Annotation of src/external/gpl3/binutils.old/dist/gold/icf.h, Revision 1.1.1.3
1.1 christos 1: // icf.h -- Identical Code Folding
2:
1.1.1.3 ! christos 3: // Copyright (C) 2009-2016 Free Software Foundation, Inc.
1.1 christos 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"
30: #include "object.h"
31:
32: namespace gold
33: {
34:
35: class Object;
36: class Input_objects;
37: class Symbol_table;
38:
39: class Icf
40: {
41: public:
42: typedef std::vector<Section_id> Sections_reachable_info;
43: typedef std::vector<Symbol*> Symbol_info;
44: typedef std::vector<std::pair<long long, long long> > Addend_info;
45: typedef std::vector<uint64_t> Offset_info;
46: typedef std::vector<unsigned int> Reloc_addend_size_info;
47: typedef Unordered_map<Section_id,
48: unsigned int,
49: Section_id_hash> Uniq_secn_id_map;
50: typedef Unordered_set<Section_id, Section_id_hash> Secn_fptr_taken_set;
51:
52: typedef struct
53: {
54: // This stores the section corresponding to the reloc.
55: Sections_reachable_info section_info;
56: // This stores the symbol corresponding to the reloc.
57: Symbol_info symbol_info;
58: // This stores the symbol value and the addend for a reloc.
59: Addend_info addend_info;
60: Offset_info offset_info;
61: Reloc_addend_size_info reloc_addend_size_info;
62: } Reloc_info;
63:
64: typedef Unordered_map<Section_id, Reloc_info,
65: Section_id_hash> Reloc_info_list;
66:
67: Icf()
68: : id_section_(), section_id_(), kept_section_id_(),
69: fptr_section_id_(),
1.1.1.2 christos 70: icf_ready_(false),
1.1 christos 71: reloc_info_list_()
72: { }
73:
74: // Returns the kept folded identical section corresponding to
75: // dup_obj and dup_shndx.
76: Section_id
1.1.1.2 christos 77: get_folded_section(Relobj* dup_obj, unsigned int dup_shndx);
1.1 christos 78:
79: // Forms groups of identical sections where the first member
80: // of each group is the kept section during folding.
81: void
82: find_identical_sections(const Input_objects* input_objects,
83: Symbol_table* symtab);
84:
85: // This is set when ICF has been run and the groups of
86: // identical sections have been formed.
87: void
88: icf_ready()
89: { this->icf_ready_ = true; }
90:
91: // Returns true if ICF has been run.
92: bool
93: is_icf_ready()
94: { return this->icf_ready_; }
95:
96: // Unfolds the section denoted by OBJ and SHNDX if folded.
97: void
1.1.1.2 christos 98: unfold_section(Relobj* obj, unsigned int shndx);
1.1 christos 99:
1.1.1.2 christos 100: // Returns the kept section corresponding to the
1.1 christos 101: // given section.
102: bool
1.1.1.2 christos 103: is_section_folded(Relobj* obj, unsigned int shndx);
1.1 christos 104:
105: // Given an object and a section index, this returns true if the
106: // pointer of the function defined in this section is taken.
107: bool
1.1.1.2 christos 108: section_has_function_pointers(Relobj* obj, unsigned int shndx)
1.1 christos 109: {
110: return (this->fptr_section_id_.find(Section_id(obj, shndx))
111: != this->fptr_section_id_.end());
112: }
113:
114: // Records that a pointer of the function defined in this section
115: // is taken.
116: void
1.1.1.2 christos 117: set_section_has_function_pointers(Relobj* obj, unsigned int shndx)
1.1 christos 118: {
119: this->fptr_section_id_.insert(Section_id(obj, shndx));
120: }
121:
122: // Checks if the section_name should be searched for relocs
123: // corresponding to taken function pointers. Ignores eh_frame
124: // and vtable sections.
125: inline bool
126: check_section_for_function_pointers(const std::string& section_name,
127: Target* target)
128: {
129: return (parameters->options().icf_safe_folding()
130: && target->can_check_for_function_pointers()
131: && target->section_may_have_icf_unsafe_pointers(
132: section_name.c_str()));
133: }
134:
135: // Returns a map of a section to info (Reloc_info) about its relocations.
136: Reloc_info_list&
137: reloc_info_list()
138: { return this->reloc_info_list_; }
1.1.1.2 christos 139:
1.1 christos 140: // Returns a mapping of each section to a unique integer.
141: Uniq_secn_id_map&
142: section_to_int_map()
143: { return this->section_id_; }
144:
145: private:
146:
147: // Maps integers to sections.
148: std::vector<Section_id> id_section_;
149: // Does the reverse.
150: Uniq_secn_id_map section_id_;
151: // Given a section id, this maps it to the id of the kept
152: // section. If the id's are the same then this section is
153: // not folded.
154: std::vector<unsigned int> kept_section_id_;
155: // Given a section id, this says if the pointer to this
156: // function is taken in which case it is dangerous to fold
157: // this function.
158: Secn_fptr_taken_set fptr_section_id_;
159: // Flag to indicate if ICF has been run.
160: bool icf_ready_;
161: // This list is populated by gc_process_relocs in gc.h.
162: Reloc_info_list reloc_info_list_;
163: };
164:
165: // This function returns true if this section corresponds to a function that
166: // should be considered by icf as a possible candidate for folding. Some
167: // earlier gcc versions, like 4.0.3, put constructors and destructors in
168: // .gnu.linkonce.t sections and hence should be included too.
169: inline bool
170: is_section_foldable_candidate(const std::string& section_name)
171: {
172: const char* section_name_cstr = section_name.c_str();
173: return (is_prefix_of(".text", section_name_cstr)
174: || is_prefix_of(".gnu.linkonce.t", section_name_cstr));
175: }
176:
177: } // End of namespace gold.
178:
179: #endif
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