// 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.
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;
// 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_(),
- num_tracked_relocs(NULL), icf_ready_(false),
+ 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);
+ 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(Object *obj, unsigned int shndx)
+ 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(Object *obj, unsigned int shndx)
+ set_section_has_function_pointers(Relobj* obj, unsigned int shndx)
{
this->fptr_section_id_.insert(Section_id(obj, shndx));
}
// corresponding to taken function pointers. Ignores eh_frame
// and vtable sections.
inline bool
- check_section_for_function_pointers(std::string section_name,
+ check_section_for_function_pointers(const std::string& section_name,
Target* target)
{
return (parameters->options().icf_safe_folding()
&& target->can_check_for_function_pointers()
- && !is_prefix_of(".rodata._ZTV", section_name.c_str())
- && !is_prefix_of(".data.rel.ro._ZTV", section_name.c_str())
- && !is_prefix_of(".eh_frame", section_name.c_str()));
+ && 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.
// function is taken in which case it is dangerous to fold
// this function.
Secn_fptr_taken_set fptr_section_id_;
- unsigned int* num_tracked_relocs;
// 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 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.