daily update
[binutils.git] / gold / symtab.h
blobc0ae35811d0cd6d5d473266e9d5da92b875ac91a
1 // symtab.h -- the gold symbol table -*- C++ -*-
3 // Copyright 2006, 2007, 2008, 2009, 2010 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.
23 // Symbol_table
24 // The symbol table.
26 #ifndef GOLD_SYMTAB_H
27 #define GOLD_SYMTAB_H
29 #include <string>
30 #include <utility>
31 #include <vector>
33 #include "elfcpp.h"
34 #include "parameters.h"
35 #include "stringpool.h"
36 #include "object.h"
38 namespace gold
41 class Mapfile;
42 class Object;
43 class Relobj;
44 template<int size, bool big_endian>
45 class Sized_relobj;
46 template<int size, bool big_endian>
47 class Sized_pluginobj;
48 class Dynobj;
49 template<int size, bool big_endian>
50 class Sized_dynobj;
51 class Versions;
52 class Version_script_info;
53 class Input_objects;
54 class Output_data;
55 class Output_section;
56 class Output_segment;
57 class Output_file;
58 class Output_symtab_xindex;
59 class Garbage_collection;
60 class Icf;
62 // The base class of an entry in the symbol table. The symbol table
63 // can have a lot of entries, so we don't want this class to big.
64 // Size dependent fields can be found in the template class
65 // Sized_symbol. Targets may support their own derived classes.
67 class Symbol
69 public:
70 // Because we want the class to be small, we don't use any virtual
71 // functions. But because symbols can be defined in different
72 // places, we need to classify them. This enum is the different
73 // sources of symbols we support.
74 enum Source
76 // Symbol defined in a relocatable or dynamic input file--this is
77 // the most common case.
78 FROM_OBJECT,
79 // Symbol defined in an Output_data, a special section created by
80 // the target.
81 IN_OUTPUT_DATA,
82 // Symbol defined in an Output_segment, with no associated
83 // section.
84 IN_OUTPUT_SEGMENT,
85 // Symbol value is constant.
86 IS_CONSTANT,
87 // Symbol is undefined.
88 IS_UNDEFINED
91 // When the source is IN_OUTPUT_SEGMENT, we need to describe what
92 // the offset means.
93 enum Segment_offset_base
95 // From the start of the segment.
96 SEGMENT_START,
97 // From the end of the segment.
98 SEGMENT_END,
99 // From the filesz of the segment--i.e., after the loaded bytes
100 // but before the bytes which are allocated but zeroed.
101 SEGMENT_BSS
104 // Return the symbol name.
105 const char*
106 name() const
107 { return this->name_; }
109 // Return the (ANSI) demangled version of the name, if
110 // parameters.demangle() is true. Otherwise, return the name. This
111 // is intended to be used only for logging errors, so it's not
112 // super-efficient.
113 std::string
114 demangled_name() const;
116 // Return the symbol version. This will return NULL for an
117 // unversioned symbol.
118 const char*
119 version() const
120 { return this->version_; }
122 // Return whether this version is the default for this symbol name
123 // (eg, "foo@@V2" is a default version; "foo@V1" is not). Only
124 // meaningful for versioned symbols.
125 bool
126 is_default() const
128 gold_assert(this->version_ != NULL);
129 return this->is_def_;
132 // Set that this version is the default for this symbol name.
133 void
134 set_is_default()
135 { this->is_def_ = true; }
137 // Return the symbol source.
138 Source
139 source() const
140 { return this->source_; }
142 // Return the object with which this symbol is associated.
143 Object*
144 object() const
146 gold_assert(this->source_ == FROM_OBJECT);
147 return this->u_.from_object.object;
150 // Return the index of the section in the input relocatable or
151 // dynamic object file.
152 unsigned int
153 shndx(bool* is_ordinary) const
155 gold_assert(this->source_ == FROM_OBJECT);
156 *is_ordinary = this->is_ordinary_shndx_;
157 return this->u_.from_object.shndx;
160 // Return the output data section with which this symbol is
161 // associated, if the symbol was specially defined with respect to
162 // an output data section.
163 Output_data*
164 output_data() const
166 gold_assert(this->source_ == IN_OUTPUT_DATA);
167 return this->u_.in_output_data.output_data;
170 // If this symbol was defined with respect to an output data
171 // section, return whether the value is an offset from end.
172 bool
173 offset_is_from_end() const
175 gold_assert(this->source_ == IN_OUTPUT_DATA);
176 return this->u_.in_output_data.offset_is_from_end;
179 // Return the output segment with which this symbol is associated,
180 // if the symbol was specially defined with respect to an output
181 // segment.
182 Output_segment*
183 output_segment() const
185 gold_assert(this->source_ == IN_OUTPUT_SEGMENT);
186 return this->u_.in_output_segment.output_segment;
189 // If this symbol was defined with respect to an output segment,
190 // return the offset base.
191 Segment_offset_base
192 offset_base() const
194 gold_assert(this->source_ == IN_OUTPUT_SEGMENT);
195 return this->u_.in_output_segment.offset_base;
198 // Return the symbol binding.
199 elfcpp::STB
200 binding() const
201 { return this->binding_; }
203 // Return the symbol type.
204 elfcpp::STT
205 type() const
206 { return this->type_; }
208 // Return true for function symbol.
209 bool
210 is_func() const
212 return (this->type_ == elfcpp::STT_FUNC
213 || this->type_ == elfcpp::STT_GNU_IFUNC);
216 // Return the symbol visibility.
217 elfcpp::STV
218 visibility() const
219 { return this->visibility_; }
221 // Set the visibility.
222 void
223 set_visibility(elfcpp::STV visibility)
224 { this->visibility_ = visibility; }
226 // Override symbol visibility.
227 void
228 override_visibility(elfcpp::STV);
230 // Set whether the symbol was originally a weak undef or a regular undef
231 // when resolved by a dynamic def.
232 inline void
233 set_undef_binding(elfcpp::STB bind)
235 if (!this->undef_binding_set_ || this->undef_binding_weak_)
237 this->undef_binding_weak_ = bind == elfcpp::STB_WEAK;
238 this->undef_binding_set_ = true;
242 // Return TRUE if a weak undef was resolved by a dynamic def.
243 inline bool
244 is_undef_binding_weak() const
245 { return this->undef_binding_weak_; }
247 // Return the non-visibility part of the st_other field.
248 unsigned char
249 nonvis() const
250 { return this->nonvis_; }
252 // Return whether this symbol is a forwarder. This will never be
253 // true of a symbol found in the hash table, but may be true of
254 // symbol pointers attached to object files.
255 bool
256 is_forwarder() const
257 { return this->is_forwarder_; }
259 // Mark this symbol as a forwarder.
260 void
261 set_forwarder()
262 { this->is_forwarder_ = true; }
264 // Return whether this symbol has an alias in the weak aliases table
265 // in Symbol_table.
266 bool
267 has_alias() const
268 { return this->has_alias_; }
270 // Mark this symbol as having an alias.
271 void
272 set_has_alias()
273 { this->has_alias_ = true; }
275 // Return whether this symbol needs an entry in the dynamic symbol
276 // table.
277 bool
278 needs_dynsym_entry() const
280 return (this->needs_dynsym_entry_
281 || (this->in_reg()
282 && this->in_dyn()
283 && this->is_externally_visible()));
286 // Mark this symbol as needing an entry in the dynamic symbol table.
287 void
288 set_needs_dynsym_entry()
289 { this->needs_dynsym_entry_ = true; }
291 // Return whether this symbol should be added to the dynamic symbol
292 // table.
293 bool
294 should_add_dynsym_entry(Symbol_table*) const;
296 // Return whether this symbol has been seen in a regular object.
297 bool
298 in_reg() const
299 { return this->in_reg_; }
301 // Mark this symbol as having been seen in a regular object.
