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Add heuristics for undefined symbol warnings.

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This commit is contained in:
Ian Lance Taylor 2007-11-14 16:53:25 +00:00
parent 3e6fe5ae73
commit 9a2d698415
13 changed files with 129 additions and 48 deletions
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2
gold/gold.cc
View file

@ -286,7 +286,7 @@ queue_final_tasks(const General_options& options,
// Queue a task to write out the symbol table.
final_blocker->add_blocker();
workqueue->queue(new Write_symbols_task(symtab,
input_objects->target(),
input_objects,
layout->sympool(),
layout->dynpool(),
of,

5
gold/i386.cc
View file

@ -100,6 +100,11 @@ class Target_i386 : public Sized_target<32, false>
std::string
do_code_fill(off_t length);
// Return whether SYM is defined by the ABI.
bool
do_is_defined_by_abi(Symbol* sym) const
{ return strcmp(sym->name(), "___tls_get_addr") == 0; }
// Return the size of the GOT section.
off_t
got_size()

4
gold/layout.cc
View file

@ -1928,8 +1928,8 @@ Write_symbols_task::locks(Workqueue* workqueue)
void
Write_symbols_task::run(Workqueue*)
{
this->symtab_->write_globals(this->target_, this->sympool_, this->dynpool_,
this->of_);
this->symtab_->write_globals(this->input_objects_, this->sympool_,
this->dynpool_, this->of_);
}
// Write_after_input_sections_task methods.

9
gold/layout.h
View file

@ -506,11 +506,12 @@ class Write_data_task : public Task
class Write_symbols_task : public Task
{
public:
Write_symbols_task(const Symbol_table* symtab, const Target* target,
Write_symbols_task(const Symbol_table* symtab,
const Input_objects* input_objects,
const Stringpool* sympool, const Stringpool* dynpool,
Output_file* of, Task_token* final_blocker)
: symtab_(symtab), target_(target), sympool_(sympool), dynpool_(dynpool),
of_(of), final_blocker_(final_blocker)
: symtab_(symtab), input_objects_(input_objects), sympool_(sympool),
dynpool_(dynpool), of_(of), final_blocker_(final_blocker)
{ }
// The standard Task methods.
@ -526,7 +527,7 @@ class Write_symbols_task : public Task
private:
const Symbol_table* symtab_;
const Target* target_;
const Input_objects* input_objects_;
const Stringpool* sympool_;
const Stringpool* dynpool_;
Output_file* of_;

28
gold/object.cc
View file

@ -25,6 +25,7 @@
#include <cerrno>
#include <cstring>
#include <cstdarg>
#include "libiberty.h"
#include "target-select.h"
#include "dwarf_reader.h"
@ -1062,9 +1063,10 @@ Input_objects::add_object(Object* obj)
{
// See if this is a duplicate SONAME.
Dynobj* dynobj = static_cast<Dynobj*>(obj);
const char* soname = dynobj->soname();
std::pair<Unordered_set<std::string>::iterator, bool> ins =
this->sonames_.insert(dynobj->soname());
this->sonames_.insert(soname);
if (!ins.second)
{
// We have already seen a dynamic object with this soname.
@ -1072,6 +1074,19 @@ Input_objects::add_object(Object* obj)
}
this->dynobj_list_.push_back(dynobj);
// If this is -lc, remember the directory in which we found it.
// We use this when issuing warnings about undefined symbols: as
// a heuristic, we don't warn about system libraries found in
// the same directory as -lc.
if (strncmp(soname, "libc.so", 7) == 0)
{
const char* object_name = dynobj->name().c_str();
const char* base = lbasename(object_name);
if (base != object_name)
this->system_library_directory_.assign(object_name,
base - 1 - object_name);
}
}
set_parameters_size_and_endianness(target->get_size(),
@ -1080,6 +1095,17 @@ Input_objects::add_object(Object* obj)
return true;
}
// Return whether an object was found in the system library directory.
bool
Input_objects::found_in_system_library_directory(const Object* object) const
{
return (!this->system_library_directory_.empty()
&& object->name().compare(0,
this->system_library_directory_.size(),
this->system_library_directory_) == 0);
}
// For each dynamic object, record whether we've seen all of its
// explicit dependencies.

10
gold/object.h
View file

@ -930,7 +930,8 @@ class Input_objects
{
public:
Input_objects()
: relobj_list_(), dynobj_list_(), target_(NULL), sonames_()
: relobj_list_(), dynobj_list_(), target_(NULL), sonames_(),
system_library_directory_()
{ }
// The type of the list of input relocateable objects.
@ -956,6 +957,11 @@ class Input_objects
void
check_dynamic_dependencies() const;
// Return whether an object was found in the system library
// directory.
bool
found_in_system_library_directory(const Object*) const;
// Iterate over all regular objects.
Relobj_iterator
@ -998,6 +1004,8 @@ class Input_objects
Target* target_;
// SONAMEs that we have seen.
Unordered_set<std::string> sonames_;
// The directory in which we find the libc.so.
std::string system_library_directory_;
};
// Some of the information we pass to the relocation routines. We

