don't use any virtual
65 // functions. But because symbols can be defined in different
66 // places, we need to classify them. This enum is the different
67 // sources of symbols we support.
70 // Symbol defined in a relocatable or dynamic input file--this is
71 // the most common case.
73 // Symbol defined in an Output_data, a special section created by
76 // Symbol defined in an Output_segment, with no associated
79 // Symbol value is constant.
83 // When the source is IN_OUTPUT_SEGMENT, we need to describe what
85 enum Segment_offset_base
87 // From the start of the segment.
89 // From the end of the segment.
91 // From the filesz of the segment--i.e., after the loaded bytes
92 // but before the bytes which are allocated but zeroed.
96 // Return the symbol name.
99 { return this->name_; }
101 // Return the (ANSI) demangled version of the name, if
102 // parameters.demangle() is true. Otherwise, return the name. This
103 // is intended to be used only for logging errors, so it's not
106 demangled_name() const;
108 // Return the symbol version. This will return NULL for an
109 // unversioned symbol.
112 { return this->version_; }
114 // Return whether this version is the default for this symbol name
115 // (eg, "foo@@V2" is a default version; "foo@V1" is not). Only
116 // meaningful for versioned symbols.
120 gold_assert(this->version_ != NULL);
121 return this->is_def_;
124 // Set whether this version is the default for this symbol name.
126 set_is_default(bool def)
127 { this->is_def_ = def; }
129 // Return the symbol source.
132 { return this->source_; }
134 // Return the object with which this symbol is associated.
138 gold_assert(this->source_ == FROM_OBJECT);
139 return this->u_.from_object.object;
142 // Return the index of the section in the input relocatable or
143 // dynamic object file.
147 gold_assert(this->source_ == FROM_OBJECT);
148 return this->u_.from_object.shndx;
151 // Return the output data section with which this symbol is
152 // associated, if the symbol was specially defined with respect to
153 // an output data section.
157 gold_assert(this->source_ == IN_OUTPUT_DATA);
158 return this->u_.in_output_data.output_data;
161 // If this symbol was defined with respect to an output data
162 // section, return whether the value is an offset from end.
164 offset_is_from_end() const
166 gold_assert(this->source_ == IN_OUTPUT_DATA);
167 return this->u_.in_output_data.offset_is_from_end;
170 // Return the output segment with which this symbol is associated,
171 // if the symbol was specially defined with respect to an output
174 output_segment() const
176 gold_assert(this->source_ == IN_OUTPUT_SEGMENT);
177 return this->u_.in_output_segment.output_segment;
180 // If this symbol was defined with respect to an output segment,
181 // return the offset base.
185 gold_assert(this->source_ == IN_OUTPUT_SEGMENT);
186 return this->u_.in_output_segment.offset_base;
189 // Return the symbol binding.
192 { return this->binding_; }
194 // Return the symbol type.
197 { return this->type_; }
199 // Return the symbol visibility.
202 { return this->visibility_; }
204 // Return the non-visibility part of the st_other field.
207 { return this->nonvis_; }
209 // Return whether this symbol is a forwarder. This will never be
210 // true of a symbol found in the hash table, but may be true of
211 // symbol pointers attached to object files.
214 { return this->is_forwarder_; }
216 // Mark this symbol as a forwarder.
219 { this->is_forwarder_ = true; }
221 // Return whether this symbol has an alias in the weak aliases table
225 { return this->has_alias_; }
227 // Mark this symbol as having an alias.
230 { this->has_alias_ = true; }
232 // Return whether this symbol needs an entry in the dynamic symbol
235 needs_dynsym_entry() const
237 return (this->needs_dynsym_entry_
238 || (this->in_reg() && this->in_dyn()));
241 // Mark this symbol as needing an entry in the dynamic symbol table.
243 set_needs_dynsym_entry()
244 { this->needs_dynsym_entry_ = true; }
246 // Return whether this symbol should be added to the dynamic symbol
249 should_add_dynsym_entry() const;
251 // Return whether this symbol has been seen in a regular object.
254 { return this->in_reg_; }
256 // Mark this symbol as having been seen in a regular object.
259 { this->in_reg_ = true; }
261 // Return whether this symbol has been seen in a dynamic object.
264 { return this->in_dyn_; }
266 // Mark this symbol as having been seen in a dynamic object.
269 { this->in_dyn_ = true; }
271 // Return the index of this symbol in the output file symbol table.
272 // A value of -1U means that this symbol is not going into the
273 // output file. This starts out as zero, and is set to a non-zero
274 // value by Symbol_table::finalize. It is an error to ask for the
275 // symbol table index before it has been set.
279 gold_assert(this->symtab_index_ != 0);
280 return this->symtab_index_;
283 // Set the index of the symbol in the output file symbol table.
285 set_symtab_index(unsigned int index)
287 gold_assert(index != 0);
288 this->symtab_index_ = index;
291 // Return whether this symbol already has an index in the output
292 // file symbol table.
294 has_symtab_index() const
295 { return this->symtab_index_ != 0; }
297 // Return the index of this symbol in the dynamic symbol table. A
298 // value of -1U means that this symbol is not going into the dynamic
299 // symbol table. This starts out as zero, and is set to a non-zero
300 // during Layout::finalize. It is an error to ask for the dynamic
301 // symbol table index before it has been set.