302 void
303 set_in_reg()
304 { this->in_reg_ = true; }
306 // Return whether this symbol has been seen in a dynamic object.
307 bool
308 in_dyn() const
309 { return this->in_dyn_; }
311 // Mark this symbol as having been seen in a dynamic object.
312 void
313 set_in_dyn()
314 { this->in_dyn_ = true; }
316 // Return whether this symbol has been seen in a real ELF object.
317 // (IN_REG will return TRUE if the symbol has been seen in either
318 // a real ELF object or an object claimed by a plugin.)
319 bool
320 in_real_elf() const
321 { return this->in_real_elf_; }
323 // Mark this symbol as having been seen in a real ELF object.
324 void
325 set_in_real_elf()
326 { this->in_real_elf_ = true; }
328 // Return whether this symbol was defined in a section that was
329 // discarded from the link. This is used to control some error
330 // reporting.
331 bool
332 is_defined_in_discarded_section() const
333 { return this->is_defined_in_discarded_section_; }
335 // Mark this symbol as having been defined in a discarded section.
336 void
337 set_is_defined_in_discarded_section()
338 { this->is_defined_in_discarded_section_ = true; }
340 // Return the index of this symbol in the output file symbol table.
341 // A value of -1U means that this symbol is not going into the
342 // output file. This starts out as zero, and is set to a non-zero
343 // value by Symbol_table::finalize. It is an error to ask for the
344 // symbol table index before it has been set.
345 unsigned int
346 symtab_index() const
348 gold_assert(this->symtab_index_ != 0);
349 return this->symtab_index_;
352 // Set the index of the symbol in the output file symbol table.
353 void
354 set_symtab_index(unsigned int index)
356 gold_assert(index != 0);
357 this->symtab_index_ = index;
360 // Return whether this symbol already has an index in the output
361 // file symbol table.
362 bool
363 has_symtab_index() const
364 { return this->symtab_index_ != 0; }
366 // Return the index of this symbol in the dynamic symbol table. A
367 // value of -1U means that this symbol is not going into the dynamic
368 // symbol table. This starts out as zero, and is set to a non-zero
369 // during Layout::finalize. It is an error to ask for the dynamic
370 // symbol table index before it has been set.
371 unsigned int
372 dynsym_index() const
374 gold_assert(this->dynsym_index_ != 0);
375 return this->dynsym_index_;
378 // Set the index of the symbol in the dynamic symbol table.
379 void
380 set_dynsym_index(unsigned int index)
382 gold_assert(index != 0);
383 this->dynsym_index_ = index;
386 // Return whether this symbol already has an index in the dynamic
387 // symbol table.
388 bool
389 has_dynsym_index() const
390 { return this->dynsym_index_ != 0; }
392 // Return whether this symbol has an entry in the GOT section.
393 // For a TLS symbol, this GOT entry will hold its tp-relative offset.
394 bool
395 has_got_offset(unsigned int got_type) const
396 { return this->got_offsets_.get_offset(got_type) != -1U; }
398 // Return the offset into the GOT section of this symbol.
399 unsigned int
400 got_offset(unsigned int got_type) const
402 unsigned int got_offset = this->got_offsets_.get_offset(got_type);
403 gold_assert(got_offset != -1U);
404 return got_offset;
407 // Set the GOT offset of this symbol.
408 void
409 set_got_offset(unsigned int got_type, unsigned int got_offset)
410 { this->got_offsets_.set_offset(got_type, got_offset); }
412 // Return the GOT offset list.
413 const Got_offset_list*
414 got_offset_list() const
415 { return this->got_offsets_.get_list(); }
417 // Return whether this symbol has an entry in the PLT section.
418 bool
419 has_plt_offset() const
420 { return this->plt_offset_ != -1U; }
422 // Return the offset into the PLT section of this symbol.
423 unsigned int
424 plt_offset() const
426 gold_assert(this->has_plt_offset());
427 return this->plt_offset_;
430 // Set the PLT offset of this symbol.
431 void
432 set_plt_offset(unsigned int plt_offset)
434 gold_assert(plt_offset != -1U);
435 this->plt_offset_ = plt_offset;
438 // Return whether this dynamic symbol needs a special value in the
439 // dynamic symbol table.
440 bool
441 needs_dynsym_value() const
442 { return this->needs_dynsym_value_; }
444 // Set that this dynamic symbol needs a special value in the dynamic
445 // symbol table.
446 void
447 set_needs_dynsym_value()
449 gold_assert(this->object()->is_dynamic());
450 this->needs_dynsym_value_ = true;
453 // Return true if the final value of this symbol is known at link
454 // time.
455 bool
456 final_value_is_known() const;
458 // Return true if SHNDX represents a common symbol. This depends on
459 // the target.
460 static bool
461 is_common_shndx(unsigned int shndx);
463 // Return whether this is a defined symbol (not undefined or
464 // common).
465 bool
466 is_defined() const
468 bool is_ordinary;
469 if (this->source_ != FROM_OBJECT)
470 return this->source_ != IS_UNDEFINED;
471 unsigned int shndx = this->shndx(&is_ordinary);
472 return (is_ordinary
473 ? shndx != elfcpp::SHN_UNDEF
474 : !Symbol::is_common_shndx(shndx));
477 // Return true if this symbol is from a dynamic object.
478 bool
479 is_from_dynobj() const
481 return this->source_ == FROM_OBJECT && this->object()->is_dynamic();
484 // Return whether this is a placeholder symbol from a plugin object.
485 bool
486 is_placeholder() const
488 return this->source_ == FROM_OBJECT && this->object()->pluginobj() != NULL;
491 // Return whether this is an undefined symbol.
492 bool
493 is_undefined() const
495 bool is_ordinary;
496 return ((this->source_ == FROM_OBJECT
497 && this->shndx(&is_ordinary) == elfcpp::SHN_UNDEF
498 && is_ordinary)
499 || this->source_ == IS_UNDEFINED);
502 // Return whether this is a weak undefined symbol.
503 bool
504 is_weak_undefined() const
505 { return this->is_undefined() && this->binding() == elfcpp::STB_WEAK; }
507 // Return whether this is an absolute symbol.
508 bool
509 is_absolute() const
511 bool is_ordinary;
512 return ((this->source_ == FROM_OBJECT
513 && this->shndx(&is_ordinary) == elfcpp::SHN_ABS
514 && !is_ordinary)
515 || this->source_ == IS_CONSTANT);
518 // Return whether this is a common symbol.
519 bool
520 is_common() const
522 if (this->source_ != FROM_OBJECT)
523 return false;
524 if (this->type_ == elfcpp::STT_COMMON)
525 return true;
526 bool is_ordinary;
527 unsigned int shndx = this->shndx(&is_ordinary);
528 return !is_ordinary && Symbol::is_common_shndx(shndx);
531 // Return whether this symbol can be seen outside this object.
532 bool
533 is_externally_visible() const
535 return (this->visibility_ == elfcpp::STV_DEFAULT
536 || this->visibility_ == elfcpp::STV_PROTECTED);
539 // Return true if this symbol can be preempted by a definition in
540 // another link unit.
541 bool
542 is_preemptible() const
544 // It doesn't make sense to ask whether a symbol defined in
545 // another object is preemptible.
546 gold_assert(!this->is_from_dynobj());
548 // It doesn't make sense to ask whether an undefined symbol
549 // is preemptible.
550 gold_assert(!this->is_undefined());
552 // If a symbol does not have default visibility, it can not be
553 // seen outside this link unit and therefore is not preemptible.
554 if (this->visibility_ != elfcpp::STV_DEFAULT)
555 return false;
557 // If this symbol has been forced to be a local symbol by a
558 // version script, then it is not visible outside this link unit
559 // and is not preemptible.
560 if (this->is_forced_local_)
561 return false;
563 // If we are not producing a shared library, then nothing is
564 // preemptible.
