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ef15dade ST |
1 | // icf.h -- Identical Code Folding |
2 | ||
55a2bb35 | 3 | // Copyright 2009, 2010 Free Software Foundation, Inc. |
ef15dade ST |
4 | // Written by Sriraman Tallam <tmsriram@google.com>. |
5 | ||
6 | // This file is part of gold. | |
7 | ||
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. | |
12 | ||
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. | |
17 | ||
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. | |
22 | ||
23 | #ifndef GOLD_ICF_H | |
24 | #define GOLD_ICF_H | |
25 | ||
26 | #include <vector> | |
27 | ||
28 | #include "elfcpp.h" | |
29 | #include "symtab.h" | |
5ac169d4 | 30 | #include "object.h" |
ef15dade ST |
31 | |
32 | namespace gold | |
33 | { | |
34 | ||
35 | class Object; | |
36 | class Input_objects; | |
37 | class Symbol_table; | |
38 | ||
ef15dade ST |
39 | class Icf |
40 | { | |
41 | public: | |
ef15dade ST |
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, | |
51 | unsigned int, | |
52 | Section_id_hash> Uniq_secn_id_map; | |
21bb3914 | 53 | typedef Unordered_set<Section_id, Section_id_hash> Secn_fptr_taken_set; |
ef15dade ST |
54 | |
55 | Icf() | |
56 | : id_section_(), section_id_(), kept_section_id_(), | |
21bb3914 | 57 | fptr_section_id_(), |
ef15dade ST |
58 | num_tracked_relocs(NULL), icf_ready_(false), |
59 | section_reloc_list_(), symbol_reloc_list_(), | |
60 | addend_reloc_list_() | |
61 | { } | |
62 | ||
63 | // Returns the kept folded identical section corresponding to | |
64 | // dup_obj and dup_shndx. | |
65 | Section_id | |
66 | get_folded_section(Object* dup_obj, unsigned int dup_shndx); | |
67 | ||
68 | // Forms groups of identical sections where the first member | |
69 | // of each group is the kept section during folding. | |
70 | void | |
71 | find_identical_sections(const Input_objects* input_objects, | |
72 | Symbol_table* symtab); | |
73 | ||
74 | // This is set when ICF has been run and the groups of | |
75 | // identical sections have been formed. | |
76 | void | |
77 | icf_ready() | |
78 | { this->icf_ready_ = true; } | |
79 | ||
80 | // Returns true if ICF has been run. | |
81 | bool | |
82 | is_icf_ready() | |
83 | { return this->icf_ready_; } | |
84 | ||
48c187ce ST |
85 | // Unfolds the section denoted by OBJ and SHNDX if folded. |
86 | void | |
87 | unfold_section(Object* obj, unsigned int shndx); | |
88 | ||
ef15dade ST |
89 | // Returns the kept section corresponding to the |
90 | // given section. | |
91 | bool | |
92 | is_section_folded(Object* obj, unsigned int shndx); | |
21bb3914 ST |
93 | |
94 | // Given an object and a section index, this returns true if the | |
95 | // pointer of the function defined in this section is taken. | |
96 | bool | |
97 | section_has_function_pointers(Object *obj, unsigned int shndx) | |
98 | { | |
99 | return (this->fptr_section_id_.find(Section_id(obj, shndx)) | |
100 | != this->fptr_section_id_.end()); | |
101 | } | |
102 | ||
103 | // Records that a pointer of the function defined in this section | |
104 | // is taken. | |
105 | void | |
106 | set_section_has_function_pointers(Object *obj, unsigned int shndx) | |
107 | { | |
108 | this->fptr_section_id_.insert(Section_id(obj, shndx)); | |
109 | } | |
110 | ||
111 | // Checks if the section_name should be searched for relocs | |
112 | // corresponding to taken function pointers. Ignores eh_frame | |
113 | // and vtable sections. | |
114 | inline bool | |
115 | check_section_for_function_pointers(std::string section_name, | |
116 | Target* target) | |
117 | { | |
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())); | |
122 | } | |
123 | ||
ef15dade ST |
124 | // Returns a map of a section to a list of all sections referenced |
125 | // by its relocations. | |
126 | Section_list& | |
127 | section_reloc_list() | |
128 | { return this->section_reloc_list_; } | |
129 | ||
130 | // Returns a map of a section to a list of all symbols referenced | |
131 | // by its relocations. | |
132 | Symbol_list& | |
133 | symbol_reloc_list() | |
134 | { return this->symbol_reloc_list_; } | |
135 | ||
136 | // Returns a maps of a section to a list of symbol values and addends | |
137 | // of its relocations. | |
138 | Addend_list& | |
139 | addend_reloc_list() | |
140 | { return this->addend_reloc_list_; } | |
141 | ||
142 | // Returns a mapping of each section to a unique integer. | |
143 | Uniq_secn_id_map& | |
144 | section_to_int_map() | |
145 | { return this->section_id_; } | |
146 | ||
147 | private: | |
148 | ||
149 | // Maps integers to sections. | |
150 | std::vector<Section_id> id_section_; | |
151 | // Does the reverse. | |
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 | |
155 | // not folded. | |
156 | std::vector<unsigned int> kept_section_id_; | |
21bb3914 ST |
157 | // Given a section id, this says if the pointer to this |
158 | // function is taken in which case it is dangerous to fold | |
159 | // this function. | |
160 | Secn_fptr_taken_set fptr_section_id_; | |
ef15dade ST |
161 | unsigned int* num_tracked_relocs; |
162 | // Flag to indicate if ICF has been run. | |
163 | bool icf_ready_; | |
164 | ||
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_; | |
169 | }; | |
170 | ||
55a2bb35 ST |
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. | |
175 | inline bool | |
176 | is_section_foldable_candidate(const char* section_name) | |
177 | { | |
178 | return (is_prefix_of(".text", section_name) | |
179 | || is_prefix_of(".gnu.linkonce.t", section_name)); | |
180 | } | |
181 | ||
ef15dade ST |
182 | } // End of namespace gold. |
183 | ||
184 | #endif |