305 gold_assert(this->dynsym_index_ != 0);
306 return this->dynsym_index_;
309 // Set the index of the symbol in the dynamic symbol table.
311 set_dynsym_index(unsigned int index)
313 gold_assert(index != 0);
314 this->dynsym_index_ = index;
317 // Return whether this symbol already has an index in the dynamic
320 has_dynsym_index() const
321 { return this->dynsym_index_ != 0; }
323 // Return whether this symbol has an entry in the GOT section.
324 // For a TLS symbol, this GOT entry will hold its tp-relative offset.
326 has_got_offset() const
327 { return this->has_got_offset_; }
329 // Return the offset into the GOT section of this symbol.
333 gold_assert(this->has_got_offset());
334 return this->got_offset_;
337 // Set the GOT offset of this symbol.
339 set_got_offset(unsigned int got_offset)
341 this->has_got_offset_ = true;
342 this->got_offset_ = got_offset;
345 // Return whether this TLS symbol has an entry in the GOT section for
346 // its module index or, if NEED_PAIR is true, has a pair of entries
347 // for its module index and dtv-relative offset.
349 has_tls_got_offset(bool need_pair) const
351 return (this->has_tls_mod_got_offset_
352 && (!need_pair || this->has_tls_pair_got_offset_));
355 // Return the offset into the GOT section for this symbol's TLS module
356 // index or, if NEED_PAIR is true, for the pair of entries for the
357 // module index and dtv-relative offset.
359 tls_got_offset(bool need_pair) const
361 gold_assert(this->has_tls_got_offset(need_pair));
362 return this->tls_mod_got_offset_;
365 // Set the GOT offset of this symbol.
367 set_tls_got_offset(unsigned int got_offset, bool have_pair)
369 this->has_tls_mod_got_offset_ = true;
370 this->has_tls_pair_got_offset_ = have_pair;
371 this->tls_mod_got_offset_ = got_offset;
374 // Return whether this symbol has an entry in the PLT section.
376 has_plt_offset() const
377 { return this->has_plt_offset_; }
379 // Return the offset into the PLT section of this symbol.
383 gold_assert(this->has_plt_offset());
384 return this->plt_offset_;
387 // Set the PLT offset of this symbol.
389 set_plt_offset(unsigned int plt_offset)
391 this->has_plt_offset_ = true;
392 this->plt_offset_ = plt_offset;
395 // Return whether this dynamic symbol needs a special value in the
396 // dynamic symbol table.
398 needs_dynsym_value() const
399 { return this->needs_dynsym_value_; }
401 // Set that this dynamic symbol needs a special value in the dynamic
404 set_needs_dynsym_value()
406 gold_assert(this->object()->is_dynamic());
407 this->needs_dynsym_value_ = true;
410 // Return true if the final value of this symbol is known at link
413 final_value_is_known() const;
415 // Return whether this is a defined symbol (not undefined or
420 return (this->source_ != FROM_OBJECT
421 || (this->shndx() != elfcpp::SHN_UNDEF
422 && this->shndx() != elfcpp::SHN_COMMON));
425 // Return true if this symbol is from a dynamic object.
427 is_from_dynobj() const
429 return this->source_ == FROM_OBJECT && this->object()->is_dynamic();
432 // Return whether this is an undefined symbol.
436 return this->source_ == FROM_OBJECT && this->shndx() == elfcpp::SHN_UNDEF;
439 // Return whether this is a common symbol.
443 return (this->source_ == FROM_OBJECT
444 && (this->shndx() == elfcpp::SHN_COMMON
445 || this->type_ == elfcpp::STT_COMMON));
448 // Return whether this symbol can be seen outside this object.
450 is_externally_visible() const
452 return (this->visibility_ == elfcpp::STV_DEFAULT
453 || this->visibility_ == elfcpp::STV_PROTECTED);
456 // Return true if this symbol can be preempted by a definition in
457 // another link unit.
459 is_preemptible() const
461 // It doesn't make sense to ask whether a symbol defined in
462 // another object is preemptible.
463 gold_assert(!this->is_from_dynobj());
465 // It doesn't make sense to ask whether an undefined symbol
467 gold_assert(!this->is_undefined());
469 return (this->visibility_ != elfcpp::STV_INTERNAL
470 && this->visibility_ != elfcpp::STV_HIDDEN
471 && this->visibility_ != elfcpp::STV_PROTECTED
472 && !this->is_forced_local_
473 && parameters->output_is_shared()
474 && !parameters->symbolic());
477 // Return true if this symbol is a function that needs a PLT entry.
478 // If the symbol is defined in a dynamic object or if it is subject
479 // to pre-emption, we need to make a PLT entry. If we're doing a
480 // static link, we don't create PLT entries.
482 needs_plt_entry() const
484 return (!parameters->doing_static_link()
485 && this->type() == elfcpp::STT_FUNC
486 && (this->is_from_dynobj()
487 || this->is_undefined()
488 || this->is_preemptible()));
491 // When determining whether a reference to a symbol needs a dynamic
492 // relocation, we need to know several things about the reference.
493 // These flags may be or'ed together.
496 // Reference to the symbol's absolute address.
498 // A non-PIC reference.