565 if (!parameters->options().shared())
566 return false;
568 // If the user used -Bsymbolic, then nothing is preemptible.
569 if (parameters->options().Bsymbolic())
570 return false;
572 // If the user used -Bsymbolic-functions, then functions are not
573 // preemptible. We explicitly check for not being STT_OBJECT,
574 // rather than for being STT_FUNC, because that is what the GNU
575 // linker does.
576 if (this->type() != elfcpp::STT_OBJECT
577 && parameters->options().Bsymbolic_functions())
578 return false;
580 // Otherwise the symbol is preemptible.
581 return true;
584 // Return true if this symbol is a function that needs a PLT entry.
585 bool
586 needs_plt_entry() const
588 // An undefined symbol from an executable does not need a PLT entry.
589 if (this->is_undefined() && !parameters->options().shared())
590 return false;
592 // An STT_GNU_IFUNC symbol always needs a PLT entry, even when
593 // doing a static link.
594 if (this->type() == elfcpp::STT_GNU_IFUNC)
595 return true;
597 // We only need a PLT entry for a function.
598 if (!this->is_func())
599 return false;
601 // If we're doing a static link or a -pie link, we don't create
602 // PLT entries.
603 if (parameters->doing_static_link()
604 || parameters->options().pie())
605 return false;
607 // We need a PLT entry if the function is defined in a dynamic
608 // object, or is undefined when building a shared object, or if it
609 // is subject to pre-emption.
610 return (this->is_from_dynobj()
611 || this->is_undefined()
612 || this->is_preemptible());
615 // When determining whether a reference to a symbol needs a dynamic
616 // relocation, we need to know several things about the reference.
617 // These flags may be or'ed together. 0 means that the symbol
618 // isn't referenced at all.
619 enum Reference_flags
621 // A reference to the symbol's absolute address. This includes
622 // references that cause an absolute address to be stored in the GOT.
623 ABSOLUTE_REF = 1,
624 // A reference that calculates the offset of the symbol from some
625 // anchor point, such as the PC or GOT.
626 RELATIVE_REF = 2,
627 // A TLS-related reference.
628 TLS_REF = 4,
629 // A reference that can always be treated as a function call.
630 FUNCTION_CALL = 8
633 // Given a direct absolute or pc-relative static relocation against
634 // the global symbol, this function returns whether a dynamic relocation
635 // is needed.
637 bool
638 needs_dynamic_reloc(int flags) const
640 // No dynamic relocations in a static link!
641 if (parameters->doing_static_link())
642 return false;
644 // A reference to an undefined symbol from an executable should be
645 // statically resolved to 0, and does not need a dynamic relocation.
646 // This matches gnu ld behavior.
647 if (this->is_undefined() && !parameters->options().shared())
648 return false;
650 // A reference to an absolute symbol does not need a dynamic relocation.
651 if (this->is_absolute())
652 return false;
654 // An absolute reference within a position-independent output file
655 // will need a dynamic relocation.
656 if ((flags & ABSOLUTE_REF)
657 && parameters->options().output_is_position_independent())
658 return true;
660 // A function call that can branch to a local PLT entry does not need
661 // a dynamic relocation.
662 if ((flags & FUNCTION_CALL) && this->has_plt_offset())
663 return false;
665 // A reference to any PLT entry in a non-position-independent executable
666 // does not need a dynamic relocation.
667 if (!parameters->options().output_is_position_independent()
668 && this->has_plt_offset())
669 return false;
671 // A reference to a symbol defined in a dynamic object or to a
672 // symbol that is preemptible will need a dynamic relocation.
673 if (this->is_from_dynobj()
674 || this->is_undefined()
675 || this->is_preemptible())
676 return true;
678 // For all other cases, return FALSE.
679 return false;
682 // Whether we should use the PLT offset associated with a symbol for
683 // a relocation. FLAGS is a set of Reference_flags.
685 bool
686 use_plt_offset(int flags) const
688 // If the symbol doesn't have a PLT offset, then naturally we
689 // don't want to use it.
690 if (!this->has_plt_offset())
691 return false;
693 // For a STT_GNU_IFUNC symbol we always have to use the PLT entry.
694 if (this->type() == elfcpp::STT_GNU_IFUNC)
695 return true;
697 // If we are going to generate a dynamic relocation, then we will
698 // wind up using that, so no need to use the PLT entry.
699 if (this->needs_dynamic_reloc(flags))
700 return false;
702 // If the symbol is from a dynamic object, we need to use the PLT
703 // entry.
704 if (this->is_from_dynobj())
705 return true;
707 // If we are generating a shared object, and this symbol is
708 // undefined or preemptible, we need to use the PLT entry.
709 if (parameters->options().shared()
710 && (this->is_undefined() || this->is_preemptible()))
711 return true;
713 // If this is a call to a weak undefined symbol, we need to use
714 // the PLT entry; the symbol may be defined by a library loaded
715 // at runtime.
716 if ((flags & FUNCTION_CALL) && this->is_weak_undefined())
717 return true;
719 // Otherwise we can use the regular definition.
720 return false;
723 // Given a direct absolute static relocation against
724 // the global symbol, where a dynamic relocation is needed, this
725 // function returns whether a relative dynamic relocation can be used.
726 // The caller must determine separately whether the static relocation
727 // is compatible with a relative relocation.
729 bool
730 can_use_relative_reloc(bool is_function_call) const
732 // A function call that can branch to a local PLT entry can
733 // use a RELATIVE relocation.
734 if (is_function_call && this->has_plt_offset())
735 return true;
737 // A reference to a symbol defined in a dynamic object or to a
738 // symbol that is preemptible can not use a RELATIVE relocation.
739 if (this->is_from_dynobj()
740 || this->is_undefined()
741 || this->is_preemptible())
742 return false;
744 // For all other cases, return TRUE.
745 return true;
748 // Return the output section where this symbol is defined. Return
749 // NULL if the symbol has an absolute value.
750 Output_section*
751 output_section() const;
753 // Set the symbol's output section. This is used for symbols
754 // defined in scripts. This should only be called after the symbol
755 // table has been finalized.
756 void
757 set_output_section(Output_section*);
759 // Return whether there should be a warning for references to this
760 // symbol.
761 bool
762 has_warning() const
763 { return this->has_warning_; }
765 // Mark this symbol as having a warning.
766 void
767 set_has_warning()
768 { this->has_warning_ = true; }
770 // Return whether this symbol is defined by a COPY reloc from a
771 // dynamic object.
772 bool
773 is_copied_from_dynobj() const
774 { return this->is_copied_from_dynobj_; }
776 // Mark this symbol as defined by a COPY reloc.
777 void
778 set_is_copied_from_dynobj()
779 { this->is_copied_from_dynobj_ = true; }
781 // Return whether this symbol is forced to visibility STB_LOCAL
782 // by a "local:" entry in a version script.
783 bool
784 is_forced_local() const
785 { return this->is_forced_local_; }
787 // Mark this symbol as forced to STB_LOCAL visibility.
788 void
789 set_is_forced_local()
790 { this->is_forced_local_ = true; }
792 // Return true if this may need a COPY relocation.
793 // References from an executable object to non-function symbols
794 // defined in a dynamic object may need a COPY relocation.
795 bool
796 may_need_copy_reloc() const
798 return (!parameters->options().output_is_position_independent()
799 && parameters->options().copyreloc()
800 && this->is_from_dynobj()
801 && !this->is_func());
804 protected:
805 // Instances of this class should always be created at a specific
806 // size.
807 Symbol()
808 { memset(this, 0, sizeof *this); }
810 // Initialize the general fields.
811 void
812 init_fields(const char* name, const char* version,
813 elfcpp::STT type, elfcpp::STB binding,
814 elfcpp::STV visibility, unsigned char nonvis);
816 // Initialize fields from an ELF symbol in OBJECT. ST_SHNDX is the
817 // section index, IS_ORDINARY is whether it is a normal section
818 // index rather than a special code.
