// symtab.h -- the gold symbol table -*- C++ -*-
-// Copyright 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
+// Copyright 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.
// This file is part of gold.
class Object;
class Relobj;
template<int size, bool big_endian>
-class Sized_relobj;
+class Sized_relobj_file;
template<int size, bool big_endian>
class Sized_pluginobj;
class Dynobj;
template<int size, bool big_endian>
class Sized_dynobj;
+template<int size, bool big_endian>
+class Sized_incrobj;
class Versions;
class Version_script_info;
class Input_objects;
class Icf;
// The base class of an entry in the symbol table. The symbol table
-// can have a lot of entries, so we don't want this class to big.
+// can have a lot of entries, so we don't want this class too big.
// Size dependent fields can be found in the template class
// Sized_symbol. Targets may support their own derived classes.
version() const
{ return this->version_; }
+ void
+ clear_version()
+ { this->version_ = NULL; }
+
// Return whether this version is the default for this symbol name
// (eg, "foo@@V2" is a default version; "foo@V1" is not). Only
// meaningful for versioned symbols.
set_is_default()
{ this->is_def_ = true; }
+ // Return the symbol's name as name@version (or name@@version).
+ std::string
+ versioned_name() const;
+
// Return the symbol source.
Source
source() const
bool
is_externally_visible() const
{
- return (this->visibility_ == elfcpp::STV_DEFAULT
- || this->visibility_ == elfcpp::STV_PROTECTED);
+ return ((this->visibility_ == elfcpp::STV_DEFAULT
+ || this->visibility_ == elfcpp::STV_PROTECTED)
+ && !this->is_forced_local_);
}
// Return true if this symbol can be preempted by a definition in
// When determining whether a reference to a symbol needs a dynamic
// relocation, we need to know several things about the reference.
- // These flags may be or'ed together.
+ // These flags may be or'ed together. 0 means that the symbol
+ // isn't referenced at all.
enum Reference_flags
{
- // Reference to the symbol's absolute address.
+ // A reference to the symbol's absolute address. This includes
+ // references that cause an absolute address to be stored in the GOT.
ABSOLUTE_REF = 1,
- // A non-PIC reference.
- NON_PIC_REF = 2,
- // A function call.
- FUNCTION_CALL = 4
+ // A reference that calculates the offset of the symbol from some
+ // anchor point, such as the PC or GOT.
+ RELATIVE_REF = 2,
+ // A TLS-related reference.
+ TLS_REF = 4,
+ // A reference that can always be treated as a function call.
+ FUNCTION_CALL = 8
};
// Given a direct absolute or pc-relative static relocation against
return true;
// A function call that can branch to a local PLT entry does not need
- // a dynamic relocation. A non-pic pc-relative function call in a
- // shared library cannot use a PLT entry.
- if ((flags & FUNCTION_CALL)
- && this->has_plt_offset()
- && !((flags & NON_PIC_REF) && parameters->options().shared()))
+ // a dynamic relocation.
+ if ((flags & FUNCTION_CALL) && this->has_plt_offset())
return false;
// A reference to any PLT entry in a non-position-independent executable
}
// Whether we should use the PLT offset associated with a symbol for
- // a relocation. IS_NON_PIC_REFERENCE is true if this is a non-PIC
- // reloc--the same set of relocs for which we would pass NON_PIC_REF
- // to the needs_dynamic_reloc function.
+ // a relocation. FLAGS is a set of Reference_flags.
bool
- use_plt_offset(bool is_non_pic_reference) const
+ use_plt_offset(int flags) const
{
// If the symbol doesn't have a PLT offset, then naturally we
// don't want to use it.
// If we are going to generate a dynamic relocation, then we will
// wind up using that, so no need to use the PLT entry.