504 // Given a direct absolute or pc-relative static relocation against
505 // the global symbol, this function returns whether a dynamic relocation
509 needs_dynamic_reloc(int flags) const
511 // No dynamic relocations in a static link!
512 if (parameters->doing_static_link())
515 // An absolute reference within a position-independent output file
516 // will need a dynamic relocation.
517 if ((flags & ABSOLUTE_REF)
518 && parameters->output_is_position_independent())
521 // A function call that can branch to a local PLT entry does not need
522 // a dynamic relocation. A non-pic pc-relative function call in a
523 // shared library cannot use a PLT entry.
524 if ((flags & FUNCTION_CALL)
525 && this->has_plt_offset()
526 && !((flags & NON_PIC_REF) && parameters->output_is_shared()))
529 // A reference to any PLT entry in a non-position-independent executable
530 // does not need a dynamic relocation.
531 if (!parameters->output_is_position_independent()
532 && this->has_plt_offset())
535 // A reference to a symbol defined in a dynamic object or to a
536 // symbol that is preemptible will need a dynamic relocation.
537 if (this->is_from_dynobj()
538 || this->is_undefined()
539 || this->is_preemptible())
542 // For all other cases, return FALSE.
546 // Given a direct absolute static relocation against
547 // the global symbol, where a dynamic relocation is needed, this
548 // function returns whether a relative dynamic relocation can be used.
549 // The caller must determine separately whether the static relocation
550 // is compatible with a relative relocation.
553 can_use_relative_reloc(bool is_function_call) const
555 // A function call that can branch to a local PLT entry can
556 // use a RELATIVE relocation.
557 if (is_function_call && this->has_plt_offset())
560 // A reference to a symbol defined in a dynamic object or to a
561 // symbol that is preemptible can not use a RELATIVE relocaiton.
562 if (this->is_from_dynobj()
563 || this->is_undefined()
564 || this->is_preemptible())
567 // For all other cases, return TRUE.
571 // Return the output section where this symbol is defined. Return
572 // NULL if the symbol has an absolute value.
574 output_section() const;
576 // Set the symbol's output section. This is used for symbols
577 // defined in scripts. This should only be called after the symbol
578 // table has been finalized.
580 set_output_section(Output_section*);
582 // Return whether there should be a warning for references to this
586 { return this->has_warning_; }
588 // Mark this symbol as having a warning.
591 { this->has_warning_ = true; }
593 // Return whether this symbol is defined by a COPY reloc from a
596 is_copied_from_dynobj() const
597 { return this->is_copied_from_dynobj_; }
599 // Mark this symbol as defined by a COPY reloc.
601 set_is_copied_from_dynobj()
602 { this->is_copied_from_dynobj_ = true; }
604 // Return whether this symbol is forced to visibility STB_LOCAL
605 // by a "local:" entry in a version script.
607 is_forced_local() const
608 { return this->is_forced_local_; }
610 // Mark this symbol as forced to STB_LOCAL visibility.
612 set_is_forced_local()
613 { this->is_forced_local_ = true; }
616 // Instances of this class should always be created at a specific
619 { memset(this, 0, sizeof *this); }
621 // Initialize the general fields.
623 init_fields(const char* name, const char* version,
624 elfcpp::STT type, elfcpp::STB binding,
625 elfcpp::STV visibility, unsigned char nonvis);
627 // Initialize fields from an ELF symbol in OBJECT.
628 template<int size, bool big_endian>
630 init_base(const char *name, const char* version, Object* object,
631 const elfcpp::Sym<size, big_endian>&);
633 // Initialize fields for an Output_data.
635 init_base(const char* name, Output_data*, elfcpp::STT, elfcpp::STB,
636 elfcpp::STV, unsigned char nonvis, bool offset_is_from_end);
638 // Initialize fields for an Output_segment.
640 init_base(const char* name, Output_segment* os, elfcpp::STT type,
641 elfcpp::STB binding, elfcpp::STV visibility,
642 unsigned char nonvis, Segment_offset_base offset_base);
644 // Initialize fields for a constant.
646 init_base(const char* name, elfcpp::STT type, elfcpp::STB binding,
647 elfcpp::STV visibility, unsigned char nonvis);
649 // Override existing symbol.
650 template<int size, bool big_endian>
652 override_base(const elfcpp::Sym<size, big_endian>&, Object* object,
653 const char* version);
655 // Override existing symbol with a special symbol.
657 override_base_with_special(const Symbol* from);
659 // Allocate a common symbol by giving it a location in the output
662 allocate_base_common(Output_data*);
665 Symbol(const Symbol&);
666 Symbol& operator=(const Symbol&);
668 // Symbol name (expected to point into a Stringpool).
670 // Symbol version (expected to point into a Stringpool). This may
672 const char* version_;
676 // This struct is used if SOURCE_ == FROM_OBJECT.
679 // Object in which symbol is defined, or in which it was first
682 // Section number in object_ in which symbol is defined.
686 // This struct is used if SOURCE_ == IN_OUTPUT_DATA.
689 // Output_data in which symbol is defined. Before
690 // Layout::finalize the symbol's value is an offset within the
692 Output_data* output_data;
693 // True if the offset is from the end, false if the offset is
694 // from the beginning.
695 bool offset_is_from_end;
698 // This struct is used if SOURCE_ == IN_OUTPUT_SEGMENT.