819 template<int size, bool big_endian>
820 void
821 init_base_object(const char* name, const char* version, Object* object,
822 const elfcpp::Sym<size, big_endian>&, unsigned int st_shndx,
823 bool is_ordinary);
825 // Initialize fields for an Output_data.
826 void
827 init_base_output_data(const char* name, const char* version, Output_data*,
828 elfcpp::STT, elfcpp::STB, elfcpp::STV,
829 unsigned char nonvis, bool offset_is_from_end);
831 // Initialize fields for an Output_segment.
832 void
833 init_base_output_segment(const char* name, const char* version,
834 Output_segment* os, elfcpp::STT type,
835 elfcpp::STB binding, elfcpp::STV visibility,
836 unsigned char nonvis,
837 Segment_offset_base offset_base);
839 // Initialize fields for a constant.
840 void
841 init_base_constant(const char* name, const char* version, elfcpp::STT type,
842 elfcpp::STB binding, elfcpp::STV visibility,
843 unsigned char nonvis);
845 // Initialize fields for an undefined symbol.
846 void
847 init_base_undefined(const char* name, const char* version, elfcpp::STT type,
848 elfcpp::STB binding, elfcpp::STV visibility,
849 unsigned char nonvis);
851 // Override existing symbol.
852 template<int size, bool big_endian>
853 void
854 override_base(const elfcpp::Sym<size, big_endian>&, unsigned int st_shndx,
855 bool is_ordinary, Object* object, const char* version);
857 // Override existing symbol with a special symbol.
858 void
859 override_base_with_special(const Symbol* from);
861 // Override symbol version.
862 void
863 override_version(const char* version);
865 // Allocate a common symbol by giving it a location in the output
866 // file.
867 void
868 allocate_base_common(Output_data*);
870 private:
871 Symbol(const Symbol&);
872 Symbol& operator=(const Symbol&);
874 // Symbol name (expected to point into a Stringpool).
875 const char* name_;
876 // Symbol version (expected to point into a Stringpool). This may
877 // be NULL.
878 const char* version_;
880 union
882 // This struct is used if SOURCE_ == FROM_OBJECT.
883 struct
885 // Object in which symbol is defined, or in which it was first
886 // seen.
887 Object* object;
888 // Section number in object_ in which symbol is defined.
889 unsigned int shndx;
890 } from_object;
892 // This struct is used if SOURCE_ == IN_OUTPUT_DATA.
893 struct
895 // Output_data in which symbol is defined. Before
896 // Layout::finalize the symbol's value is an offset within the
897 // Output_data.
898 Output_data* output_data;
899 // True if the offset is from the end, false if the offset is
900 // from the beginning.
901 bool offset_is_from_end;
902 } in_output_data;
904 // This struct is used if SOURCE_ == IN_OUTPUT_SEGMENT.
905 struct
907 // Output_segment in which the symbol is defined. Before
908 // Layout::finalize the symbol's value is an offset.
909 Output_segment* output_segment;
910 // The base to use for the offset before Layout::finalize.
911 Segment_offset_base offset_base;
912 } in_output_segment;
913 } u_;
915 // The index of this symbol in the output file. If the symbol is
916 // not going into the output file, this value is -1U. This field
917 // starts as always holding zero. It is set to a non-zero value by
918 // Symbol_table::finalize.
919 unsigned int symtab_index_;
921 // The index of this symbol in the dynamic symbol table. If the
922 // symbol is not going into the dynamic symbol table, this value is
923 // -1U. This field starts as always holding zero. It is set to a
924 // non-zero value during Layout::finalize.
925 unsigned int dynsym_index_;
927 // The GOT section entries for this symbol. A symbol may have more
928 // than one GOT offset (e.g., when mixing modules compiled with two
929 // different TLS models), but will usually have at most one.
930 Got_offset_list got_offsets_;
932 // If this symbol has an entry in the PLT section, then this is the
933 // offset from the start of the PLT section. This is -1U if there
934 // is no PLT entry.
935 unsigned int plt_offset_;
937 // Symbol type (bits 0 to 3).
938 elfcpp::STT type_ : 4;
939 // Symbol binding (bits 4 to 7).
940 elfcpp::STB binding_ : 4;
941 // Symbol visibility (bits 8 to 9).
942 elfcpp::STV visibility_ : 2;
943 // Rest of symbol st_other field (bits 10 to 15).
944 unsigned int nonvis_ : 6;
945 // The type of symbol (bits 16 to 18).
946 Source source_ : 3;
947 // True if this is the default version of the symbol (bit 19).
948 bool is_def_ : 1;
949 // True if this symbol really forwards to another symbol. This is
950 // used when we discover after the fact that two different entries
951 // in the hash table really refer to the same symbol. This will
952 // never be set for a symbol found in the hash table, but may be set
953 // for a symbol found in the list of symbols attached to an Object.
954 // It forwards to the symbol found in the forwarders_ map of
955 // Symbol_table (bit 20).
956 bool is_forwarder_ : 1;
957 // True if the symbol has an alias in the weak_aliases table in
958 // Symbol_table (bit 21).
959 bool has_alias_ : 1;
960 // True if this symbol needs to be in the dynamic symbol table (bit
961 // 22).
962 bool needs_dynsym_entry_ : 1;
963 // True if we've seen this symbol in a regular object (bit 23).
964 bool in_reg_ : 1;
965 // True if we've seen this symbol in a dynamic object (bit 24).
966 bool in_dyn_ : 1;
967 // True if this is a dynamic symbol which needs a special value in
968 // the dynamic symbol table (bit 25).
969 bool needs_dynsym_value_ : 1;
970 // True if there is a warning for this symbol (bit 26).
971 bool has_warning_ : 1;
972 // True if we are using a COPY reloc for this symbol, so that the
973 // real definition lives in a dynamic object (bit 27).
974 bool is_copied_from_dynobj_ : 1;
975 // True if this symbol was forced to local visibility by a version
976 // script (bit 28).
977 bool is_forced_local_ : 1;
978 // True if the field u_.from_object.shndx is an ordinary section
979 // index, not one of the special codes from SHN_LORESERVE to
980 // SHN_HIRESERVE (bit 29).
981 bool is_ordinary_shndx_ : 1;
982 // True if we've seen this symbol in a real ELF object (bit 30).
983 bool in_real_elf_ : 1;
984 // True if this symbol is defined in a section which was discarded
985 // (bit 31).
986 bool is_defined_in_discarded_section_ : 1;
987 // True if UNDEF_BINDING_WEAK_ has been set (bit 32).
988 bool undef_binding_set_ : 1;
989 // True if this symbol was a weak undef resolved by a dynamic def
990 // (bit 33).
991 bool undef_binding_weak_ : 1;
994 // The parts of a symbol which are size specific. Using a template
995 // derived class like this helps us use less space on a 32-bit system.
997 template<int size>
998 class Sized_symbol : public Symbol
1000 public:
1001 typedef typename elfcpp::Elf_types<size>::Elf_Addr Value_type;
1002 typedef typename elfcpp::Elf_types<size>::Elf_WXword Size_type;
1004 Sized_symbol()
1007 // Initialize fields from an ELF symbol in OBJECT. ST_SHNDX is the
1008 // section index, IS_ORDINARY is whether it is a normal section
1009 // index rather than a special code.
1010 template<bool big_endian>
1011 void
1012 init_object(const char* name, const char* version, Object* object,
1013 const elfcpp::Sym<size, big_endian>&, unsigned int st_shndx,
1014 bool is_ordinary);
1016 // Initialize fields for an Output_data.
1017 void
1018 init_output_data(const char* name, const char* version, Output_data*,
1019 Value_type value, Size_type symsize, elfcpp::STT,
1020 elfcpp::STB, elfcpp::STV, unsigned char nonvis,
1021 bool offset_is_from_end);
1023 // Initialize fields for an Output_segment.
