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2010-01-11 Doug Kwan <dougkwan@google.com>

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* arm.cc (Arm_relobj::do_gc_process_relocs): New method.
	(Target_arm::do_finalize_sections): Define special EXIDX section
	symbols only if referenced.
	* gc.h (Garbage_collection::add_reference): New method.
	(gc_process_relocs): Use Garbage_collection::add_reference to avoid
	code duplication.
This commit is contained in:
Doug Kwan 2010-01-12 07:22:56 +00:00
parent d0a91bd8c7
commit 99e5bff2f9
3 changed files with 70 additions and 15 deletions
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9
gold/ChangeLog
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@ -1,3 +1,12 @@
2010-01-11 Doug Kwan <dougkwan@google.com>
* arm.cc (Arm_relobj::do_gc_process_relocs): New method.
(Target_arm::do_finalize_sections): Define special EXIDX section
symbols only if referenced.
* gc.h (Garbage_collection::add_reference): New method.
(gc_process_relocs): Use Garbage_collection::add_reference to avoid
code duplication.
2010-01-11 Ian Lance Taylor <iant@google.com>
* script.cc (Version_script_info::build_expression_list_lookup):

46
gold/arm.cc
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@ -1178,6 +1178,10 @@ class Arm_relobj : public Sized_relobj<32, big_endian>
void
do_read_symbols(Read_symbols_data* sd);
// Process relocs for garbage collection.
void
do_gc_process_relocs(Symbol_table*, Layout*, Read_relocs_data*);
private:
// List of stub tables.
typedef std::vector<Stub_table<big_endian>*> Stub_table_list;
@ -4235,6 +4239,44 @@ Arm_relobj<big_endian>::do_read_symbols(Read_symbols_data* sd)
read_arm_attributes_section<big_endian>(this, sd);
}
// Process relocations for garbage collection. The ARM target uses .ARM.exidx
// sections for unwinding. These sections are referenced implicitly by
// text sections linked in the section headers. If we ignore these implict
// references, the .ARM.exidx sections and any .ARM.extab sections they use
// will be garbage-collected incorrectly. Hence we override the same function
// in the base class to handle these implicit references.
template<bool big_endian>
void
Arm_relobj<big_endian>::do_gc_process_relocs(Symbol_table* symtab,
Layout* layout,
Read_relocs_data* rd)
{
// First, call base class method to process relocations in this object.
Sized_relobj<32, big_endian>::do_gc_process_relocs(symtab, layout, rd);
unsigned int shnum = this->shnum();
const unsigned int shdr_size = elfcpp::Elf_sizes<32>::shdr_size;
const unsigned char* pshdrs = this->get_view(this->elf_file()->shoff(),
shnum * shdr_size,
true, true);
// Scan section headers for sections of type SHT_ARM_EXIDX. Add references
// to these from the linked text sections.
const unsigned char* ps = pshdrs + shdr_size;
for (unsigned int i = 1; i < shnum; ++i, ps += shdr_size)
{
elfcpp::Shdr<32, big_endian> shdr(ps);
if (shdr.get_sh_type() == elfcpp::SHT_ARM_EXIDX)
{
// Found an .ARM.exidx section, add it to the set of reachable
// sections from its linked text section.
unsigned int text_shndx = this->adjust_shndx(shdr.get_sh_link());
symtab->gc()->add_reference(this, text_shndx, this, i);
}
}
}
// Arm_dynobj methods.
// Read the symbol information.
@ -5081,12 +5123,12 @@ Target_arm<big_endian>::do_finalize_sections(
Symbol_table::PREDEFINED,
exidx_section, 0, 0, elfcpp::STT_OBJECT,
elfcpp::STB_GLOBAL, elfcpp::STV_HIDDEN, 0,
false, false);
false, true);
symtab->define_in_output_data("__exidx_end", NULL,
Symbol_table::PREDEFINED,
exidx_section, 0, 0, elfcpp::STT_OBJECT,
elfcpp::STB_GLOBAL, elfcpp::STV_HIDDEN, 0,
true, false);
true, true);
// For the ARM target, we need to add a PT_ARM_EXIDX segment for
// the .ARM.exidx section.

30
gold/gc.h
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@ -108,6 +108,21 @@ class Garbage_collection
Section_id secn)
{ this->cident_sections_[section_name].insert(secn); }
// Add a reference from the SRC_SHNDX-th section of SRC_OBJECT to
// DST_SHNDX-th section of DST_OBJECT.
void
add_reference(Object* src_object, unsigned int src_shndx,
Object* dst_object, unsigned int dst_shndx)
{
Section_id src_id(src_object, src_shndx);
Section_id dst_id(dst_object, dst_shndx);
Section_ref::iterator p = this->section_reloc_map_.find(src_id);
if (p == this->section_reloc_map_.end())
this->section_reloc_map_[src_id].insert(dst_id);
else
p->second.insert(dst_id);
}
private:
Worklist_type work_list_;
@ -261,25 +276,14 @@ gc_process_relocs(
}
if (parameters->options().gc_sections())
{
Section_id src_id(src_obj, src_indx);
Section_id dst_id(dst_obj, dst_indx);
Garbage_collection::Section_ref::iterator map_it;
map_it = symtab->gc()->section_reloc_map().find(src_id);
if (map_it == symtab->gc()->section_reloc_map().end())
{
symtab->gc()->section_reloc_map()[src_id].insert(dst_id);
}
else
{
Garbage_collection::Sections_reachable& v(map_it->second);
v.insert(dst_id);
}
symtab->gc()->add_reference(src_obj, src_indx, dst_obj, dst_indx);
if (cident_section_name != NULL)
{
Garbage_collection::Cident_section_map::iterator ele =
symtab->gc()->cident_sections()->find(std::string(cident_section_name));
if (ele == symtab->gc()->cident_sections()->end())
continue;
Section_id src_id(src_obj, src_indx);
Garbage_collection::Sections_reachable&
v(symtab->gc()->section_reloc_map()[src_id]);
Garbage_collection::Sections_reachable& cident_secn(ele->second);