701 // Output_segment in which the symbol is defined. Before
702 // Layout::finalize the symbol's value is an offset.
703 Output_segment* output_segment;
704 // The base to use for the offset before Layout::finalize.
705 Segment_offset_base offset_base;
709 // The index of this symbol in the output file. If the symbol is
710 // not going into the output file, this value is -1U. This field
711 // starts as always holding zero. It is set to a non-zero value by
712 // Symbol_table::finalize.
713 unsigned int symtab_index_;
715 // The index of this symbol in the dynamic symbol table. If the
716 // symbol is not going into the dynamic symbol table, this value is
717 // -1U. This field starts as always holding zero. It is set to a
718 // non-zero value during Layout::finalize.
719 unsigned int dynsym_index_;
721 // If this symbol has an entry in the GOT section (has_got_offset_
722 // is true), this is the offset from the start of the GOT section.
723 // For a TLS symbol, if has_tls_tpoff_got_offset_ is true, this
724 // serves as the GOT offset for the GOT entry that holds its
725 // TP-relative offset.
726 unsigned int got_offset_;
728 // If this is a TLS symbol and has an entry in the GOT section
729 // for a module index or a pair of entries (module index,
730 // dtv-relative offset), these are the offsets from the start
731 // of the GOT section.
732 unsigned int tls_mod_got_offset_;
733 unsigned int tls_pair_got_offset_;
735 // If this symbol has an entry in the PLT section (has_plt_offset_
736 // is true), then this is the offset from the start of the PLT
738 unsigned int plt_offset_;
741 elfcpp::STT type_ : 4;
743 elfcpp::STB binding_ : 4;
744 // Symbol visibility.
745 elfcpp::STV visibility_ : 2;
746 // Rest of symbol st_other field.
747 unsigned int nonvis_ : 6;
748 // The type of symbol.
750 // True if this symbol always requires special target-specific
752 bool is_target_special_ : 1;
753 // True if this is the default version of the symbol.
755 // True if this symbol really forwards to another symbol. This is
756 // used when we discover after the fact that two different entries
757 // in the hash table really refer to the same symbol. This will
758 // never be set for a symbol found in the hash table, but may be set
759 // for a symbol found in the list of symbols attached to an Object.
760 // It forwards to the symbol found in the forwarders_ map of
762 bool is_forwarder_ : 1;
763 // True if the symbol has an alias in the weak_aliases table in
766 // True if this symbol needs to be in the dynamic symbol table.
767 bool needs_dynsym_entry_ : 1;
768 // True if we've seen this symbol in a regular object.
770 // True if we've seen this symbol in a dynamic object.
772 // True if the symbol has an entry in the GOT section.
773 // For a TLS symbol, this GOT entry will hold its tp-relative offset.
774 bool has_got_offset_ : 1;
775 // True if the symbol has an entry in the GOT section for its
777 bool has_tls_mod_got_offset_ : 1;
778 // True if the symbol has a pair of entries in the GOT section for its
779 // module index and dtv-relative offset.
780 bool has_tls_pair_got_offset_ : 1;
781 // True if the symbol has an entry in the PLT section.
782 bool has_plt_offset_ : 1;
783 // True if this is a dynamic symbol which needs a special value in
784 // the dynamic symbol table.
785 bool needs_dynsym_value_ : 1;
786 // True if there is a warning for this symbol.
787 bool has_warning_ : 1;
788 // True if we are using a COPY reloc for this symbol, so that the
789 // real definition lives in a dynamic object.
790 bool is_copied_from_dynobj_ : 1;
791 // True if this symbol was forced to local visibility by a version
793 bool is_forced_local_ : 1;
796 // The parts of a symbol which are size specific. Using a template
797 // derived class like this helps us use less space on a 32-bit system.
800 class Sized_symbol : public Symbol
803 typedef typename elfcpp::Elf_types<size>::Elf_Addr Value_type;
804 typedef typename elfcpp::Elf_types<size>::Elf_WXword Size_type;
809 // Initialize fields from an ELF symbol in OBJECT.
810 template<bool big_endian>
812 init(const char *name, const char* version, Object* object,
813 const elfcpp::Sym<size, big_endian>&);
815 // Initialize fields for an Output_data.
817 init(const char* name, Output_data*, Value_type value, Size_type symsize,
818 elfcpp::STT, elfcpp::STB, elfcpp::STV, unsigned char nonvis,
819 bool offset_is_from_end);
821 // Initialize fields for an Output_segment.
823 init(const char* name, Output_segment*, Value_type value, Size_type symsize,
824 elfcpp::STT, elfcpp::STB, elfcpp::STV, unsigned char nonvis,
825 Segment_offset_base offset_base);
827 // Initialize fields for a constant.
829 init(const char* name, Value_type value, Size_type symsize,
830 elfcpp::STT, elfcpp::STB, elfcpp::STV, unsigned char nonvis);
832 // Override existing symbol.
833 template<bool big_endian>
835 override(const elfcpp::Sym<size, big_endian>&, Object* object,
836 const char* version);
838 // Override existing symbol with a special symbol.
840 override_with_special(const Sized_symbol<size>*);
842 // Return the symbol's value.
845 { return this->value_; }
847 // Return the symbol's size (we can't call this 'size' because that
848 // is a template parameter).