1024 void
1025 init_output_segment(const char* name, const char* version, Output_segment*,
1026 Value_type value, Size_type symsize, elfcpp::STT,
1027 elfcpp::STB, elfcpp::STV, unsigned char nonvis,
1028 Segment_offset_base offset_base);
1030 // Initialize fields for a constant.
1031 void
1032 init_constant(const char* name, const char* version, Value_type value,
1033 Size_type symsize, elfcpp::STT, elfcpp::STB, elfcpp::STV,
1034 unsigned char nonvis);
1036 // Initialize fields for an undefined symbol.
1037 void
1038 init_undefined(const char* name, const char* version, elfcpp::STT,
1039 elfcpp::STB, elfcpp::STV, unsigned char nonvis);
1041 // Override existing symbol.
1042 template<bool big_endian>
1043 void
1044 override(const elfcpp::Sym<size, big_endian>&, unsigned int st_shndx,
1045 bool is_ordinary, Object* object, const char* version);
1047 // Override existing symbol with a special symbol.
1048 void
1049 override_with_special(const Sized_symbol<size>*);
1051 // Return the symbol's value.
1052 Value_type
1053 value() const
1054 { return this->value_; }
1056 // Return the symbol's size (we can't call this 'size' because that
1057 // is a template parameter).
1058 Size_type
1059 symsize() const
1060 { return this->symsize_; }
1062 // Set the symbol size. This is used when resolving common symbols.
1063 void
1064 set_symsize(Size_type symsize)
1065 { this->symsize_ = symsize; }
1067 // Set the symbol value. This is called when we store the final
1068 // values of the symbols into the symbol table.
1069 void
1070 set_value(Value_type value)
1071 { this->value_ = value; }
1073 // Allocate a common symbol by giving it a location in the output
1074 // file.
1075 void
1076 allocate_common(Output_data*, Value_type value);
1078 private:
1079 Sized_symbol(const Sized_symbol&);
1080 Sized_symbol& operator=(const Sized_symbol&);
1082 // Symbol value. Before Layout::finalize this is the offset in the
1083 // input section. This is set to the final value during
1084 // Layout::finalize.
1085 Value_type value_;
1086 // Symbol size.
1087 Size_type symsize_;
1090 // A struct describing a symbol defined by the linker, where the value
1091 // of the symbol is defined based on an output section. This is used
1092 // for symbols defined by the linker, like "_init_array_start".
1094 struct Define_symbol_in_section
1096 // The symbol name.
1097 const char* name;
1098 // The name of the output section with which this symbol should be
1099 // associated. If there is no output section with that name, the
1100 // symbol will be defined as zero.
1101 const char* output_section;
1102 // The offset of the symbol within the output section. This is an
1103 // offset from the start of the output section, unless start_at_end
1104 // is true, in which case this is an offset from the end of the
1105 // output section.
1106 uint64_t value;
1107 // The size of the symbol.
1108 uint64_t size;
1109 // The symbol type.
1110 elfcpp::STT type;
1111 // The symbol binding.
1112 elfcpp::STB binding;
1113 // The symbol visibility.
1114 elfcpp::STV visibility;
1115 // The rest of the st_other field.
1116 unsigned char nonvis;
1117 // If true, the value field is an offset from the end of the output
1118 // section.
1119 bool offset_is_from_end;
1120 // If true, this symbol is defined only if we see a reference to it.
1121 bool only_if_ref;
1124 // A struct describing a symbol defined by the linker, where the value
1125 // of the symbol is defined based on a segment. This is used for
1126 // symbols defined by the linker, like "_end". We describe the
1127 // segment with which the symbol should be associated by its
1128 // characteristics. If no segment meets these characteristics, the
1129 // symbol will be defined as zero. If there is more than one segment
1130 // which meets these characteristics, we will use the first one.
1132 struct Define_symbol_in_segment
1134 // The symbol name.
1135 const char* name;
1136 // The segment type where the symbol should be defined, typically
1137 // PT_LOAD.
1138 elfcpp::PT segment_type;
1139 // Bitmask of segment flags which must be set.
1140 elfcpp::PF segment_flags_set;
1141 // Bitmask of segment flags which must be clear.
1142 elfcpp::PF segment_flags_clear;
1143 // The offset of the symbol within the segment. The offset is
1144 // calculated from the position set by offset_base.
1145 uint64_t value;
1146 // The size of the symbol.
1147 uint64_t size;
1148 // The symbol type.
1149 elfcpp::STT type;
1150 // The symbol binding.
1151 elfcpp::STB binding;
1152 // The symbol visibility.
1153 elfcpp::STV visibility;
1154 // The rest of the st_other field.
1155 unsigned char nonvis;
1156 // The base from which we compute the offset.
1157 Symbol::Segment_offset_base offset_base;
1158 // If true, this symbol is defined only if we see a reference to it.
1159 bool only_if_ref;
1162 // This class manages warnings. Warnings are a GNU extension. When
1163 // we see a section named .gnu.warning.SYM in an object file, and if
1164 // we wind using the definition of SYM from that object file, then we
1165 // will issue a warning for any relocation against SYM from a
1166 // different object file. The text of the warning is the contents of
1167 // the section. This is not precisely the definition used by the old
1168 // GNU linker; the old GNU linker treated an occurrence of
1169 // .gnu.warning.SYM as defining a warning symbol. A warning symbol
1170 // would trigger a warning on any reference. However, it was
1171 // inconsistent in that a warning in a dynamic object only triggered
1172 // if there was no definition in a regular object. This linker is
1173 // different in that we only issue a warning if we use the symbol
1174 // definition from the same object file as the warning section.
1176 class Warnings
1178 public:
1179 Warnings()
1180 : warnings_()
1183 // Add a warning for symbol NAME in object OBJ. WARNING is the text
1184 // of the warning.
1185 void
1186 add_warning(Symbol_table* symtab, const char* name, Object* obj,
1187 const std::string& warning);
1189 // For each symbol for which we should give a warning, make a note
1190 // on the symbol.
1191 void
1192 note_warnings(Symbol_table* symtab);
1194 // Issue a warning for a reference to SYM at RELINFO's location.
1195 template<int size, bool big_endian>
1196 void
1197 issue_warning(const Symbol* sym, const Relocate_info<size, big_endian>*,
1198 size_t relnum, off_t reloffset) const;
1200 private:
1201 Warnings(const Warnings&);
1202 Warnings& operator=(const Warnings&);
1204 // What we need to know to get the warning text.
1205 struct Warning_location
1207 // The object the warning is in.
1208 Object* object;
1209 // The warning text.
1210 std::string text;
1212 Warning_location()
1213 : object(NULL), text()
1216 void
1217 set(Object* o, const std::string& t)
1219 this->object = o;
1220 this->text = t;
1224 // A mapping from warning symbol names (canonicalized in
1225 // Symbol_table's namepool_ field) to warning information.
1226 typedef Unordered_map<const char*, Warning_location> Warning_table;
1228 Warning_table warnings_;
1231 // The main linker symbol table.
1233 class Symbol_table
1235 public:
1236 // The different places where a symbol definition can come from.
1237 enum Defined
1239 // Defined in an object file--the normal case.
1240 OBJECT,
1241 // Defined for a COPY reloc.
1242 COPY,
1243 // Defined on the command line using --defsym.
1244 DEFSYM,
1245 // Defined (so to speak) on the command line using -u.
1246 UNDEFINED,
1247 // Defined in a linker script.
1248 SCRIPT,
1249 // Predefined by the linker.
1250 PREDEFINED,
1253 // The order in which we sort common symbols.