- if (this->needs_dynamic_reloc(FUNCTION_CALL
- | (is_non_pic_reference
- ? NON_PIC_REF
- : 0)))
+ if (this->needs_dynamic_reloc(flags))
return false;
// If the symbol is from a dynamic object, we need to use the PLT
&& (this->is_undefined() || this->is_preemptible()))
return true;
- // If this is a weak undefined symbol, we need to use the PLT
- // entry; the symbol may be defined by a library loaded at
- // runtime.
- if (this->is_weak_undefined())
+ // If this is a call to a weak undefined symbol, we need to use
+ // the PLT entry; the symbol may be defined by a library loaded
+ // at runtime.
+ if ((flags & FUNCTION_CALL) && this->is_weak_undefined())
return true;
// Otherwise we can use the regular definition.
return true;
// A reference to a symbol defined in a dynamic object or to a
- // symbol that is preemptible can not use a RELATIVE relocaiton.
+ // symbol that is preemptible can not use a RELATIVE relocation.
if (this->is_from_dynobj()
|| this->is_undefined()
|| this->is_preemptible())
bool
may_need_copy_reloc() const
{
- return (!parameters->options().shared()
+ return (!parameters->options().output_is_position_independent()
&& parameters->options().copyreloc()
&& this->is_from_dynobj()
&& !this->is_func());
}
+ // Return true if this symbol was predefined by the linker.
+ bool
+ is_predefined() const
+ { return this->is_predefined_; }
+
+ // Return true if this is a C++ vtable symbol.
+ bool
+ is_cxx_vtable() const
+ { return is_prefix_of("_ZTV", this->name_); }
+
protected:
// Instances of this class should always be created at a specific
// size.
void
init_base_output_data(const char* name, const char* version, Output_data*,
elfcpp::STT, elfcpp::STB, elfcpp::STV,
- unsigned char nonvis, bool offset_is_from_end);
+ unsigned char nonvis, bool offset_is_from_end,
+ bool is_predefined);
// Initialize fields for an Output_segment.
void
Output_segment* os, elfcpp::STT type,
elfcpp::STB binding, elfcpp::STV visibility,
unsigned char nonvis,
- Segment_offset_base offset_base);
+ Segment_offset_base offset_base,
+ bool is_predefined);
// Initialize fields for a constant.
void
init_base_constant(const char* name, const char* version, elfcpp::STT type,
elfcpp::STB binding, elfcpp::STV visibility,
- unsigned char nonvis);
+ unsigned char nonvis, bool is_predefined);
// Initialize fields for an undefined symbol.
void
// index, not one of the special codes from SHN_LORESERVE to
// SHN_HIRESERVE (bit 29).
bool is_ordinary_shndx_ : 1;
- // True if we've seen this symbol in a real ELF object (bit 30).
+ // True if we've seen this symbol in a "real" ELF object (bit 30).
+ // If the symbol has been seen in a relocatable, non-IR, object file,
+ // it's known to be referenced from outside the IR. A reference from
+ // a dynamic object doesn't count as a "real" ELF, and we'll simply
+ // mark the symbol as "visible" from outside the IR. The compiler
+ // can use this distinction to guide its handling of COMDAT symbols.
bool in_real_elf_ : 1;
// True if this symbol is defined in a section which was discarded
// (bit 31).
// True if this symbol was a weak undef resolved by a dynamic def
// (bit 33).
bool undef_binding_weak_ : 1;
+ // True if this symbol is a predefined linker symbol (bit 34).