851 { return this->symsize_; }
853 // Set the symbol size. This is used when resolving common symbols.
855 set_symsize(Size_type symsize)
856 { this->symsize_ = symsize; }
858 // Set the symbol value. This is called when we store the final
859 // values of the symbols into the symbol table.
861 set_value(Value_type value)
862 { this->value_ = value; }
864 // Allocate a common symbol by giving it a location in the output
867 allocate_common(Output_data*, Value_type value);
870 Sized_symbol(const Sized_symbol&);
871 Sized_symbol& operator=(const Sized_symbol&);
873 // Symbol value. Before Layout::finalize this is the offset in the
874 // input section. This is set to the final value during
881 // A struct describing a symbol defined by the linker, where the value
882 // of the symbol is defined based on an output section. This is used
883 // for symbols defined by the linker, like "_init_array_start".
885 struct Define_symbol_in_section
889 // The name of the output section with which this symbol should be
890 // associated. If there is no output section with that name, the
891 // symbol will be defined as zero.
892 const char* output_section;
893 // The offset of the symbol within the output section. This is an
894 // offset from the start of the output section, unless start_at_end
895 // is true, in which case this is an offset from the end of the
898 // The size of the symbol.
902 // The symbol binding.
904 // The symbol visibility.
905 elfcpp::STV visibility;
906 // The rest of the st_other field.
907 unsigned char nonvis;
908 // If true, the value field is an offset from the end of the output
910 bool offset_is_from_end;
911 // If true, this symbol is defined only if we see a reference to it.
915 // A struct describing a symbol defined by the linker, where the value
916 // of the symbol is defined based on a segment. This is used for
917 // symbols defined by the linker, like "_end". We describe the
918 // segment with which the symbol should be associated by its
919 // characteristics. If no segment meets these characteristics, the
920 // symbol will be defined as zero. If there is more than one segment
921 // which meets these characteristics, we will use the first one.
923 struct Define_symbol_in_segment
927 // The segment type where the symbol should be defined, typically
929 elfcpp::PT segment_type;
930 // Bitmask of segment flags which must be set.
931 elfcpp::PF segment_flags_set;
932 // Bitmask of segment flags which must be clear.
933 elfcpp::PF segment_flags_clear;
934 // The offset of the symbol within the segment. The offset is
935 // calculated from the position set by offset_base.
937 // The size of the symbol.
941 // The symbol binding.
943 // The symbol visibility.
944 elfcpp::STV visibility;
945 // The rest of the st_other field.
946 unsigned char nonvis;
947 // The base from which we compute the offset.
948 Symbol::Segment_offset_base offset_base;
949 // If true, this symbol is defined only if we see a reference to it.
953 // This class manages warnings. Warnings are a GNU extension. When
954 // we see a section named .gnu.warning.SYM in an object file, and if
955 // we wind using the definition of SYM from that object file, then we
956 // will issue a warning for any relocation against SYM from a
957 // different object file. The text of the warning is the contents of
958 // the section. This is not precisely the definition used by the old
959 // GNU linker; the old GNU linker treated an occurrence of
960 // .gnu.warning.SYM as defining a warning symbol. A warning symbol
961 // would trigger a warning on any reference. However, it was
962 // inconsistent in that a warning in a dynamic object only triggered
963 // if there was no definition in a regular object. This linker is
964 // different in that we only issue a warning if we use the symbol
965 // definition from the same object file as the warning section.
974 // Add a warning for symbol NAME in object OBJ. WARNING is the text
977 add_warning(Symbol_table* symtab, const char* name, Object* obj,
978 const std::string& warning);
980 // For each symbol for which we should give a warning, make a note
983 note_warnings(Symbol_table* symtab);
985 // Issue a warning for a reference to SYM at RELINFO's location.
986 template<int size, bool big_endian>
988 issue_warning(const Symbol* sym, const Relocate_info<size, big_endian>*,
989 size_t relnum, off_t reloffset) const;
992 Warnings(const Warnings&);
993 Warnings& operator=(const Warnings&);
995 // What we need to know to get the warning text.
996 struct Warning_location
998 // The object the warning is in.
1000 // The warning text.
1004 : object(NULL), text()
1008 set(Object* o, const std::string& t)
1015 // A mapping from warning symbol names (canonicalized in
1016 // Symbol_table's namepool_ field) to warning information.
1017 typedef Unordered_map<const char*, Warning_location> Warning_table;
1019 Warning_table warnings_;
1022 // The main linker symbol table.
1027 // COUNT is an estimate of how many symbosl will be inserted in the
1028 // symbol table. It's ok to put 0 if you don't know; a correct
1029 // guess will just save some CPU by reducing hashtable resizes.
1030 Symbol_table(unsigned int count, const Version_script_info& version_script);
1034 // Add COUNT external symbols from the relocatable object RELOBJ to
1035 // the symbol table. SYMS is the symbols, SYM_NAMES is their names,
1036 // SYM_NAME_SIZE is the size of SYM_NAMES. This sets SYMPOINTERS to
1037 // point to the symbols in the symbol table.