1254 enum Sort_commons_order
1256 SORT_COMMONS_BY_SIZE_DESCENDING,
1257 SORT_COMMONS_BY_ALIGNMENT_DESCENDING,
1258 SORT_COMMONS_BY_ALIGNMENT_ASCENDING
1261 // COUNT is an estimate of how many symbols will be inserted in the
1262 // symbol table. It's ok to put 0 if you don't know; a correct
1263 // guess will just save some CPU by reducing hashtable resizes.
1264 Symbol_table(unsigned int count, const Version_script_info& version_script);
1266 ~Symbol_table();
1268 void
1269 set_icf(Icf* icf)
1270 { this->icf_ = icf;}
1272 Icf*
1273 icf() const
1274 { return this->icf_; }
1276 // Returns true if ICF determined that this is a duplicate section.
1277 bool
1278 is_section_folded(Object* obj, unsigned int shndx) const;
1280 void
1281 set_gc(Garbage_collection* gc)
1282 { this->gc_ = gc; }
1284 Garbage_collection*
1285 gc() const
1286 { return this->gc_; }
1288 // During garbage collection, this keeps undefined symbols.
1289 void
1290 gc_mark_undef_symbols(Layout*);
1292 // During garbage collection, this ensures externally visible symbols
1293 // are not treated as garbage while building shared objects.
1294 void
1295 gc_mark_symbol_for_shlib(Symbol* sym);
1297 // During garbage collection, this keeps sections that correspond to
1298 // symbols seen in dynamic objects.
1299 inline void
1300 gc_mark_dyn_syms(Symbol* sym);
1302 // Add COUNT external symbols from the relocatable object RELOBJ to
1303 // the symbol table. SYMS is the symbols, SYMNDX_OFFSET is the
1304 // offset in the symbol table of the first symbol, SYM_NAMES is
1305 // their names, SYM_NAME_SIZE is the size of SYM_NAMES. This sets
1306 // SYMPOINTERS to point to the symbols in the symbol table. It sets
1307 // *DEFINED to the number of defined symbols.
1308 template<int size, bool big_endian>
1309 void
1310 add_from_relobj(Sized_relobj<size, big_endian>* relobj,
1311 const unsigned char* syms, size_t count,
1312 size_t symndx_offset, const char* sym_names,
1313 size_t sym_name_size,
1314 typename Sized_relobj<size, big_endian>::Symbols*,
1315 size_t* defined);
1317 // Add one external symbol from the plugin object OBJ to the symbol table.
1318 // Returns a pointer to the resolved symbol in the symbol table.
1319 template<int size, bool big_endian>
1320 Symbol*
1321 add_from_pluginobj(Sized_pluginobj<size, big_endian>* obj,
1322 const char* name, const char* ver,
1323 elfcpp::Sym<size, big_endian>* sym);
1325 // Add COUNT dynamic symbols from the dynamic object DYNOBJ to the
1326 // symbol table. SYMS is the symbols. SYM_NAMES is their names.
1327 // SYM_NAME_SIZE is the size of SYM_NAMES. The other parameters are
1328 // symbol version data.
1329 template<int size, bool big_endian>
1330 void
1331 add_from_dynobj(Sized_dynobj<size, big_endian>* dynobj,
1332 const unsigned char* syms, size_t count,
1333 const char* sym_names, size_t sym_name_size,
1334 const unsigned char* versym, size_t versym_size,
1335 const std::vector<const char*>*,
1336 typename Sized_relobj<size, big_endian>::Symbols*,
1337 size_t* defined);
1339 // Define a special symbol based on an Output_data. It is a
1340 // multiple definition error if this symbol is already defined.
1341 Symbol*
1342 define_in_output_data(const char* name, const char* version, Defined,
1343 Output_data*, uint64_t value, uint64_t symsize,
1344 elfcpp::STT type, elfcpp::STB binding,
1345 elfcpp::STV visibility, unsigned char nonvis,
1346 bool offset_is_from_end, bool only_if_ref);
1348 // Define a special symbol based on an Output_segment. It is a
1349 // multiple definition error if this symbol is already defined.
1350 Symbol*
1351 define_in_output_segment(const char* name, const char* version, Defined,
1352 Output_segment*, uint64_t value, uint64_t symsize,
1353 elfcpp::STT type, elfcpp::STB binding,
1354 elfcpp::STV visibility, unsigned char nonvis,
1355 Symbol::Segment_offset_base, bool only_if_ref);
1357 // Define a special symbol with a constant value. It is a multiple
1358 // definition error if this symbol is already defined.
1359 Symbol*
1360 define_as_constant(const char* name, const char* version, Defined,
1361 uint64_t value, uint64_t symsize, elfcpp::STT type,
1362 elfcpp::STB binding, elfcpp::STV visibility,
1363 unsigned char nonvis, bool only_if_ref,
1364 bool force_override);
1366 // Define a set of symbols in output sections. If ONLY_IF_REF is
1367 // true, only define them if they are referenced.
1368 void
1369 define_symbols(const Layout*, int count, const Define_symbol_in_section*,
1370 bool only_if_ref);
1372 // Define a set of symbols in output segments. If ONLY_IF_REF is
1373 // true, only defined them if they are referenced.
1374 void
1375 define_symbols(const Layout*, int count, const Define_symbol_in_segment*,
1376 bool only_if_ref);
1378 // Define SYM using a COPY reloc. POSD is the Output_data where the
1379 // symbol should be defined--typically a .dyn.bss section. VALUE is
1380 // the offset within POSD.
1381 template<int size>
1382 void
1383 define_with_copy_reloc(Sized_symbol<size>* sym, Output_data* posd,
1384 typename elfcpp::Elf_types<size>::Elf_Addr);
1386 // Look up a symbol.
1387 Symbol*
1388 lookup(const char*, const char* version = NULL) const;
1390 // Return the real symbol associated with the forwarder symbol FROM.
1391 Symbol*
1392 resolve_forwards(const Symbol* from) const;
1394 // Return the sized version of a symbol in this table.
1395 template<int size>
1396 Sized_symbol<size>*
1397 get_sized_symbol(Symbol*) const;
1399 template<int size>
1400 const Sized_symbol<size>*
1401 get_sized_symbol(const Symbol*) const;
1403 // Return the count of undefined symbols seen.
1404 size_t
1405 saw_undefined() const
1406 { return this->saw_undefined_; }
1408 // Allocate the common symbols
1409 void
1410 allocate_commons(Layout*, Mapfile*);
1412 // Add a warning for symbol NAME in object OBJ. WARNING is the text
1413 // of the warning.
1414 void
1415 add_warning(const char* name, Object* obj, const std::string& warning)
1416 { this->warnings_.add_warning(this, name, obj, warning); }
1418 // Canonicalize a symbol name for use in the hash table.
1419 const char*
1420 canonicalize_name(const char* name)
1421 { return this->namepool_.add(name, true, NULL); }
1423 // Possibly issue a warning for a reference to SYM at LOCATION which
1424 // is in OBJ.
1425 template<int size, bool big_endian>
1426 void
1427 issue_warning(const Symbol* sym,
1428 const Relocate_info<size, big_endian>* relinfo,
1429 size_t relnum, off_t reloffset) const
1430 { this->warnings_.issue_warning(sym, relinfo, relnum, reloffset); }
1432 // Check candidate_odr_violations_ to find symbols with the same name
1433 // but apparently different definitions (different source-file/line-no).
1434 void
1435 detect_odr_violations(const Task*, const char* output_file_name) const;
1437 // Add any undefined symbols named on the command line to the symbol
1438 // table.
1439 void
1440 add_undefined_symbols_from_command_line(Layout*);
1442 // SYM is defined using a COPY reloc. Return the dynamic object
1443 // where the original definition was found.
1444 Dynobj*
1445 get_copy_source(const Symbol* sym) const;
1447 // Set the dynamic symbol indexes. INDEX is the index of the first
1448 // global dynamic symbol. Pointers to the symbols are stored into
1449 // the vector. The names are stored into the Stringpool. This
1450 // returns an updated dynamic symbol index.
