// icf.h -- Identical Code Folding
-// Copyright 2009, 2010 Free Software Foundation, Inc.
+// Copyright (C) 2009-2020 Free Software Foundation, Inc.
// Written by Sriraman Tallam <tmsriram@google.com>.
// This file is part of gold.
#include "elfcpp.h"
#include "symtab.h"
+#include "object.h"
namespace gold
{
class Input_objects;
class Symbol_table;
-typedef std::pair<Object*, unsigned int> Section_id;
-
class Icf
{
public:
- struct Section_id_hash
- {
- size_t operator()(const Section_id& loc) const
- { return reinterpret_cast<uintptr_t>(loc.first) ^ loc.second; }
- };
-
- typedef std::vector<Section_id> Sections_reachable_list;
+ 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 Unordered_map<Section_id,
- Sections_reachable_list,
- Section_id_hash> Section_list;
- typedef Unordered_map<Section_id, Symbol_info, Section_id_hash> Symbol_list;
- typedef Unordered_map<Section_id, Addend_info, Section_id_hash> Addend_list;
+ 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_(),
- num_tracked_relocs(NULL), icf_ready_(false),
- section_reloc_list_(), symbol_reloc_list_(),
- addend_reloc_list_()
+ 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(Object* dup_obj, unsigned int dup_shndx);
+ 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.
// Unfolds the section denoted by OBJ and SHNDX if folded.
void
- unfold_section(Object* obj, unsigned int shndx);
+ unfold_section(Relobj* obj, unsigned int shndx);
- // Returns the kept section corresponding to the
+ // Returns the kept section corresponding to the
// given section.
bool
- is_section_folded(Object* obj, unsigned int shndx);
-
- // Returns a map of a section to a list of all sections referenced
- // by its relocations.
- Section_list&
- section_reloc_list()
- { return this->section_reloc_list_; }
-
- // Returns a map of a section to a list of all symbols referenced
- // by its relocations.
- Symbol_list&
- symbol_reloc_list()
- { return this->symbol_reloc_list_; }
-
- // Returns a maps of a section to a list of symbol values and addends
- // of its relocations.
- Addend_list&
- addend_reloc_list()
- { return this->addend_reloc_list_; }
-
+ 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()
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.
// section. If the id's are the same then this section is
// not folded.
std::vector<unsigned int> kept_section_id_;
- unsigned int* num_tracked_relocs;
+ // 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_;
-
- // These lists are populated by gc_process_relocs in gc.h.
- Section_list section_reloc_list_;
- Symbol_list symbol_reloc_list_;
- Addend_list addend_reloc_list_;
+ // 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 char* section_name)
+is_section_foldable_candidate(const std::string& section_name)
{
- return (is_prefix_of(".text", section_name)
- || is_prefix_of(".gnu.linkonce.t", 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.
projects / deliverable / binutils-gdb.git / blobdiff