1038 template<int size, bool big_endian>
1040 add_from_relobj(Sized_relobj<size, big_endian>* relobj,
1041 const unsigned char* syms, size_t count,
1042 const char* sym_names, size_t sym_name_size,
1043 typename Sized_relobj<size, big_endian>::Symbols*);
1045 // Add COUNT dynamic symbols from the dynamic object DYNOBJ to the
1046 // symbol table. SYMS is the symbols. SYM_NAMES is their names.
1047 // SYM_NAME_SIZE is the size of SYM_NAMES. The other parameters are
1048 // symbol version data.
1049 template<int size, bool big_endian>
1051 add_from_dynobj(Sized_dynobj<size, big_endian>* dynobj,
1052 const unsigned char* syms, size_t count,
1053 const char* sym_names, size_t sym_name_size,
1054 const unsigned char* versym, size_t versym_size,
1055 const std::vector<const char*>*);
1057 // Define a special symbol based on an Output_data. It is a
1058 // multiple definition error if this symbol is already defined.
1060 define_in_output_data(const char* name, const char* version,
1061 Output_data*, uint64_t value, uint64_t symsize,
1062 elfcpp::STT type, elfcpp::STB binding,
1063 elfcpp::STV visibility, unsigned char nonvis,
1064 bool offset_is_from_end, bool only_if_ref);
1066 // Define a special symbol based on an Output_segment. It is a
1067 // multiple definition error if this symbol is already defined.
1069 define_in_output_segment(const char* name, const char* version,
1070 Output_segment*, uint64_t value, uint64_t symsize,
1071 elfcpp::STT type, elfcpp::STB binding,
1072 elfcpp::STV visibility, unsigned char nonvis,
1073 Symbol::Segment_offset_base, bool only_if_ref);
1075 // Define a special symbol with a constant value. It is a multiple
1076 // definition error if this symbol is already defined.
1078 define_as_constant(const char* name, const char* version,
1079 uint64_t value, uint64_t symsize, elfcpp::STT type,
1080 elfcpp::STB binding, elfcpp::STV visibility,
1081 unsigned char nonvis, bool only_if_ref);
1083 // Define a set of symbols in output sections. If ONLY_IF_REF is
1084 // true, only define them if they are referenced.
1086 define_symbols(const Layout*, int count, const Define_symbol_in_section*,
1089 // Define a set of symbols in output segments. If ONLY_IF_REF is
1090 // true, only defined them if they are referenced.
1092 define_symbols(const Layout*, int count, const Define_symbol_in_segment*,
1095 // Define SYM using a COPY reloc. POSD is the Output_data where the
1096 // symbol should be defined--typically a .dyn.bss section. VALUE is
1097 // the offset within POSD.
1100 define_with_copy_reloc(Sized_symbol<size>* sym, Output_data* posd,
1101 typename elfcpp::Elf_types<size>::Elf_Addr);
1103 // Look up a symbol.
1105 lookup(const char*, const char* version = NULL) const;
1107 // Return the real symbol associated with the forwarder symbol FROM.
1109 resolve_forwards(const Symbol* from) const;
1111 // Return the sized version of a symbol in this table.
1114 get_sized_symbol(Symbol* ACCEPT_SIZE) const;
1117 const Sized_symbol<size>*
1118 get_sized_symbol(const Symbol* ACCEPT_SIZE) const;
1120 // Return the count of undefined symbols seen.
1122 saw_undefined() const
1123 { return this->saw_undefined_; }
1125 // Allocate the common symbols
1127 allocate_commons(const General_options&, Layout*);
1129 // Add a warning for symbol NAME in object OBJ. WARNING is the text
1132 add_warning(const char* name, Object* obj, const std::string& warning)
1133 { this->warnings_.add_warning(this, name, obj, warning); }
1135 // Canonicalize a symbol name for use in the hash table.
1137 canonicalize_name(const char* name)
1138 { return this->namepool_.add(name, true, NULL); }
1140 // Possibly issue a warning for a reference to SYM at LOCATION which
1142 template<int size, bool big_endian>
1144 issue_warning(const Symbol* sym,
1145 const Relocate_info<size, big_endian>* relinfo,
1146 size_t relnum, off_t reloffset) const
1147 { this->warnings_.issue_warning(sym, relinfo, relnum, reloffset); }
1149 // Check candidate_odr_violations_ to find symbols with the same name
1150 // but apparently different definitions (different source-file/line-no).
1152 detect_odr_violations(const Task*, const char* output_file_name) const;
1154 // SYM is defined using a COPY reloc. Return the dynamic object
1155 // where the original definition was found.
1157 get_copy_source(const Symbol* sym) const;
1159 // Set the dynamic symbol indexes. INDEX is the index of the first
1160 // global dynamic symbol. Pointers to the symbols are stored into
1161 // the vector. The names are stored into the Stringpool. This
1162 // returns an updated dynamic symbol index.
1164 set_dynsym_indexes(unsigned int index, std::vector<Symbol*>*,
1165 Stringpool*, Versions*);
1167 // Finalize the symbol table after we have set the final addresses
1168 // of all the input sections. This sets the final symbol indexes,
1169 // values and adds the names to *POOL. *PLOCAL_SYMCOUNT is the
1170 // index of the first global symbol. OFF is the file offset of the
1171 // global symbol table, DYNOFF is the offset of the globals in the
1172 // dynamic symbol table, DYN_GLOBAL_INDEX is the index of the first
1173 // global dynamic symbol, and DYNCOUNT is the number of global
1174 // dynamic symbols. This records the parameters, and returns the
1175 // new file offset. It updates *PLOCAL_SYMCOUNT if it created any
1178 finalize(off_t off, off_t dynoff, size_t dyn_global_index, size_t dyncount,
1179 Stringpool* pool, unsigned int *plocal_symcount);
1181 // Write out the global symbols.
