e173ea00c2
PR gold/21066 * gc.h (gc_process_relocs): Track relocations in .eh_frame sections when ICF is enabled, even though the .eh_frame sections themselves are not foldable. * icf.cc (get_section_contents): Change arguments to permit operation on just part of a section. Include extra identity regions in the referring section's contents recursively. (match_sections): Lock object here instead of in get_section_contents so that get_section_contents can operate recursively. (Icf::add_ehframe_links): New method. (Icf::find_identical_sections): Pass .eh_frame sections to add_ehframe_links(). Increase default iteration count from 2 to 3 because handling exception info typically requires one extra iteration. * icf.h (Icf::extra_identity_list_): New data member with accessor. (is_section_foldable_candidate): Include .gcc_except_table sections. * options.h: Update documentation for new default ICF iteration count. * testsuite/Makefile.am (icf_test_pr21066): New test case. * testsuite/Makefile.in: Regenerate. * testsuite/icf_test_pr21066.cc: New source file. * testsuite/icf_test_pr21066.sh: New test script.
210 lines
6.7 KiB
C++
210 lines
6.7 KiB
C++
// icf.h -- Identical Code Folding
|
|
|
|
// Copyright (C) 2009-2019 Free Software Foundation, Inc.
|
|
// Written by Sriraman Tallam <tmsriram@google.com>.
|
|
|
|
// This file is part of gold.
|
|
|
|
// This program is free software; you can redistribute it and/or modify
|
|
// it under the terms of the GNU General Public License as published by
|
|
// the Free Software Foundation; either version 3 of the License, or
|
|
// (at your option) any later version.
|
|
|
|
// This program is distributed in the hope that it will be useful,
|
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
// GNU General Public License for more details.
|
|
|
|
// You should have received a copy of the GNU General Public License
|
|
// along with this program; if not, write to the Free Software
|
|
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
|
|
// MA 02110-1301, USA.
|
|
|
|
#ifndef GOLD_ICF_H
|
|
#define GOLD_ICF_H
|
|
|
|
#include <vector>
|
|
|
|
#include "elfcpp.h"
|
|
#include "symtab.h"
|
|
#include "object.h"
|
|
|
|
namespace gold
|
|
{
|
|
|
|
class Object;
|
|
class Input_objects;
|
|
class Symbol_table;
|
|
|
|
class Icf
|
|
{
|
|
public:
|
|
typedef std::vector<Section_id> Sections_reachable_info;
|
|
typedef std::vector<Symbol*> Symbol_info;
|
|
typedef std::vector<std::pair<long long, long long> > Addend_info;
|
|
typedef std::vector<uint64_t> Offset_info;
|
|
typedef std::vector<unsigned int> Reloc_addend_size_info;
|
|
typedef Unordered_map<Section_id,
|
|
unsigned int,
|
|
Section_id_hash> Uniq_secn_id_map;
|
|
typedef Unordered_set<Section_id, Section_id_hash> Secn_fptr_taken_set;
|
|
|
|
typedef struct
|
|
{
|
|
// This stores the section corresponding to the reloc.
|
|
Sections_reachable_info section_info;
|
|
// This stores the symbol corresponding to the reloc.
|
|
Symbol_info symbol_info;
|
|
// This stores the symbol value and the addend for a reloc.
|
|
Addend_info addend_info;
|
|
Offset_info offset_info;
|
|
Reloc_addend_size_info reloc_addend_size_info;
|
|
} Reloc_info;
|
|
|
|
typedef Unordered_map<Section_id, Reloc_info,
|
|
Section_id_hash> Reloc_info_list;
|
|
|
|
// A region of some other section that should be considered part of
|
|
// a section for ICF purposes. This is used to avoid folding sections
|
|
// that have identical text and relocations but different .eh_frame
|
|
// information.
|
|
typedef struct
|
|
{
|
|
Section_id section;
|
|
section_offset_type offset;
|
|
section_size_type length;
|
|
} Extra_identity_info;
|
|
|
|
typedef std::multimap<Section_id, Extra_identity_info> Extra_identity_list;
|
|
|
|
Icf()
|
|
: id_section_(), section_id_(), kept_section_id_(),
|
|
fptr_section_id_(),
|
|
icf_ready_(false),
|
|
reloc_info_list_()
|
|
{ }
|
|
|
|
// Returns the kept folded identical section corresponding to
|
|
// dup_obj and dup_shndx.
|
|
Section_id
|
|
get_folded_section(Relobj* dup_obj, unsigned int dup_shndx);
|
|
|
|
// Forms groups of identical sections where the first member
|
|
// of each group is the kept section during folding.