+ bool is_predefined_ : 1;
};
// The parts of a symbol which are size specific. Using a template
init_output_data(const char* name, const char* version, Output_data*,
Value_type value, Size_type symsize, elfcpp::STT,
elfcpp::STB, elfcpp::STV, unsigned char nonvis,
- bool offset_is_from_end);
+ bool offset_is_from_end, bool is_predefined);
// Initialize fields for an Output_segment.
void
init_output_segment(const char* name, const char* version, Output_segment*,
Value_type value, Size_type symsize, elfcpp::STT,
elfcpp::STB, elfcpp::STV, unsigned char nonvis,
- Segment_offset_base offset_base);
+ Segment_offset_base offset_base, bool is_predefined);
// Initialize fields for a constant.
void
init_constant(const char* name, const char* version, Value_type value,
Size_type symsize, elfcpp::STT, elfcpp::STB, elfcpp::STV,
- unsigned char nonvis);
+ unsigned char nonvis, bool is_predefined);
// Initialize fields for an undefined symbol.
void
bool only_if_ref;
};
+// Specify an object/section/offset location. Used by ODR code.
+
+struct Symbol_location
+{
+ // Object where the symbol is defined.
+ Object* object;
+ // Section-in-object where the symbol is defined.
+ unsigned int shndx;
+ // For relocatable objects, offset-in-section where the symbol is defined.
+ // For dynamic objects, address where the symbol is defined.
+ off_t offset;
+ bool operator==(const Symbol_location& that) const
+ {
+ return (this->object == that.object
+ && this->shndx == that.shndx
+ && this->offset == that.offset);
+ }
+};
+
// This class manages warnings. Warnings are a GNU extension. When
// we see a section named .gnu.warning.SYM in an object file, and if
// we wind using the definition of SYM from that object file, then we
SCRIPT,
// Predefined by the linker.
PREDEFINED,
+ // Defined by the linker during an incremental base link, but not
+ // a predefined symbol (e.g., common, defined in script).
+ INCREMENTAL_BASE,
};
// The order in which we sort common symbols.
SORT_COMMONS_BY_ALIGNMENT_ASCENDING
};
- // COUNT is an estimate of how many symbosl will be inserted in the
+ // COUNT is an estimate of how many symbols will be inserted in the
// symbol table. It's ok to put 0 if you don't know; a correct
// guess will just save some CPU by reducing hashtable resizes.
Symbol_table(unsigned int count, const Version_script_info& version_script);
void
gc_mark_undef_symbols(Layout*);
- // During garbage collection, this ensures externally visible symbols
- // are not treated as garbage while building shared objects.
+ // This tells garbage collection that this symbol is referenced.
void
- gc_mark_symbol_for_shlib(Symbol* sym);
+ gc_mark_symbol(Symbol* sym);
// During garbage collection, this keeps sections that correspond to
// symbols seen in dynamic objects.
// *DEFINED to the number of defined symbols.
template<int size, bool big_endian>
void
- add_from_relobj(Sized_relobj<size, big_endian>* relobj,
+ add_from_relobj(Sized_relobj_file<size, big_endian>* relobj,
const unsigned char* syms, size_t count,
size_t symndx_offset, const char* sym_names,
size_t sym_name_size,
- typename Sized_relobj<size, big_endian>::Symbols*,
+ typename Sized_relobj_file<size, big_endian>::Symbols*,
size_t* defined);
// Add one external symbol from the plugin object OBJ to the symbol table.
const char* sym_names, size_t sym_name_size,
const unsigned char* versym, size_t versym_size,
const std::vector<const char*>*,
- typename Sized_relobj<size, big_endian>::Symbols*,
+ typename Sized_relobj_file<size, big_endian>::Symbols*,
size_t* defined);
+ // Add one external symbol from the incremental object OBJ to the symbol
+ // table. Returns a pointer to the resolved symbol in the symbol table.
+ template<int size, bool big_endian>
+ Sized_symbol<size>*
+ add_from_incrobj(Object* obj, const char* name,
+ const char* ver, elfcpp::Sym<size, big_endian>* sym);
+
// Define a special symbol based on an Output_data. It is a
// multiple definition error if this symbol is already defined.
Symbol*
finalize(off_t off, off_t dynoff, size_t dyn_global_index, size_t dyncount,
Stringpool* pool, unsigned int* plocal_symcount);
+ // Set the final file offset of the symbol table.
