1 | /* Communication between registering jump thread requests and |
2 | updating the SSA/CFG for jump threading. |
3 | Copyright (C) 2013-2023 Free Software Foundation, Inc. |
4 | |
5 | This file is part of GCC. |
6 | |
7 | GCC is free software; you can redistribute it and/or modify |
8 | it under the terms of the GNU General Public License as published by |
9 | the Free Software Foundation; either version 3, or (at your option) |
10 | any later version. |
11 | |
12 | GCC is distributed in the hope that it will be useful, |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
15 | GNU General Public License for more details. |
16 | |
17 | You should have received a copy of the GNU General Public License |
18 | along with GCC; see the file COPYING3. If not see |
19 | <http://www.gnu.org/licenses/>. */ |
20 | |
21 | #ifndef _TREE_SSA_THREADUPDATE_H |
22 | #define _TREE_SSA_THREADUPDATE_H 1 |
23 | |
24 | enum jump_thread_edge_type |
25 | { |
26 | EDGE_START_JUMP_THREAD, |
27 | EDGE_COPY_SRC_BLOCK, |
28 | EDGE_COPY_SRC_JOINER_BLOCK, |
29 | EDGE_NO_COPY_SRC_BLOCK |
30 | }; |
31 | |
32 | // We keep the registered jump threading opportunities in this |
33 | // vector as edge pairs (original_edge, target_edge). |
34 | |
35 | class jump_thread_edge |
36 | { |
37 | public: |
38 | jump_thread_edge (edge e, jump_thread_edge_type t) : e (e), type (t) {} |
39 | |
40 | edge e; |
41 | jump_thread_edge_type type; |
42 | }; |
43 | |
44 | class jump_thread_path_allocator |
45 | { |
46 | public: |
47 | jump_thread_path_allocator (); |
48 | ~jump_thread_path_allocator (); |
49 | jump_thread_edge *allocate_thread_edge (edge, jump_thread_edge_type); |
50 | vec<jump_thread_edge *> *allocate_thread_path (); |
51 | private: |
52 | DISABLE_COPY_AND_ASSIGN (jump_thread_path_allocator); |
53 | obstack m_obstack; |
54 | }; |
55 | |
56 | // Abstract class for the jump thread registry. |
57 | // |
58 | // When all candidates have been registered with |
59 | // register_jump_thread(), thread_through_all_blocks() is called to |
60 | // update the CFG. |
61 | |
62 | class jt_path_registry |
63 | { |
64 | public: |
65 | jt_path_registry (bool backedge_threads); |
66 | virtual ~jt_path_registry (); |
67 | bool register_jump_thread (vec<jump_thread_edge *> *); |
68 | bool thread_through_all_blocks (bool ); |
69 | void push_edge (vec<jump_thread_edge *> *path, edge, jump_thread_edge_type); |
70 | vec<jump_thread_edge *> *allocate_thread_path (); |
71 | void debug (); |
72 | protected: |
73 | void debug_path (FILE *, int pathno); |
74 | vec<vec<jump_thread_edge *> *> m_paths; |
75 | unsigned long m_num_threaded_edges; |
76 | private: |
77 | virtual bool update_cfg (bool ) = 0; |
78 | bool cancel_invalid_paths (vec<jump_thread_edge *> &path); |
79 | jump_thread_path_allocator m_allocator; |
80 | // True if threading through back edges is allowed. This is only |
81 | // allowed in the generic copier in the backward threader. |
82 | bool m_backedge_threads; |
83 | DISABLE_COPY_AND_ASSIGN (jt_path_registry); |
84 | }; |
85 | |
86 | // Forward threader path registry using a custom BB copier. |
87 | |
88 | class fwd_jt_path_registry : public jt_path_registry |
89 | { |
90 | public: |
91 | fwd_jt_path_registry (); |
92 | ~fwd_jt_path_registry (); |
93 | void remove_jump_threads_including (edge); |
94 | private: |
95 | bool update_cfg (bool ) override; |
96 | void mark_threaded_blocks (bitmap threaded_blocks); |
97 | bool thread_block_1 (basic_block, bool noloop_only, bool joiners); |
98 | bool thread_block (basic_block, bool noloop_only); |
99 | bool (class loop *loop, |
100 | bool ); |
101 | class redirection_data *lookup_redirection_data (edge e, enum insert_option); |
102 | |
103 | hash_table<struct removed_edges> *m_removed_edges; |
104 | |
105 | // Main data structure to hold information for duplicates of BB. |
106 | hash_table<redirection_data> *m_redirection_data; |
107 | }; |
108 | |
109 | // Backward threader path registry using a generic BB copier. |
110 | |
111 | class back_jt_path_registry : public jt_path_registry |
112 | { |
113 | public: |
114 | back_jt_path_registry (); |
115 | private: |
116 | bool update_cfg (bool ) override; |
117 | void adjust_paths_after_duplication (unsigned curr_path_num); |
118 | bool duplicate_thread_path (edge entry, edge exit, basic_block *region, |
119 | unsigned n_region, unsigned current_path_no); |
120 | bool rewire_first_differing_edge (unsigned path_num, unsigned edge_num); |
121 | }; |
122 | |
123 | // Rather than search all the edges in jump thread paths each time DOM |
124 | // is able to simply if control statement, we build a hash table with |
125 | // the deleted edges. We only care about the address of the edge, not |
126 | // its contents. |
127 | struct removed_edges : nofree_ptr_hash<edge_def> |
128 | { |
129 | static hashval_t hash (edge e) { return htab_hash_pointer (e); } |
130 | static bool equal (edge e1, edge e2) { return e1 == e2; } |
131 | }; |
132 | |
133 | extern unsigned int estimate_threading_killed_stmts (basic_block); |
134 | |
135 | enum bb_dom_status |
136 | { |
137 | /* BB does not dominate latch of the LOOP. */ |
138 | DOMST_NONDOMINATING, |
139 | /* The LOOP is broken (there is no path from the header to its latch. */ |
140 | DOMST_LOOP_BROKEN, |
141 | /* BB dominates the latch of the LOOP. */ |
142 | DOMST_DOMINATING |
143 | }; |
144 | |
145 | enum bb_dom_status determine_bb_domination_status (class loop *, basic_block); |
146 | |
147 | // In tree-ssa-dom.cc. |
148 | extern void free_dom_edge_info (edge); |
149 | |
150 | #endif |
151 | |