2
gold/options.cc
View file

@ -483,7 +483,7 @@ General_options::General_options()
output_file_name_("a.out"),
is_relocatable_(false),
strip_(STRIP_NONE),
allow_shlib_undefined_(true),
allow_shlib_undefined_(false),
symbolic_(false),
detect_odr_violations_(false),
create_eh_frame_hdr_(false),

76
gold/symtab.cc
View file

@ -1524,7 +1524,8 @@ Symbol_table::sized_finalize(unsigned index, off_t off, Stringpool* pool)
// Write out the global symbols.
void
Symbol_table::write_globals(const Target* target, const Stringpool* sympool,
Symbol_table::write_globals(const Input_objects* input_objects,
const Stringpool* sympool,
const Stringpool* dynpool, Output_file* of) const
{
if (parameters->get_size() == 32)
@ -1532,7 +1533,8 @@ Symbol_table::write_globals(const Target* target, const Stringpool* sympool,
if (parameters->is_big_endian())
{
#ifdef HAVE_TARGET_32_BIG
this->sized_write_globals<32, true>(target, sympool, dynpool, of);
this->sized_write_globals<32, true>(input_objects, sympool,
dynpool, of);
#else
gold_unreachable();
#endif
@ -1540,7 +1542,8 @@ Symbol_table::write_globals(const Target* target, const Stringpool* sympool,
else
{
#ifdef HAVE_TARGET_32_LITTLE
this->sized_write_globals<32, false>(target, sympool, dynpool, of);
this->sized_write_globals<32, false>(input_objects, sympool,
dynpool, of);
#else
gold_unreachable();
#endif
@ -1551,7 +1554,8 @@ Symbol_table::write_globals(const Target* target, const Stringpool* sympool,
if (parameters->is_big_endian())
{
#ifdef HAVE_TARGET_64_BIG
this->sized_write_globals<64, true>(target, sympool, dynpool, of);
this->sized_write_globals<64, true>(input_objects, sympool,
dynpool, of);
#else
gold_unreachable();
#endif
@ -1559,7 +1563,8 @@ Symbol_table::write_globals(const Target* target, const Stringpool* sympool,
else
{
#ifdef HAVE_TARGET_64_LITTLE
this->sized_write_globals<64, false>(target, sympool, dynpool, of);
this->sized_write_globals<64, false>(input_objects, sympool,
dynpool, of);
#else
gold_unreachable();
#endif
@ -1573,11 +1578,13 @@ Symbol_table::write_globals(const Target* target, const Stringpool* sympool,
template<int size, bool big_endian>
void
Symbol_table::sized_write_globals(const Target* target,
Symbol_table::sized_write_globals(const Input_objects* input_objects,
const Stringpool* sympool,
const Stringpool* dynpool,
Output_file* of) const
{
const Target* const target = input_objects->target();
const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
unsigned int index = this->first_global_index_;
const off_t oview_size = this->output_count_ * sym_size;
@ -1599,25 +1606,8 @@ Symbol_table::sized_write_globals(const Target* target,
{
Sized_symbol<size>* sym = static_cast<Sized_symbol<size>*>(p->second);
// Optionally check for unresolved symbols in shared libraries.
// This is controlled by the --allow-shlib-undefined option. We
// only warn about libraries for which we have seen all the
// DT_NEEDED entries. We don't try to track down DT_NEEDED
// entries which were not seen in this link. If we didn't see a
// DT_NEEDED entry, we aren't going to be able to reliably
// report whether the symbol is undefined.
if (sym->source() == Symbol::FROM_OBJECT
&& sym->object()->is_dynamic()
&& sym->shndx() == elfcpp::SHN_UNDEF
&& sym->binding() != elfcpp::STB_WEAK
&& !parameters->allow_shlib_undefined())
{
// A very ugly cast.
Dynobj* dynobj = static_cast<Dynobj*>(sym->object());
if (!dynobj->has_unknown_needed_entries())
gold_error(_("%s: undefined reference to '%s'"),
sym->object()->name().c_str(), sym->name());
}
// Possibly warn about unresolved symbols in shared libraries.
this->warn_about_undefined_dynobj_symbol(input_objects, sym);
unsigned int sym_index = sym->symtab_index();
unsigned int dynsym_index;
@ -1749,6 +1739,42 @@ Symbol_table::sized_write_symbol(
osym.put_st_shndx(shndx);
}
// Check for unresolved symbols in shared libraries. This is
// controlled by the --allow-shlib-undefined option.
// We only warn about libraries for which we have seen all the
// DT_NEEDED entries. We don't try to track down DT_NEEDED entries
// which were not seen in this link. If we didn't see a DT_NEEDED
// entry, we aren't going to be able to reliably report whether the
// symbol is undefined.
// We also don't warn about libraries found in the system library
// directory (the directory were we find libc.so); we assume that
// those libraries are OK. This heuristic avoids problems in
// GNU/Linux, in which -ldl can have undefined references satisfied by
// ld-linux.so.
inline void
Symbol_table::warn_about_undefined_dynobj_symbol(
const Input_objects* input_objects,
Symbol* sym) const
{
if (sym->source() == Symbol::FROM_OBJECT
&& sym->object()->is_dynamic()
&& sym->shndx() == elfcpp::SHN_UNDEF
&& sym->binding() != elfcpp::STB_WEAK
&& !parameters->allow_shlib_undefined()
&& !input_objects->target()->is_defined_by_abi(sym)
&& !input_objects->found_in_system_library_directory(sym->object()))
{
// A very ugly cast.
Dynobj* dynobj = static_cast<Dynobj*>(sym->object());
if (!dynobj->has_unknown_needed_entries())
gold_error(_("%s: undefined reference to '%s'"),
sym->object()->name().c_str(), sym->name());
}
}
// Write out a section symbol. Return the update offset.
void