1451 unsigned int
1452 set_dynsym_indexes(unsigned int index, std::vector<Symbol*>*,
1453 Stringpool*, Versions*);
1455 // Finalize the symbol table after we have set the final addresses
1456 // of all the input sections. This sets the final symbol indexes,
1457 // values and adds the names to *POOL. *PLOCAL_SYMCOUNT is the
1458 // index of the first global symbol. OFF is the file offset of the
1459 // global symbol table, DYNOFF is the offset of the globals in the
1460 // dynamic symbol table, DYN_GLOBAL_INDEX is the index of the first
1461 // global dynamic symbol, and DYNCOUNT is the number of global
1462 // dynamic symbols. This records the parameters, and returns the
1463 // new file offset. It updates *PLOCAL_SYMCOUNT if it created any
1464 // local symbols.
1465 off_t
1466 finalize(off_t off, off_t dynoff, size_t dyn_global_index, size_t dyncount,
1467 Stringpool* pool, unsigned int* plocal_symcount);
1469 // Status code of Symbol_table::compute_final_value.
1470 enum Compute_final_value_status
1472 // No error.
1473 CFVS_OK,
1474 // Unsupported symbol section.
1475 CFVS_UNSUPPORTED_SYMBOL_SECTION,
1476 // No output section.
1477 CFVS_NO_OUTPUT_SECTION
1480 // Compute the final value of SYM and store status in location PSTATUS.
1481 // During relaxation, this may be called multiple times for a symbol to
1482 // compute its would-be final value in each relaxation pass.
1484 template<int size>
1485 typename Sized_symbol<size>::Value_type
1486 compute_final_value(const Sized_symbol<size>* sym,
1487 Compute_final_value_status* pstatus) const;
1489 // Return the index of the first global symbol.
1490 unsigned int
1491 first_global_index() const
1492 { return this->first_global_index_; }
1494 // Return the total number of symbols in the symbol table.
1495 unsigned int
1496 output_count() const
1497 { return this->output_count_; }
1499 // Write out the global symbols.
1500 void
1501 write_globals(const Stringpool*, const Stringpool*,
1502 Output_symtab_xindex*, Output_symtab_xindex*,
1503 Output_file*) const;
1505 // Write out a section symbol. Return the updated offset.
1506 void
1507 write_section_symbol(const Output_section*, Output_symtab_xindex*,
1508 Output_file*, off_t) const;
1510 // Loop over all symbols, applying the function F to each.
1511 template<int size, typename F>
1512 void
1513 for_all_symbols(F f) const
1515 for (Symbol_table_type::const_iterator p = this->table_.begin();
1516 p != this->table_.end();
1517 ++p)
1519 Sized_symbol<size>* sym = static_cast<Sized_symbol<size>*>(p->second);
1520 f(sym);
1524 // Dump statistical information to stderr.
1525 void
1526 print_stats() const;
1528 // Return the version script information.
1529 const Version_script_info&
1530 version_script() const
1531 { return version_script_; }
1533 private:
1534 Symbol_table(const Symbol_table&);
1535 Symbol_table& operator=(const Symbol_table&);
1537 // The type of the list of common symbols.
1538 typedef std::vector<Symbol*> Commons_type;
1540 // The type of the symbol hash table.
1542 typedef std::pair<Stringpool::Key, Stringpool::Key> Symbol_table_key;
1544 // The hash function. The key values are Stringpool keys.
1545 struct Symbol_table_hash
1547 inline size_t
1548 operator()(const Symbol_table_key& key) const
1550 return key.first ^ key.second;
1554 struct Symbol_table_eq
1556 bool
1557 operator()(const Symbol_table_key&, const Symbol_table_key&) const;
1560 typedef Unordered_map<Symbol_table_key, Symbol*, Symbol_table_hash,
1561 Symbol_table_eq> Symbol_table_type;
1563 // Make FROM a forwarder symbol to TO.
1564 void
1565 make_forwarder(Symbol* from, Symbol* to);
1567 // Add a symbol.
1568 template<int size, bool big_endian>
1569 Sized_symbol<size>*
1570 add_from_object(Object*, const char* name, Stringpool::Key name_key,
1571 const char* version, Stringpool::Key version_key,
1572 bool def, const elfcpp::Sym<size, big_endian>& sym,
1573 unsigned int st_shndx, bool is_ordinary,
1574 unsigned int orig_st_shndx);
1576 // Define a default symbol.
1577 template<int size, bool big_endian>
1578 void
1579 define_default_version(Sized_symbol<size>*, bool,
1580 Symbol_table_type::iterator);
1582 // Resolve symbols.
1583 template<int size, bool big_endian>
1584 void
1585 resolve(Sized_symbol<size>* to,
1586 const elfcpp::Sym<size, big_endian>& sym,
1587 unsigned int st_shndx, bool is_ordinary,
1588 unsigned int orig_st_shndx,
1589 Object*, const char* version);
1591 template<int size, bool big_endian>
1592 void
1593 resolve(Sized_symbol<size>* to, const Sized_symbol<size>* from);
1595 // Record that a symbol is forced to be local by a version script or
1596 // by visibility.
1597 void
1598 force_local(Symbol*);
1600 // Adjust NAME and *NAME_KEY for wrapping.
1601 const char*
1602 wrap_symbol(const char* name, Stringpool::Key* name_key);
1604 // Whether we should override a symbol, based on flags in
1605 // resolve.cc.
1606 static bool
1607 should_override(const Symbol*, unsigned int, Defined, Object*, bool*, bool*);
1609 // Report a problem in symbol resolution.
1610 static void
1611 report_resolve_problem(bool is_error, const char* msg, const Symbol* to,
1612 Defined, Object* object);
1614 // Override a symbol.
1615 template<int size, bool big_endian>
1616 void
1617 override(Sized_symbol<size>* tosym,
1618 const elfcpp::Sym<size, big_endian>& fromsym,
1619 unsigned int st_shndx, bool is_ordinary,
1620 Object* object, const char* version);
1622 // Whether we should override a symbol with a special symbol which
1623 // is automatically defined by the linker.
1624 static bool
1625 should_override_with_special(const Symbol*, Defined);
1627 // Override a symbol with a special symbol.
1628 template<int size>
1629 void
1630 override_with_special(Sized_symbol<size>* tosym,
1631 const Sized_symbol<size>* fromsym);
1633 // Record all weak alias sets for a dynamic object.
1634 template<int size>
1635 void
1636 record_weak_aliases(std::vector<Sized_symbol<size>*>*);
1638 // Define a special symbol.
1639 template<int size, bool big_endian>
1640 Sized_symbol<size>*
1641 define_special_symbol(const char** pname, const char** pversion,
1642 bool only_if_ref, Sized_symbol<size>** poldsym,
1643 bool* resolve_oldsym);
1645 // Define a symbol in an Output_data, sized version.
1646 template<int size>
1647 Sized_symbol<size>*
1648 do_define_in_output_data(const char* name, const char* version, Defined,
1649 Output_data*,
1650 typename elfcpp::Elf_types<size>::Elf_Addr value,
1651 typename elfcpp::Elf_types<size>::Elf_WXword ssize,
1652 elfcpp::STT type, elfcpp::STB binding,
1653 elfcpp::STV visibility, unsigned char nonvis,
1654 bool offset_is_from_end, bool only_if_ref);
1656 // Define a symbol in an Output_segment, sized version.
1657 template<int size>
1658 Sized_symbol<size>*
1659 do_define_in_output_segment(
1660 const char* name, const char* version, Defined, Output_segment* os,
1661 typename elfcpp::Elf_types<size>::Elf_Addr value,
1662 typename elfcpp::Elf_types<size>::Elf_WXword ssize,
1663 elfcpp::STT type, elfcpp::STB binding,
1664 elfcpp::STV visibility, unsigned char nonvis,
1665 Symbol::Segment_offset_base offset_base, bool only_if_ref);
1667 // Define a symbol as a constant, sized version.