|
|
void
|
|
find_identical_sections(const Input_objects* input_objects,
|
|
Symbol_table* symtab);
|
|
|
|
// This is set when ICF has been run and the groups of
|
|
// identical sections have been formed.
|
|
void
|
|
icf_ready()
|
|
{ this->icf_ready_ = true; }
|
|
|
|
// Returns true if ICF has been run.
|
|
bool
|
|
is_icf_ready()
|
|
{ return this->icf_ready_; }
|
|
|
|
// Unfolds the section denoted by OBJ and SHNDX if folded.
|
|
void
|
|
unfold_section(Relobj* obj, unsigned int shndx);
|
|
|
|
// Returns the kept section corresponding to the
|
|
// given section.
|
|
bool
|
|
is_section_folded(Relobj* obj, unsigned int shndx);
|
|
|
|
// Given an object and a section index, this returns true if the
|
|
// pointer of the function defined in this section is taken.
|
|
bool
|
|
section_has_function_pointers(Relobj* obj, unsigned int shndx)
|
|
{
|
|
return (this->fptr_section_id_.find(Section_id(obj, shndx))
|
|
!= this->fptr_section_id_.end());
|
|
}
|
|
|
|
// Records that a pointer of the function defined in this section
|
|
// is taken.
|
|
void
|
|
set_section_has_function_pointers(Relobj* obj, unsigned int shndx)
|
|
{
|
|
this->fptr_section_id_.insert(Section_id(obj, shndx));
|
|
}
|
|
|
|
// Checks if the section_name should be searched for relocs
|
|
// corresponding to taken function pointers. Ignores eh_frame
|
|
// and vtable sections.
|
|
inline bool
|
|
check_section_for_function_pointers(const std::string& section_name,
|
|
Target* target)
|
|
{
|
|
return (parameters->options().icf_safe_folding()
|
|
&& target->can_check_for_function_pointers()
|
|
&& target->section_may_have_icf_unsafe_pointers(
|
|
section_name.c_str()));
|
|
}
|
|
|
|
// Returns a map of a section to info (Reloc_info) about its relocations.
|
|
Reloc_info_list&
|
|
reloc_info_list()
|
|
{ return this->reloc_info_list_; }
|
|
|
|
// Returns a map from section to region of a different section that should
|
|
// be considered part of the key section for ICF purposes.
|
|
Extra_identity_list&
|
|
extra_identity_list()
|
|
{ return this->extra_identity_list_; }
|
|
|
|
// Returns a mapping of each section to a unique integer.
|
|
Uniq_secn_id_map&
|
|
section_to_int_map()
|
|
{ return this->section_id_; }
|
|
|
|
private:
|
|
|
|
bool
|
|
add_ehframe_links(Relobj* object, unsigned int ehframe_shndx,
|
|
Reloc_info& ehframe_relocs);
|
|
|
|
// Maps integers to sections.
|
|
std::vector<Section_id> id_section_;
|
|
// Does the reverse.
|
|
Uniq_secn_id_map section_id_;
|
|
// Given a section id, this maps it to the id of the kept
|
|
// section. If the id's are the same then this section is
|
|
// not folded.
|
|
std::vector<unsigned int> kept_section_id_;
|
|
// Given a section id, this says if the pointer to this
|
|
// function is taken in which case it is dangerous to fold
|
|
// this function.
|
|
Secn_fptr_taken_set fptr_section_id_;
|
|
// Flag to indicate if ICF has been run.
|
|
bool icf_ready_;
|
|
// This list is populated by gc_process_relocs in gc.h.
|
|
Reloc_info_list reloc_info_list_;
|
|
// Regions of other sections that should be considered part of
|
|
// each section for ICF purposes.
|
|
Extra_identity_list extra_identity_list_;
|
|
};
|
|
|
|
// This function returns true if this section corresponds to a function that
|
|
// should be considered by icf as a possible candidate for folding. Some
|
|
// earlier gcc versions, like 4.0.3, put constructors and destructors in
|
|
// .gnu.linkonce.t sections and hence should be included too.
|
|
// The mechanism used to safely fold functions referenced by .eh_frame
|
|
// requires folding .gcc_except_table sections as well; see "Notes regarding
|
|
// C++ exception handling" at the top of icf.cc for an explanation why.
|
|
inline bool
|
|
is_section_foldable_candidate(const std::string& section_name)
|
|
{
|
|
const char* section_name_cstr = section_name.c_str();
|
|
return (is_prefix_of(".text", section_name_cstr)
|
|
|| is_prefix_of(".gcc_except_table", section_name_cstr)
|
|
|| is_prefix_of(".gnu.linkonce.t", section_name_cstr));
|
|
}
|
|
|
|
} // End of namespace gold.
|
|
|
|
#endif
|