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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: | |
b487ad64 | 42 | typedef std::vector<Section_id> Sections_reachable_info; |
ef15dade ST |
43 | typedef std::vector<Symbol*> Symbol_info; |
44 | typedef std::vector<std::pair<long long, long long> > Addend_info; | |
b487ad64 | 45 | typedef std::vector<uint64_t> Offset_info; |
ef15dade ST |
46 | typedef Unordered_map<Section_id, |
47 | unsigned int, | |
48 | Section_id_hash> Uniq_secn_id_map; | |
21bb3914 | 49 | typedef Unordered_set<Section_id, Section_id_hash> Secn_fptr_taken_set; |
ef15dade | 50 | |
b487ad64 ST |
51 | typedef struct |
52 | { | |
53 | // This stores the section corresponding to the reloc. | |
54 | Sections_reachable_info section_info; | |
55 | // This stores the symbol corresponding to the reloc. | |
56 | Symbol_info symbol_info; | |
57 | // This stores the symbol value and the addend for a reloc. | |
58 | Addend_info addend_info; | |
59 | Offset_info offset_info; | |
60 | } Reloc_info; | |
61 | ||
62 | typedef Unordered_map<Section_id, Reloc_info, | |
63 | Section_id_hash> Reloc_info_list; | |
64 | ||
ef15dade ST |
65 | Icf() |
66 | : id_section_(), section_id_(), kept_section_id_(), | |
21bb3914 | 67 | fptr_section_id_(), |
ef15dade | 68 | num_tracked_relocs(NULL), icf_ready_(false), |
b487ad64 | 69 | reloc_info_list_() |
ef15dade ST |
70 | { } |
71 | ||
72 | // Returns the kept folded identical section corresponding to | |
73 | // dup_obj and dup_shndx. | |
74 | Section_id | |
75 | get_folded_section(Object* dup_obj, unsigned int dup_shndx); | |
76 | ||
77 | // Forms groups of identical sections where the first member | |
78 | // of each group is the kept section during folding. | |
79 | void | |
80 | find_identical_sections(const Input_objects* input_objects, | |
81 | Symbol_table* symtab); | |
82 | ||
83 | // This is set when ICF has been run and the groups of | |
84 | // identical sections have been formed. | |
85 | void | |
86 | icf_ready() | |
87 | { this->icf_ready_ = true; } | |
88 | ||
89 | // Returns true if ICF has been run. | |
90 | bool | |
91 | is_icf_ready() | |
92 | { return this->icf_ready_; } | |
93 | ||
48c187ce ST |
94 | // Unfolds the section denoted by OBJ and SHNDX if folded. |
95 | void | |
96 | unfold_section(Object* obj, unsigned int shndx); | |
97 | ||
ef15dade ST |
98 | // Returns the kept section corresponding to the |
99 | // given section. | |
100 | bool | |
101 | is_section_folded(Object* obj, unsigned int shndx); | |
21bb3914 ST |
102 | |
103 | // Given an object and a section index, this returns true if the | |
104 | // pointer of the function defined in this section is taken. | |
105 | bool | |
106 | section_has_function_pointers(Object *obj, unsigned int shndx) | |
107 | { | |
108 | return (this->fptr_section_id_.find(Section_id(obj, shndx)) | |
109 | != this->fptr_section_id_.end()); | |
110 | } | |
111 | ||
112 | // Records that a pointer of the function defined in this section | |
113 | // is taken. | |
114 | void | |
115 | set_section_has_function_pointers(Object *obj, unsigned int shndx) | |
116 | { | |
117 | this->fptr_section_id_.insert(Section_id(obj, shndx)); | |
118 | } | |
119 | ||
120 | // Checks if the section_name should be searched for relocs | |
121 | // corresponding to taken function pointers. Ignores eh_frame | |
122 | // and vtable sections. | |
123 | inline bool | |
8a75a161 | 124 | check_section_for_function_pointers(const std::string& section_name, |
21bb3914 ST |
125 | Target* target) |
126 | { | |
127 | return (parameters->options().icf_safe_folding() | |
128 | && target->can_check_for_function_pointers() | |
8a75a161 DK |
129 | && target->section_may_have_icf_unsafe_pointers( |
130 | section_name.c_str())); | |
21bb3914 ST |
131 | } |
132 | ||
b487ad64 ST |
133 | // Returns a map of a section to info (Reloc_info) about its relocations. |
134 | Reloc_info_list& | |
135 | reloc_info_list() | |
136 | { return this->reloc_info_list_; } | |
ef15dade ST |
137 | |
138 | // Returns a mapping of each section to a unique integer. | |
139 | Uniq_secn_id_map& | |
140 | section_to_int_map() | |
141 | { return this->section_id_; } | |
142 | ||
143 | private: | |
144 | ||
145 | // Maps integers to sections. | |
146 | std::vector<Section_id> id_section_; | |
147 | // Does the reverse. | |
148 | Uniq_secn_id_map section_id_; | |
149 | // Given a section id, this maps it to the id of the kept | |
150 | // section. If the id's are the same then this section is | |
151 | // not folded. | |
152 | std::vector<unsigned int> kept_section_id_; | |
21bb3914 ST |
153 | // Given a section id, this says if the pointer to this |
154 | // function is taken in which case it is dangerous to fold | |
155 | // this function. | |
156 | Secn_fptr_taken_set fptr_section_id_; | |
ef15dade ST |
157 | unsigned int* num_tracked_relocs; |
158 | // Flag to indicate if ICF has been run. | |
159 | bool icf_ready_; | |
b487ad64 ST |
160 | // This list is populated by gc_process_relocs in gc.h. |
161 | Reloc_info_list reloc_info_list_; | |
ef15dade ST |
162 | }; |
163 | ||
55a2bb35 ST |
164 | // This function returns true if this section corresponds to a function that |
165 | // should be considered by icf as a possible candidate for folding. Some | |
166 | // earlier gcc versions, like 4.0.3, put constructors and destructors in | |
167 | // .gnu.linkonce.t sections and hence should be included too. | |
168 | inline bool | |
169 | is_section_foldable_candidate(const char* section_name) | |
170 | { | |
171 | return (is_prefix_of(".text", section_name) | |
172 | || is_prefix_of(".gnu.linkonce.t", section_name)); | |
173 | } | |
174 | ||
ef15dade ST |
175 | } // End of namespace gold. |
176 | ||
177 | #endif |