1 // icf.h -- Identical Code Folding
3 // Copyright 2009, 2010 Free Software Foundation, Inc.
4 // Written by Sriraman Tallam <tmsriram@google.com>.
6 // This file is part of gold.
8 // This program is free software; you can redistribute it and/or modify
9 // it under the terms of the GNU General Public License as published by
10 // the Free Software Foundation; either version 3 of the License, or
11 // (at your option) any later version.
13 // This program is distributed in the hope that it will be useful,
14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 // GNU General Public License for more details.
18 // You should have received a copy of the GNU General Public License
19 // along with this program; if not, write to the Free Software
20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
21 // MA 02110-1301, USA.
42 typedef std::vector
<Section_id
> Sections_reachable_list
;
43 typedef std::vector
<Symbol
*> Symbol_info
;
44 typedef std::vector
<std::pair
<long long, long long> > Addend_info
;
45 typedef Unordered_map
<Section_id
,
46 Sections_reachable_list
,
47 Section_id_hash
> Section_list
;
48 typedef Unordered_map
<Section_id
, Symbol_info
, Section_id_hash
> Symbol_list
;
49 typedef Unordered_map
<Section_id
, Addend_info
, Section_id_hash
> Addend_list
;
50 typedef Unordered_map
<Section_id
,
52 Section_id_hash
> Uniq_secn_id_map
;
53 typedef Unordered_set
<Section_id
, Section_id_hash
> Secn_fptr_taken_set
;
56 : id_section_(), section_id_(), kept_section_id_(),
58 num_tracked_relocs(NULL
), icf_ready_(false),
59 section_reloc_list_(), symbol_reloc_list_(),
63 // Returns the kept folded identical section corresponding to
64 // dup_obj and dup_shndx.
66 get_folded_section(Object
* dup_obj
, unsigned int dup_shndx
);
68 // Forms groups of identical sections where the first member
69 // of each group is the kept section during folding.
71 find_identical_sections(const Input_objects
* input_objects
,
72 Symbol_table
* symtab
);
74 // This is set when ICF has been run and the groups of
75 // identical sections have been formed.
78 { this->icf_ready_
= true; }
80 // Returns true if ICF has been run.
83 { return this->icf_ready_
; }
85 // Unfolds the section denoted by OBJ and SHNDX if folded.
87 unfold_section(Object
* obj
, unsigned int shndx
);
89 // Returns the kept section corresponding to the
92 is_section_folded(Object
* obj
, unsigned int shndx
);
94 // Given an object and a section index, this returns true if the
95 // pointer of the function defined in this section is taken.
97 section_has_function_pointers(Object
*obj
, unsigned int shndx
)
99 return (this->fptr_section_id_
.find(Section_id(obj
, shndx
))
100 != this->fptr_section_id_
.end());
103 // Records that a pointer of the function defined in this section
106 set_section_has_function_pointers(Object
*obj
, unsigned int shndx
)
108 this->fptr_section_id_
.insert(Section_id(obj
, shndx
));
111 // Checks if the section_name should be searched for relocs
112 // corresponding to taken function pointers. Ignores eh_frame
113 // and vtable sections.
115 check_section_for_function_pointers(std::string section_name
,
118 return (parameters
->options().icf_safe_folding()
119 && target
->can_check_for_function_pointers()
120 && !is_prefix_of(".rodata._ZTV", section_name
.c_str())
121 && !is_prefix_of(".eh_frame", section_name
.c_str()));
124 // Returns a map of a section to a list of all sections referenced
125 // by its relocations.
128 { return this->section_reloc_list_
; }
130 // Returns a map of a section to a list of all symbols referenced
131 // by its relocations.
134 { return this->symbol_reloc_list_
; }
136 // Returns a maps of a section to a list of symbol values and addends
137 // of its relocations.
140 { return this->addend_reloc_list_
; }
142 // Returns a mapping of each section to a unique integer.
145 { return this->section_id_
; }
149 // Maps integers to sections.
150 std::vector
<Section_id
> id_section_
;
152 Uniq_secn_id_map section_id_
;
153 // Given a section id, this maps it to the id of the kept
154 // section. If the id's are the same then this section is
156 std::vector
<unsigned int> kept_section_id_
;
157 // Given a section id, this says if the pointer to this
158 // function is taken in which case it is dangerous to fold
160 Secn_fptr_taken_set fptr_section_id_
;
161 unsigned int* num_tracked_relocs
;
162 // Flag to indicate if ICF has been run.
165 // These lists are populated by gc_process_relocs in gc.h.
166 Section_list section_reloc_list_
;
167 Symbol_list symbol_reloc_list_
;
168 Addend_list addend_reloc_list_
;
171 // This function returns true if this section corresponds to a function that
172 // should be considered by icf as a possible candidate for folding. Some
173 // earlier gcc versions, like 4.0.3, put constructors and destructors in
174 // .gnu.linkonce.t sections and hence should be included too.
176 is_section_foldable_candidate(const char* section_name
)
178 return (is_prefix_of(".text", section_name
)
179 || is_prefix_of(".gnu.linkonce.t", section_name
));
182 } // End of namespace gold.