+ void
+ set_file_offset(off_t off)
+ { this->offset_ = off; }
+
// Status code of Symbol_table::compute_final_value.
enum Compute_final_value_status
{
// No error.
CFVS_OK,
- // Unspported symbol section.
+ // Unsupported symbol section.
CFVS_UNSUPPORTED_SYMBOL_SECTION,
// No output section.
CFVS_NO_OUTPUT_SECTION
typedef std::pair<Stringpool::Key, Stringpool::Key> Symbol_table_key;
+ // The hash function. The key values are Stringpool keys.
struct Symbol_table_hash
{
- size_t
- operator()(const Symbol_table_key&) const;
+ inline size_t
+ operator()(const Symbol_table_key& key) const
+ {
+ return key.first ^ key.second;
+ }
};
struct Symbol_table_eq
typedef Unordered_map<Symbol_table_key, Symbol*, Symbol_table_hash,
Symbol_table_eq> Symbol_table_type;
+ // A map from symbol name (as a pointer into the namepool) to all
+ // the locations the symbols is (weakly) defined (and certain other
+ // conditions are met). This map will be used later to detect
+ // possible One Definition Rule (ODR) violations.
+ struct Symbol_location_hash
+ {
+ size_t operator()(const Symbol_location& loc) const
+ { return reinterpret_cast<uintptr_t>(loc.object) ^ loc.offset ^ loc.shndx; }
+ };
+
+ typedef Unordered_map<const char*,
+ Unordered_set<Symbol_location, Symbol_location_hash> >
+ Odr_map;
+
// Make FROM a forwarder symbol to TO.
void
make_forwarder(Symbol* from, Symbol* to);
// Whether we should override a symbol, based on flags in
// resolve.cc.
static bool
- should_override(const Symbol*, unsigned int, Defined, Object*, bool*, bool*);
+ should_override(const Symbol*, unsigned int, elfcpp::STT, Defined,
+ Object*, bool*, bool*);
// Report a problem in symbol resolution.
static void
// Whether we should override a symbol with a special symbol which
// is automatically defined by the linker.
static bool
- should_override_with_special(const Symbol*, Defined);
+ should_override_with_special(const Symbol*, elfcpp::STT, Defined);
// Override a symbol with a special symbol.
template<int size>
do_allocate_commons_list(Layout*, Commons_section_type, Commons_type*,
Mapfile*, Sort_commons_order);
+ // Returns all of the lines attached to LOC, not just the one the
+ // instruction actually came from. This helps the ODR checker avoid
+ // false positives.
+ static std::vector<std::string>
+ linenos_from_loc(const Task* task, const Symbol_location& loc);
+
// Implement detect_odr_violations.
template<int size, bool big_endian>
void
// they are defined.
typedef Unordered_map<const Symbol*, Dynobj*> Copied_symbol_dynobjs;
- // A map from symbol name (as a pointer into the namepool) to all
- // the locations the symbols is (weakly) defined (and certain other
- // conditions are met). This map will be used later to detect
- // possible One Definition Rule (ODR) violations.
- struct Symbol_location
- {
- Object* object; // Object where the symbol is defined.
- unsigned int shndx; // Section-in-object where the symbol is defined.
- off_t offset; // Offset-in-section where the symbol is defined.
- bool operator==(const Symbol_location& that) const
- {
- return (this->object == that.object
- && this->shndx == that.shndx
- && this->offset == that.offset);
- }
- };
-
- struct Symbol_location_hash
- {
- size_t operator()(const Symbol_location& loc) const
- { return reinterpret_cast<uintptr_t>(loc.object) ^ loc.offset ^ loc.shndx; }
- };
-
- typedef Unordered_map<const char*,
- Unordered_set<Symbol_location, Symbol_location_hash> >
- Odr_map;
-
// We increment this every time we see a new undefined symbol, for
// use in archive groups.
size_t saw_undefined_;
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