1668 template<int size>
1669 Sized_symbol<size>*
1670 do_define_as_constant(
1671 const char* name, const char* version, Defined,
1672 typename elfcpp::Elf_types<size>::Elf_Addr value,
1673 typename elfcpp::Elf_types<size>::Elf_WXword ssize,
1674 elfcpp::STT type, elfcpp::STB binding,
1675 elfcpp::STV visibility, unsigned char nonvis,
1676 bool only_if_ref, bool force_override);
1678 // Add any undefined symbols named on the command line to the symbol
1679 // table, sized version.
1680 template<int size>
1681 void
1682 do_add_undefined_symbols_from_command_line(Layout*);
1684 // Add one undefined symbol.
1685 template<int size>
1686 void
1687 add_undefined_symbol_from_command_line(const char* name);
1689 // Types of common symbols.
1691 enum Commons_section_type
1693 COMMONS_NORMAL,
1694 COMMONS_TLS,
1695 COMMONS_SMALL,
1696 COMMONS_LARGE
1699 // Allocate the common symbols, sized version.
1700 template<int size>
1701 void
1702 do_allocate_commons(Layout*, Mapfile*, Sort_commons_order);
1704 // Allocate the common symbols from one list.
1705 template<int size>
1706 void
1707 do_allocate_commons_list(Layout*, Commons_section_type, Commons_type*,
1708 Mapfile*, Sort_commons_order);
1710 // Implement detect_odr_violations.
1711 template<int size, bool big_endian>
1712 void
1713 sized_detect_odr_violations() const;
1715 // Finalize symbols specialized for size.
1716 template<int size>
1717 off_t
1718 sized_finalize(off_t, Stringpool*, unsigned int*);
1720 // Finalize a symbol. Return whether it should be added to the
1721 // symbol table.
1722 template<int size>
1723 bool
1724 sized_finalize_symbol(Symbol*);
1726 // Add a symbol the final symtab by setting its index.
1727 template<int size>
1728 void
1729 add_to_final_symtab(Symbol*, Stringpool*, unsigned int* pindex, off_t* poff);
1731 // Write globals specialized for size and endianness.
1732 template<int size, bool big_endian>
1733 void
1734 sized_write_globals(const Stringpool*, const Stringpool*,
1735 Output_symtab_xindex*, Output_symtab_xindex*,
1736 Output_file*) const;
1738 // Write out a symbol to P.
1739 template<int size, bool big_endian>
1740 void
1741 sized_write_symbol(Sized_symbol<size>*,
1742 typename elfcpp::Elf_types<size>::Elf_Addr value,
1743 unsigned int shndx, elfcpp::STB,
1744 const Stringpool*, unsigned char* p) const;
1746 // Possibly warn about an undefined symbol from a dynamic object.
1747 void
1748 warn_about_undefined_dynobj_symbol(Symbol*) const;
1750 // Write out a section symbol, specialized for size and endianness.
1751 template<int size, bool big_endian>
1752 void
1753 sized_write_section_symbol(const Output_section*, Output_symtab_xindex*,
1754 Output_file*, off_t) const;
1756 // The type of the list of symbols which have been forced local.
1757 typedef std::vector<Symbol*> Forced_locals;
1759 // A map from symbols with COPY relocs to the dynamic objects where
1760 // they are defined.
1761 typedef Unordered_map<const Symbol*, Dynobj*> Copied_symbol_dynobjs;
1763 // A map from symbol name (as a pointer into the namepool) to all
1764 // the locations the symbols is (weakly) defined (and certain other
1765 // conditions are met). This map will be used later to detect
1766 // possible One Definition Rule (ODR) violations.
1767 struct Symbol_location
1769 Object* object; // Object where the symbol is defined.
1770 unsigned int shndx; // Section-in-object where the symbol is defined.
1771 off_t offset; // Offset-in-section where the symbol is defined.
1772 bool operator==(const Symbol_location& that) const
1774 return (this->object == that.object
1775 && this->shndx == that.shndx
1776 && this->offset == that.offset);
1780 struct Symbol_location_hash
1782 size_t operator()(const Symbol_location& loc) const
1783 { return reinterpret_cast<uintptr_t>(loc.object) ^ loc.offset ^ loc.shndx; }
1786 typedef Unordered_map<const char*,
1787 Unordered_set<Symbol_location, Symbol_location_hash> >
1788 Odr_map;
1790 // We increment this every time we see a new undefined symbol, for
1791 // use in archive groups.
1792 size_t saw_undefined_;
1793 // The index of the first global symbol in the output file.
1794 unsigned int first_global_index_;
1795 // The file offset within the output symtab section where we should
1796 // write the table.
1797 off_t offset_;
1798 // The number of global symbols we want to write out.
1799 unsigned int output_count_;
1800 // The file offset of the global dynamic symbols, or 0 if none.
1801 off_t dynamic_offset_;
1802 // The index of the first global dynamic symbol.
1803 unsigned int first_dynamic_global_index_;
1804 // The number of global dynamic symbols, or 0 if none.
1805 unsigned int dynamic_count_;
1806 // The symbol hash table.
1807 Symbol_table_type table_;
1808 // A pool of symbol names. This is used for all global symbols.
1809 // Entries in the hash table point into this pool.
1810 Stringpool namepool_;
1811 // Forwarding symbols.
1812 Unordered_map<const Symbol*, Symbol*> forwarders_;
1813 // Weak aliases. A symbol in this list points to the next alias.
1814 // The aliases point to each other in a circular list.
1815 Unordered_map<Symbol*, Symbol*> weak_aliases_;
1816 // We don't expect there to be very many common symbols, so we keep
1817 // a list of them. When we find a common symbol we add it to this
1818 // list. It is possible that by the time we process the list the
1819 // symbol is no longer a common symbol. It may also have become a
1820 // forwarder.
1821 Commons_type commons_;
1822 // This is like the commons_ field, except that it holds TLS common
1823 // symbols.
1824 Commons_type tls_commons_;
1825 // This is for small common symbols.
1826 Commons_type small_commons_;
1827 // This is for large common symbols.
1828 Commons_type large_commons_;
1829 // A list of symbols which have been forced to be local. We don't
1830 // expect there to be very many of them, so we keep a list of them
1831 // rather than walking the whole table to find them.
1832 Forced_locals forced_locals_;
1833 // Manage symbol warnings.
1834 Warnings warnings_;
1835 // Manage potential One Definition Rule (ODR) violations.
1836 Odr_map candidate_odr_violations_;
1838 // When we emit a COPY reloc for a symbol, we define it in an
1839 // Output_data. When it's time to emit version information for it,
1840 // we need to know the dynamic object in which we found the original
1841 // definition. This maps symbols with COPY relocs to the dynamic
1842 // object where they were defined.
1843 Copied_symbol_dynobjs copied_symbol_dynobjs_;
1844 // Information parsed from the version script, if any.
1845 const Version_script_info& version_script_;
1846 Garbage_collection* gc_;
1847 Icf* icf_;
1850 // We inline get_sized_symbol for efficiency.
1852 template<int size>
1853 Sized_symbol<size>*
1854 Symbol_table::get_sized_symbol(Symbol* sym) const
1856 gold_assert(size == parameters->target().get_size());
1857 return static_cast<Sized_symbol<size>*>(sym);
1860 template<int size>
1861 const Sized_symbol<size>*
1862 Symbol_table::get_sized_symbol(const Symbol* sym) const
1864 gold_assert(size == parameters->target().get_size());
1865 return static_cast<const Sized_symbol<size>*>(sym);
1868 } // End namespace gold.
1870 #endif // !defined(GOLD_SYMTAB_H)