11
gold/symtab.h
View file

@ -46,6 +46,7 @@ class Dynobj;
template<int size, bool big_endian>
class Sized_dynobj;
class Versions;
class Input_objects;
class Output_data;
class Output_section;
class Output_segment;
@ -1055,7 +1056,7 @@ class Symbol_table
// Write out the global symbols.
void
write_globals(const Target*, const Stringpool*, const Stringpool*,
write_globals(const Input_objects*, const Stringpool*, const Stringpool*,
Output_file*) const;
// Write out a section symbol. Return the updated offset.
@ -1177,8 +1178,8 @@ class Symbol_table
// Write globals specialized for size and endianness.
template<int size, bool big_endian>
void
sized_write_globals(const Target*, const Stringpool*, const Stringpool*,
Output_file*) const;
sized_write_globals(const Input_objects*, const Stringpool*,
const Stringpool*, Output_file*) const;
// Write out a symbol to P.
template<int size, bool big_endian>
@ -1189,6 +1190,10 @@ class Symbol_table
const Stringpool*, unsigned char* p
ACCEPT_SIZE_ENDIAN) const;
// Possibly warn about an undefined symbol from a dynamic object.
void
warn_about_undefined_dynobj_symbol(const Input_objects*, Symbol*) const;
// Write out a section symbol, specialized for size and endianness.
template<int size, bool big_endian>
void

11
gold/target.h
View file

@ -137,6 +137,12 @@ class Target
code_fill(off_t length)
{ return this->do_code_fill(length); }
// Return whether SYM is known to be defined by the ABI. This is
// used to avoid inappropriate warnings about undefined symbols.
bool
is_defined_by_abi(Symbol* sym) const
{ return this->do_is_defined_by_abi(sym); }
protected:
// This struct holds the constant information for a child class. We
// use a struct to avoid the overhead of virtual function calls for
@ -188,6 +194,11 @@ class Target
do_code_fill(off_t)
{ gold_unreachable(); }
// Virtual function which may be implemented by the child class.
virtual bool
do_is_defined_by_abi(Symbol*) const
{ return false; }
private:
Target(const Target&);
Target& operator=(const Target&);

7
gold/testsuite/Makefile.am
View file

@ -30,12 +30,9 @@ if GCC
if NATIVE_LINKER
TESTS += debug_msg.sh
TESTS += debug_msg.sh undef_symbol.sh
check_DATA += debug_msg.err
# TESTS += undef_symbol.sh
# check_DATA +=undef_symbol.err
check_DATA += debug_msg.err undef_symbol.err
NATIVE_PROGS = \
constructor_test \

7
gold/testsuite/Makefile.in
View file

@ -42,8 +42,8 @@ POST_UNINSTALL = :
build_triplet = @build@
host_triplet = @host@
target_triplet = @target@
@GCC_TRUE@@NATIVE_LINKER_TRUE@am__append_1 = debug_msg.sh
@GCC_TRUE@@NATIVE_LINKER_TRUE@am__append_2 = debug_msg.err
@GCC_TRUE@@NATIVE_LINKER_TRUE@am__append_1 = debug_msg.sh undef_symbol.sh
@GCC_TRUE@@NATIVE_LINKER_TRUE@am__append_2 = debug_msg.err undef_symbol.err
@FN_PTRS_IN_SO_WITHOUT_PIC_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@am__append_3 = \
@FN_PTRS_IN_SO_WITHOUT_PIC_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@ two_file_shared_1_nonpic_test \
@FN_PTRS_IN_SO_WITHOUT_PIC_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@ two_file_shared_2_nonpic_test \
@ -573,9 +573,6 @@ INCLUDES = \
check_SCRIPTS = debug_msg.sh
check_DATA = $(am__append_2)
TESTS = object_unittest $(am__append_1) $(NATIVE_TESTING)
# TESTS += undef_symbol.sh
# check_DATA +=undef_symbol.err
@GCC_TRUE@@NATIVE_LINKER_TRUE@NATIVE_PROGS = constructor_test \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ constructor_static_test \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ two_file_test \

5
gold/x86_64.cc
View file

@ -113,6 +113,11 @@ class Target_x86_64 : public Sized_target<64, false>
std::string
do_code_fill(off_t length);
// Return whether SYM is defined by the ABI.
bool
do_is_defined_by_abi(Symbol* sym) const
{ return strcmp(sym->name(), "__tls_get_addr") == 0; }
// Return the size of the GOT section.
off_t
got_size()