1183 write_globals(const Input_objects*, const Stringpool*, const Stringpool*,
1184 Output_file*) const;
1186 // Write out a section symbol. Return the updated offset.
1188 write_section_symbol(const Output_section*, Output_file*, off_t) const;
1190 // Dump statistical information to stderr.
1192 print_stats() const;
1194 // Return the version script information.
1195 const Version_script_info&
1196 version_script() const
1197 { return version_script_; }
1200 Symbol_table(const Symbol_table&);
1201 Symbol_table& operator=(const Symbol_table&);
1203 // Make FROM a forwarder symbol to TO.
1205 make_forwarder(Symbol* from, Symbol* to);
1208 template<int size, bool big_endian>
1210 add_from_object(Object*, const char *name, Stringpool::Key name_key,
1211 const char *version, Stringpool::Key version_key,
1212 bool def, const elfcpp::Sym<size, big_endian>& sym,
1213 const elfcpp::Sym<size, big_endian>& orig_sym);
1216 template<int size, bool big_endian>
1218 resolve(Sized_symbol<size>* to,
1219 const elfcpp::Sym<size, big_endian>& sym,
1220 const elfcpp::Sym<size, big_endian>& orig_sym,
1221 Object*, const char* version);
1223 template<int size, bool big_endian>
1225 resolve(Sized_symbol<size>* to, const Sized_symbol<size>* from,
1226 const char* version ACCEPT_SIZE_ENDIAN);
1228 // Record that a symbol is forced to be local by a version script.
1230 force_local(Symbol*);
1232 // Whether we should override a symbol, based on flags in
1235 should_override(const Symbol*, unsigned int, Object*, bool*);
1237 // Override a symbol.
1238 template<int size, bool big_endian>
1240 override(Sized_symbol<size>* tosym,
1241 const elfcpp::Sym<size, big_endian>& fromsym,
1242 Object* object, const char* version);
1244 // Whether we should override a symbol with a special symbol which
1245 // is automatically defined by the linker.
1247 should_override_with_special(const Symbol*);
1249 // Override a symbol with a special symbol.
1252 override_with_special(Sized_symbol<size>* tosym,
1253 const Sized_symbol<size>* fromsym);
1255 // Record all weak alias sets for a dynamic object.
1258 record_weak_aliases(std::vector<Sized_symbol<size>*>*);
1260 // Define a special symbol.
1261 template<int size, bool big_endian>
1263 define_special_symbol(const char** pname, const char** pversion,
1264 bool only_if_ref, Sized_symbol<size>** poldsym
1265 ACCEPT_SIZE_ENDIAN);
1267 // Define a symbol in an Output_data, sized version.
1270 do_define_in_output_data(const char* name, const char* version, Output_data*,
1271 typename elfcpp::Elf_types<size>::Elf_Addr value,
1272 typename elfcpp::Elf_types<size>::Elf_WXword ssize,
1273 elfcpp::STT type, elfcpp::STB binding,
1274 elfcpp::STV visibility, unsigned char nonvis,
1275 bool offset_is_from_end, bool only_if_ref);
1277 // Define a symbol in an Output_segment, sized version.
1280 do_define_in_output_segment(
1281 const char* name, const char* version, Output_segment* os,
1282 typename elfcpp::Elf_types<size>::Elf_Addr value,
1283 typename elfcpp::Elf_types<size>::Elf_WXword ssize,
1284 elfcpp::STT type, elfcpp::STB binding,
1285 elfcpp::STV visibility, unsigned char nonvis,
1286 Symbol::Segment_offset_base offset_base, bool only_if_ref);
1288 // Define a symbol as a constant, sized version.
1291 do_define_as_constant(
1292 const char* name, const char* version,
1293 typename elfcpp::Elf_types<size>::Elf_Addr value,
1294 typename elfcpp::Elf_types<size>::Elf_WXword ssize,
1295 elfcpp::STT type, elfcpp::STB binding,
1296 elfcpp::STV visibility, unsigned char nonvis,
1299 // Allocate the common symbols, sized version.
1302 do_allocate_commons(const General_options&, Layout*);
1304 // Implement detect_odr_violations.
1305 template<int size, bool big_endian>
1307 sized_detect_odr_violations() const;
1309 // Finalize symbols specialized for size.
1312 sized_finalize(off_t, Stringpool*, unsigned int*);
1314 // Finalize a symbol. Return whether it should be added to the
1318 sized_finalize_symbol(Symbol*);
1320 // Add a symbol the final symtab by setting its index.
1323 add_to_final_symtab(Symbol*, Stringpool*, unsigned int* pindex, off_t* poff);
1325 // Write globals specialized for size and endianness.
1326 template<int size, bool big_endian>
1328 sized_write_globals(const Input_objects*, const Stringpool*,
1329 const Stringpool*, Output_file*) const;
1331 // Write out a symbol to P.
1332 template<int size, bool big_endian>
1334 sized_write_symbol(Sized_symbol<size>*,
1335 typename elfcpp::Elf_types<size>::Elf_Addr value,
1337 const Stringpool*, unsigned char* p
1338 ACCEPT_SIZE_ENDIAN) const;
1340 // Possibly warn about an undefined symbol from a dynamic object.
1342 warn_about_undefined_dynobj_symbol(const Input_objects*, Symbol*) const;
1344 // Write out a section symbol, specialized for size and endianness.
1345 template<int size, bool big_endian>
1347 sized_write_section_symbol(const Output_section*, Output_file*, off_t) const;
1349 // The type of the symbol hash table.
1351 typedef std::pair<Stringpool::Key, Stringpool::Key> Symbol_table_key;
1353 struct Symbol_table_hash
1356 operator()(const Symbol_table_key&) const;
1359 struct Symbol_table_eq
1362 operator()(const Symbol_table_key&, const Symbol_table_key&) const;
1365 typedef Unordered_map<Symbol_table_key, Symbol*, Symbol_table_hash,
1366 Symbol_table_eq> Symbol_table_type;
1368 // The type of the list of common symbols.
1369 typedef std::vector<Symbol*> Commons_type;
1371 // The type of the list of symbols which have been forced local.
1372 typedef std::vector<Symbol*> Forced_locals;
1374 // A map from symbols with COPY relocs to the dynamic objects where
1375 // they are defined.
1376 typedef Unordered_map<const Symbol*, Dynobj*> Copied_symbol_dynobjs;
1378 // A map from symbol name (as a pointer into the namepool) to all
1379 // the locations the symbols is (weakly) defined (and certain other
1380 // conditions are met). This map will be used later to detect
1381 // possible One Definition Rule (ODR) violations.
1382 struct Symbol_location
1384 Object* object; // Object where the symbol is defined.
1385 unsigned int shndx; // Section-in-object where the symbol is defined.
1386 off_t offset; // Offset-in-section where the symbol is defined.
1387 bool operator==(const Symbol_location& that) const
1389 return (this->object == that.object
1390 && this->shndx == that.shndx
1391 && this->offset == that.offset);
1395 struct Symbol_location_hash
1397 size_t operator()(const Symbol_location& loc) const
1398 { return reinterpret_cast<uintptr_t>(loc.object) ^ loc.offset ^ loc.shndx; }
1401 typedef Unordered_map<const char*,
1402 Unordered_set<Symbol_location, Symbol_location_hash> >
1405 // We increment this every time we see a new undefined symbol, for
1406 // use in archive groups.
1408 // The index of the first global symbol in the output file.
1409 unsigned int first_global_index_;
1410 // The file offset within the output symtab section where we should
1413 // The number of global symbols we want to write out.
1414 unsigned int output_count_;
1415 // The file offset of the global dynamic symbols, or 0 if none.
1416 off_t dynamic_offset_;
1417 // The index of the first global dynamic symbol.
1418 unsigned int first_dynamic_global_index_;
1419 // The number of global dynamic symbols, or 0 if none.
1420 unsigned int dynamic_count_;
1421 // The symbol hash table.
1422 Symbol_table_type table_;
1423 // A pool of symbol names. This is used for all global symbols.
1424 // Entries in the hash table point into this pool.
1425 Stringpool namepool_;
1426 // Forwarding symbols.
1427 Unordered_map<const Symbol*, Symbol*> forwarders_;
1428 // Weak aliases. A symbol in this list points to the next alias.
1429 // The aliases point to each other in a circular list.
1430 Unordered_map<Symbol*, Symbol*> weak_aliases_;
1431 // We don't expect there to be very many common symbols, so we keep
1432 // a list of them. When we find a common symbol we add it to this
1433 // list. It is possible that by the time we process the list the
1434 // symbol is no longer a common symbol. It may also have become a
1436 Commons_type commons_;
1437 // A list of symbols which have been forced to be local. We don't
1438 // expect there to be very many of them, so we keep a list of them
1439 // rather than walking the whole table to find them.
1440 Forced_locals forced_locals_;
1441 // Manage symbol warnings.
1443 // Manage potential One Definition Rule (ODR) violations.
1444 Odr_map candidate_odr_violations_;
1446 // When we emit a COPY reloc for a symbol, we define it in an
1447 // Output_data. When it's time to emit version information for it,
1448 // we need to know the dynamic object in which we found the original
1449 // definition. This maps symbols with COPY relocs to the dynamic
1450 // object where they were defined.
1451 Copied_symbol_dynobjs copied_symbol_dynobjs_;
1452 // Information parsed from the version script, if any.
1453 const Version_script_info& version_script_;
1456 // We inline get_sized_symbol for efficiency.
1460 Symbol_table::get_sized_symbol(Symbol* sym ACCEPT_SIZE) const
1462 gold_assert(size == parameters->get_size());
1463 return static_cast<Sized_symbol<size>*>(sym);
1467 const Sized_symbol<size>*
1468 Symbol_table::get_sized_symbol(const Symbol* sym ACCEPT_SIZE) const
1470 gold_assert(size == parameters->get_size());
1471 return static_cast<const Sized_symbol<size>*>(sym);
1474 } // End namespace gold.
1476 #endif // !defined(GOLD_SYMTAB_H)